Wow, thanks for that! The best news is that now that you all have endorsed it I can be reassured that you will correct any of the scientific errors I will undoubtably make ;)
Topic suggestions and missing substantiations welcomed.
[Response: No problem. I think William suggested that it be placed in a wiki format so that it can be updated and corrected efficiently - that might be worth thinking about. We'd love to help out. Similarly, let us know if you want something dealt with in a little more depth... - gavin]
I’ve been reading this for some time now. The point by point explanations was a nice thought, just make sure -all of you scientists :) – that it stays as scientifically accurate and up to date as possible.
This is a wonderful resource. What would be great is a What Will They Think Of Next?” section there, or described here. That way they can be “headed them off at the pass”. I’m particulary thinking of the
1. Trend skeptics (it’s no happening)
2. Attribution skeptics (it’s not our fault)
3. Impact skeptics (it won’t be that bad)
line of thought from Stefan Rahmstorf’s article for Munich Re (http://www.pik-potsdam.de/~stefan/Publications/Other/rahmstorf_climate_sceptics_2004.pdf) where explains how most skeptics are finally convinced it’s happening, and are somewhat through the fact that man has caused (and is causing) GW. Now I feel like I’m seeing more of “it won’t be that bad” (especially in those pesky ‘balanced’ news reports) – and while modelling gives some regional impacts, obviously the generalizations will have to do until the science catches up.
Here’s some general areas about Why They Think It Won’t Be That Bad But It Will:
- First and foremost is that the predictions are just that – predictions. Could the GW be below the prediction? Yes, and it could easier be *higher*.
- Northwest passage opened up north of N. America with the melting Arctic ice
habitat destruction, native peoples uprooted are obvious, but I’m thinking of more “business” impacts such as melting permafrost cracks pipelines and transportation roads. Maybe insurance costs going up on ocean transports due to more/more intense storms?
- Carbon fertilization effect
only good for a small increase (I think?) and along with higher temps is bad
I’m sure there’s a whole host more…..
Comment by Ed Arnold-Berkovits — 13 Mar 2006 @ 5:19 PM
Nice work, Coby! Also, re #8, everyone note that the new Sierra Club blog is heavily featuring material from RC (and now from A few Things Ill-Considered). The Club blog is a good mechanism for getting this material out to folks all over the US and Canada who really need it as a tool in implementing the Club’s new #1 priority on climate change.
The Lovelock thread from February is closed. May I comment here?
Lovelock’s new book has a page of maps showing:
Hotter = mostly desert over the world
Colder = mostly forests.
My readings of paleoclimatology usually reverse this…
(eg: “Why does Gaia prefer ice ages, with their larger deserts and reduced tropical rainforests”. Blair Dowden â�� 19 Feb 2006)
I usually read that colder periods have a lot of dust, implying deserts.
Hotter periods are usually described as forested (eg dinosaurs at the pole)
Caveat: tropical forests seem currently vulnerable to ringbarking & then burning, and some say once gone they may not return (perhaps meaning ‘will take many hundreds of years’?) …Walk about in Tikal in thick jungle, in what was a city centre 1100 years ago. The ‘wild’ forest is reportedly rich in fruit trees, escapees from classic gardens?
As far as types of climate skeptics, what about those that claim that we’ve passed the tipping point, and there is nothing we can do to stop the changes from happening now?
[Response: Well, at a discussion we had over lunch last week, a cynic pointed out the three phases of skeptics' response to environmental problems:
Phase 1: "There is no problem."
Phase 2: "OK there is a problem, but it's exaggerated and not really serious."
Phase 3: "Now it's too late to stop it."
I notice that recently climate skeptics arguments are indeed shifting into phase 3; more and more you hear the argument that yes, there is a serious problem, but it's better to adapt to the changes rather than try and stop the warming.
Any argument will do, as long as we don't have to change... -stefan]
Coby, RealClimate, and others on both sides of the divide seem to be slowly (or not-so-slowly) spreading my work with Wikipedia around the net. Not to mention the appearances at AGU and the recent NAS panel. So, I am wondering: Does anyone have any requests?
[Response:You could add the curve of recent (since 1952) modern measurements of solar activity, such as cosmic galactic rays and 10.7 cm solar flux: there is no clear trend in these records (e.g see Richardson, I. G., E. W. Cliver, and H. V. Cane (2002), 'Long-term trends in interplanetary magnetic field strength and solar wind structure during the twentieth century', J. Geophys. Res., 107(A10), 1304, doi:10.1029/
2001JA000507 or Benestad, GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L15714, doi:10.1029/2005GL023621, 2005). -rasmus]
I am relatively new to understanding global warming and only became more interested through reading wikipedia and subsequently asking William to point me in the right direction for reading – I liked his style and trusted what he wrote. He did, and in that way became a “father figure” for me – dont all laugh at once particularly when he is roughly the same age as my own children and with his own children younger than some of my grandchildren.
Through that I came to RealClimate and came to trust them too and some but not all, regular posters : I am not so sensitive as some of you who think that “mockery” (see the Greenland Ice blog) is not part of a scientist’s tools : we are all human and trust isnt broken by mockery – it must be difficult for people like William and Gavin, both on record as saying they are always right or maybe almost always right, to deal with the same tired old arguments every day. But they do it in good spirit and that takes guts.
So the issue for me is “trust”. Now RealClimate is accrediting (if I may use that word) Mr Beck’s site on the basis that it is good and accurate and on the assumption, certainly assumed by Mr Beck, that corrections for errors will be dealt with or at least posted by RealClimate. Is that correct please? Editorial control?
Please dont think I am being overly critical here but I’ve been there and done that – it has something to do with age.
Understanding and dealing with virtual communities is also something to do with age – I havent been there and done that : at least not yet but I’m learning fast.
I can’t hear the word “sceptic” anymore. Wasn’t that word populismarized by Lomborg & friends? Why not use a word made by our own, like denialist ?
Comment by Florifulgurator — 14 Mar 2006 @ 8:28 AM
Drag, some of your figures go left to right, others go right to left (time sequence). I realize the originals you draw from do that. But if you could always put the old on the left and the new on the right, or vice versa, and do it consistently, it’d make the images much easier to comprehend when viewed as a group.
Dragonsflight: It seems like every time I hear someone with little knowledge of the field talk about your figures they ask, “But why isn’t there huge warming at the end? The only data set which shows big warming near the present time is the modern instrumental record. That must be the one that’s wrong.”
The reason, of course, is that most of these data sets end before the modern rapid warming and hence miss most of it, but also end close enough to the end of the graph that this is not obvious that they do not continue to the present. It would be nice if this was made more clear on the graphs.
Comment by Blaine Johnston — 14 Mar 2006 @ 10:04 AM
Great job Coby!
But some of the entries need proof reading. In a brief look of some of the topics, I found one spelling error and one case of a plural noun and singular verb. I thought of posting comments, but it would seem easier to do it all at once. Let me know if you would like some help with the proof reading.
I am reading the Tim Flannerys the Weather Makers at the moment myself and it is a fascinating read for the most part. I wonder if anyone at realclimate has picked it up and taken a look. Be good to hear a few comments from Gavin etc on the book.
According to Tim Flannery, climatologists seem to be suggesting that by 2050 at present rates of fossill fuel consumption we will have hit 550 parts per million of CO2, double pre industrial levels and this would indeed spell disaster as global warming would be around 5 deg C on average give or take a degree or two.
There are many other fascinating things in the book especially to do with the complexity of climate, especially feedback and the non linear nature of all things bound to earth.
Re #21; the conventional wisdom is that the warming due to CO2 doubling is around 3 C or 5 F, not 5 C. The sensitivity you quote is considered barely plausible by some and implausible by others; it’s certainly far from a consensus estimate.
Also (and this is a crucial fact in understanding the situation) the warming is not instantaneous. About half the warming due to a CO2 perturbation is delayed by some decades, so the likelihood of seeing 5 C by 2050 is very small. On the other hand, while we won’t see the warming due to a given CO2 perturbation instantaneously, it’s pretty much certain that we will see it eventually.
Fortunately there is almost certainly still enough time to avoid anything like a 5C perturbation, which would be vastly more catastrophic than the loss of a percentage point or two in economic growth rates that has some people so exercised.
I did not say 5c by 2050, I said a doubling of CO2 by 2050, and yes climate latency is many decades behind so 5C (give or take a degree or two) by 2100 I think is what he is saying.
He also mentions Global Dimming and it possibly offsetting global warming but I am unsure about this as realclimate has reported it as bogus in a recent article, well it needs more investigation anyway.
[Response: Doubling of CO2 by 2050 is pretty pessimistic - 2080 or so is more likely (in the unlikely outcome that nothing is done to reduce emissions). PS. We never said that Global Dimming was 'bogus', just that a particular documentary on the topic was rather alarmist and did not give enough proper context. - gavin]
Re Dragons Flight:
Overall, I think your work is excellent. However, some nitpicks:
Your 25 year graph uses the CRU dataset, which has 2005 as 0.1 C cooler than 1998. The NASA GISSTEMP dataset has slightly different values, with 2005 being a bit warmer than 1998. Due to NASA’s results, here in the US 2005 was widely reported as ‘the warmest year ever’. I feel some may look at your graph and think ‘Aha! 2005 was actually *cooler* than 1998! the liberal media is wrong, and global warming is a hoax!’. I’m not suggesting you switch to GISSTEMP (since my understanding is the two agree within their uncertainties), but A short explanation of why your graph appears to differ with certain media headlines, and the meaning of this difference with respect to the recent warming trend would improve your page. Relevant RealClimate article .
Links to other temperature data sets would also be nice.
Like Hank, I think it’s confusing for the layman that nearly half (450 kyr, 5 Myr, 65 Myr, and 500 Myr) of the graphs are ‘backward’. I know this is a result of a long and reasonable tradition from geology, paleontology, and paleoclimatology, of graphing deep time as increasing to the right, but non-scientists are used to seeing the present on the right, not on the left.
I notice your 12 kyr graph has a mark indicating the 2004 temp, and an explanation that the recent warming is below the effective resolution of the graph (with respect to rapid fluctuations) . This is much appreciated, and I think something similar would improve the 450 kyr, 5 Myr, 65 Myr, and 500 Myr graphs.
Finally, thank you for your work on graphs, and thanks to Coby for his ‘a few things ill-considered’ (finally, one on-topic phrase … :-) ), and thanks to RealClimate.
[Response: We've been trying to improve the navigation - but clearly we are not there yet! With respect to the MWP, it is not a 'denigration' to be a regional phenomena (I wonder what ENSO would think about that...). The problem with the global MWP idea is that for well dated proxies, the putative MWP doesn't tend to line up very well across regions (Bradley, Science, 2002; Osbourn and Briffa, 2005; D'Arrigo et al, 2005) and so in the global mean things tend to cancel out. But the number of quality records are not high, and so coverage is spotty. It's possible that with better data, the MWP will look more consistent, but as it stands, the evidence does not support as widespread a warming event as we have seen in the late 20th Century. - gavin]
Re #13 comments: I would suggest a 2a: “Well, sure we’re seeing the early signs and we can’t let the situation go on indefinitely, but it’s too expensive to deal with it now and we can be confident that advances in technology will make it cheap and easy to deal with in the future.” I’ve even seen this reasoning extended to support for building large numbers of new coal plants since the cheap and plentiful electricity will get us to those promised techno fixes that much sooner.
Re #18, I’m beginning to lean toward evasionist. It seems that as long these folks are convinced that nothing very bad is likely to happen to them (within their lifetimes), they just don’t see climate change as a problem and will continue to rationalize inaction. Probably the classic example of this kind of thinking is Lomborg’s “Copenhagen Consensus” wherein it was argued that the money to reduce global warming is better spent on other human needs (water supply, anti-malaria, etc.). I was holding my breath for a while waiting for news of Lomborg actually working on one or more of these other issues, but now I find I’ve had to resume steady breathing.
I have been quietly preparing a non-Wiki site as a venue of first publication for my graphical work. In the process I have been doing things to clarify the reuse policy (which I want to be liberal) and make the series visually more consistent. As much as it galls me to do (earth science training and what not), this includes producing figures with the present day consistantly shown on the right for better comparison across the series.
Re: 20, 25
Putting present day marks on the very long-term plots is problematic because the scales and timing would make it very difficult to see. It also becomes a dangerously apples to oranges comparison if one tries to compare a global annual value to data that is both greatly smoothed and often less than global. As llewelly suggests I may add comments to the description pages about this.
Tim Flannery to me at any rate is a connectionist in the gaia tradition of earth science.
He states on page 197/198 of his recent book that the Amazon creates its own rainfall via transpiration and increased Co2 is causing the stomata to open for less time allowing less water to escape as transpiration. Transpiration is rainfall in the amazon such is the volume of water given off. By 2100 transpiration will be 20 % less than it is now, another major factor here is a persistant el nino effect that sequesters carbon by turning land mass carbon sinks into carbon sources.Rainfall over all of the Amazon will fall from 5mm to 2mm a day. By 2100 the Amazon will begin to die basically due to global temperatures being 5 C hotter than today. Some massive release of carbon from Amazon soil will push Co2 levels to 1000 ppm.
As far as I know, there is no evidence of recent acceleration that is statistically distinguishable from noise. If you are refering to the Church and White paper in GRL, they are looking at data from 1870-2000, and the significance of their result is mostly constrained by what I might call a kink around the 1930s. While their data is consistent with a long-term acceleration, it is not really a compelling exposition of what might happen in the future given global warming driven climate change. Or put another way, I find their graphs less interesting than the amount of press surrounding them would suggest.
Wasn’t the impact of Krakatoa a drop in world wide temp, by about a degree, centigrade?
[Response: No, it was a few tenths of a degree C at most. See the CRU global mean temperature series. The global mean response to explosive volcanism and solar irradiance explains a modest fraction of the observed global mean surface temperature changes recorded since the mid 19th century, but only anthropogenic factors can explain the substantial warming trend of the late 20th century. - mike]
The crop devastation was far more significant. The rise in global temp can be drastically offset by a volcano, in a period a lot shorter than the ‘global warming theory’.
[Response: The statement reflects a misunderstanding of the timescales on which these different forcings primarily act. See the links provided above. - mike]
Curious as to the output of the volcanoes, in regard to the actual co2 output v. man-made.
[Response: Then I suggest you go to Coby's FAQ, which covers that... -Stefan]
With reference to your prediction that a doubling of CO2 by 2050 is pretty pessimistic, I was wondering if anybody has any data (or more likely an inclination) on the impact of fast-industrialising nations Vs the actual curbing of emmissions developed countries may achieve?
I don’t want to be pessimistic but when I read that “China has plans for about 560 new coal-fired plants, and India 213 – without any consideration for carbon capture” (New Scientist, 2005), I do indeed become pessimistic.
On the original thread, thanks a million to the Real Climate crew and also Coby’s excellent site – it’s much appreciated.
Those are some beautiful graphs, it looks like just about all my favorites are your work. As for requests, I would like to see a models vs observations 20th century with some appropriate smoothing, eg the last or all of the plots here: http://www.grida.no/climate/ipcc_tar/wg1/fig12-7.htm smoothed perhaps to a 5 yr mean like the red line on the GISS analysis. People still look at the non-smoothed ones and note where a particular year is off by as much as .5oC, silly as that observation may be. Actually I see one that has that in it: http://en.wikipedia.org/wiki/Image:Climate_Change_Attribution.png maybe that’s the one I want.
Thanks very much for the encouraging and complimentary words. WRT corrections, comments at the article in question are probably the easiest for me, I will just delete them after fixing the problem. If it is easier (ala the proof reading offer from Leonard, #21) to email a bunch at once that is much appreciated, use (remove #Space “coby 101 @ gmail . com”). I will be discussing the wiki approach offered in #1 once some of my deer-in-the-headlights feelings subside…
or 92 being the coldest year on record, along with 1915…?
[Response: "92 being the coldest year on record". Hunh? You need to take a more careful look at the CRU global surface temperature record you were referred to once already. As for 1816, its one of the best examples of precisely the point that has been stressed by us previously with regard to the essential distinction between regional and hemispheric/global anomalies: "See e.g. our review paper (Schmidt et al, 2004), where the response of a climate model to estimated past changes in natural forcing due to solar irradiance variations and explosive volcanic eruptions, is shown to match the spatial pattern of reconstructed temperature changes during the "Little Ice Age" (which includes enhanced cooling in certain regions such as Europe) as well as the smaller hemispheric-mean changes." - mike]
The Tunguska effect on stratospheric clouds needs a magnitude — to factor in compared with the known forcings and feedbacks.
I do recall reading somewhere that more stratospheric clouds are being seen at lower latitudes in recent decades (Great Britan has published some nice photos) — but do we have a historical (or artistic!) record of them occurring so far south before Tunguska?
I wonder whether Tunguska’s effects could have been much greater than those of all the anthropogenic large/high-altitude airbursts we have on record in the last fifty years or so?
I think I recall the amount of water injected into the stratosphere by jet aircraft in each of the last three or four decades amounts to something like a quarter the amount injected by natural processes.
Description with several paintings, basing pictures on witness reports:
“… estimate is that the Tunguska had an explosive energy roughly on order of 60 A-bombs, or 500 KT of TNT. It was closer in effect to a very large H-bomb.” http://www.psi.edu/projects/siberia/siberia.html
Here’s a trace of it:
“… a pulse of cosmic iridium has been reported to coincide with the 1908 Tunguska impact event. It is likely that many events of Tunguska magnitude should be preserved in a deep ice core….” http://www.gisp2.sr.unh.edu/NOTEBOOKS/Notebook2.html
I doubt there’s a good proxy for the presence or absence of noctilucent clouds, except the art museums!
In reply to Mark and his insistence about the effect of Krakatoa.
I’ll start with this graph of radiative forcings. Scroll to the bottom. The bottom graph is of volcanic radiative forcings, in Wm-2. Negative values cause cooling. Notice the downward spikes are all very narrow. The cooling effects are short lived. This paper by Alan Robock seems to give a reasonable (to me, but I am neither a climatologist nor a vulcanologist) explanation of how volcanoes affect climate. Robock claims cooling effects of volcanoes last 1-3 years. Next, compare graph 6.8 (d) to the graph at the top of the same page, 6.8 (a). Notice the sustained upward trend, which becomes very strong, particularly after about 1970. The volcanic cooling effects may occasionally be larger in magnitude, but they are very short lived.
Using the years of eruption from table 1 in the previously linked Robock paper, a few of the downward spikes in 6.8 (d) are easily associated with major eruptions. Pardon me for ignoring the many minor eruptions which also contribute to these spikes. The biggest – at about 6.4 Wm-2 – is Tambora, in 1815, responsible for the Year Without a Summer. Next biggest is probably Krakatoa , in 1883. There is some disagreement at about 1982, when El Chichon erupted. Robock’s reconstruction has El Chichon (and other lesser volcanoes) causing a much stronger radiative forcing than Sato’s. Robock’s has El Chichon stronger than Krakatoa, but Sato’s has it weaker. Since they agree on Krakatoa’s radiative forcing, I take Krakatoa to be the second biggest. The far right spike I take to be Pinatubo‘s 1991 eruption, with some addition from Hudson‘s 1992 eruption. Two other spikes – probably Cosiguina, Nicaragua, 1835, and Katmai, Alaska, 1912, are similar in size to the Pinatubo spike. Note this usgs page has some information about weather-affects of volcanoes that I have not covered here. (It says nothing about Krakatoa, however.)
It seems to me there are about 6 downward spikes in the volcanic radiative forcing that are of magnitude comparable to or greater than that recently reached by well-mixed greenhouse gasses (WMGG). Again, compare 6.8 (d) to 6.8 (a) . Tambora 1815 and Cosiguina 1835 predate the instrumental global temperature record , and are hard to pick out on a 1 kyr reconstruction. Tambora is widely reported to have lowered global temps by as much as 3 C. However, in the above linked 1 kyr reconstruction, it looks to me like the 1815 global temp dip is only about 0.2 C. (Although the dip appears, and looks about the same size, in most of the reconstructions in the graph, it is smaller than the differences in the reconstructions.) I take this to mean that even the effects of Tambora, a much larger eruption than Krakatoa, were too short lived to be accurately captured by such reconstructions, and therefor, too short lived to have much effect on long-term trends. A year without a summer, ruined crops in New England and Europe, but it nonetheless had little significant effect on long-term trends. Krakatoa seems similar, but smaller. 1.2 C of global cooling appears to be widely reported, but the seemingly associated dip in instrumental global temperature records is maybe 0.1 C at most. This too may be due to the effects being too short-lived to be captured by such records, but note that annual averages do not appear to capture any larger a dip after 1883 than the 5-year smoothed averages. (I can’t help but wonder if 1.2 C is simply over-reporting of the most exciting number – perhaps the top end of a range of uncertainties, or research that was later rejected?) The downward spikes in radiative forcing which I associate with El Chichon and Pinatubo also seem to appear to have very small and short-lived effects.
The cooling effects of volcanoes appear so short lived I am tempted to suggest a Krakatoa a decade would be required to counteract human-induced global warming. That seems unlikely …
Mike, and other people loooking for short-term alterations in the 1000 year temperature record:
You need to read the methods of the papers to see how the data has been processed to form the lines shown. As an example, the data in line number 6 has been smoothed: “Each regional temperature record was standardized by removal of the long-term mean and division by the standard deviation after decadal smoothing (lowpass filtering at f = 0.1 cycle/year).” (Mann & Jones 2003).
Looking for any climactic events that operate on a time scale shorter than the smoothing is sort of a waste of time.
I doubt there’s a good proxy for the presence or absence of noctilucent clouds, except the art museums!
I think you are confusing polar stratospheric clouds (PSC) with noctilucent clouds (NLC) here. Noctilucent clouds have been first reported in 1885 (Jesse, Meteorol. Zeit.; Leslie, Nature). People working on the field (including colleagues at my institute are pretty sure that they did not exist before as there was an International Polar Year in 1882/83 which did not report them.
Although a connection to the Krakatoa eruption is often quoted for the appearence of noctilucent clouds, there is no convincing proof of the exact connection of these two events.
About polar stratospheric clouds, I can’t tell you much. Maybe someone else knows more.
Dragonsflight, regarding plots of sea level rise. I haven’t read Church’s paper so I haven’t been able to see for myself. Which is why I was hoping you’d make a plot :) But I believe it’s the most authoritative amalgamation of topex/poseidon and gauge data to date. I think gauge data after calibration to poseidon is likely to be more realistic.
Also, while we’re on the topic, what about quaternary sea level. The sea level calculated by Shackleton from Vostock d18O data doesn’t show too good correlation with ice ages (from visual inspection, I know his calculation of the phasing comes out right). Are there better sea level data from this period. I have seen some in a recent presentation by Hansen Slide 16 or thereabouts that are quite different.
I know that this is slightly off topic but the recent readings of the thermohaline system in the atlantic seems to be telling us the evaporation at the equator has increased thus causing the upper layers of the Ocean to increase in salinity whilst the northern Atlantic waters are becomming fresher due to increased rainfall from precipitation. This increased salinity vs increased freshness is causing the thermohaline system to speed up thus carrying more heat (is this possible ?) from the equator to the poles and hence bringing about its slow demise.
Could realclimate comment on this at all and state whether it is possibly true ?
Slightly off topic and I may have mentioned this before, but methinks a review of Carl Wunch’s latest in Quaternary Research would make for a valuable contribution to the site. Not exactly convinced by wind fields, but it is an interesting contribution. I wonder how many other big ideas in palaeoclimatology he is going to go after!
volcanic eruptions produce about 110 million tons of CO2 each year.
Human activities contribute almost 1,100,000 million tons of CO2 each year.
Comment by Lawrence McLean — 15 Mar 2006 @ 7:40 AM
I watched the BBC Meltdown program last night and it demonstrated how climate models match past climate, quite nicely.
If it does turn out that the MWP was more widespread than we currently consider, I presume that the climate models parameters could be adjusted to accommodate that information.
I was wondering whether the adjustments for, say, a MWP as warm as today would impact on the estimates of the climate sensitivity to CO2?
[I suspect there are loads of things ill-understood within this question!]
[Response: Let's suppose that some brand new data-set proved definitively that the MWP was globally as warm as today. What would that imply for climate sensitivity or climate modelling? Nothing. The reason is that sensitivity is made of two components - the forcing and the response. Unless the forcing terms could be similarly tightly constrained (particularly solar and volcanic), there will always be a wide error bar on any climate sensitivity derived from the MWP. Those error bars currently easily encompass the range of sensitivities shown by current models, and so do not cause any inconsistency. As an aside, although constraining climate models using paleo-data is often talked about, as a practical matter it never happens - the evaluation of climate model parameterisations is done on the much better observed present day data. Paleo-climate modelling is much more useful as a way of testing hypotheses about what caused previous changes, and validating the model in the meantime - see this recent example. -gavin]
[Response: Gavin, if I may contradict you on one point: climate sensitivity in climate models is being constrained with paleo data. But not with the MWP but with the Last Glacial Maximum, see the study by our PhD student Thomas Schneider von Deimling (in press with Climate Dynamics). The Last Glacial Maximum also has a lot of data uncertainty, but the signal is much larger, so that you do get a useable signal/noise ratio there. -Stefan]
[Response: Adding in my own two cents, it remains difficult to produce hemispheric-scale medieval warmth comparable to that of the late 20th century using anything but a rather extreme and improbable scenario of extremely high solar irradiance, that is unsupported by any existing reconstruction of solar variability over the past millennium. So, in practice, some contraints are provided by paleo measurements over the past millennium, arguably even more so if one uses the dual constraints of surface temperature and pre-anthropogenic co2 variation in the context of a coupled climate/carbon cycle model as in Gerber et al (2003). -mike]
Armin — yes, I am confused about whether there’s a difference between “polar stratospheric” and “noctilucent” clouds — other than how far from the poles they are being observed. Both are stratospheric; both are noctilucent (high enough the sun lights them up long after sunset); some appear farther south and others don’t. I thought from what I’ve read that the only difference is location where observed, and that the difference in naming is because they have been observed farther from the poles in the last century or two. But I’d welcome more info or a pointer from anyone.
Re 52: The term “noctilucent clouds” is generally intended to mean mesospheric clouds, not stratospheric.
Comment by Dragons flight — 15 Mar 2006 @ 12:51 PM
Re #51 (Stefan’s comment)
Stefan, is there a (pre)view of that article possible?
If on uses the LGM-Holocene transition, it seems to me that it is possible to have a general climate sensitivity for all actors and feedbacks together, but quite impossible to make a differentiation in sensitivities for insolation/latitude changes, ice and vegetation feedback and CO2/CH4 feedback/forcing during the transition, as these all overlap in the transition period…
And I suppose that the Holocene sensitivity is not necessary the same as the LGM-Holocene sensitivity , as the ice albedo/vegetation feedback is much less now, for the same initial forcing.
[Response: Ferdinand, two good points to ask.
The study is based on a large ensemble of model simulations (1,000), in order to vary the key uncertain parameters, and it uses all forcings including ice sheet, vegetation, dust load and insolation changes in addition to CO2. With all of these model versions, both the Last Glacial Maximum climate and a CO2-doubling climate are computed. The latter gives you the sensitivity to CO2 doubling, of course - and here it is not assumed that this is the same for glacial climate and Holocene, that is one of the strengths of this approach. With all of these model versions, you get a different climate of the Last Glacial Maximum - only some of which pass muster when compared with the actual data from this time. You throw out all other models as unrealistic. Put simply, because CO2 lowering does play an important role for glacial climate (next to all the other forcings), if you have a model with an unrealistically great sensitivity to CO2, then your glacial climate is going to be too cold.. We found that all of the model versions with a climate sensitity greater than 4.3 ºC failed the test with the glacial climate data (considering also uncertainty in forcing and paleo data), hence we conclude that climate sensitivity is unlikely to be greater than 4.3 ºC. For details, wait for the paper - should be out shortly in Climate Dynamics, we've already had the proofs. -Stefan]
Hank, there is fundamental difference between noctilucent clouds (NLC) and polar stratospheric clouds (PSC).
NLC occur in the summer mesopause region at around 83km. They are thought to be made of water ice which may be polluted by some dust or metals from meteoric ablation. Although there is very little water vapour at these heights, the polar summer mesopause temperatures are low enough (typically 130K) to allow particle formation. There are some nice pictures and explanations here. Outside the summer season, the mesopause region is too warm for NLC formation.
NLC are usually observed polewards of 60Â° latitude but they have been seen occasionally further equatorwards. Three have been a few sightings even in Utah (40N). See e.g. Taylor et al. 2002. NLC occurrence frequency shows a correlation to the 11-year solar cycle. Some years ago, there was some discussion of an increase in NLC but this has been laid to rest with longer data sets becoming available. M. Gadsen has done a lot of work on this and Google Scholar will help you find the papers.
PSC occur in the stratosphere roughly between 15-30km in winter. They can consist of water ice, sulphuric acid droplets or nitric acid tri-hydrate. Depending on temperature, a specific cloud can consist of one of these or a combination of these. They are sometimes also called mother-of-pearl clouds because they can display beautiful colours.
PSC are involved in the destruction of the ozone layer via heterogeneous chemistry on the surface of the PSC particles and de-nitrification. When it gets colder than the threshold for PSC formation (roughly 195K) not only do these beautiful clouds form but also ozone destruction is enhanced.
Hope this clears up the difference between noctilucent clouds and polar stratospheric clouds. If you need more info, you can email me privately.
Re #27 It’s very interesting to see how often Lomborg is criticised on this website. In fact, Lomborg has repeatedly declared that he believes that global warming is happening and that it is human caused. His only discrepancies are related to the prevalent policies advocated to mitigate it. But this website is not about public policies but just about climate science.
I wonder what this constant criticism of Lomborg on this website reveals. Most probably that many AGW-thesis enthusiasts have an environmentalist bias (Lomborg does criticize the alleged science behind other environmental issues). Hopefully not an ideological bias of that kind among contributors and mainstream climate scientists.
[Response: Read the GW chapter of TSE. Its full of nit-picks, many of which (like the MSU stuff) have turned out to be wrong - William]
Comment by Mikel Marinelarena — 16 Mar 2006 @ 3:52 PM
Interestingly, there seems to be some disagreement between the climate model response to the 1883 Krakatoa eruption [very noticeable] and the observed global temperature record [somewhat of a damp squib]. This suggests one of three [four?] possibilities [or a combination thereof]:
1. The climate models are over-sensitive to the volcanic aerosol forcing.
a. Because they are over sensitive to aerosols [ie the model is wrong and the obs are right]
b. Because they are over sensitive to radiative forcing more generally. [ie the model is wrong and the obs are right and climate sensitivity is lower than the models suggest]
2. The temperature reconstruction is faulty. [ie the model is right and the obs are wrong]
3. The [volcano aerosol] forcing reconstruction is faulty. [ie the model and the obs may both be right]
In fact the main discrepancy seems to be with the sea surface temperature [SST] response, the land surface response is quite good. This discrepancy is that the obs don’t have a Krakatoa-induced dip, whereas the models do.
Interestingly, this difference appears to be reversed for a dip in the SST obs around 1910, when the model ocean doesn’t show a large response. I note that this appears to be correlated with a volcanic eruption where Sato et al and Robauck & Free disagree on the radiative forcing of the volcano, so this later discrepancy may depend on the dataset used for the volcanoe forcing in the model.
However, the main point is that the [negative] forcing from volcanic eruptions is shortlived [a few years at most] since the aerosols eventually get rained out, whereas the forcing from CO2 is long-lived because the CO2 accumulates in the atmosphere.
[Response: Well spotted! This discrepency has been investigated by us in the Hansen et al (submitted) paper looking at the transient runs. Check out Fig 7/section 4.2 (p11). Basically, while there is some uncertainty in the size of the forcing (which could play a role), a more likely reason is that the ocean temperature reconstructions fail to capture the strength of the cooling. If the comparison of the model is just done over land where there are station data, than (although the record is a little noisier) the match to the model is much better. The comparison for Pinatubo shows that the models are appropriately sensitive to volcanic aerosols, and the land station match implies that the aersosol forcing is not that far off. - gavin]
Re #58 Leaving nitpicks aside, Lomborg actually declares himself a supporter of AGW. But even if he weren’t, I had understood that ad-hominems such as the one in post 27 were not welcome on this website.
By the way, I’m still waiting for my reply to Hank Roberts in http://www.realclimate.org/index.php?p=268 to be published. 2 days already and counting. I had to submit previous posts several times before they could eventually see the light. Are my moderately sceptical opinions being censored??
If so, could you be so kind and let me know, so that I stop wasting my time composing them?
Many thanks in advance.
[Response: Do you consider it "censorship" when a newspaper declines publication of Letters to the Editor that are deemed irrelevant, repetitive or just uninteresting? In order to keep the discussions more on-target and avoid repetition of positions that have been aired amply before, we have indeed decided to be a little more aggressive in moderating the comments. In doing this moderation, it does seem to me that a disproportionate share of comments I've deleted on the grounds of repetitiveness, inflammatoriness, dullness or just plain wrongness have been from the skeptical side. I don't think that reflects any prejudice on my part, but more the general impoverishment of scientifically credible ideas on the part of the skeptics. As for post 27 on Lomborg, I don't see anything the least ad hominem about it. It is very common for that community to declare that there are more pressing things to spend money on than avoiding global warming, but when that argument never gets translated into action on such self-declared priorities, one begins, quite legitimately, to suspect that it's just a ruse or delaying tactic. To put it another way, if those who declare we should be spending on clean water instead in fact fail to make any successful arguments resulting in more spending on clean water, one has to suspect that their arguments for clean water vs. global warming are not so convincing after all. To be sure, one should look at the arguments themselves, but if the proponents of such action fail to act, that's valid data. --raypierre]
Comment by Mikel Marinelarena — 17 Mar 2006 @ 1:46 PM
Here’s another new resource that may be useful and I think answers a need that has been mentioned here before for a concise summary of recent climate change science: the World Resources Institute has published a 14-page “issue brief” entitled “Climate science 2005: Major new discoveries“. It is available from the WRI website in PDF format, and the content is also available as web pages on the WRI site:
2005 was a year in which the scientific discoveries and new research on climate change confirmed the fears and concerns of the science community. The findings reported in the peer-reviewed journals last year point to an unavoidable conclusion: The physical consequences of climate change are no longer theoretical; they are real, they are here, and they can be quantified.
In this short paper, WRI reviews some of the major discoveries from the past year. Taken collectively, they suggest that the world may well have moved past a key physical tipping point.
In addition, the science tells us the effects of climate change are at a scale that adds enormous urgency not only to the efforts to prevent additional change, but equally important, to efforts to adapt to the impacts already occurring.
Finally, the science makes it clear that additional climate impacts will result even if emissions of greenhouse gases are halted immediately.
A wide body of scientific and technical literature was reviewed in the preparation of this paper, including key general science journals (Nature and Science), several technical journals (Geophysical Research Letters, Annals of the Missouri Botanical Gardens, Ecology Letters, Ecology, Environment International, and Journal of Climate) and material from key web sites and international organizations (RealScience.org, the UN’s Food and Agriculture Organization, the U.S. Department of Energy, and others).
Each scientific paper is briefly described, along with the full citation to the original paper, and a short comment regarding the implications of each discovery is offered.
With all that being the case, you do not have to worry about my posting here any more. Even though one would expect a great improvement from now on, with NO more comments being repetitive, irrelevant, uninteresting, inflammatory, dull or just plain wrong :-)
[Response: I can't promise that moderation will be 100% effective at achieving the goals of making the discussion more informative, nor can I promise that it will never be the case that a comment gets unfairly deleted. Nonetheless, it is hoped that a little more active moderation will improve the quality of discussion. --raypierre]
Comment by Mikel Marinelarena — 17 Mar 2006 @ 3:01 PM
I looked at the blog: “A few things ill-considered” and objected right away with this:
“But in the natural process, every tonne of carbon going into the atmosphere is balanced by one coming out. What we have done is to alter only one side of this balance, we put CO2 into the air but, unlike nature, we are not taking it out. ”
Which is absolute nonesense. If nature was perfectly balanced there would be no glacial cycle. Right now, nature, in the absence of man, would be spewing out net carbon, don’t need to look beyond the previous glacial cycles to see this obvious point. Peat burns during dry interglacial periods, forests burn, soil oxidize, tundra unfreezes, natural coal burns. I would be suprised if the Canadian tar sands have not burned in the past.
And man takes out a lot of carbon. Man is a squirrel, after all, he uses carbon energy on the margins. We never hear much about the carbon man takes out because all the climatologists are having a bonanza on the well measured carbon we are putting in. More research carbon research will balance this falshood.
And my final point, of course we manage a lot of the fluxes, we are the top squirrel. We have almost half the surface carbon under our control to some extent, no wonder we emit so much carbon.
[Response: I think a case could be made that the item you cite should be edited a bit, but I don't think it's quite fair to call the claim "absolute nonsense." As an approximation to the situation, it's almost correct. You're quite right that the natural carbon cycle is not completely in balance -- that's why CO2 can fluctuate between glacial and interglacial cycles, or on longer time scales between the generally high Cretaceous values and the lower Pleistocene ones. Still, if one compares the annual imbalance needed to cause such changes with the kind of imbalance created today by anthropogenic CO2, it's not such bad approximation to consider the unperturbed system to be in a state of balance. You are certainly correct, though, that the precision of the wording in the item could be improved. --raypierre]
I may need to clarify the wording a bit. But I did expand on this “there’s no balance” objection in the comments:
“Balance is of course going to be relative to a timeframe. In the timeframe relevant to the discussion of an anthropogenic disturbance to the climate system it is quite clear that a balance did exist. This is evidenced by the stable concentration of CO2 in the atmosphere over the last several thousand years and also by the stable pH levels that have been reconstructed from analysis of foraminifera shells in ocean sediments. So, no significant changes in CO2 levels in the ocean and no significant changes in CO2 levels in the air over many thousands of years tells us that the large fluxes in and out of the ocean and the atmosphere were in fact in balance during all this time. This is NOT an assumption it is an OBSERVATION.”
So while yes, on a long enough timeframe there are plenty of natural disturbances to a balanced carbon cycle, but I don’t see it as relevant and it is certainly not a credible reason to reject the anthropogenic nature of the CO2 rise.
Regarding the timescales of the response of the atmospheric and oceanic carbon dioxide pools to fossil fuel emissions: Perhaps it’s worth noting that there is a dynamic balance involved, more like a balance of rates then a balance of opposing forces.
The limited ability of the oceans to absorb the CO2 that’s been injected into the atmosphere over the past century is due to physical mixing limitations. If the atmospheric half life of CO2 is ~100 yrs and the oceanic turnover mixing time is on the order of several thousand years, it will take around a millenia of high CO2 levels for the system to reach equilibrium. Measuring pH using fossil shells is then a method of tracking CO2 changes over longer timescales with coarser resolution. CO2 trapped in air bubbles in ancient glaciers is a much finer scale since it takes less then a year for the atmosphere to mix well, and CO2 residence time is around a century. The point is, even the strictly physical factors in modelling the carbon cycle are very complex, which is why a historical record is important for comparison (but see the second link below for a fair and balanced rebuttal to the ice record).
Note that we will be feeling the effects of the CO2 in the atmosphere today for the next century at least, by any measurement. Water will rain out in a few days perhaps- most of the concern with the weather has to do with “‘what is the water vapor going to do over the next few days”. Climate science thus views water as a feedback effect of climate forcings (climate is averaged over some number of years), as this very site explains in great detail. water vapor.
Even more complexities arise due to the chemical and biological interactions with CO2. Consider the ‘balance of payments’ between photosynthesis and rock weathering (CO2 removal mechanisms) on one hand, and biological respiration and fires on the other (CO2 addition mechanisms). Unlike water, CO2 won’t rain out of the atmosphere (unless carbonic acid forms in raindrops, goes into rivers, precipitates out as sea shells). However, as the physical record shows, the atmospheric levels have been fairly consistent and lower then today. Unless of course, you want to believe this: CO2 concentrations using 19th century technology
It’d be nice to imagine that the biosphere, in response to higher CO2 levels, is growing in response and that there will be an acclerated rate of photosynthesis. What is the comparison between the current rate of fossil fuel emissions and the current rate of atmospheric CO2 increase? Isn’t it 50% of the total fossil carbon observed, with 50% accounted for by a hidden sink? Is it the biosphere serving as a atmospheric buffer for carbon dioxide from fossil sources? In one sense, the overall ‘health’ or activity of the biosphere might be measured by comparing the rates of the carbon cycle, the nitrogen cycle, the water cycle, etc. Finally, if this is so then why hasn’t the biosphere gone and absorbed the excess fossil CO2? That could be due to overlying factors involving deforestation and desertification. This statement isn’t meant to reassure that the biosphere would save us; it could perhaps adjust happily to a situation san human beings at a slightly higher temperature. Point being that the biosphere cycles a huge amount of carbon through the atmosphere every year in a distributed fashion, yet the atmospheric levels of CO2 remain fairly constant until humans start injecting tons of fossil carbon into the atmosphere. Too bad we couldn’t have injected all those billions of tons of CO2 into the Martian atmosphere, where they would have warmed the planet up a bit. It seems much less controversial when you talk about CO2 and the Martian atmosphere, doesn’t it?
It does seems to indicate that planting trees as a form of temporary carbon storage (trees that live several hundred years, at least) would be a good idea. Indeed, the oceanographer John Martin said famously and irreverently that he could deliver an ice age with a tanker full of iron, while discussing the role of iron limitation on photosynthesis and nitrogen cycling in various regions of the open oceans. The general idea of promoting biosphere functions and limiting fossil carbon emissions has many positive effects. Other choices would include more of the Road Warrior theme: A warming future
If we talk human causes, then why is it never mentioned that we spend billions to prevent eutrophication of the freshwater systems on land which could take out three times the carbon as the ocean over short periods? In a normal glacial cycle, these systems should be packing co2 in thick layers leaving detritis on the floors of the lakes, indefinitely.
Or, look at the little ice age. If we examine only the human causes, then it is easy to calculate that over a 750 period, medieval man could have removed 10 Gt of carbon from well managed sustainable forests. He built Europe on those forests alone, putting a good deal of that carbon into cities. He left the forests in aggressive growth mode, coppicing sections at a time. The deciduous trees would sprout back, leaving the existing root structure intact. My vostok ice core data shows a steady decline in co2 just during that period, prior to the little ice age.
The problem with focusing on “bad” emissions is we need to understand how man works marginally different than “nature”.
The second danger of focusing on “bad” emissions we may may fail to detect a more serious underlying problem.
Matt, I wish you’d get yourself a web page and invite comments. You write without any footnotes or references, so it’s very hard to say anything about it; you post chunks in whatever topic happens to be lively so there’s no continuity. Please do this in a coherent way somewhere.
Single example not meant for followup here — most cut wood becomes sawdust and scrap and rots; most lumber lasts less long than the tree it would have stood in. Most standing trees are mostly ‘dead’ heartwood preserved from decomposition better than any human technique permits. Fallen trees in the forest have far more life in them than live trees because the heartwood is rapidly consumed and becomes other forms of life. http://www.kfoa.co.nz/faqs.htm#3
Forest fires and logging turn trees rapidly into carbon dioxide. Few wood houses last a century. Little furniture lasts a century. Pallets and scrap last only a few years.
You can look this stuff up. If you’d put numbers on your assumptions and say where you get them, it would be possible to think usefully about what you are writing. Right now it seems clever fiction for the most part. If you have a basis for it, please, find a forum and pull it together.
[Response: I agree with this remark. Sometimes we let wild ideas through because they promote interesting discussion, or simply because we all have day jobs to attend to and can't spend a lot of time evaluating each comment. However, repeated lengthy postings of the same general idea without making any attempt at validating it against results readily available in the literature does not serve any useful purpose. So, Matt, I would be pleased if you would keep your posts more concise, and refrain from continually re-introducing this topic until you have some new numbers or new ideas to offer. Also, as Hank says, it would be nice if you would try to keep your postings at least somewhat related to the article under discussion. --raypierre]
Re: #68, “The problem with focusing on ‘bad’ emissions is we need to understand how man works marginally different than ‘nature’.”
Man works very differently from “nature”. Nature does not burn off millions of tons of coal for electrical uses, resulting in the emissions of billions of tons of CO2. Nature does not chop down millions of hectares of ancient forests, resulting in the emission of CO2 from decaying organic matter. Nature does not drill billions of barrels of oil from the ground only to burn it in automobiles, resulting in the emissions of billions of tons of CO2 into the atmosphere.
“The second danger of focusing on ‘bad’ emissions we may may fail to detect a more serious underlying problem.”
And this problem would be what? Can you name it? If not, why do you state such a thing?
Sorry if this deviates from the debate but I’d just like to know if anybody knows of a link to Peter Wadham’s ‘Chimneys’ piece with regard to the THC? I’d certainly like to read what he’s said for an essay I’m doing, rather than relying on The Times article (A tenuous link to the ‘GOOD CLIMATE DEBATE’ thread after all?!).
The EGU site -it was at their conference in Vienna that his remarks originally sparked the media hysteria- is most unhelpful as is university. Anyway, thanks for your time if anyone knows anything, much appreciated.
Re #172: Plus there was a more recent post relating to the THC in January. To find it, check under the “oceans” post category in the right bar. Also, very likely Wadhams has a web site, and if so it may contain much of interest.
Thanks very much for the responses, I had read the previous posts with interest but wanted to try and find an official sourse for the original research other than ‘The Times’ article; no luck on a website for the good professor but I’ve found an email address and will post any links if I get a reply.
You’ll find a reference to an article 3-4 years ago in which Waldman is a coauthor, and this in the comments:
Now a little science, the descending columns of water that Wadham talks about are known as Open-Ocean Convection or Mid-Gyre convection and it occurs in the deep ocean under very specific circumstances, The only locations where it occurs with convection all the way to the ocean bottom are in the Greenland Sea, Labrador Sea, and perhaps occasionally in the Weddell Sea.
However from USNA course on Polar Oceanography this is what they teach about OOC: It is an ephemeral process, in that it stops and starts, sometimes on the order of days, and occurs over a small area, with the convection restricted to a scale of ~100 km, but with descending plumes being even smaller.
One of three sites for open-ocean convection in the Arctic is in the Greenland Sea as there exists a background cyclonic gyre, and a weakly stratified water column. Cold, relatively fresh surface water overlies a uniform column of Greenland Sea Deep Water (GSDW) which is relatively fresh, but very cold. In winter, the stratification is broken down by surface cooling and ice formation. Periodically, the cold Jan Mayen current and atmospheric conditions allow freezing to occur in a several hundred kilometer long bulge of pancake ice known as the Odden ice tongue. Winds blow this newly formed ice out of the Greenland Gyre region, so that the ice is melted at the southern edge, and continues to form on the Northern edge, so that the salinity of the gyre waters can be continuously reduced until deep convection can take place.
Sounds like something the submariners can tell us more about, if they’re allowed to!
Of course, their opinion was given short thrift, with one rebutter on this board pointing out that Barrows had experienced continued warming, and this was evidence, of course, for what else, human induced global warming from CO2 emissions.
Hinkel, K.M., Nelson, F.E., Klene, A.E. and Bell, J.H. 2003. The urban heat island in winter at Barrow, Alaska. International Journal of Climatology 23: 1889-1905.
The summary below comes from, where else, a bought and paid for web site I am sure controlled by big oil. But, my question for this group of scientists, Can this be true?
Barrow, Alaska, which is situated on the Arctic Coastal Plain at the western edge of the Barrow Peninsula near the Chuckchi Sea at 71.3°N, 156.5°W, is described by the authors as “the northernmost settlement in the USA and the largest native community in the Arctic,” the population of which “has grown from about 300 residents in 1900 to more than 4600 in 2000.”
What was done
In mid-June of 2001, Hinkel et al. installed 54 temperature-recording instruments in and around Barrow, half of them within the urban area and the other half distributed across approximately 150 km2 of surrounding land, all of which provided air temperature data at hourly intervals 1.8 meters above the surface of the ground. In this paper, they describe the results they obtained for the following winter (December 2001-March 2002).
What was learned
Based on urban-rural spatial averages for the entire winter period, the urban area was found to be 2.2°C warmer than the rural area. During this period, the mean daily urban-rural temperature difference increased with decreasing temperature, “reaching a peak value of around 6°C in January-February.” It was also determined that the daily urban-rural temperature difference increased with decreasing wind speed, such that under calm conditions (< 4 knots or 2 m s-1) the daily urban-rural temperature difference was 3.2°C in the winter. Last of all, under simultaneous calm and cold conditions, the urban-rural temperature difference was observed to achieve hourly magnitudes exceeding 9°C.
What it means
For a town of less than 5000 people, Barrow has an urban heat island effect that is huge. Perhaps that is why global warming is thought by some to be so strong in high northern latitudes: even small congregations of people in these regions can create a significantly elevated near-surface air temperature where they live and work.
[Response: The Hinkel et al study you quote is quite interesting (though not new), showing that energy use in the high Arctic can contribute to an 'urban' effect during the winter. The paper clearly states that there is no such effect in summer though (when Barrow has been warming almost as fast). One thing you forgot to look into is where the NWS station in Barrow is located and whether it even counts as 'urban' in the context of this study. (Actually it is some way out though the mean temperature anomalies are about average). One interesting point they raise is that any UHI phenomena vanishes when the wind is strong -exactly the same process that Parker (2004) used in his analysis. If this phenomena were widespread and seriously contaminating the processed records then the trends on windy days would be smaller than the trends on calm days. That they are the same indicates that this is not very large effect. I have nothing against this being studied further, but I doubt that any major changes will develop - basically because the ancillary evidence of warming is so clear (ocean heat content, glacier retreat, permafrost melting - especially in Alaska!). Better data is always to be wanted, but I wouldn't put any money on it changing the picture radically. -gavin]
[Response: The other point to make is that the existence of the UHI is no great shock. What you need to show is a UHI effect on *trends*. This is obviously much harder, as you need a long term record -William]
One thing you forgot to look into is where the NWS station in Barrow is located and whether it even counts as ‘urban’ in the context of this study. (Actually it is some way out though the mean temperature anomalies are about average).
That cut-paste is from a well-known skeptic site (lookit the familiar format). I suspect they didn’t “forget” anything, as it has been shown many times that they don’t “forget”. But it would be nice to source it and not hide where the info. came from [e.g. what are you afraid of?].
Until the “most of the surface temp rise = UHI” folks get out there and collect their own data on this well-studied subject, there won’t be anything but this type of argument.
Anyone can find one station with glaring numbers. Let’s see hundreds with glaring numbers. Go git ‘em. If they’re out there like you wish, it should be easy.
Re #78: Haven’t we discussed all of this before, not just the Alaska climatology site but Hinkel et al as well? I remember spending a few minutes locating the Barrow NWS station, which is unsurprisingly out by the airport south of town, and posting that information. I also remember pointing out (to you, I assume) that the Alaska site is simply neutral on the global warming issue. What the site says is that warming is not proceeding in an even manner relative to the CO2 rise, which is true and unsurprising. Even global average temp trends are pretty uneven relative to CO2 rise, and this effect tends to be much exaggerated when individual regions are looked at.
Re Wadham’s work on the diminishing number of chimneys in the Greenland Sea.
The work is covered by two observational papers and one
modelling paper. These are Wadhams et al (Geophysical Research Letters
2002, 2004, on chimneys) and Wilkinson and Wadhams (Journal of Geophysical Research 2003, on salt fluxes). Thanks to Hank for his prior response.
Back on the subject of good climate debate – has anyone seen the following uber-sceptic piece which has just appeared in Scientific American: http://blog.sciam.com/index.php?title=are_you_a_global_warming_skeptic_part_ii&more=1&c=1&tb=1&pb=1
Perhaps the complete antithesis to what Coby has done…
What upsets me about it is the apparent brainwashing by the media getting the general public thinking there is a lack of consensus or great disparities/disagreements between scientists. Here is the question I’m referring to:
“Do you think most scientists agree with one another about whether or not global warming is happening, or do you think there is a lot of disagreement among scientists on this issue?”
Stephen, that site appears to collect announced polling results and publish some of them (more for paying subscribers) but it’s a hodgepodge of what appear contradictory results (different polls, different questions).
You quote one saying by 64:35 the American public thinks most scientists disagree whether global warming is happening (warming, not anthropogenic warming, just warming)
On the same page is another saying
“the world’s temperature may have been going up slowly over the past 100 years. … Do you think this has probably been happening…? — and 85% say yes, they think this has probably been happening.
Different polls — so we can’t just boggle, but nevertheless:
85% of the American public is convinced warming is happening;
64% think the scientific community has no consensus on whether it’s happening.
Where do the citizens get better information than the scientists?
Answer — something about the polling is giving confusing results.
Hmm, anthropogenic or not something is happening. I just read another article in the mainstream media which as a long time scuba diver I have been observing in person for some time now. It may not even be due exclusively to warming but the coral reefs are severly stressed around the globe. I am not a professional marine biologist but I think I can safely say that if the coral is dying the rest of those ecosystems are sure to follow. If nothing else it can’t be too good for the sport diving, fishing and tourism industries in the affected areas. See http://www.cnn.com/2006/TECH/science/03/31/coral.death.ap/index.html
Anyway since we don’t have absolute proof that such warming trends are anthropogenic in nature (pun intended) why don’t we all just crank up the AC and go out and buy a new SUV or two. Why the heck would we want to err on the side of caution.
Coral reefs bleaching and dying is very serious and deserves wider coverage. I think it is a very strong indication of unprecedented (on human species timescales) warming and is impossible to dismiss as normal in any way given the multi-millenial age of these structures/organisms.