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  1. Stefan,

    I am wondering, during your stakeholder workshop, if there was discussion about how to handle the inevitable issue of property loss and evacuation. Preceding actual property loss, we should expect insurance rates to rise and become unaffordable (as with earthquake insurance in California), and at some point down the road, property values will plunge, since no one will want to buy a house that will be wiped out by rising seas.

    I am wondering how local property owners are looking at this issue? I am also trying to get a handle on what kind of timeline the public reaction will play out on? Will property values degrade 1 year, 10 years, 100 years before the property loss? How will public planning plan for and manage risk?

    This is different from earthquakes in California, where people build, knowing that it is a gamble. In NC, people built, not knowing about climate change and sea level rise. As the knowledge becomes commonplace, and property losses assured, how does the property owner handle the loss? As with the tobacco industry, do Big Oil/Coal and the carbon emitting industries get taken to court by the effected states and a “Master Settlement Agreement” – similar to what happened in the states versus Big Tobacco – get implemented to compensate for loss?

    Comment by jaykimball — 24 Jun 2012 @ 1:11 PM

  2. “How will public planning plan for and manage risk?”

    Planning? PLANNING??

    Where do you think you are, North Korea?!

    Comment by Sufferin' Succotash — 24 Jun 2012 @ 2:32 PM

  3. > banks are naturally moving landward

    That’s what I recall from Pilkey’s book “The Beaches Are Moving” — someone else in an earlier thread recently said they’re migrating seaward. Is that being argued?

    [Response:See paper linked with that statement, Stefan ]

    Comment by Hank Roberts — 24 Jun 2012 @ 2:32 PM

  4. Further to Jay’s remarks about insurance there are some problems with the way insurance firms in the US are dealing with climate change. These problems have to do with liability for damages caused by climate change induced by polluters. In order to make a consistent and robust case for not bearing responsibility for customer damage liabilities insurance firms have to stopper their ears to other facts.

    It seems likely this cognitive dissonance in the insurance community will cause increasing tensions, particularly when it comes to reinsurance.

    See article here for explanations.

    Comment by dbostrom — 24 Jun 2012 @ 2:47 PM

  5. Far out.


    Comment by David B. Benson — 24 Jun 2012 @ 5:02 PM

  6. Stefan:

    Thank you, thank you, for the pictures! I think you guys should do this more often.


    Comment by Steve Fish — 24 Jun 2012 @ 5:09 PM

  7. Interesting! We’re heading off to the outer banks for a family vacation in a couple of weeks. I plan to teach the kids a little about sea level rise while we’re there, so this is very timely. We plan to visit the breach at Hatteras that hurricane Irene cut last summer. The daily mail has some great photos:
    (probably the only time I’ll ever link approvingly to the Mail).

    So what else should we look out for while we’re there? Are there opportunities for educating tourists (and residents) about sea level rise with some hands on fieldwork?

    Comment by Steve Easterbrook — 24 Jun 2012 @ 5:18 PM

  8. Local councils in Victoria Australia were complaining that the 80cm SLR restrictions by 2100 was hampering development, The Victorian Parliament solved the problem by redefining SLR to 20cm by 2040 for development application compliance. Now those same councils are demanding indemnity from future liability associated with SLR.

    Not only in NC


    Comment by john byatt — 24 Jun 2012 @ 5:34 PM

  9. I foot per 20 years does not seem scary. Is a that linear increase, or exponential?

    Comment by KevinM — 24 Jun 2012 @ 5:55 PM

  10. > Now those same councils are demanding indemnity

    “… reminds me of the man who murdered both his parents, and then when sentence was about to be pronounced pleaded for mercy on the grounds that he was an orphan” — A. Lincoln

    Comment by Hank Roberts — 24 Jun 2012 @ 6:17 PM

  11. RCP 4.5? Optimist.

    Comment by Steve Bloom — 24 Jun 2012 @ 7:10 PM

  12. 1 foot per 20 years does not seem scary. Is a that linear increase, or exponential?

    When your house is underwater does it matter what the graph looked like?

    Things below +10ft in New York, New York w/”only” 5′ increase in sea level:

    Population 232,589
    Homes 100,970


    Comment by dbostrom — 24 Jun 2012 @ 7:48 PM

  13. > does not seem scary

    It’s not the longterm average that floods you.

    Look at the slope in those pictures, or look up a topo map.
    A foot vertical is much more horizontal.

    A hurricane’s onshore winds push water into the Sound (behind the Banks) through channels and sometimes overland.

    After the eye of the storm passes, the wind direction reverses and begins pushing that water, plus whatever rainfall is coming down the rivers, back out through the “inlet” channels (including newly cut ones) toward the ocean.

    Take a look:


    Storm surge adds to or subtracts from the tidal variation, depending on the timing. A large surge that comes inland may be held there by a subsequent high tide, for example, before pushing back out.

    Back before property boundaries and overcrowding, during really high water, houses floated between the sea-side and Sound-side dunes, and wherever they ended up, people put them back on new foundations and there they stayed.

    (I spent quite a few childhood summers at Beaufort, as a faculty brat around Duke’s Marine Lab, long ago)

    Comment by Hank Roberts — 24 Jun 2012 @ 7:49 PM

  14. Aside: when looking at the satellite imagery, you’ll notice another interesting feature in the area, one answer to “hey, what else could go wrong?”

    Comment by Hank Roberts — 24 Jun 2012 @ 7:54 PM

  15. Steve Easterbrook @7 — Check out the Cape Hatteras light. Regarding SLR, inspect the base of the tower.

    Comment by David B. Benson — 24 Jun 2012 @ 8:11 PM

  16. Actually I suppose it would be better to use North Carolina as an example of what “just” 5′ of change does.

    North Carolina.

    Note the distribution of years. No wonder developers are nervous about this.

    Comment by dbostrom — 24 Jun 2012 @ 8:17 PM

  17. Insurers will want to protect themselves by making sure that the real estate industry is identified for permitting and/or encouraging people to place their homes in harm’s way. And it’s hard not to wonder how the real estate industry lobbied as North Carolina’s legislators worked up their preposterous law.

    Comment by Lance Olsen — 24 Jun 2012 @ 9:19 PM

  18. Hank Roberts (#3) mentions Orrin Pilkey’s book “The Beaches Are Moving”, which provides an opportunity to plug the Pilkey’s (father & son) “Global Climate Change: A Primer”. Beautifully written, illustrated and produced, it makes a great gift for those ‘unconvinced’ among your friends or family. And a good resource for the rest of us.

    Comment by Pat Cassen — 24 Jun 2012 @ 9:39 PM

  19. The Climate Central maps above refer to the combined effects of surge and sea level change. This video from today shows what planners will increasingly face and why it’s sheer folly to pretend that everything’s going to be ok for coastal development.

    The scenes from that video, happening more often and with more severity. It’s not complicated but if you’re a coastal developer acknowledging the problem is an existential threat, too early.

    Comment by dbostrom — 24 Jun 2012 @ 10:43 PM

  20. More Stefan and Crew in the Guardian: Scientists warn US east coast over accelerated sea level rise

    Comment by dbostrom — 24 Jun 2012 @ 11:27 PM

  21. This is a very good finding that will enable the American government to come to reality that climate change is real and no matter wherever you are , the wrath of the catastrophe will get you.
    Its time now you accelerated funding to our southern NGOs to reduce the global warming as we go green and plant trees to avert the rate of climate change.

    Edward Paul MUnaaba
    Executive Director
    Africa Partnership on Climate Change Coalition

    Comment by EDWARD PAUL MUNAABA — 25 Jun 2012 @ 12:34 AM

  22. I’ve just found Arctic regions much more vulnerable to change than thought.

    Is it relevant to this thread?

    Comment by Geoff Beacon — 25 Jun 2012 @ 3:43 AM

  23. It would be (very) interesting to know whether a salt marsh can accumulate at greater than a millimetre a year. Are there any examples where the subsidence rate is faster, but a marsh is still keeping pace?

    Comment by ozajh — 25 Jun 2012 @ 4:12 AM

  24. “Planning? PLANNING??

    Where do you think you are, North Korea?!”

    If Freddie and Fannie stopped taking loans without flood (and everything else) coverage, then the market would lead the way, methinks.

    As the world’s wealthy increase in numbers while coastlines decline, it could evolve into a sort of rental mentality which still supports high prices. Like a 20 year lease. Climate science improves, the insurance industry will listen, and folks will pretty much know how their insurance premiums will rise decades in advance. Just one of the many costs of living large.

    And don’t forget the winners. Pick some land with the proper slope and elevation and you could have some pretty stable shoreline in a hundred years. And with all that shallow water in front of you, hurricanes are less of an issue. Nice gift for the grandchildren’s grandchildren.

    Comment by Jim Larsen — 25 Jun 2012 @ 4:35 AM

  25. It’s probably worth reminding the governments of North Carolina, Virginia and Victoria (and any other states named for English monarchs) that commanding the tides didn’t work last time an English monarch tried it:

    (but at least he didn’t even pretend to think it’d make any difference).

    Comment by Ed Davies — 25 Jun 2012 @ 5:45 AM

  26. Although the geology is a little different to North Carolina’s, sections of the East Anglian coast face similar problems.
    The rate at which this is occuring is not thought to have changed signficantly in at least 2,000 years – about a metre per year.
    But extreme weather events can lead to serious damage virtually overnight, as happened at Dunwich.
    Once an important commercial port, the harbour and 400 homes were swept into the sea during storms in the 13th-14th centuries, reducing it to a small village.

    Rising sea levels and more energetic waves seem to be making the problems of coastal erosion worse.
    Two of the most obvious locations where this is happening are at Happisburgh in Norfolk (pronounced “Hazeburrer” by locals) and near to Southwold in Suffolk.
    At both places, houses near to the clifftops are in danger of falling into the sea

    A survey done at Happisburgh between 2001-6 using LiDar, found that there were two main causes:-

    1- Wintertime erosion caused by groundwater, coupled with increased seasonal storminess, causing small-scale, frequent, shallow landsliding of the soft sandstone cliffs.
    2- Summertime Wave, accompanied by landsliding.

    See this video clip for the effect on the population:-
    “Living with coastal erosion in Happisburgh, East Anglia” Duration: 3:03

    Near Southwold, Peter Boggis, the “King Cnut of East Anglia” has decided to take matters into his own hands.
    For nearly a decade, the retired engineer has been building an earth bank at the base of the natural cliff to provide an extra barrier against the North Sea.
    So far he’s deposited at least 250,000 tonnes of compacted clay soil from building sites at the base of the cliff.
    The last time I looked, his house was still there, but I get the feeling that he’s fighting a losing battle.

    Comment by prianikoff — 25 Jun 2012 @ 5:45 AM

  27. priankoff: But extreme weather events can lead to serious damage virtually overnight, as happened at Dunwich.

    If it’s the town I’m thinking of Dunwich was also a good example of our short chronological perspective and rapid growth on unstable coastlines. The town and port were developed relatively quickly in a location that with a longer perspective would have been plainly wrong.

    Now we have that perspective but it’s an open question if we’ll use it.

    Comment by dbostrom — 25 Jun 2012 @ 10:11 AM

  28. On the position of insurers, you need to remember that the industry writes property coverage a year at a time. What will happen 20 years from now is, by definition, irrelevant to what the carrier should charge for risk in 2012.

    Nor will a reinsurer/insurer conflict actually happen. If reinsurers fundamentally change their view of property risk (meaning they raise rates or restrict the availability of coverage) the resulting constriction of supply will force up rates. That is, the relationship between reinsurers and insurers is self-regulating and will find stability.

    Comment by garhighway — 25 Jun 2012 @ 12:10 PM

  29. Aaaah, the old “We don’t believe you because we were heading into an Ice Age in the 1970’s, and well, anyway Daddy PROMISED ME that we wuz’uh just gonna make like, ‘It’s gonna be da 1950’s 4-EVER!”, type scenario,’ eh what, Old Chaps, Komrades, Fellow Global Conspirators for Imposition of Common Sense upon the “Seething Masses (of Stoopidity)”?
    It is indeed a fact that, in my Oceanography Classes, in the early ’80’s, it was indeed assumed that the Milancovich Cycles were pointing us towaards another Ice Age….though, in my view,that’s simply all the more reason to be worried about Global Warming; as it IS occuring, and IF we were headed ‘into another Ice Age’, but ‘things are getting warmer, and the Planets Ice Sheets and Glaciers, EVERYWHERE, are ALL MELTING instead’, then that probably means that Global Warming is not just “Real”, it’s “So Freaking R-E-A-L!!!!” that it’s REVERSED THE ‘HEADED FOR ANOTHER ICE AGE’ OVERALL TENDENCY OF THE GLOBAL CLIMATE!!!!
    We Could Fix This, NC-20s’ o’ da wurld – We, The People, you see; It’s JUST the kind of Commie-wealth, Pinkobama Political Philosophy that the “Peoples Republic” of America needs!
    Why, in 2005 “The Peoples Republics” of China and The Untied State of America were both tied at about 500 Mwh of PV Panel production per annum; by 2001, “The Peoples Republic” of China was making 11,000 Mwh, and “The ‘We, The Peoples’ Republic of The United States of America” was making 650 Mwh!
    But, Oooooh NOOOO, Dr. Chu shouldn’t have given any money to SOLYNDRA, should he have?
    No, he should have wasted it on generating some Realpolitik that doesn’t SCARE THEM – just like NC-20 has wasted it’s ‘members’ donations and dues!

    Comment by James Staples — 25 Jun 2012 @ 1:32 PM

  30. > weakening of the Atlantic overturning circulation

    I’m confused. This was a hot topic back in 2005, but starting around 2007-2011 there was a constant buzz that no, in fact the circulation is not slowing. Google for links, I think NASA used satellites to confirm there was no slowdown, indeed a slight speed up. Very confusing.

    Comment by John — 25 Jun 2012 @ 2:09 PM

  31. “Of course, global sea-level rise has already accelerated in the course of global warming…”

    Has accelerated in the past, yes, but does not show any sign of accelerating at present (i.e. over the last 20 years).

    Their sea-level data from 1993-present show an average rising trend of +3.14mm/yr and deceleration of -0.057mm/yr^2
    (Data available at

    And, no, I didn’t cherry-pick a start date… I’ve used all the data they report.

    Comment by Russ R. — 25 Jun 2012 @ 3:01 PM

  32. Perhaps, IMO, the most drastic aspect of Global Warming is the increasing acidification of the ocean, which is almost always omitted from discussions related to the ocean and sealevel rise. My question: Is there any evidence found witin core samples of past increasing ocean acidification in connection to past Global Warming events? It seems all the focus is on what’s going to happen ashore, with little thought given to what a plankton dieoff will cause.

    Comment by Karlof1 — 25 Jun 2012 @ 4:11 PM

  33. Expected sea level rise is based on models that have dramatically understated loss of Arctic sea ice in the last few years, and explicitly do not include ice dynamics.

    When the Arctic sea ice has melted, the heat fluxes that had gone into melting sea ice will go into melting the GIS. In addition, feedbacks from an ice free sea surface will supply additional heat to the Arctic environment, and the Greenland Ice Sheet will melt rapidly, and big blocks of ice will slide into the sea without melting.

    I do not see Climate Science offering a prudent and rational estimate of expected sea level rise. The scenarios offered by Climate Science are comforting stories for children. The above is looking back at a period of stable climate. It says nothing useful about how sea level will change when the GIS is the primary heat sink in the Arctic. However, given these season’s melt, that may be sooner rather than later.

    We cannot use past sea level rises as a guide for expected sea level rise because current forcing is greater than past forcing. If current forcing is ten times faster than it was in the past then we have to consider that sea level rise events may be ten times larger than they were in the past. However, climate is a non-linear system so that in fact, a larger forcing may bring a very much larger rate of sea level rise.

    Comment by Aaron Lewis — 25 Jun 2012 @ 4:46 PM


    What’s the reason to think a 19-year span could be likely sufficient to detect a change in rate?

    Comment by Hank Roberts — 25 Jun 2012 @ 5:32 PM

  35. Aaron: I do not see Climate Science offering a prudent and rational estimate of expected sea level rise.

    Presuming that we don’t have a noise problem causing model/observation divergence then models need a plausible means of accounting for the divergence; anything less would be definitively irrational and not science.

    Comment by dbostrom — 25 Jun 2012 @ 8:48 PM

  36. ozajh @23:

    It would be (very) interesting to know whether a salt marsh can accumulate at greater than a millimetre a year.

    Some of the marsh grasses can cope with sediment accumulation of centimetres per year. As an example, Parkgate in the Dee Estuary (UK) was a popular beach resort in the 1930s but by the 1950s the beach had turned into a salt marsh for a considerable distance from the old promenade.

    I gather that in many places, however, there is insufficient sediment arriving for there to be rapid accumulation. Also, the resulting marsh would likely have a very different species composition from the original.

    Does anyone know how house prices are responding at Happisburgh? Those that are on the edge of the cliff are no doubt unsellable but what about houses, say, half a kilometre back from the sea?

    Comment by Richard Simons — 25 Jun 2012 @ 9:06 PM

  37. “And it’s hard not to wonder how the real estate industry lobbied as North Carolina’s legislators worked up their preposterous law.”
    NC House Bill 819 was introduced by Pat McElraft, who lists her occupations as “Technical Sales Representative – Microbiology Products Company and Real Estate Broker”, and she lives on Emerald Isle, an upscale development barrier island – no lobbyists needed.

    jaykimball @ 24 Jun 2012 at 1:11 PM says “Preceding actual property loss, we should expect insurance rates to rise and become unaffordable (as with earthquake insurance in California)…” Don’t worry, Ms. McElrath has introduced more legislation that addresses this problem, HB820

    “SECTION 2. Purpose. – The Commission shall study the following:

    (1) The feasibility and advisability of replacing the North Carolina Insurance Underwriting Association and the North Carolina Joint Underwriting Association with a statewide catastrophic fund which pools the risks to North Carolina policy holders from all types of natural disasters.

    (2) Whether coastal insurance rates on policies ceded to the North Carolina Insurance Underwriting Association, the composition of the Association’s Board of Directors, and the Association’s plan of operations are efficient, economical, fair, and nondiscriminatory in protecting the interests of beach and coastal areas of the State, compared to other coastal states.

    (3) Whether the data and methodologies used by the North Carolina Insurance Underwriting Association in estimating probable maximum loss accurately model insurable risks for property located in the beach and coastal areas of the State.

    (4) The feasibility and advisability of offering coastal and beach area property owners the option of self‑insuring by declining wind and hail coverage in situations where no third party has an insurable interest in the property.

    (5) The adequacy of accounting and oversight of the North Carolina Insurance Underwriting Association’s accumulated surplus.

    (6) Whether the mitigation credits provided by the North Carolina Insurance Underwriting Association pursuant to G.S. 58‑45‑45(e) are fair and nondiscriminatory and whether the schedule of credits, when compared to the cost of mitigation measures provides adequate incentive for beach and coastal area property owners to invest in such measures.”

    Or at least addresses the problem insofar as it adversely affects profitable beach development – for the rest of us in the state who will end up subsidizing pooled insurance for coastal areas at risk, not so much.

    Comment by Brian Dodge — 25 Jun 2012 @ 10:02 PM

  38. Richard Simons @35,

    Thank you for that response. I can see that the amount of sediment entering (or leaving via erosion, for that matter) could easily be a dominant factor.

    However, I was actually wondering how much material can be generated by a marsh itself. If it’s fast enough, one COULD imagine a protective mechanism where a (perhaps porous-but-not-too-porous) retaining wall gets put in at an appropriate level (which may of course be below mean sea level). The marsh would then grow behind this wall, with the top of the wall being raised up at intervals in tune with sea level rise. This would also act as a carbon sink.

    Better not to have the warming and sea level rise occur in the first place, of course.

    Comment by ozajh — 26 Jun 2012 @ 12:24 AM

  39. Great story. We don’t have such interesting field trips in computer science.

    Is the NC state legislature also planning to legislate the value of pi?

    I seem to recall a figure of about 100x the horizontal encroachment vs. sea level rise, e.g., 1m sea level rise means the coastline retreats 100m inland. Obviously at best this is a rule of thumb and would vary highly from place to place, but this does give some indication in general terms of what a given sea level rise implies.

    Comment by Philip Machanick — 26 Jun 2012 @ 2:48 AM

  40. @32 Aaron Lewis: If I read the paper by Schaeffer et al correctly the Copenhagen reference (BAU?) scenario could lead to about 6.5 meters of SLR by 2300, excluding the risk of ‘nonlinear, dynamical responses from the ice sheets’.

    They also say: ‘One of the largest uncertainties at present is the response of the Greenland and Antarctic ice sheets, where process-based models do not capture the full response so far observed, nor the timescales of response seen in the paleorecord.’

    So it seems the authors of the paper largely agree with you. If not, I hope they will comment.

    Comment by Lennart van der Linde — 26 Jun 2012 @ 4:40 AM

  41. Russ,
    Historically, sea level rise has increased during warming periods (compare the rise in the 1925-1945 period with those before and after).

    Sea level has also risen during the cooling periods, just not as much. The increased rate of rise from 1985-2005 is similar in magnitude to the previous period (within measurement uncertainty). Based on the available data, it would be perfectly acceptable to state that sea level rise accelerated in the past 20 years, and you are correct in saying that the sea level rise is currently not continuing to accelerate. Based on historical data and trends, it seems reasonable to conclude that sea level will continue to rise somewhere between 18 and 27 cm by 2100. A return to the lower rate of rise in the late 19th century seems highly unlikey, unless a similar cooling trend commences.

    Comment by Dan H. — 26 Jun 2012 @ 7:12 AM

  42. Lennart van der Linde #40 says

    If I read the paper by Schaeffer et al correctly the Copenhagen reference (BAU?) scenario could lead to about 6.5 meters of SLR by 2300, excluding the risk of ‘nonlinear, dynamical responses from the ice sheets’.

    Eh, where did you get 6.5 meters from? Visually extrapolating a graph? That’s pretty bold, given the uncertainties involved (also discussed in the paper), which increase with both temperature and time elapsed, and which could go in either direction. And decimetric precision?

    …but yes, 6.5 m could happen. As could some other value in a pretty broad range…

    Comment by Martin Vermeer — 26 Jun 2012 @ 7:18 AM

  43. sea level rise is currently not continuing to accelerate.

    Can you tell me how you managed to measure the instantaneous acceleration of sea level rise? Yes, that is a trick question. Thanks in advance.

    Comment by Thomas Lee Elifritz — 26 Jun 2012 @ 8:42 AM

  44. “Can you tell me how you managed to measure the instantaneous acceleration of sea level rise?”

    I didn’t measure the instantaneous acceleration. I measured the average acceleration over the the last 19 years. In case you want to try it yourself, here’s how:

    1. I downloaded the data as text from here:

    2. I copied the text data into an excel spreadsheet and ran the “Text to Columns” functions.

    3. I plotted the data in a scatter chart with the year values on the x-axis and the observed sea-level values on the y-axis.

    4. Finally, I plotted a 2nd order polynomial trend line which showed acceleration (or rather, deceleration) of -0.057 mm/yr^2.

    And so I concluded that over the last 19 years, sea level rise has not accelerated.

    Comment by Russ R. — 26 Jun 2012 @ 9:27 AM

  45. prianikoff (25 Jun 2012 at 5:45 AM) writes:

    Although the geology is a little different to North Carolina’s, sections of the East Anglian coast face similar problems.
    The rate at which this is occuring is not thought to have changed signficantly in at least 2,000 years – about a metre per year.

    Now that would be serious sea level rise. 2000 meters in 2000 years!

    Comment by Ned — 26 Jun 2012 @ 9:37 AM

  46. Question for Stefan

    The Sallenger et al. paper in Nature Climate Change says
    “Mean Northeast Hotspot SLRD (sea level rise differnece) is a factor of 3 to 4 larger than global SLRD. For the 60-yr window, the global SLRD during 1950 to 2009 is 0:59 mm/yr(u sing reconstructed time series ref-14), compared with NEH SLRD of 1:97 mm/yr.” Church and White (2011 – Surveys in Geophysics) say: “We estimate the rise in global average sea level from satellite altimeter data for 1993–2009 and from coastal and island sea-level measurements from 1880 to 2009. For 1993–2009 and after correcting for glacial isostatic adjustment, the estimated rate of rise is 3.2 ± 0.4 mm year-1 from the satellite data and 2.8 ± 0.8 mm year-1 from the in situ data.”

    Can you reconcile these differnt global rates? The global estimates seem pretty far apart, unless I am trying to compare apples and oranges (increases versus rates of increases).

    Comment by Tom — 26 Jun 2012 @ 10:48 AM

  47. Ned @45: I don’t think he was talking about sea level rise…

    Comment by Marco — 26 Jun 2012 @ 11:32 AM

  48. Russ R., why do you believe that data set has enough data points for a trend estimate to be made? Significance is calculated and you didn’t do that yet.
    Grumbine on this is helpful:

    Comment by Hank Roberts — 26 Jun 2012 @ 11:35 AM

  49. And so I concluded that over the last 19 years, sea level rise has not accelerated.

    I was more interested in the concept of instantaneous acceleration. Sorry to be such a jerk.

    Comment by Thomas Lee Elifritz — 26 Jun 2012 @ 11:45 AM

  50. This may be helpful (paywalled, all I see is the abstract; it hasn’t been cited by anyone yet).
    Advances in Space Research
    Volume 47, Issue 7, 1 April 2011, Pages 1248–1255

    Minimum time span of TOPEX/Poseidon, Jason-1 and Jason-2 global altimeter data to detect a significant trend and acceleration in sealevel change

    “The present study aims to estimate a minimum time span of the global mean sea level time series (from TOPEX/Poseidon, Jason-1 and Jason-2 satellite altimetry) which is sufficient to detect a statistically meaningful trend in global sea level variation. In addition, the objective of this paper is also to seek a minimum time span required to detect a significant acceleration in sea level change.

    Detecting a trend is based upon the Cox–Stuart statistical test. In order to make the analysis representative a stepwise procedure is proposed…. Detecting an acceleration is based on the same procedure, however, applied to the differenced global mean sea level time series.

    We infer that the trend in the global mean sea level time series (January 1993–April 2010) corrected for the global isostatic adjustment can be detected for all significance levels from the set S with the probability close to 1 after 110 satellite cycles (approximately 2.99 years). The corresponding estimate based on the data without correcting for the global isostatic adjustment is equal to 114 satellite cycles (approximately 3.09 years). Over the majority of the study period it is impossible to detect any acceleration in sea level rise. However, for the time spans of approximately 400 and 500 satellite cycles an acceleration may be detected with probability of approximately 0.4. These specific time spans correspond to the periods with reduced rates of sea level change.”

    [Response:Statistical significance of a trend or acceleration calculation, given the noise in the data, is obviously one minimum condition for interpreting these numbers. More interesting though is the question on what time scale you might see a physically meaningful acceleration due to global warming (rather than e.g. the effects natural decadal variability that is unrelated to global warming). Based on our analysis (see Rahmstorf et al., Climate Dynamics 2011) the altimeter data set is clearly too short to give any meaningful acceleration in this sense. stefan

    Comment by Hank Roberts — 26 Jun 2012 @ 12:05 PM

  51. @42 Martin Vermeer: The 6,5 meters SLR in 2300 in the CPH reference scenario I extrapolated from this table in your paper:

    My reasoning was: max 139 cm of SLR in 2100 + max rate of SLR of 26 mm/yr in 2100 ‘could’ mean about 6,5 meters by 2300, if that rate of SLR would continue for two centuries.

    I admit that the table does not give all the information needed to make this extrapolation, and for lower scenarios the rate of SLR declines significantly after 2100, so that’s why I asked if I understood correctly. So the question is if and how fast the rate of SLR declines after 2100 in the CPH reference scenario. Do your modelling results give an answer to that question? And did you also model even higher scenarios than CPH reference? If so, what were the results for those?

    Comment by Lennart van der Linde — 26 Jun 2012 @ 12:55 PM

  52. I live hear the Virginia and North Carolina shores; public concern about sea level rise is small compared to concerns about hurricanes. Their impact is much more immediate. It is harder to tie hurricanes to global warming then SLR, even though hurricane damage is affected by sea level and ocean temperature. Still, the way to affect public policy is through scares of hurricanes, rather then SLR directly.

    Most hurricane damage along the shore is by water, as opposed to wind. Private insurance companies insure against wind damage only, and insurance rates have increased about 300% in the past decade along the shore. Flood insurance, granted by the Federal Government, has not increased nearly as much.

    For almost 50 years Federal flood insurance has been attacked as one of the stupidest Federal handouts, since it encouranges building in flood prone areas. Without it, public conern about global warming would probably be greater.

    Right-wingers who contest the idea of SLR are typically opposed to federal programs. As far as I know they have not attacked Federal flood insurance. This inconsistency could be used to question their credibility.

    Comment by T. Marvell — 26 Jun 2012 @ 2:14 PM

  53. T. Marvell: I live hear the Virginia and North Carolina shores; public concern about sea level rise is small compared to concerns about hurricanes.

    Yeah, and that’s odd because with hurricane behavior held at a constant sea level rise is going to guarantee that the impact of each storm making landfall will be worse.

    Not to bang on about it but the Climate Central interactive sea level map illustrates this nicely. It’s about changing probabilities; a neighborhood need not be permanently underwater before it’s effectively useless.

    Comment by dbostrom — 26 Jun 2012 @ 2:53 PM

  54. And another note…a storm doesn’t have to be a hurricane to have major impacts…see Florida today. Extreme weather events do not have to rise to the various naming thresholds to cause major impacts.

    Comment by Tokodave — 26 Jun 2012 @ 3:46 PM

  55. Here’s another weird outcome of living in a pretend world.

    Fifty years from now people who insist that sea level behavior has not varied from bygone times will have to explain more frequent and severe coastal flooding by some other means; it’ll be necessary to invent an alternative explanation for observations. Thus something else will have to be exaggerated, perhaps hurricanes. Supposing that hurricanes behave no differently, some folks nonetheless will need to insist that hurricanes are worse.

    That is, presuming human nature still precludes “oops, I’m wrong.”

    I’m sure some philosopher somewhere has explored the notion that facts are conservative, that it’s not possible to vanish the real.

    Comment by dbostrom — 26 Jun 2012 @ 4:19 PM

  56. The article said: “The group tries to discredit the credibility of science by propagating the myth that climate science predicted global cooling in the 1970s. In truth this cooling idea was never main-stream but a small minority view also in the 1970s.”

    Here’s Mr. George Will just flat out lying in a 2006 opinion piece published in what was at one time a decent paper: (

    “when he was 20 he was told to be worried, very worried, about global cooling. Science magazine (Dec. 10, 1976) warned of “extensive Northern Hemisphere glaciation.” ”

    Now Mister Will didn’t expect anyone would actually go and look at the actual papers he was misrepresenting. Here’s the one mentioned above: Variations in the Earth’s Orbit: Pacemaker of the Ice Ages J. D. Hays, John Imbrie, N. J. Shackleton

    Here’s the relevant cut and paste quote from the Hays et al article:
    A model of future climate based on the observed orbital-climate relationships, but ignoring anthropogenic effects, predicts that the long-term trend over the next sevem thousand years is toward extensive Northern Hemisphere glaciation.

    As you can see there is nothing in the actual text that suggests we ought to be “worried, very worried” (as Mr Will prevaricated), or even mildly alarmed, about the extensive Northern Hemisphere glaciation that were predicted would occur on a 7,000 year time scale by a single climate model in the absence of anthropogenic effects.

    I provided a similar illumination of Mr Will’s mendacity in a comment on the column at the time they published it and which stayed there for some time but as far as I can it has now been removed. From time to time it seems worth bringing up. At the time I was surprised that George Will didn’t know how easy it was to debunk his lies but in retrospect I’m thinking that maybe he didn’t care, knowing that they’d be repeated 1,000s of times anyway.

    Comment by John E. Pearson — 26 Jun 2012 @ 4:26 PM

  57. John E. Person wrote: “At the time I was surprised that George Will didn’t know how easy it was to debunk his lies but in retrospect I’m thinking that maybe he didn’t care”

    Your retrospective thinking is correct. George Will didn’t care.

    The evidence that he didn’t care is that over the course of several Post columns about global warming, he repeated lies that had already been thoroughly debunked, not only by letters to the editor from scientific organizations, but by the Post’s own reporters.

    And the Post’s editorial page editor, Fred Hiatt, didn’t care either. His response to the debunking of Will’s lies was to assert that Will’s columns were “an important contribution to the debate” and to continue publishing them, even though they contained the same lies that had already been debunked.

    Comment by SecularAnimist — 26 Jun 2012 @ 5:16 PM

  58. Lennart van der Linde #51:

    My reasoning was: max 139 cm of SLR in 2100 + max rate of SLR of 26 mm/yr in 2100 ‘could’ mean about 6,5 meters by 2300, if that rate of SLR would continue for two centuries.

    OK, I see. Ball-park reasonable, but that ‘if’ is a big one. Yes, the other scenarios see the rate of sea-level rise go down after 2100, and it’s a reasonable question whether this also applies to CPH reference and CPH policy.

    Looking at Figure 2 we see that, up to 2100, the increase in rate indeed goes down. Whether the rate itself does at any point? To know that, we would need to have these curves (and uncertainty bands) extended by two more centuries. Extending the underlying temperature curves amounts to making assumptions on human behaviour (by 2100 we are already looking at 3 degrees plus. How dumb can we get? Don’t answer that), available fossil-fuel stocks, and technologies. We didn’t want to go there.

    Note that the “point” of our paper is not so much showing how bad it can get; rather, to provide actionable information on the effect of various mitigation approaches, and levels of aggressiveness in mitigation, that have been floated or pre-exist in the literature.

    Comment by Martin Vermeer — 26 Jun 2012 @ 10:43 PM

  59. Some fun remedial (for me) reading on the topic of sea level. The gravitational part is especially amazing. Buy waterfront property in Iceland, watch it grow…

    These polar ice caps are Stouffer’s gorillas. They keep sea level higher than it would otherwise be for thousands of kilometers around both land masses, and correspondingly lower elsewhere.

    If the polar ice sheets shrink, though — as they’re currently doing, especially in Greenland and West Antarctica — their gravitational pull weakens and so does their hold on the surrounding water. About a year ago, Jerry Mitrovica, a geophysicist who teaches an entire course on sea level at Harvard, co-authored a paper in Science that laid out what would likely happen if the West Antarctic ice sheet, the smaller of the two sheets that cover the Antarctic continent, were to melt. (Like a complete shutdown of the Gulf Stream, this is not considered likely anytime soon. But recent satellite measurements have shown that glaciers that drain the ice sheet have begun moving faster toward the sea).

    If you simply spread the resulting increase in sea level evenly around the world, it would amount to about 5 meters’ worth. But the ice sheet’s gravity is currently keeping sea level artificially low in the Northern Hemisphere, so if it disappeared, the actual increase along the U.S. mid-Atlantic coast would be more like 6.3 meters. In other words, as the West Antarctic Ice Sheet melts and loses mass, its pull on the surrounding ocean will lessen. Seas will drop around Antarctica and parts of the Southern Hemisphere, and that water will be displaced to more northerly areas, such as the east coast of the U.S.

    Now that the gorilla has made its presence known, Stouffer is working with Mitrovica to understand its effects in greater detail. A joint paper, due out in a few months, will look into the gravitationally driven sea-level changes a melting Greenland could trigger. “The signal is so large,” says Stouffer, “that if you own beachfront property in Iceland, and all of the ice on Greenland melts and adds seven meters to average sea level, you end up with more beach. But in Hawaii, you get your seven meters of sea-level rise plus an extra two or three on top of that. It’s phenomenal to me that it matters that much.”

    The Secret of Sea Level Rise: It Will Vary Greatly by Region

    Comment by dbostrom — 27 Jun 2012 @ 12:53 AM

  60. …and another reason why we didn’t want to go there is that our semi-empirical model is calibrated only over a period where there were temperature variations of up to 1 degree C. While it seems reasonable to extrapolate out to 1.5 – 2 degrees of warming, extrapolation of such a simple linear model to three degrees plus, sustained over many years, would become questionable.

    Comment by Martin Vermeer — 27 Jun 2012 @ 1:57 AM

  61. re.45,47

    I meter/year is the average rate of coastal erosion for that section of the East Anglian coast. This is based on historical and archaeological evidence dating back to Roman times.
    The geological evidence indicates that it’s been similar for more like 5,000 years.

    The Eustatic Sea level rise affects the rate, but is not the only factor. As on the East Coast of the USA, this is a coast near a former Glacial margin, so it’s tending to sink.

    Comment by prianikoff — 27 Jun 2012 @ 3:26 AM

  62. @Martin Vermeer 58: I hope the point of your paper will be well taken. This information seems very important to me. Nevertheless, the additional point I’m taking from your paper seems equally important: if we don’t mitigate agressively enough we take a significant risk of levels and rates of SLR that will be very hard or impossible to adapt to, even for a rich country like The Netherlands.

    If I read your paper correctly than your conclusions go further than those of the Dutch Delta Committee:

    They thought 3,5 to 4 meters SLR by 2200 the worst case scenario. It seems their highest warming scenario by 2100 was somewhat higher still than your CPH reference scenario. If not, let us know.

    Your CPH reference could lead to max 4 meters SLR by 2200, by the same ball-park approach as above. So an even warmer scenario, like the Delta Committee could presumably lead to even some more SLR by 2200.

    I hope we will be wiser than to let it come that far, but so far we can’t be sure of that. Information like this may help us become wiser sooner.

    Comment by Lennart van der Linde — 27 Jun 2012 @ 4:17 AM

  63. Re #1 & #4 and Insurance

    In my part of the country (Maine) insurance companies and lawyers got interested in the prospects of sea level rise with a changing climate at least 5 years ago. While outside of my area, I believe both groups continue to solicit information from the science community. What they do with this information is, of course, another matter. The state’s coastal communities are likewise taking sea level rise seriously because coastal erosion is already a problem in some areas.

    Comment by BillS — 27 Jun 2012 @ 11:23 AM

  64. Steve Easterbrook – outside of the lighthouses and beaches and dunes, there isn’t really a lot to see on the outer banks, but when I lived there one of my favorite places was Ft. Macon (captured during the Civil War and well preserved.) There was a live oak forest just outside of Emerald Isle. I could always find a rattlesnake in there somewhere. I fear the forest is probably gone now. I was lucky to be there before the big development took place.

    Comment by JCH — 27 Jun 2012 @ 1:47 PM

  65. Steve Easterbrook & JCH….

    The importance of barrier islands is not what you can see but what you don’t. The dune structure of the islands themselves is interesting and within each subsection are ecologies that often exist no where else. Behind the islands into the protected bays and sounds are the nurseries for a vast web of marine and terrestrial creatures. From the backside of barrier islands, across the bays to the tidal salt marshes of the continental shore are the spawning grounds, the breeding grounds for thousands of species that do not exist in any other environment. Yet, this is a naturally dynamic environment and the creatures therein have adapted and, as with all such places, the mix changes as the environment changes.

    Want to know what barriers islands are really about? Find an old bay-man and ask him to show you about.

    Comment by BillS — 27 Jun 2012 @ 6:44 PM

  66. Is similar work being done along Assateague Island or further down along the Delmarva Peninsula? Subsidence from an ancient bolide impact may provide a useful range of background rates there.

    Comment by Chris Dudley — 27 Jun 2012 @ 11:00 PM

  67. A question : when do you expect the acceleration to be statistically significant enough to be detectable, reaching say a 5 mm or 0.2 inches/yr ? It may be reasonable to wait a little bit to be sure your semi-empirical model is really confirmed by observations before “planning” anything for the next 100 years, to say nothing of 300 years ..

    [Response: Your point is about model validation, and there are two possibilities. Either you wait some decades to see whether the projections come true. Or you validate with hindcasts. For example, in this paper I have shown that when you calibrate the model only with the first half of the data (i.e. the period 1880 to 1940), you can quite nicely predict the sea level rise since 1940 with it. -Stefan]

    Comment by Gilles — 28 Jun 2012 @ 2:37 AM

  68. Gilles and Stefan,
    The Rahmstorf paper does show a reasonable correlation between 1880 and 2000. However, the paper forecast that SLR should have reached the 5mm/yr rate by now, with error bars from ~3.75 – 6.25 mm/yr (extrapolating fig. 1 out to 2010). The most recent SLR lies clearly outside this range. If an acceleration in SLR is to occur, it should be readily evident in the very near term, in order to reach some of the higher predictions.

    Comment by Dan H. — 28 Jun 2012 @ 9:13 AM

  69. > Either you wait some decades to see whether the
    > projections come true. Or you validate with hindcasts.

    Very helpful to see this implication spelled out clearly, Stefan — you wouldn’t write that in the published paper, written for people who understand statistics.

    For the rest of us :-) it helps to be here working out clearly the very basic information about how you can get information by looking at this particular data set, which has this amount of internal noise/variability during this particular time span.

    Am I right that each high tide (one per 24 hours, in North Carolina, compared to two in 24 hours in California) can be a data point?

    I understand, I think, that to do a significance calculation on noisy data takes a certain number of data points or observations — for “annual” data you have to wait years; but for tides?

    (I’m trying always to remember my fellow citizens’ average reading comprehension for _non_scientific material is somewhere around 7th or 8th grade; so I’m trying to ask this stuff as simply as possible.)

    Comment by Hank Roberts — 28 Jun 2012 @ 12:01 PM

  70. Dan H. does bad science (or just likes to smear confusion around).

    >(extrapolating fig. 1 out to 2010)

    Figure 1 is a graph projecting the second half the 1900s using data that stopped at 1940. The entire point is to show that the model’s forecast fits the already measured data when you only use the first half of the set. Its purpose is not to project in the future. The paper did not forecast anything about what is happening now with Figure 1. Surely you wouldn’t take a model and run it on data from 1880-1940 to forecast into the future, you’d include the entire data set.

    BTW, that’s also not the paper, it’s the response to comments. I assume you cannot be talking about the actual paper because Figure 1 in the paper is not a forecast.

    Lay readers – yet another example of Dan H. not understanding the source material.

    Comment by Unsettled Scientist — 28 Jun 2012 @ 4:58 PM

  71. I don’t think the Norfolk coast of England is a good example – as noted, it has degraded continuously for quite a long time. There are places that grow and places that diminish, and the geography of that area makes it one of the diminishing ones. We visited it in the early 60s and there were crumbling houses then. Of course, this will increase, but it makes it a bad example.

    Gilles likes to throw dust in the eyes but waiting on events seems particularly foolish in the light of the increase in newsworthy disasters lately. It seems pretty clear that a complex of interrelated phenomena are making flooding and droughts worse, as predicted, increasing the seasons for destructive insects, and other large and small changes over time. It would be nice if people were a bit more interested in things that happen beyond their own horizons (world rather than local weather news, for example, over time) and more observant. The increase in personal portable media allows people to seek virtual rather than real entertainment.

    Comment by Susan Anderson — 28 Jun 2012 @ 11:21 PM

  72. Norfolk Coast near East Anglian Coast. I think the meter per year loss was meant to be horizontal rather than vertical and matches our observation; also agree it’s a bad argument.

    The Delmarva/Chesapeake area is likely in real trouble, between toxifying shallow water and a lot of low ground.

    Comment by Susan Anderson — 28 Jun 2012 @ 11:28 PM

  73. Dan H. lectures Gilles and Stefan on Dan’s misinterpretation of the meaning of the Rahmstorf paper. It would appear Dan H. doesn’t know Stefan’s last name. Or

    …. dagnabbit, hooked again.

    Comment by Hank Roberts — 29 Jun 2012 @ 12:26 AM

  74. Here’s the bill that passed the NC Senate

    Comment by Tom Adams — 29 Jun 2012 @ 7:43 PM

  75. At 52, the write stated
    Right-wingers who contest the idea of SLR are typically opposed to federal programs. As far as I know they have not attacked Federal flood insurance. This inconsistency could be used to question their credibility.

    Well, a little research might be useful before making such an argument—arguments that are easily refuted can damage the credibility of those who put them forward and tarnish other arguments that they are associated with.

    I believe that the bulk of the criticism of subsidized flood insurance comes from the right.

    See, for example, at page 15.

    I did a search on the cato website and got a number of hits.A quick scan of these hits did not reveal any that were positive.

    Given that federally-subsidized flood insurance is (a) an unnecessary and inefficient intervention in a part of the economy in which the market could work, and (b) flood insurance nets out as a transfer from taxpayers to a selected class, one would expect that the right would oppose it. One would hope the left would oppose it also and that support would be restricted to those who own property in flood plains. Maybe it more or less is; if, perhaps they care more and lobby harder than the rest of us.


    Comment by Observer — 30 Jun 2012 @ 5:47 PM

  76. 75: Observer. All God’s dangers ain’t a Cato institute. As the late Tip O’Neil said, “All politics is local.”

    Comment by John E. Pearson — 30 Jun 2012 @ 7:57 PM

  77. … support would be restricted to those who own property in flood plains. Maybe it more or less is; if, perhaps they care more and lobby harder than the rest of us.
    successfully lobbied 94% of the House??

    Comment by flxible — 30 Jun 2012 @ 10:30 PM

  78. I believe that the bulk of the criticism of subsidized flood insurance comes from the right.

    Cato is not “the right”. Nor the “bulk of the right”. Do your homework.

    Comment by dhogaza — 30 Jun 2012 @ 10:45 PM

  79. I have lived in NC for 20 years. There are few coastlines as volatile as the barrier islands of NC (especially the Outer Banks). The coastline is in constant flux due to the Gulf Stream and periodic hammering by hurricanes. Forget about decadal changes, I have seen enormous changes from week to week.

    I cannot think of worse place to conduct a study of sea level rise due to the tremendous natural variability. Why not conduct a sea level rise study of the Rock of Gibraltar and other relatively fixed shorelines? Places where the volatility is low.

    [edit – uncalled for]

    [Response: You need to read the previous post on why people are looking in NC – it has nothing to do with the shifting coastlines, but rather that the salt marshes are affected by post-glacial sinking which meants that accumulating sediment is accessible and can be examined to see periods of relative accelaration and decellaration. – gavin]

    Comment by OldNavy — 30 Jun 2012 @ 11:32 PM

  80. re.71

    The coastline in Norfolk and Suffolk isn’t uniformly in retreat.
    Eroded sand is often deposited further along the coast, causing sandspits and beaches to grow at certain locations.
    Coastal defence works can mitigate the rate of retreat, while dredging the offshore sandbanks can increase it.

    For instance, in the centre of Southwold, money has been spent on beach nourishment and maintaining the sea defences.
    Whereas, north of the town, where there are fewer homes and no tourist facilities, spending has been cut.
    It’s in the latter areas that coastal erosion is occuring most rapidly.

    However last summer, I noticed that a section of footpath near the town centre beach was closed due to subsidence.
    Officially this was put down to “rabbit activity”.
    As Sizewell Nuclear power station is only 10 miles south, I just hope the rabbits aren’t breeding faster due to global warming!
    Last March the Department for Environment conducted an unpublished analysis which said Sizewell is at at “high risk” of flooding and coastal erosion because of climate change
    (as are 12/19 other nuclear power stations in the UK).

    As part 1 of the video about Happisburgh shows, revetments which once slowed down erosion are falling into disrepair.

    This is a deliberate policy, usually described as “Managed Retreat”.
    It entails allowing the coastal marshlands to expand and the sea to permeate reclaimed agricultural land.
    The theory being that this will become a buffer zone, preventing disastrous flooding in the future.
    The economic arguiment is that the cost of maintaining sea defences outweighs the value of the properties threatened.
    It’s also argued that building “hard” sea defences cause problems elsewhere along the coast.

    Some useful comparisons could be drawn with the Netherlands.
    East Anglia and the Fenland have close historical associations with Holland.
    In the 17th century, Dutch engineers helped drain the marshes and opened up the region for intensive farming.
    Even then, it was a very contentious issue, as much common land was enclosed in the process.
    As the land dried out, it fell below the level of the drainage ditches.
    Only the advent of steam pumps prevented the Fens being flooded again.

    The Dutch have a more agressive attitude towards their coastal defences.
    The West Frisian Islands are a chain of barrier islands, not unlike those on the US East coast.
    Periodically, they’re split apart by storm surges, disappear and re-grow.
    Attempts to fill in the channels seperating them from mainland have always failed.

    But the Dutch spend a lot more on coastal defence, because allowing their coast to be breached threatens the densley populated low-lying region inland.
    As their saying goes:-
    “Hier gaan over het tij, de wind, de maan en wij”
    Perhaps they need to work global warming into that (if they can get it rhyme).

    Comment by prianikoff — 1 Jul 2012 @ 3:25 AM

  81. It would seem to me that it is pointless to argue whether support for subsidized flood insurance comes from the right or the left. It is either a good idea or it is not.

    NC-20’s silliness is manifest whether they come crying to the ebil gummint for insurance relief or not. That is just a measure of how sincere they are–and thier webpage makes a pretty good case that they are not already.

    Comment by Ray Ladbury — 1 Jul 2012 @ 7:57 AM

  82. prianikof: I just hope the rabbits aren’t breeding faster due to global warming!

    Night of the Lepus:

    members of a small Arizona town…battle thousands of mutated, carnivorous killer rabbits.

    Comment by dbostrom — 1 Jul 2012 @ 8:35 AM

  83. Re: 78 and 81 above.

    78, well sure, Cato is not the bulk of the right.
    But, do a search on
    “A recent study by the National Wildlife Federation, a leading environmental group, documents the high tide of insanity that is the federal flood insurance program….”
    “This policy brief will survey how human nature, facilitated by well-intentioned but flawed government policy, leads more people and property into harm’s way, undermines insurance markets, and transfers the costs of flood risk to distant taxpayers.”

    Milton Friedman
    “Friedman corrected the questioner and noted that he did not come out against private aid for flood victims but instead was against the Federal Government providing discounted flood insurance in advance to home purchasers which motivated people to build houses in areas where they otherwise would not have been able to obtain insurance privately.”

    “Perhaps hoping to undercut my credibility by eliciting my opposition to federally subsidized flood insurance (a program that he likely believes to be beyond controversy), I explained how those guarantees cost society money by eliminating barriers that would normally prevent people from living in potentially dangerous flood zones. The congressman gave no indication that he ever considered these arguments.”

    I could go on and on but why?

    Re, 81.
    In some absolute sense it is not important what the political views of those who support and oppose flood insurance are.

    But, if one wants to understand political disputes or influence the development of policy, it probably helps to understand the facts. If, as I think likely, support for flood insurance is stronger on the left than on the right, telling people that the right is the problem may make people think less of the right but it probably will not help in moving towards the adoption of more ecologically sound public policy.

    But, of course, as in many things, the best action depends on your goal. I don’t see how an undocumented assertion that the right supports flood insurance serves environmental policy goals.

    Comment by Observer — 1 Jul 2012 @ 1:31 PM

  84. So how much exactly is the AMOC slowing? What are the causes? Is this related to the very cold, wet summer much of Europe seems to be having? Is it getting slower, and is that rate of slowing accelerating (if that makes sense)? Any possibility that it will stop altogether?

    On a different tack, do the above studies on global sea-level rise include results from this study showing that GIS is near a tipping point?

    (Sorry for all the impertinent questions.)

    Comment by wili — 1 Jul 2012 @ 2:40 PM

  85. Observer:

    “I could go on and on but why?”

    Good call, because it’s pointless. Because for every critic on the right I can find two on the left, if you insist on playing this pointless game.

    I’m with Ray:

    It would seem to me that it is pointless to argue whether support for subsidized flood insurance comes from the right or the left.

    It is also pointless to argue that the NC-20 group is unrepresentative of a fairly broad swath of the right …

    Comment by dhogaza — 1 Jul 2012 @ 3:23 PM

  86. > AMOC
    try Google Scholar, limit to 2012; the first 2 hits as of now are:

    Climate science: A grip on ice-age ocean circulation
    J Marotzke – Nature, 2012 –
    … Second, the AMOC in ocean-only models such as that used by Oka and colleagues has long been known to be overly sensitive to minute details entered into the simulations …

    Moored instruments show decadal drop in AMOC strength
    C Schultz – Eos, Transactions American Geophysical Union, 2012 –
    … They found that the supraglacial lakes move in a direction and with a speed that differs from ice shelf flow: parallel to the grounding … that AMOC will slow down as Earth’s temperatures rise due to anthropogenic warm- ing, which could have serious climate consequences for …

    Comment by Hank Roberts — 1 Jul 2012 @ 3:40 PM

  87. Observer:

    I have been an environmentalist since the 1960’s. I have never met a single environmentalist who supported government-subsidized flood insurance. Of course, back in the 1960’s, when the term “conservative” actually meant something, there were more environmentalists on both sides of the fence. In general, while “conservatives” vacillate on approval or disapporval of government-subsidized flood insurance (depending on where their investments are placed), through the years, environmentalists (who by now have been forced to the left) have consistently opposed such flood insurance:,270616

    It appears you are arguing from your own opinion, rather than from any factual basis. At any rate, it doesn’t matter, as others have said. With the current lack of any meaningful action to slow global warming, rising sea levels will put a quick end to government-subsidized flood insurance programs – just as soon as the party of denial comes to its senses, that is.

    Comment by Craig Nazor — 1 Jul 2012 @ 9:22 PM

  88. Re, #87.

    I think I am in general agreement with the views set forth in #87. I think that many environmental organizations, perhaps a substantial majority, oppose subsidized flood insurance. Moreover, it is probably the case that many of the environmental organizations that do not have such a position have not thought about it. (I’m on the board of one such organization—we don’t have a position regarding flood insurance but, I think that, if we did have a position it would be in opposition to such subsidies.)

    However, environmentalists and the left are two different classifications.

    If one want’s to study this point carefully, I suggest classifying organizations into 4 categories left, left&environmental, right, right&environmental. Then calculate the frequency with with groups in each class support or oppose flood insurance. I think the non-environmental left would lag the non-environmental right.

    Two last observations—one a cheap shot.

    I. Flood insurance was pushed by Lyndon Johnson and was first enacted when he was president.

    II. (This is the cheap and misleading, albeit factually correct, observation.) The U.S. Senate voted out a flood insurance bill last Friday. All 19 votes against it were Republicans—including senators from those notoriously flood-prone states Idaho, Utah, and Arizonak. But it was also opposed by Graham and Rubio. See

    However, see for a sign that cui bono is a good guide to understanding strong support for flood insurance.

    Comment by observer — 2 Jul 2012 @ 7:57 AM

  89. The Brunswick nuclear plant is located in Southport, NC and the reactor building is at an elevation of twenty feet. My recollection is that the design basis for this reactor (which happens to be of the same type as some of the Fukushima reactors) was a storm surge of 22 feet. There was a Senate hearing which looked at the risks of rising sealevel on domestic infrastructure at which the NRC was encouraged to study the risk specifically of rising sea level on nuclear plant design, but I can’t seem to locate any news item to indicate that this is indeed happening. Sound engineering practice would seem to call for a re-examination of design if the underlying assumptions have changed.

    Comment by Ed Beroset — 2 Jul 2012 @ 8:49 AM

  90. Scientists need to stress the fact that size matters and we’re dealing with enormous sizes.
    You fellows know that the volume of the World Ocean is around 3,100 million cubic miles, and its average depth is about 13,000 ft. (miles and feet used for American minds).
    Thus it’s small wonder that in the near future when the ocean warms even very slightly, and thermal expansion occurs, the sea level will rise a few feet (a tiny blip given the scales involved).
    Or that over time, ice sheets melting (average thickness 7,000 ft.) can cause the sea level to rise about 20 ft. for Greenland and 180 ft. for Antarctica (a very small amount given the vastness of the World Ocean).
    These relative sizes, combined with the fact that 90% of global warming is absorbed by the oceans, should be easy to depict pictorially or graphically, so that Americans can get it through their heads that this is happening.

    Comment by s.b. ripman — 2 Jul 2012 @ 1:02 PM

  91. 79 Old Navy said, “I cannot think of worse place to conduct a study of sea level rise due to the tremendous natural variability. Why not conduct a sea level rise study of the Rock of Gibraltar and other relatively fixed shorelines? Places where the volatility is low.”

    Perhaps my experience is unusual, but I’ve found that perhaps 50% of all the common-sense snap-judgements I make with regard to science are 180 degrees off. There are so many variables, and the order of magnitude for each is essentially unknowable until one does the science. Common sense tells us the Earth is flat. Just look for yourself!

    (I’m still sitting on that PIOMAS post, waiting for the melt season to get going. I can’t see any way that the estimates are even remotely accurate. Fig 3 estimates 15,000 km3 by 2015 when last year was ~4. Sounds really wrong to me. So, my assumption is that the PIOMAS post is my Gibraltar. Interestingly, Hank said nobody was predicting an increase in sea ice – uh, well, figure 3 seems way explicit. Again, my assumption is that I’m missing something and the graph which says the CCSM4 mean for 2015 is ~15k means something other than what it “obviously” does. To me, it seems to mean that either CCSM4 is seriously flawed, PIOMAS volume estimates are way off, or the recent past has been an incredible outlier and we’re likely in for a huge increase in sea ice. Since nobody else sees it that way, I’m stuck…)

    Comment by Jim Larsen — 2 Jul 2012 @ 1:22 PM

  92. Jim Larsen says: 2 Jul 2012 at 1:22 PM “Hank said nobody was predicting …”
    What? Where?

    Comment by Hank Roberts — 2 Jul 2012 @ 5:04 PM

  93. Old Navy asked> “I cannot think of worse place to conduct a study of sea level rise due to the tremendous natural variability [of the NC coast]. Why not conduct a sea level rise study of the Rock of Gibraltar and other relatively fixed shorelines? Places where the volatility is low.”

    I’d like to address a misunderstanding that I think the subtext of this highlights.

    The question assumes we can only measure SLR using “marker on a rock”-type measurements. We have other means such as buoys and satellites.

    Places made of extremely solid rock, even (for the sake of argument) “erosion-proof” places would still not be suitable for measuring global sea level rise (SLR). That is a figure which must be built by taking evidence from many different places because SLR is not uniform along the world’s coastlines. It is not analogous to ice melting into a glass or water’s expansion as you heat a pot on the stove. For example, the currents make ice melt from the Antarctic impact some coastlines, but not others.

    So if one wishes to know about how SLR is going to impact the Carolina coast, regional studies must be done. The Regional Sea Level (RSL) is what people like public planners in NC need to look at, not the global SLR. If the RSL rise is greater than the global SLR, then that location is going to have to deal with the impacts of our rising oceans sooner than the rest of us.

    Because of this regional variation the ocean as a whole must be studied. One cannot just go find a solid rock somewhere and mark the high water point each day. That will only tell you about what is happening at that rock and could either over or underestimate the global average rise in sea level.

    So to summarise a direct answer: Studies in Gibraltar won’t help in NC much other than the piece they play in building our larger understanding. NC’s vulnerable coast increases the necessity of studying the region. That vulnerability extends inland and is not limited to the barrier islands.

    Comment by Unsettled Scientist — 2 Jul 2012 @ 6:16 PM

  94. More on the idea of Regional Sea Level issues.

    East Coast faces faster sea level rise Cities from North Carolina to Massachusetts see waters rising more rapidly

    “We have direct evidence of a hot spot stretching from Cape Hatteras in North Carolina to just above Boston,” says Asbury Sallenger Jr., an oceanographer at the U.S. Geological Survey’s St. Petersburg Coastal and Marine Science Center in Florida. “The area has an unusual sea level rise acceleration compared to the rest of the United States.”

    Climate change has, on average, raised the surface of the world’s oceans in recent decades by melting glaciers and causing seawater to expand as it warms. But the rise hasn’t been uniform, like water filling a bathtub. It has happened at different speeds in different places, thanks to wind patterns, currents and other regional factors that shape ocean surfaces.

    Comment by Unsettled Scientist — 2 Jul 2012 @ 10:07 PM

  95. Observer:

    I would say that those who support federally-subsidized flood insurance are those who either are invested in or represent those who are invested in flood-prone real estate. I think that “right” or “left” have little to do with it. You have given no evidence whatsoever (other than your own opinion) to prove otherwise.

    But I am still having a hard time understanding where you are coming from. What present-day organization would you charaterize as “right&environmental”? By “right,” I am assuming that you mean the current Republican agenda.

    Comment by Craig Nazor — 2 Jul 2012 @ 10:30 PM

  96. You can look this stuff up. It’s not simple, not just elevation or “flood plain” location:
    Many flood risks depend on changes upstream or downstream and the maps change year to year.

    You wouldn’t have any clue that, for example, upstream development had changed rainwater percolation rates increasing the risk of a flood in your location — or have any way to calculate that risk or price insurance on it — in a pure free market mythical universe. This is one of the reasons why people organize.

    Comment by Hank Roberts — 2 Jul 2012 @ 11:41 PM

  97. 88 Observer noted that the 19 senators who voted against the flood insurance reform bill were Republicans. Assuming this is the same bill quoted above: “Several members of both parties agreed that a top priority of the bill is eliminating the red ink that the National Flood Insurance Program (NFIP) has generated over the past several decades. Members noted that the NFIP is nearly $18 billion in debt, and spoke in favor of the bill that would require the phasing in of actuarially sound rates for flood insurance policies, and phasing out taxpayer subsidized rates.”

    So, to make your self-described misleading point a bit less so, the bill ENDS taxpayer-subsidized flood insurance via what seems like a rational phase-out period. Thus, those 19 Republicans voted against ending subsidized flood insurance. Maybe they didn’t like the phase out period, or wanted to explicitly turn over the system to the private sector afterwards. Maybe they like things as they are/were. Guess you’d have to ask them…

    As to whether more right-wingers or left-wingers support subsidized flood insurance, perhaps a reasonable estimate would be the percentage of each who own or market or otherwise have an interest in property in a flood-prone area. You won’t find many Democrat real estate agents in Miami who would support the above bill. Nothing like good old self-interest to make most any capitalist go communist and vice-versa! This isn’t a right-left issue, but a special interest issue.

    This bill, along with work such as described in the OP showing the increasing risk over time, looks like it has the possibility to cause a tremendous long-term decline in value along the coasts. When your house is expected to be destroyed on a regular basis, insurance can be pricey.

    Hmm, perhaps this is going too far, but now that we’ve got the coastal dwellers paying for their own insurance, what about the billions for flood control? Shouldn’t New Orleans residents pay for their own dikes? Shouldn’t the decision about how much to pay for dikes (aka how high) be a local one? With insurance dangling lower rates for higher dikes, the market can handle the issue.

    Comment by Jim Larsen — 2 Jul 2012 @ 11:43 PM

  98. More expensive real estate gone: a foot of sea rise in two decades in California

    anyone wanna crunch the numbers for real estate financial losses from this one and Sallenger ? NPV of assumed income flows (taxes, bonds, mort_gages…) turning into losses from having to build protection or demolish ?

    developers are gonna squeal like pigs. so are their bankers.


    P.S. apparently the word relating a lien on a property to a financial obligation is spam…

    Comment by sidd — 3 Jul 2012 @ 12:12 AM

  99. 92 Hank said, ” “Hank said nobody was predicting …”
    What? Where?”

    Durn. I KNEW you were going to ask that and I STILL posted without digging through all the posts…

    Well, I looked for “Hank” on the PIOMAS thread, and found that you’re rather prolific! But I didn’t find the comment I was looking for. Sigh. I also looked for “Nobody” and got nothing. So, let me attribute my remembering you being who said it as great admiration for what you bring to this site. I suppose it was on another thread, and probably not you since you don’t remember it.

    Be that as it may, what do you make of fig. 3 in the PIOMAS post? What does it “really” say about sea ice predictions for 2015? My logic was – sea ice returns to norm quickly (low memory) – so within a few years the ice volume should be unlinked to current conditions and the median run becomes the prediction regardless of current conditions. Fig 3 shows median run of 15k in 2015. Thus, since none of the experts showed the slightest indication that either PIOMAS or CCSM4 aren’t pretty durn good, our current 4k is due to skyrocket. The numbers are just too far apart to say otherwise. All I’ve got is PIOMAS sucks, CCSM4 sucks, or sea ice is set to triple or quadruple in volume. What’s my error?

    Comment by Jim Larsen — 3 Jul 2012 @ 12:25 AM

  100. > what do you make of fig. 3

    Hang on, I’ll ask the guy on the next barstool over.
    Whoever he is, he’ll be as reliable as I would be interpreting scientists’ work for you.

    Oh, wait, there’s a better way: take my standard advice and apply it.

    Ask the scientists at the PIOMAS site, not some guy on a blog!

    Start with what they have posted on their website.
    Read the paper they link to.
    Ask questions the smart way.

    When scientists are unwilling to speculate beyond what they tell you they can do from what they know, that _is_ the answer.

    Comment by Hank Roberts — 3 Jul 2012 @ 11:47 AM

  101. Does the AGW theory itself rely more on computer models or it based on paleo data?

    Comment by surveyor7^2 — 3 Jul 2012 @ 4:46 PM

  102. surveyor7^2: Does the AGW theory itself…

    Learn more efficiently, start here: Spencer Weart’s The Discovery of Global Warming

    The Argument Clinic is here.

    Comment by dbostrom — 3 Jul 2012 @ 5:46 PM

  103. > surveyor ….
    Neither of those is basic, though both help.

    See the Science Links in the right sidebar?
    The first one, to the AIP, has the background.

    AIP, Spencer Weart’s “Discovery of Global Warming”

    Comment by Hank Roberts — 3 Jul 2012 @ 5:49 PM

  104. surveyor7^2 @101 — AGW is not a ‘theory’ but a consequence of the physics of planetary climates in the presence of heat-trapping gases when a source (humans) adds a plentiful supply of a heat-trapping gas, carbon dioxide. The most important principles of planetary climates are determined from experimental data; the ressults are used to construct climate models and to intrepret the paleo data.

    I recommend reading “The Discovery of Global Warming” by Spencer Weart:

    Comment by David B. Benson — 3 Jul 2012 @ 6:23 PM

  105. Surveyor7^2, the only thing anthropogenic about AGW is how additional CO2 is currently getting into the atmosphere. The rest is basic physics and chemistry.

    You’ve been given good advice: read Spencer Weart’s book. I suggest you take it.

    Comment by Jim Eager — 3 Jul 2012 @ 8:37 PM

  106. North Carolina lawmakers REJECT sea level rise predictions

    no surprise, really, since Republicans control both houses of the North Carolina legislature.

    only real question is, will Bev Perdue veto this errant nonsense?

    Comment by Xavier Onnasis — 3 Jul 2012 @ 9:40 PM

  107. Jim Eager:The only thing anthropogenic about AGW is how additional CO2 is currently getting into the atmosphere.

    Heirloom quality expression.

    Comment by dbostrom — 3 Jul 2012 @ 10:33 PM

  108. After enduring national ridicule for proposing a bill to outlaw any coastal sea level projections based on climate change data, the state’s Republican-controlled Legislature came up with a compromise Tuesday. Lawmakers effectively put the sea level debate on hold by asking for more studies – but none that involve climate change.

    N.C. to sea level forecasters: Ignore climate change data for now (LA Times)

    Projections include continuing ridicule.

    Comment by dbostrom — 3 Jul 2012 @ 11:44 PM

  109. Xavier Onnasis,

    The piece accuses the legislators of putting their head in the sand.

    I’m sorry, but where those legislators have placed their head, sand would feel very uncomfortable.

    Comment by Ray Ladbury — 4 Jul 2012 @ 6:50 AM

  110. Unfortunately, the corporate spending unleashed by the Supreme Court’s Citizens United decision has contributed to the Republicans taking over our state legislature for the first time in a long time. This has radically altered the state’s politics for the worse resulting in a multitude of legislative atrocities the sea level legislation being the most ridiculous. I have read that the group promoting this legislation is made up of coastal developers, whom I assume would be long gone with the money by the time the actual sea level rise exceeds dictated predictions leaving the people who bought the property to deal with the consequences.
    It is sad to see money and ideology determining our government’s policies rather than reality.

    Comment by Barbara — 4 Jul 2012 @ 11:11 AM

  111. Regarding “Hotspot of accelerated sea-level rise on the Atlantic coast of North America” published in Nature CC, I would like to know how the use of the IPCC’s A1B scenerio is justified when emission are currently tracked above the A1FI scenerio? How will this effect the projected results of future sea level rise?

    I suspect I know the result (hotter and higher), but want confirmation.

    Comment by wolfheinl — 4 Jul 2012 @ 11:43 AM

  112. Thank you all for your replies. I found the links useful.

    The reason why I ask is that while I was discussing the issue with someone, they made the comment “the AGW theory does not rely on computer models”. I find the assertion vague and he wouldn’t elaborate on the assertion. When I researched the issue, I found that although Arrhenius didn’t have access to computer models, he did use simple models and mechanical models we used by others doing the early research. I also found in the links you gave that climate scientists have been using computer models since the middle of the 20th century to advance, test and validate the theory.

    Is the assertion, “the AGW theory does not rely on computer models” make any sense and if not how important are they? I’m not sure that answer can be found at Wearts website.

    Comment by surveyor7^2 — 4 Jul 2012 @ 2:58 PM

  113. Surveyor7^2,
    Computer models are just an expression of the physics in a scientific model. You can do the same with pencil and paper in a simplified fashion. Computer models are useful tools. They allow us to explore lots of different possibilities that add to our understanding of the one realization we see in our world. They add understanding, but they are by no means the basis of anthropogenic climate change–that’s just physics.

    Comment by Ray Ladbury — 4 Jul 2012 @ 3:08 PM

  114. Elaborating on Ray’s remarks, Newton successfully modeled extremely simple gravitational effects with equations executed by hand. Later we find the same equations run on computers and used to successfully fly spacecraft within 200km of a moon orbiting a planet some 630 million kilometers distant despite complex gravitational dynamics. Running Newton’s simple equations on a computer allows them to be applied to a problem beyond the speed and accuracy of human ability but at root the same physics and same mathematics are being performed.

    Don’t get too hung up on the term “computer model.”

    Comment by dbostrom — 4 Jul 2012 @ 3:50 PM

  115. So do you two agree that the AGW theory does rely on computer models?
    Or can that be answered with a yes or no?

    Comment by surveyor7^2 — 4 Jul 2012 @ 5:31 PM

  116. Surveyor7^2, all of science uses models. That’s what a hypothesis is: a model of the phenomena being studied. Those models, or hypotheses, are tested to compare them to reality, to see how accurately they describe and make predictions about the real world, and they are revised as necessary.

    In fact, all of science is a model of physical reality as we currently understand it. As new data and observations become available, the model that is science evolves to take them into account and is then retested, and by doing so our understanding expands.

    Comment by Jim Eager — 4 Jul 2012 @ 7:20 PM

  117. Re: #114 (surveyor7^2)

    It depends on what you mean by “computer model.” If you mean a mathematical or physical model, for which we just happen to use a computer to do the arithmetic, then all the commenters who are trying to beat you over the head with “all science is models” are right. Pay attention to them, because if that’s what you mean by “computer models” then your question is useless. Science is modeling reality, and using a computer to do the arithmetic is just plain smart — not doing so is just plain stupid.

    If you mean simulations of climate, in which a computer calculates the time evolution of the atmosphere, ocean, possibly ice sheets and sea ice and plant growth and carbon dissolving in the ocean and glaciers melting and so on and so forth etc. etc., all based on our best understanding of how those things work (most of which is basic laws of physics), and which requires so much arithmetic it can only be done with computers, then I can answer your question definitively: No. AGW theory does not rely on computer models. Period.

    They are, however, the best tool we have to make predictions.

    Comment by tamino — 5 Jul 2012 @ 12:18 AM

  118. “So do you two agree that the AGW theory does rely on computer models?”

    Nope. You could divide up the calculations amongst a hundred million science and math graduate students, and it would take a hundred or thousand times longer – to get the same answer. Math is math. Most of the time, the math quantifies a measurement, which has some inherent and quantifiable error, like the temperature, or the mass of the carbon and oxygen atoms, and the bond strengths between them in a CO2 molecule, which determine the frequency and strength of the infrared absorption. Sometimes the math is purely counting – like when you calculate blackbody radiation from first principles, T appears as a multiplier 4 times – so blackbody radiation varies with the fourth power of temperature, not somewhere in between t^3.99 and t^4.01, depending on how Anthony Watts is holding his mouth on a given day. The math doesn’t change because the model calculations are being done quickly and efficiently by computer instead of paper and pencil.
    Don’t let yourself get confused by some slick denialist conflating wrong(inaccurate) with wrong(conceptually), like Pat Michaels in his congressional testimony saying that since the error bars on aerosol forcing range from zero to -2w/m^2, that this allowed so much wiggle room that he could “give you any answer you want”; this is a lie – there is no way he can honestly give you an answer that has positive aerosol forcing – that’s outside the range of the error bars, and the best estimate is a negative forcing, which he chose to ignore, in order to get the answer HE wanted, that climate sensitivity is low.

    Comment by Brian Dodge — 5 Jul 2012 @ 1:29 AM

  119. Oh, wait, there’s a better way: take my standard advice and apply it.

    Ask the scientists at the PIOMAS site, not some guy on a blog!

    Start with what they have posted on their website.
    Read the paper they link to.
    Ask questions the smart way.

    Comment by noi that van phong — 5 Jul 2012 @ 2:23 AM

  120. Their choice of time frame is pretty smart. A study period until 2015 may hold off economy-wrecking opposition. That deadline will also motivate owners and developers to get ‘er built by 2015.

    North Carolina is encouraging a bubble. They’re fun on the upslope, but when everybody agrees that the shiny new developments will be uninsurable at rational rates in some number of decades, some folks are going to be left holding the bag.

    Develop now and get it all sold by 2015.

    Comment by Jim Larsen — 5 Jul 2012 @ 3:18 AM

  121. Surveyor7^2,
    Define “rely”. Certainly, you do not need a computer model to show that adding CO2 to the atmosphere will warm the planet. Pen and paper along with the absorption spectrum of CO2 is sufficient for that. What computer models do is add understanding. In fact, they are among the most important tools for limiting CO2 sensitivity on the high side as well as the low.

    Computer models are not necessary to demonstrate that warming is a threat. Without them, they are an unbounded threat.

    Comment by Ray Ladbury — 5 Jul 2012 @ 4:27 AM

  122. Surveyor, find out what “rely” means to this friend of yours.

    If he’s using “rely” to mean “can’t stand up without leaning on” — not so.

    If he’s using it to mean “helps improve understanding” — yes, they do.

    Show him Spencer Weart’s history. Much was undrstood before the first modern computers were built. Much calculation was improved on by using computers.

    If he doesn’t want to read the history, or have it read to him, then he’s just copypasting what he thinks is a clever trick question and isn’t interested in the answer.

    Comment by Hank Roberts — 5 Jul 2012 @ 4:59 AM

  123. Surveyor7^2: I am not clear what you mean by ‘AGW theory’. Do you mean the fact that CO2 absorbs in the infrared? Or that the level of CO2 in the atmosphere is increasing? Or the fact that the increase in CO2 is coming from human activity? Or the prediction that this will cause global temperatures to increase? Or possibly the observation (from multifarious sources) that global temperatures are increasing? None of these are scientific theories and none of them require the use of computers.

    Where computers come in useful is to churn through the vast amounts of data needed to get a fairly detailed understanding of what is going on and what is likely to happen.

    I also do not understand why ‘model’ is a dirty word to climate change denialists. A climate model is really just a mathematical description of how climatologists understand the system to work which can then be compared against reality. If it seems to be close, then it may be possible to make some sort of predictions from it. It’s rather like a car designer making a model of a car (these days, in a computer) to study how it might react in a cross-wind or even how potential buyers react to its appearance. Do those who object to climate models also object to car models? If not, why not?(

    Comment by Richard Simons — 5 Jul 2012 @ 8:20 AM

  124. @Surveyor7^2: It’s difficult to give an answer because the question is so strange. It’s like asking if automobiles rely on robots. You could argue “Yes, most mass-produced automobiles today are at least partially assembled and finished using robotic technology.” Or you could say, “No, automobiles can be, have been and are produced without them.” Both are correct but probably uninformative. The informative part could be derived by asking what the questioner thinks the assertion implies which is what Richard Simmons discusses @122.

    Comment by Ed Beroset — 5 Jul 2012 @ 8:42 AM

  125. Anyone who anticipates something about what the future may hold is using a model. Some models are more detailed and rigorous than others. Anyone who wants to convince others to disregard physics-based climate simulation models should be ready with good evidence that they have a superior alternative model, otherwise they’re essentially saying that since you don’t have perfect vision, you should walk around with your eyes closed.

    Comment by Kevin Stanley — 5 Jul 2012 @ 9:37 AM

  126. It’s an amazing thing how nutters can confound perception and generate a lot of unnecessary commotion by making the obvious toxic. Scientists use computers. Once upon a time they used slide-rules. Did people get their knickers in such a twist over “slide-rule modeling”?

    Computers can has bad joo joo, must fling pooh.

    Comment by Radge Havers — 5 Jul 2012 @ 12:20 PM

  127. Almost every time someone asks a “yes or no” question, the correct answer is “it depends.” This is especially true in fields that rely upon evidence and reason instead of polemics and ideology. Often the question itself has many implicit assumptions the person posing the question didn’t even realize when asking.

    Comment by Unsettled Scientist — 5 Jul 2012 @ 3:23 PM

  128. Hi folks, I am a seismologist that teaches an intro geology class. I struggle a bit with explaining at what time scale global average temperatures become meaningful in understanding climate change. I’ve heard about 15 years, but was wondering how that number is arrived at. Is it from simply looking at the time series? Or is it more from prior knowledge that various oscillations will be averaged out over that time period. Thanks!

    Comment by DS — 5 Jul 2012 @ 4:13 PM

  129. DS, the time period is a property of the time series data set itself. Robert Grumbine has a good post on the subject here:

    Tamino also did a post on this at Open Mind, but I can’t find my link to it right now.

    Comment by Jim Eager — 5 Jul 2012 @ 5:22 PM

  130. DS,

    One way I like to think of it, for the global average temperature, would be 15 years of data on either side of the point where you want to know what the trend is. This leads to a common talking point you might hear from some “it hasn’t warmed in the last decade” or so. People will look 15 years ago and curve of the temps forward from that point. You need to use data on both sides of the point to establish the trend at that point. So the past 3 decades of data will tell us what the trend was 15 years ago.

    I hope I haven’t over simplified this, and if I’m inaccurate someone better informed here will correct me I’m sure.

    Comment by Unsettled Scientist — 5 Jul 2012 @ 5:50 PM

  131. DS @127 — At least 30 years of data are required, according to WMO. Checking the actual ‘natural’ variations and applying standard statistical measures, one concludes than 30 years isn’t actually long enough to average out those variations. If I remember rightly, 45 years is the minimum based on the various global surface temperature products, GIStemp, HadCRUT and the one from NOAA’s NCDC.

    Comment by David B. Benson — 5 Jul 2012 @ 9:44 PM

  132. Re: #127 (DS)

    For the time span needed to achieve statistical significance, see this post. As for “meaningful,” perhaps that’s a value judgement?

    Comment by tamino — 5 Jul 2012 @ 10:31 PM

  133. 122 Richard said, “I also do not understand why ‘model’ is a dirty word to climate change denialists. A climate model is really just a mathematical description of how climatologists understand the system to work which can then be compared against reality”

    It’s a matter of trust. Denialists sincerely believe something similar to:

    Top climate scientists got there by cheating. They are a sort of mole, their primary goal is to warp the science to fit their masters’ agenda, which is to prevent the advance of climate science, and instead spread lies long enough to allow for the myth of imminent catastrophe to initiate the overthrow of the free world and its replacement with a small cohort of human hunter-gatherers.

    So, looking through un-rose-colored glasses, a climate model is just a mathematical description of climatologists’ agenda, which can then be twisted (via techniques such as adjusting past temperatures downward) to encompass the generally falsifying data flowing in.

    Comment by Jim Larsen — 6 Jul 2012 @ 12:16 AM

  134. Whenever you see a time span stated, ask for a cite to the source; then look at whether the source is giving the usual ballpark number, or giving an actual calculation. The actual answer depends on exactly what data set is used and on various assumptions. If those aren’t provided, it’s a ballpark estimate. Robert Grumbine and Tamino give answers with the required details. They don’t disagree, they describe the particular example they use and how it’s done.

    Comment by Hank Roberts — 6 Jul 2012 @ 12:57 AM

  135. #132–

    The best satire is often the result of taking its object with (apparent) deadly seriousness…

    IOTW, thanks for a nice reductio, Jim!

    I’d only add that one of the memes revealed by the “Phil Jones hatemail” linked on another thread was that climate science (and, we must presume, related policy) has somehow been responsible for many thousands of deaths in the developing world by killing economic growth there)–this, despite the very publicly available facts that:

    1) Kyoto specifically excluded the developing world, and
    2) Economic growth rates there have generally been far higher than in the “developed world” for a decade or more, and public health measures have been showing concomitant improvements.

    Call it an ugly theory slain by beautiful fact.

    Comment by Kevin McKinney — 6 Jul 2012 @ 10:00 AM

  136. DS,
    There is no magic number regarding the time scale for global temperatures. The AMS uses the last 3 decades as its average temperature, when comparing recent temperatures to the averages. Temperatures changes can occur over much shorter timeframes, depending on several factors, so waiting three decades may not be necessary. At other times, much longer timeframes are necessary to witness any changes. Oscillations have historically been averaged out over longer timeframes, typically 60 years, or 120 years for two cycles (30 years can be deceiving, if it occurs on either the high or low side of the cycle).

    Comment by Dan H. — 8 Jul 2012 @ 10:27 PM

  137. May I ask a stupid question? Will the volume of voids from underground caves, lava tubes etc. that have not been inundated until now not cause a lag in sea level rise?
    Sorry, it’s probably a really dumb question. It’s just that I have been wondering what the void space in the earth’s crust could be… A bit like a sponge, if there are lots of voids and until now they had not been flooded, when the sea starts to seep in, wouldn’t it take a long time before they were filled and we began to see a sensible SLR on the surface?

    Comment by Toni — 9 Jul 2012 @ 4:33 PM

  138. Toni: …when the sea starts to seep in, wouldn’t it take a long time before they were filled and we began to see a sensible SLR on the surface?

    The only truly stupid question is one that goes unasked. The real risk of stupidity comes with listening to answers from dilettantes (me and myriads of others).

    All the same this seems like a question amenable to reckless and half-informed speculation.

    Picturing the problem with excessive groundwater withdrawal from shallow aquifers near the ocean yields a suggestive answer. Overpumping a shallow aquifer in contact with a seacoast tends to result in seawater invading the aquifer. That’s a telltale that the land near the ocean at and below sea level is already saturated with seawater.

    Short of having some really enormous (outlandish “hollow Earth” science fiction scale) voids that are somehow still dry while still being open to flooding by seawater the accounting for void spaces is already taken care of automatically; the observed sea level rise rate already incorporates progressive flooding of pore and void space.

    Comment by dbostrom — 9 Jul 2012 @ 9:11 PM

  139. Toni @136 — Briefly, no. At more length: mostly the ground pores and larger voids are full of water, sometimes quite fresh and sometimes exceedingly salty. When ground water is pumped out near most seacoasts the ocean water invades. Further inland pumping causes the pores to collapse so the rechange rate is slowed.

    SLR will progress almost independently of the degree of invasion of ocean water under the ground as this simplly displaces some of the fresher water.

    [Disclaimer: I’m an amateur at this, but I’ve been an amateur geologist for over 50 years now.]

    Comment by David B. Benson — 9 Jul 2012 @ 9:19 PM

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