It is all good science but is it relevant? In the previous piece, you wrote that the North Atlantic had been chosen because it had the longest record, but the North Atlantic is not typical of hurricane basins. To its north is the Arctic Ocean which is covered in sea ice. The multi-year ice there has been melting and flowing back into the North Atlantic through the Fram Strait. This cold fresh water will have been preventing the sea surface temperatures in the North Atlantic from rising, in the same way as a melting lump of ice in a glass of water keeps the surface temperature at 0 C.
Thus expecting a change in hurricane activity due to rising sea surface temperatures (caused by global warming) may be a little premature in the North Atlantic.
This highlights a problem with the climate that seems to be ignored by scientists. The science is now so complicated, and with each aspect only discussed by experts that field, that no one is allowed or willing to take the broader view. Reductionism rules, and earth system science stagnates.
Re #1 — Andy:
An interesting article, but I think you may have missed another Cat 5 hurricane that made U.S. landfall in modern times i.e., Andrew in 1992. This brings up an interesting point that may have been commented on here before. During the 20th century 3 Cat 5 hurricanes made U.S landfall – the Labor Day Hurricane (1935), Camille (1969), and Andrew (1992). That suggests at least a multidecadal return period for Cat 5 hurricanes making North American landfall. But two such hurricanes – Felix and Dean – made landfall in Nicaragua and the Yucatan Peninsula in August 2007 (according to their Wikipedia pages…).
Sedimentological studies can provide local records of the frequency of intense hurricanes. When a strong hurricane strikes a coastline with sandy barrier islands, coarse deposits of sand and shell are washed into the lagoon behind the barrier island. The overwash deposits are easily distinquished from the more poorly sorted lagoonal sediments, and can be recovered through a technique called vibra-coring. These deposits contain materials that can be radiometrically dated, so a timeline of severe storms can be constructed. To date, these methods have been used to estimate the frequency of intense storms since sea level reached its current level and barrier islands stabilized. For example, a study by S. Knowles ( http://purl.fcla.edu/fcla/dl/SF00000099.pdf )shows four major storms striking Sarasota Bay, Florida, in the last 5,000 years. If conducted regionally, or grouped in a metastudy, the sedimentary record may provide information on the frequency of intense storms along the US Gulf and Atlantic coasts.
Would not the ratio chart show prejudices towards modern wx data collecting standards towards storm classification? Older storms were classifed by a combination of wind, pressure, and wave heights, while today, wind is the primary criteria.
When I used to live in New Mexico, tropical storm remnants -or more frequently moisture blown off of eastern Pacific tropical storms caught up the the North American monsoon was an important increment to the annual precipitation. I’ve heard that the isotopic composition of moisture from tropical weather is distinct. Perhaps there might exist some proxy signals in records of the southwest monsoon?
One source of storm records that doesn’t seem to have been utilised is the records kept by the Royal and other navies. The ships of navies kept pretty detailed records of the weather and between them will have substantial coverage of the world’s oceans. Of course, going through the records might be a trifle daunting, but I think that a lot of the necessary collation will have already been done.
Anyway, just a suggestion.
Thomas – people did look into trying to get a record of those oxygen isotope changes by looking at tree rings. However, the coverage isn’t comprehensive so you can’t really use it to get a record of Atlantic basin hurricane activity (offshore hurricanes don’t register), just the history of that particular tree.
“It draws no conclusions about the effect of AGW on hurricanes (neither ‘climate change’ nor ‘global warming’ occurs in the paper). Nor does it claim to have shown that ‘late 20th century Atlantic hurricane frequency is not at all unusual’ . Indeed, the most recent year they examine is 1990, whereas 1995 is usually viewed as the start of the recent high activity.
The method they use is important, but it can only detect whether hurricanes which cause significant O18 depleted rain to fall on the trees sampled. (Note they fail to detect the above average seasons of 1893 and 1898.) Further, they make no claim to be able to detect the number of hurricanes in a season, or the intensity of a hurricane. Although they do not attempt to calculate the proportion of total Atlantic activity their method detects, it does not seem amiss to suggest their method detects only a small fraction of total Atlantic activity. Had it been extended to include recent hurricane years (not necessarily feasible with tree-ring studies), it might well be insufficient to detect a trend.”
Regarding comment #3. Andy Revkin’s article does refer to Hurricane Andrew,but Dr. Landsea describes it as a category 4 storm. The fact that he can’t answer whether it has a 1.0 % or 0.5% or 0.1% chance of occurrence shows how far we need to go in categorizing and understanding the recurrence interval of these very severe storms.
Going back to comment #6 it is often mentioned that El Nino leads to greater wind shear reducing hurricane activity in the Atlantic Basin. This past hurricane season a La Nina was building, that has in part been the cause of the cool winter in the west. However, over the Gulf of Mexico and Caribbean looking at the daily satellite imagery with my classes it seemed that Wind shear was high as La Nina built this year. Is this usual when there significantly changing conditions in the tropical pacific? It was also evident the wind shear was reduced at the southern edge of the hurricane formation zone, which is where the Category 5′s formed.
Talking about El Nino and atlantic hurricane activity.
If in the habit of checking global sea surface temperature maps daily, it is nearly impossible to not notice that El Nino conditions(high sst’s and episodes of trade wind reversals) in the central pacific does not rule out the possibility of cold anomalies dominating the east for months to come. Current sst’s looks like 2/3 La Nina and 1/3 El Nino, with the el nino part closest to the Atlantic. Is this unusual ?
Re: 11. Haven’t read the Landsea et al. 2004 paper in the Bulletin of the AMS, but the National Hurricane Center’s web page for Hurricane Andrew (http://www.nhc.noaa.gov/1992andrew_add.html), in referring to that paper, seems to suggest they concluded it was a Cat 5:
” In particular, Hurricane Andrew is now indicated to have made landfall on the lower Florida east coast with Category 5 intensity on the Saffir-Simpson Hurricane Scale.”
Looks to me like the usual suspects making the usual misinformed/disinformed arguments and preying on the same ignorant fools as ever. Makes me wonder if any of these guys have ever cracked even an IPCC executive summary.
Hank, I think the “investment” could pay off quite handily, as long as you aren’t too particular about where the money came from.
RE #16, perhaps these investors have invested in seashore land near the Atlantic or Gulf of Mexico at top dollar, and they’d like to see their land value increase. The idea we may be facing increasing hurricanes, sea rise, and sea surges would be very bad news to them (on top of the real estate slump and all), so simply deny it and get others to believe them….at least long enough to sell their investments (once the real estate slump is over) at very high profit.
Well Craig RC notes these sort of places all the time. I hadn’t seen this one before. Somebody dropped it on me in a diatribe yesterday. Same players out with a new false front of legitimacy. I think exposing it for what it is has value. The global warming test recycled from that old West Virginia site is telling too. Every denier uses this same stuff. It never goes away.
Twelve-hour long drop in temperatures overwhelms a century of warming
Over the past half day, anecdotal evidence for a cooling planet has exploded. Switzerland has had its coldest night for weeks, Munich has experienced frozen fountains, several rats perished by cold in Rome, numerous cars crashed because of heavy snowfalls in the streets of London – the list goes on and on.
The total amount of cooling in all these places over the last twelve hours ranges from 10C up to 15C, a value largely overwhelming all the warming recorded over the past 100 years. All in twelve hours time.
Scientists quoted in a past DailyTech article link the cooling to reduced solar activity which they claim is a much larger driver of climate change than man-made greenhouse gases. The dramatic cooling seen in just twelve hours time seems to bear that out. This demonstrates that more powerful factors are now cooling the Earth.
Upshot: The quoted scientists would be right: It was the sun…
Re #22 “Please debunk these”.
Have patience, time will debunk them :-(
Comment by Martin Vermeer — 27 Feb 2008 @ 12:57 PM
Such a temperature drop is not unusual for a change from El Niño to La Niña conditions. From February 1998 to November 2000 you find a temperature drop of 0.597 C in the same dataset. Nothing new in the world. And there is always natural variability (on multiple timescales) overlayed which can strengthen or weaken the ENSO influence.
My thinking — aside from it getting warmer elsewhere & it’s the average that’s important, or one cold snap does not a cooling trend make, or it’s pretty hot where I live in S. Texas (hotter than most winters, I believe) — could this be an indication of the ocean conveyor or thermohaline current slowing down?? I also read recently that while scientists think this unlikely in the near future, they have not ruled it out in the more distant future. But like nearly everything else about GW, scientists may be underestimating this (due to their necessary (to protect their reputations) focus on avoiding false positives).
Also I have a theory that there will be more wild swings in local temps, a greater day to day variance, even along side a warming trend & a lower average variance between night and day temps (this is just based on a not-so-educated guess).
Comment by Lynn Vincentnathan — 27 Feb 2008 @ 1:42 PM
hmm i think this is flickering – small and big fluctuations. Something liek positive feedbacks. At least this is how i interpret it when i think about it. Well ok i read now the above suggested links. To bad im really busy atm with my stupid HP scanner :D
Lynn Vincentnathan (27) — The weather this winter is thought to be due to a strong La Nina combined with a prolonged solar minimum.
Not attributed to anything to do with climate change.
Comment by David B. Benson — 27 Feb 2008 @ 3:22 PM
Lynn: Clearly this is a case of changing baselines. I imagine in 50 years if they get any substantial snowfall at all in Chicago it will make the news and some old crotchity fellas will mumble about how they were right all along to deny the earth is warming. Has it been that cold this winter? Compared to say the 1970′s? I know in the Lodgepole Pine forests of the western U.S. they are still waiting for those two weeks of -40f night temps that used to keep pine beetles in check. Has the artic ocean refrozen to a depth of 3 meters or more? How about in our neck of the woods. I think the last time Galveston had freezing temps was in 1990 or thereabouts. I have an 1870 map of Galveston Bay with a hand written note on the back, “bay frozen today with 5″ of slush”. Could you imagine that happening today? Do you remember the 3 days of below freezing daytime temps in 1989 that Corpus Christi experienced? I suppose if that happened this year Rush Limbaugh would do a live broadcast proclaiming global warming has stopped. Was that really so long ago? It seems like a different world today doesn’t it? How could things be changing so rapidly and people not stand up and scream. Are humans really that short of memory when it comes to the natural world? As for me and my banana tree; we’re doing just fine this winter up here near Houston.
I hear you Andrew. Up here in Washington State, we had a tornado in January and days of temps in the upper 50s/lo 60s in february. I’ve seen hummingbirds buzzing around throughout the winter looking really healthy so far.
Comment by Philippe Chantreau — 27 Feb 2008 @ 11:36 PM
I lived in Chicago in the 70′s and now I live in Grand Rapids, Michigan (which doesn’t get as cold as Chicago, but we get tons and tons of snow-it’s phenomenal really). Whle this year has been more snowy than the last several in GR, we didn’t get more snow than winters 7-8 years ago. And Chicago got a lot MORE snow in the 70′s and the winters were a lot colder then than they are now. Although I have been complaining about this winter to anyone who will listen, it is mild compared to the ones I remember from 30 years ago in Chicago, for sure.
I’ve seen hummingbirds buzzing around throughout the winter looking really healthy so far.
For the record, Anna’s hummingbirds are winter residents in WA/OR, so seeing healthy hummers buzzing around during winter is not a big deal. Unless you’re seeing rufous or (in the drier part of the state) black-chinned etc. Now that would be interesting …
I just looked them up, Dhogaza and you’re right. I am pretty sure they are the normal winter residents, so nothing new there. I guess they just seemed exotic to me for having seen hummingbirds mainly in Africa and Southern US before. The little buzzers are also hard to identify. Bu thanks to you and Hank for the tips.
Comment by Philippe Chantreau — 28 Feb 2008 @ 11:57 AM
Philippe, you’re not the first person to be surprised to learn that we have winter resident hummers in the PNW.
Though they don’t winter anywhere near OR/WA, rufous hummingbirds are expanding their wintering range northward, as far east and north as Alabama (their historical wintering range has been mostly mexico with some in the southwest US). Is this related to global warming? We don’t know, but a large number of species are expanding their ranges northward, so we certainly can’t rule it out (pitiful attempt to stay on-topic, see?)
However, as far as I know, no hummingbird as of yet has expanded its range to AFRICA :) Might I humbly suggest you need a better pair of binoculars? Or a more accurate bird book?
Subject: NOAA: Increased Hurricane Losses Due to More People, Wealth Along Coastlines, Not Stronger Storms
FOR IMMEDIATE RELEASE – February 21, 2008*** NEWS FROM NOAA ***
NATIONAL OCEANIC & ATMOSPHERIC ADMINISTRATION U. S. DEPARTMENT OF COMMERCE WASHINGTON, DC
Contact: Dennis Feltgen, NOAA 305-229-4404Increased Hurricane Losses Due to More People,
Wealth Along Coastlines, Not Stronger Storms, New Study Says
A team of scientists have found that the economic damages from hurricanes have increased in the U.S. over time due to greater population, infrastructure, and wealth on the U.S. coastlines, and not to any spike in the number or intensity of hurricanes.
“We found that although some decades were quieter and less damaging in the U.S. and others had more land-falling hurricanes and more damage, the economic costs of land-falling hurricanes have steadily increased over time,” said Chris Landsea, one of the researchers as well as the science and operations officer at NOAA’s National Hurricane Center in Miami. “There is nothing in the U.S. hurricane damage record that indicates global warming has caused a significant increase in destruction along our coasts.”
Link to paper: http://sciencepolicy.colorado.edu/admin/publication_files/resource-2476-2008.02.pdf
RE the coldsnap deniers, they also point out extreme increase of snowfall. But isn’t that what’s predicted in a GW world? GW increases water vapor retention in the atmosphere, which comes down as severe precipitation events, ususally rain, but if the weather gets colder (in its usual seasonal and daily fluctuations between warmer and colder temps), that could mean extreme snow events.
So again, the denialists have proven GW as a done deal fact. At this rate of success, the denialists will soon have proven the thermohaline ocean conveyor has shut down….maybe by next year.
re: 40. As a meteorologist, I think that is quite a misleading statement and somewhat of a red-herring by Landsea. Most published, peer-reviewed trend studies on hurricanes focus on the number and/or intensity of the storms, not on economic damage or destruction due to only land-falling storms. By focusing on land-falling storms, he is only considering a small subset of storms. There is no question that the coastal area growth and population have grown exponentially along over the past four or five decades.
First comment: The authors mention a couple of factors they could not include in the analyses. One is building standards. They argue, that stronger building codes only have been introduced recently and therefore would not influence the result. However, building standards also can change without codes over time. I am not economist, but I suppose that building quality might have to do something with wealth, since more solid building is more expensive. This would suggest, that with increasing wealth building quality might have improved, which would decrease losses today.
A second point is warning. The possibilities to warn people against coming hurricanes have improved over time without doubt. I do not know what possibilities people really have to reduce damage costs if they are warned early enough (maybe a reader living at the U.S. coast could help), but I am not sure that it is negligible. Both factors, when not accounted for, lead to an overestimate of past damages in the author’s normalizations.
Third point: Losses very strongly depend on where the storm hits land. If Katrina would not have hit New Orleans, but hit land somewhere to the east or west, damages would have been drastically lower. Same thing with the hurricane that hit Miami. If it would have hit land at a less dense populated area, damages would have been much less. Considering the relatively small sample (only around 150 storms), an artificial trend in the very noisy distribution of population density in landfall locations might be significant and should be investigated. It might either lead to an artificial negative or positive bias in the trend.
Second comment: As the authors mention, there is no significant trend in the geophysical data (hurricane frequency and intensity on U.S. landfalls). So why should we expect an increase in losses due to changes in the geophysical data? If there isn’t an influence of climate change on geophysical data, why to go a long way round an analyse loss data to show that there is no trend?
Third comment: Basically, there are a couple of problems with statistics of extreme events. Changes in extreme events, which are rare by definition, must be enormous until it is possible to detect statistically significant trends. As Frei and Schär (J. Climate, 14, 1568–1584) have shown, a frequency change by a factor of 1.5 can be detected with a probability of only 0.2 for events with an average return period of 100 days. For the U.S. hurricane landalls (about 150 events in 100 years), the return period is more than 200 years, which further lowers the detection probability. Thus we have a very low probability to detect even a 50% increase in U.S. landfalls over the last century. If we look at losses, the above mentioned noise of population density at landfall location adds up and further decreases detection probability. Moreover, there are less than 20 events which account for more than half of the losses. To detect a trend in such a small number is extremly unlikely, even if the frequency has doubled. Thus, the probability to detect any climate change related trends in loss statistics belongs to the category hopeless.
I was recently searching for some information on the “State of the Weather” in the Southern Hemisphere the other day and was unsuccessful in finding general information. I did just come across an article in this blog someone posted an article were they mention that Australia has seen it’s warmest January on record.Does anyone know of any information about what’s going on in the Southern Hemisphere? Are they experiencing extreme weather as well???
I had to make this comment as well since everyone is OT anyways: We got a snowstorm here the other day in Albany NY, i’m sure most of you are aware of the big storm that dropped heavy snow and caused sever storms in FL at the same time. What absolutely blew my mind were the size of the snowflakes. At one point, they were almost magical, like in a fantasy… I had to go outside and experience it. I bundled up and went outside. I was wearing a black polo fleece that was a perfect backdrop for the snowflakes. When I tell you the diameter of these snowflakes were at least equal to that of a large plum, I’m not joking. they were HUGE. My camera wouldn’t work for me, because I was dumbfounded. I called it GW Snow… it was there was so much moisture in the Atmosphere the snowflakes could grow bigger and bigger. They were so big. i was covered in snow within a minute. Never seen anything like it, and living in Albany NY, I’ve seen lots of snow storms, although, before this year, the winters have been exrremely warm/mild, and snowless. Rainy, yes, but not really snowy.
Re: posts 15 & 16,
On a different forum where I post in favour of AGW, the denialists brought up ICECAP. I chose to examine who their ‘experts’ were. The ones whose names I’d seen before are (working down the list):-
See if you can predict some more denialists with surnames beginning with later alphabet letters who might be on the list …….
Comment by Bob Clipperton (UK) — 29 Feb 2008 @ 4:36 AM
[Note: This comment was posted to the wrong thread--it has been relocated here (w/ a response)]
Robert Bauserman Says:
28 February 2008 at 1:49 PM
I am a bit confused about the difference in how the two proxies correlate with storm frequency. You write:
…the coral proxies show a positive correlation to wind shear over the MDR, but a negative correlation north of it. …The sediment proxy shows a positive correlation to wind shear over the MDR and no correlation north of it.
So how do we get from this to the statement that the two proxies are corrleated to wind shear in opposite directions? If both of them are positively correlated to wind shear over the MDR, and outside of the MDR one is negatively correlated and the other uncorrelated, I fail to see the difference in the direction of the relationship. Help me out here! (And yes, I have studied statistics). What am I missing?
[Response: Oops..., you are right. There is an erroneous inversion in the text on the coral proxies (it's obvious from Fig. 2 in Nyberg et al.). Thanks!... fixed. -Urs]
Sorry to interject an idea not on topic. Being as I was raise near the “affected” region one of the measures we consider in regards to TCs were the “Treasure Ships”. Most of the dates of the wrecks are well documented and though they in themselves may not specify the count they may provide some insight to possible intensity. There is also the character of how many of these ships were stabilized during the storms. Rather then journey out to deep waters away from land many of the Captains would attempt to get close to the Leeward side of a land form and anchor out with at least one hook on the land form as a type of lifeline in the event of disaster.
Other incidental considerations may related to the amount of erosion over time since the land hooks were dropped. As a general rule the intent was to walk the anchor a few hundred feet onto land. (A notable example is a wreck off Melbourne Beach FL. in that the land hook was found on the shoreline in 1962. Given that most replenishment activities did not begin until after this time it would suggest that the original shore line had to be a few hundred feet out into the surf at the time of the wreck.) With the rate of erosion in this region being less then 1 foot per decade on average, and generally subject to hundred year storms, this region seldom received the full brunt of TC conditions, these types of measures may help add to the proxy data quality.
Comment by L. David Cooke — 29 Feb 2008 @ 11:59 AM
RE #45, I’m thinking if the tables are turned here and we’re in the future with GW going full force, say 2C increase, and we take “GW increases hurricane intensity” as our null hypothesis (as environmentalists and policy-makers and potential & actual victims of GW should), then we would also have just as a serious problem in proving GW is NOT causing the landfalling hurricanes that hit densely populated, expensive property areas & cause enormous damage, harm, and expense.
And since it is the GHGs we’re emitting today (& yesterday) that will contribute to this scenario in the future, then in addition to building better hurricane-proof buildings and higher levees, we should also be seriously reducing our GHGs right now.
I understand that scientists and lawyers defending clients against being sued for GW need to have high standards in avoiding false positives, but the rest of us don’t need such high standards. Especially when reducing GHGs here in the U.S. by 75% could save us a great deal of money without lowering living standards or productivity (some of that money could then be plowed into building more hurricane-proof buildings). With new compressed air car tech on the horizon to supersede the hydrogen concept, it looks like we may be able to reduce GHGs even further; see:
Sorry Dhogaza, I was slacking on ornithological erudition. I was actually referring to sunbirds, that are not quite adept at hovering and can not fly backwards. They’re also larger, therefore easier to spot and identify, even without binoculars, which are not very useful in the forest most of the time :)
Comment by Philippe Chantreau — 29 Feb 2008 @ 12:16 PM
Chris S (46) — Drought in central Chile, attributed to La Nina. Recent flooding in several countries in southeastern Africa.
That is all I noticed, following the news daily. (Try BBC)
Comment by David B. Benson — 29 Feb 2008 @ 12:40 PM
Re: 46. Part of what is happening is that the Great Lakes are bleeding themselves out. Less ice cover in the winter and warmer Lake waters attributed to the warming climate have increased surface evaporation and are producing more lake effect snow. Unfortunately a lot of this snow falls out of the Lake’s watersheds. The upper Great Lakes are at near record low water levels.
Re #47 and the appearance of Reid Bryson on Bob Clipperton’s list.
Something I have wondered about: Back in the 70s, Reid Bryson was perhaps the best-credentialled of those worrying about The Next Ice Age arriving soon. Pat Michaels got his Ph.D. in ecological climatology from the University of Wisconsin. Although I have looked at both bios, I have found no indication of whether Michaels was one of Bryson’s Ph.D. students. Just curious.
Re #16: Hank, the fossil fuel industry and similar very much are investing in these denialist information outlets. They don;t get direct dividends, but from their point of view delay = $. Such investments are arguably their most lucrative. What’s odd is that ICECAP would describe the investments in such terms. OTOH maybe their use of the term can be explained by the extreme libertarian POV that virtue tracks self-interest.
Lynn… Hansen has recently presented his expectation that CO2 levels must be brought below 350ppm and maybe as low as 300ppm for the long term health of our planet. This will require that we must go below zero emissions and begin to actively sink CO2 as soon as possible. See his Feb08 pdf or power point on his web site. http://www.columbia.edu/~jeh1/ I understand he has a paper in the works backing up his statements.
The New Scientist article merely summarized a paper by Damon Matthews and Ken Caldeira published in Geophysical Research Letters:
Only zero emissions can prevent a warmer planet
13:49 29 February 2008
NewScientist.com news service
Greenhouse gas emissions will have to be eliminated completely to stabilise the Earth’s climate and prevent temperatures from rising. That’s the conclusion of climatologists in the US who say that our current efforts to merely stabilise emissions will not be enough.
Damon Matthews, from Concordia University in Canada, and Ken Caldeira, from the Carnegie Institution for Science, Stanford, USA, used a global climate model to study how greenhouse emissions would need to change in order to stabilise global temperatures over the next few hundred years. Previous studies have only looked at what happens when emissions are stabilised…So far industrial emissions total around 450 billion tonnes. “Even if we eliminated carbon dioxide today we are still committed to a global temperature rise of around 0.8 ºC lasting at least 500 years,” says Caldeira…Roger Pielke, a climate policy expert at the University of Colorado in Boulder, agrees with the findings. “This research makes the case that simply stabilising concentrations is insufficient to stabilise temperatures. Their argument, if widely accepted, raises the bar on what it means to mitigate climate change,” he says.
There isn’t any lack of good data about hurricanes making landfall in the US. Until someone can demonstrate that hurricanes have for some reason become less likely to hit the US, this argument and discussion is a ruse.
A prominent Australian economist came to that conclusion as well as he handed our current gov his interim paper of the economic effects of climate change and pressed our gov for a 90% reduction in emmissions by 2050 intead of the proposed 60% limit to avert a disater for us economically stating that australia is extremely vunerable to the worsening effects of CC. I was heartened to hear a few weeks back that the head of GM in america said that future cars will have to be significantly cleaner and that the days of the big ‘yank tank’ were numbered and that new fuel sources will have to be discovered or improved upon. Here a leading US corporation is speaking up and saying we will have to have radical change in the products it sells. Anything less than almost total global cessation in the burning of fossil fuels is the only way to eventually mitigate CC and to prevent uncontrollable +ve loops from happening.
Comment by Lawrence Coleman — 2 Mar 2008 @ 10:33 AM
The concept of “stabilizing” the climate implies two things.
1. The climate is unstable
2. The climate is normally stable without human interference.
RE #65, I think they are looking at it from a “what’s best for human and other life” POV. I don’t think anyone here actually suggests that the climate is static. There have been extreme global warming hysteresis cases in the past and even without human intervention one would expect such sometime in the future. For instance, 95% of life on earth died 251 mya during the end-Permian extinction.
But since we people have been smart enough to develop the technology that may be triggering a new global warming hysteresis wipe out of life on earth, you’d think we might be smart enough to halt or reduce this. Time will tell.
Comment by Lynn Vincentnathan — 3 Mar 2008 @ 2:45 PM
For me these statistics appear not too interesting. Few data points, noisy observation quality. Interesting as discussion topics, but nothing reliable can come out of them as such.
How about the basic physics that generate the storms? So far I have found that there are about 9 preconditions for a hurricane to form. Right season, suitable latitude bands, oceanic environment, adequate surface water temperature, depth of warm water, high humidity profile (no dry layers), low wind shear, presence of an easterly wave, possibly a low CCN (dust) count.
Several of these factors relate to what happens in Africa. Recent changes include drying out of Lake Chad in central Africa, which turned an intensely evaporating surface into a dust bowl. Some 25000 sqkm (in 1960) diminished into 1600 sqkm now …
I saw recently a report saying that the tropical band has expanded by about 4 degrees. In West Africa there is a long linear east-west coastline, roughly matching the northern edge of the tropical band. Band expansion turns some relevant precursor processes from oceanic into coastal/inland types. In general the change in that area appears uncertain as climate models can not decide on a trend on humidity/rain (or can they?).
Some 8000 years ago when the global temperatures were about 2 degrees warmer, Sahara was a grass savanna with lakes and rivers. There even was a huge Lake Super-Chad (one million sqkm), some 60 times larger than today. Recent trend is the direct opposite, a drier climate despite of general warming. A different input, though. Then it was high solar intensity, now it is strong greenhouse effect and major land use change.
Pacific storms should be in some respects different. There is little impact from a large, dry continent up-stream.
The basic physic is pretty straightforward to me, atmospheric instability, a parcel of relative cold air situated above a relative warm surface is all it takes to form an hurricane like whirlwind.
Picture of an arctic hurricane: http://nsidc.org/arcticmet/patterns/polar_low.html
“In satellite imagery polar lows show characteristic spiral or comma shaped patterns of deep clouds, sometimes with an inner “eye” similar to those seen in tropical cyclones. Convective cloud bands occupy the surroundings (see figure below). Analysis of aircraft and radiosonde data collected during field experiments reveals that polar lows may possess warm cores. This finding, coupled with their appearance in satellite imagery, has prompted some investigators to refer to polar lows as “arctic hurricanes,” although they seldom, if ever, possess hurricane strength winds”
His “research” (published in Natural Hazards Review) demonstrates that hurricanes are not getting more destructive, and that six of the ten most destructive storms occurred before 1945. The article also refers to “23 inches of sea level rise this century” under business as usual as though that is the current expectation.