There was an interesting piece that appeared in the October 12 edition of the Seattle Times, “Q&A: Global warming — a world of evidence”. This follows up on a previous article by journalist Sandi Doughton in the October 9 issue of the Times, “The Truth About Global Warming”.
In the Q&A, a group of University of Washington scientists, including atmospheric scientist and climate researcher J. Mike Wallace, weigh in with answers to questions fielded from the paper’s readers. Many of the questions, such as “Isn’t it true that scientists in the 1970s said the earth was cooling?” are quite similar to those we’ve addressed here at RealClimate (see “The Global Cooling Myth”).
Wallace’s perspectives are particularly interesting because he is both a highly respected climate researcher (and National Academy of Sciences member) and, like a number of other long-time researchers in the field, was once a “skeptic” (in the best sense of the word) regarding the evidence for anthropogenic climate change. However, like many other such researchers, he has become convinced by the compelling weight of evidence indicating human influence on climate that has unfolded over the past decade, remarking that “with each passing year the evidence has gotten stronger — and is getting stronger still.“
Re #46,
Not yet read the report, but I have read the Levitus e.a. papers. The same problem as for the ice melting emerges here: reliable (deep) ocean measurements are only available since 1955, the previous warming of the oceans is only known from sea surface measurements… Further, the abstract indicates that the faster warming of the Arctic Oceans is modeled, not measured… In Levitus e.a. 2005, figure #2 indicates that the heat content for certain latitudes (10N-30N) has increased 3-6 times more than for the 70N-90N latitudes…
Check your inbox, Steve.
D
Re #47
Indeed a horror story, extrapolated from a 30 years trend, from midst a cool period to midst a warm period. What if the story should have been based on a 70 years trend (warm, cool, warm)?
Three items: 1. Thanks to Steve Bloom for all of the references. 2. Thanks to Ferdinand for explaining his position on why he doesn’t accept AGW being responsible for arctic warming and why he doesn’t believe projections are credible. I don’t think he represents folks who claim that Greenland is cooling. 3. Ferdinand, given that I like your points regarding the shortness of various time series in the Arctic (notwithstanding Steve Bloom’s good suggestion that we look at the big picture), how many more years of warming trends that continue in general accordance with model predictions would it take to convince you? Or are future trends relatively unimportant, from your perspective regarding mechanistic understanding, because of warmth in the 1930s and 1940s when GHG concentrations were lower?
Re #50 (FE): Here’s how the scientists writing in EOS summed things up:
‘The Arctic system is moving toward a new state that falls outside the envelope of glacial-interglacial fluctuations that prevailed during recent Earth history. This future Arctic is likely to have dramatically less permanent ice than exists at present. At the present rate of change, a summer ice-free Arctic Ocean within a century is a real possibility, a state not witnessed for at least a million years. The change appears to be driven largely by feedback-enhanced global climate warming, and there seem to be few, if any, processes or feedbacks within the Arctic system that are capable of altering the trajectory toward this “super interglacial” state.’
That’s a pretty strong statement. What members of the media twisted their arms and made them say that? Ferdinand, your problem is with the scientific consensus itself, not the press coverage.
#49, A common problem of going back in time, say to the 1930’s, is that there were very few if any High Arctic stations North of 65 degrees. Especially over the North American Arctic, there might have been trading posts, but to my knowledge there were no stations. The record then is almost none-existent on the Canadian American side, while there surely was some stations on the Russian side. I can’t be critical on your point that it was warmer then, but I can be skeptical. There is after all the human record. A central Baffin elder living at about 70 North once told me that heating oil barrels froze in 1933, he said that it was the coldest year of his life. That does not sound like a warm period.
RE #56 – Being skeptical or anecdotal is not very scientific when facts are presented. In addition, many warming periods being quoted have about a 30 year span which means they began around 1975, which was in the miidle of a cool period.
Heating oil is likely to freeze every winter in Baffin. One year (1933) does not negate a warm period. The warm period peaked around 1940 in most areas.
OK, a couple of hours on Google Scholar reading papers and I find http://www.nersc.no/MACESIZ/Papers/ove04.pdf ., a thoroughgoing reanalysis of the entire surface record in the Arctic going back into the 19th century. The question of whether the long-term record supports the existence of the postulated 50-year trend (not 70-year) was of primary interest to them, and the short answer is that it doesn’t. The rest of the historic variability is explained, and the warming of the last 15 years is identified as both anomalous and very likely to be a consequence of GHGs. There’s an interesting discussion of the vulnerability of the Arctic under current circumstances to abrupt additional warming leading to loss of most sea ice, melting of all the permafrost, much more rapid melting of Greenland, etc.
Re #56 – The GHCN-ERSST climate record indeed shows a record low winter temperature in 1934 (with 1933 close behind) in the eastern Arctic. I wonder how much this matters in light of the following.
Re #55 – The same EOS report contains this statement: “Approximately 98% of the energy supplied annually to the Arctic system is advected from lower latitudes by the atmosphere.”
Is this correct? If so, then arctic temperatures are merely a side effect of events further south, and this is the wrong place to look for evidence of global warming. Going back to basics, what is the basis for enhanced greenhouse warming in the arctic? The increased albedo from melting arctic ice should not matter very much, but the newly exposed cold surface water might absorb extra carbon dioxide, acting as a negative feedback on the whole system. Is there a estimate of how significant this might be? And what part do ocean currents play in the remaining 2% of arctic temperatures?
As Ferdinand pointed out back in #31, the correlation between the NAO and arctic temperatures is not clear. There is certainly not a year by year match, if the data in this graph is correct. On the other hand, arctic temperatures do generally seem to magnify changes further south. I have not had the chance to read the Overland paper just provided. Maybe it will help.
#59, The elder, deceased, said it was colder then with 1933 very memorably colder. Your advection point is correct, however advection is the result of extensive cooling, sort of like a thermal engine where cold and warm air is continuously exchanged, this process slows down when the Arctic is warmer.
The Arctic cools down substantially depending on how much heat is lost especially during the long night, it is an ideal location for determining Global Warming trends because of wider temperature discrepancies caused by apparently minor (CO2) changes.
The current warming trend 1998-2005, has no precedent in recent Arctic memory, there were a few unique occasions when open water was seen during mid-winter over Barrow Strait, but this was at roughly 10 year intervals, now the intervals are totally irregular, but between Islands ice cover is not the best indication of warming, monthly temperature readings for the past 4 years or so, have been mostly above normal by 1 to the occasional 4 to 5 degrees. They rarely go below the 1951-1980 normal.
Re #54,
Steve, re point 3: In my opinion, an extended trend of between 10 and 20 years in the future will make it clear in how far the recent warming is natural: if it is mainly internal natural variability, the 50(+) year cycle should stear to lower temperatures from now on. If it is solar, then the trend should level off by now (except if solar activity should change either side in the near future). If it is mainly greenhouse gases, the trend should go on to the positive side… Of course, a large volcanic eruption may – temporarely – change that all.
Ten years will be enough to test (and adjust if necessary) the models to give a best fit of reality. Meanwhile, research for fossil fuel alternatives should be boosted, to drop in where possible, regardless if the models overestimate or underestimate the real influence of greenhouse gases…
I have two related questions. When will the Greenland ice sheet completely melt into the sea? And is there any reason in the world to think that it won’t?
[Response: See Gregory et al, Nature(2004). The abstract is as follows:
The Greenland ice-sheet would melt faster in a warmer climate and is likely to be eliminated — except for residual glaciers in the mountains — if the annual average temperature in Greenland increases by more than about 3 °C. This could raise the global average sea-level by 7 metres over a period of 1,000 years or more. We show here that concentrations of greenhouse gases will probably have reached levels before the year 2100 that are sufficient to raise the temperature past this warming threshold.
See also this commentary in Nature. -mike]
Re #55,
Steve, the problem is in the sentence: “At the present rate of change”, because that is based on the trend of the past 30 years. Of course that would implicate disaster on middle-long term. But one need to be cautious with the time frame. As said in the Overland e.a. paper:
“Our decadal analysis reinforces the point made by other authors that care must be taken in selecting intervals for calculating linear trends. For example, from examining Fig. 2, Siberia and Alaska (stations 24â??37) would show a positive trend over the previous 40 yr in a regression analysis, even though the main feature was a single decadal warming episode in the 1980s that was followed by cool anomalies.”
Re #58,
The Overland e.a. paper indeed is interesting, as it shows the different trends in different seasons.
This brings me to a correction: The drop in summer temperatures for Illulisat, Greenland, I mentioned in comment #50 is not true: As the Illulisat station ceased operation in 1980, I added the nearby Egedesminde station data. This was no problem for the yearly averages, as these are near identical for the overlapping period, but summer temperatures of Egedesminde show a constant bias of 3 C below Illulisat temperatures. Quite strange for nearby stations, but may be caused by local circumstances (prevailing wind direction from land or seaside?)
Further, I don’t see that the 50(+) year oscillation is discarded, as that is clearly present in the PCA for winter pattern B (see Fig. 5). That the 1930-1940 period was warmer than present for the Arctic as a whole in winter is shown in the time-longitude plot of yearly averages in Figure 2. The warming was mainly around the Atlantic, Europe and West Siberia (there even until 1957). The difference with the current warming is that it now is more evenly distributed around the Arctic.
Thanks again Ferdinand (#61). But I fear that even with 10 years of continued warming (including natural variability around that warming trend), there will still be powerful people/entities arguing against AGW and, unlike you, against any actions to reduce anthropogenic GHGs. I suspect that even if temperatures increase faster than the expected trend, whereas some people will say “Look, AGW is even worse than we thought”, some other people will say “See, they don’t know anything about the climate — something else is responsible for this.” It will be an interesting 10 years until then, and frustrating for many.
Re #59 & dark oceans not absorbing much more heat than white snow/ice.
As a kitchen scientist & folklorist, I have this insight: “A watched ocean (esp if it’s deep) never warms….” I.e., maybe there IS some warming because of the lower albedo, but we just don’t know about it yet as we watch it day to day, because the sea is so massive & deep, such warming would be imperceptable at first…but like that watched pot, if we just turn away a while, then look again, presto, we may see it’s warming…
Also that (diminishing) ice in the glass (sea) might be keeping the water cold, and when it’s all melted, the warming might happen fairly rapidly.
But then I’m not a scientist…
Re #62 – This New Scientist summary gives a slightly different picture of when the Greenland ice cap will melt than the abstract that was quoted.
“If warming stabilises at 3 degrees Celsius, the ice sheet could survive for several thousand years. But if temperatures rise by 8 degrees Celsius, which several scenarios predict, then it would disappear in 1000 years.”
[Response: I’m not sure I see any inconsistency between the two statements. It would of course be odd if there were an inconsistency. After all, Gregory, the primary author of the study in question, was the origin of both statements. -mike]
Another bit about Tropical Cyclones, particularly those of the Atlantic sector. The following graph of hurricanes over the past 75 years can be found here:
http://www.theglobeandmail.com/bnfiles/pics/2005graphics/1020hurrgrfx.jpg
One can fairly easily visualise a best-fit line from around the 1930s to the present and see an increase in the number of storms. This may be, in part, due to increased populations, but since hurricanes are tough to miss, it is probably all-encompassing. (Heck, even 1920s technology had Marconi and Morse code telegraphing so ships’ captains could let others know about the storms.)
It seems that the melting of the Greenland inland ice is not yet for tomorrow. Thanks to Tom Rees at UKweatherworld, here a link to a story from Reuters about the latest satellite data which indicates that the overall ice sheet thickened 54 cm in the past 11 years. But the accuracy of the satellite is less for the (melting) edges, which may compensate for the thicking at higher levels…
[Response:This is related to a new Science express paper (Johannessen et al, 2005) which gives some of the best data yet on the elevation trends for the last decade or so. Interestingly, much of the variability they see is related to the NAO index (high index implies less accumulation), but they are not able to give a full mass balance of the ice sheet (as you correctly say). There is a review paper on a similar topic by Alley and coauthors in this week’s Science as well. -gavin]
Re #66 – The wording of the abstract quoted in #62 leaves the impression that 3 degrees of warming will melt the Greenland ice cap in 1000 years, although read very carefully it does not quite say that. The report says it will take 8 degrees to do that.
The reality is bad enough. Why twist words to make it sound worse than it is?
[Response:It is unfair to accuse the authors of twisting words. You are exploiting a highly semantic point (i.e., what the authors meant by “more than 3C”). The topic is in fact discussed in great detail in a review paper by Alley et al just out in this week’s Science. These authors note that a warming of 3.8C will lead to the eventual melting of the Greenland ice sheet. This is consistent with other studies indicating that 3C is an approximate threshold for the eventual melting of the Greenland ice sheet. There are no inconsistencies here. Now lets move on to other topics. -mike]
Re #67 – I see no increase in the number of storms from looking at the graph, and I understand that warming ocean water is not linked to number of storms. It is linked to the intensity of those storms. However, I note that the most intense storms this year have passed through the Gulf of Mexico, which is a warm, shallow body of water. Unlike the Atlantic ocean, I do not believe there is a long term warming trend there.
[Response:Your statement is not quite accurate. Wilma achieved the greatest strength (lowest central pressure: 882 mb) of any Atlantic Hurricane on record without entering the Gulf of Mexico. For a discussion of what can and cannot be concluded about possible relationships between recent Hurricane activity and climate change, please see our post on Hurricanes and Global Warming: Is There a Connection?. -mike]
I was struck by John Wallace’s assertion (in the Seattle Times article) that “The warming is much more rapid than most of the natural variations we’ve seen in the past.” Is that true? I’m having trouble reconciling that statement with this paper by Kendrick Taylor, and to a lesser extent, ice core data. Looking by eye, the Vostok graph seems to show temperature rebounds after an ice age to be around 8 degrees C. in say, 6000 years. That by itself would seem to support Wallace’s statement, since it would work out to about 1 degree C. per 750 years. But that’s an Antarctica average based on air samples that were each gradually trapped in the ice over thousands of years. There must have been brief periods of very rapid temperature change mixed in there (certainly on the regional level) in addition to slower-warming periods, and I’m under the impression other data (such as Greenland ice cores and deep-sea cores) support that scenario as well.
#67 – “One can fairly easily visualise a best-fit line from around the 1930s to the present and see an increase in the number of storms.”
What I see is a flat trend until about 1995 or so.
It’s great to see this story getting attention here! I hail from Seattle and the ST is my home paper. As it turns out, Sandi Doughton interviewed me for this story and I provided her with much of her information on global warming skeptics and the tropospheric satellite record. It was great to be a part of it. – SC
Just found this:
Greenland icecap thickens despite warming
http://abc.net.au/science/news/stories/s1485573.htm
“Greenland’s icecap has thickened slightly in recent years despite concerns that it is thawing out due to global warming, says an international team of scientists.”
re: 73
Note that the article concludes by saying:
“A separate study in today’s issue of Science reports that sea levels are probably rising slightly because of a melt of ice sheets.
“Ice sheets now appear to be contributing modestly to sea level rise because warming has increased mass loss from coastal areas more than warming has increased mass gain from enhanced snowfall in cold central regions,” the report by a team led by Professor Richard Alley of Pennsylvania State University in the US says.
“Greenland presently makes the largest contribution to sea level rise.””
Re: #71, “What I see is a flat trend until about 1995 or so.”
The rate of tropical storm and hurricane increase is certainly not great prior to 1995. However, I fit a best-fit line myself on the actual newspaper (of which I am a subscriber) and found a slight increase. What is alarming is the post-1995 record, which makes it look like the oceans have lagged in terms of temperature increase until the last decade. It now looks like the plaent is in for something terrible in this part of the world, and in other regions which are affected by tropical cyclones, a massive increase in the numbers and intensities of such storms.
I know circulation patterns (currents) are primarily responsible for thermal transmission. In my view, however, the ocean-atmospheric couplet is becoming more and more of a factor in the warming or cooling of the oceans.
Re #69 – I was wrong about Wilma. It strengthened in the Caribbean, which shows a clear pattern of warming, especially this year. It is reasonable to conclude that global warming played a part in Wilma’s intensity. I note that the RealClimate article confirms there is no link between sea surface temperatures and hurricane frequency (which is extreme this year), but it is linked to intensity (also high this year).
Re #60 – I am still having a hard time understanding the statement “Approximately 98% of the energy supplied annually to the Arctic system is advected from lower latitudes by the atmosphere.” from the EOS paper, and confirmed by wayne davidson. Does this mean only 2% of the energy comes from the sun? Given that average arctic insolation is about 100 watts per square meter, this makes no sense. A better idea of the energy balance in the arctic might help me understand events there better.
Speaking of Greenland cooling and the ice sheet thickening, I am struck by the image of northern surface air temperature change for 1980-1999 in the Nansen Environmental and Remote Sensing Center paper, p. 7. It shows Greenland as a small island of cooling in a large sea of warming. I guess ice caps are resiliant, but how long can this situation last?
Re #s 59 and 65: The albedo change when sea ice melts is by no means considered to be insignificant. Quoting from http://nsidc.org/news/press/20050928_trendscontinue.html , the recent press release on this year’s record low sea ice extent:
‘The trend in sea ice decline, lack of winter recovery, early onset of spring melting, and warmer-than-average temperatures suggest a system that is trapped in a loop of positive feedbacks, in which responses to inputs into the system cause it to shift even further away from normal.
‘One of these positive feedbacks centers on increasingly warm temperatures. Serreze explained that as sea ice declines because of warmer temperatures, the loss of ice is likely to lead to still-further ice losses. Sea ice reflects much of the sun’s radiation back into space, whereas dark ice-free ocean absorbs more of the sun’s energy. As sea ice melts, Earth’s overall albedo, the fraction of energy reflected away from the planet, decreases. The increased absorption of energy further warms the planet.
‘â??Feedbacks in the system are starting to take hold,â?? argues NSIDC Lead Scientist Ted Scambos. Moreover, these feedbacks could change our estimate of the rate of decline of sea ice. â??Right now, our projections for the future use a steady linear decline, but when feedbacks are involved the decline is not necessarily steadyâ??it could pick up speed.â??’
#76, I am not sure also about that 98% figure, but there is definitely some very strong advection activity on a continuous basis, feeding heat to several distinct circumpolar geographical locations in the Arctic every day.
I would like to ask a Gulf coast Climate/Historian a question, you never know, may be someone like Gulf Coast resident like Mr Wallace reads Real Climate.
After speaking to a native Floridian who was around in the 40’s, I was surprised to learn that hurricanes then, didn’t seem to be as numerous as 2005. An account about those numerous hurricanes in the 40’s would be nice to hear about, since they are mentionned so oftenly as reoccuring today..
Judith Curry, Kerry Emanuel and Kevin Trenberth have come out swinging and are now saying that there is a causal relationship between global warming, increased SSTs and stronger hurricanes.
Curry is interviewed at http://pubs.acs.org/subscribe/journals/esthag-w/2005/oct/policy/pt_curry.html :
“What you can do is show an unambiguous link between the increase in hurricane intensity and the warming sea surface temperatures. And if you look for why the sea surface temperatures are warming since the 1970s, you donâ??t have any explanation other than greenhouse warming.”
Wow. There’s a more detailed joint statement at http://www.ametsoc.org/atmospolicy/EnvironmentalScienceSeminarSeries.html . I am *so* happy that these prominent scientists have decided to come out swinging. Among other things, in the interview Curry goes after Bill Gray, James O’Brien, Max Mayfield and Roger Pielke Jr. for the various negative roles they’ve been playing. (Chris Landsea is not named, but he’s there in spirit!) The timing with Wilma could not be better for this, of course. Yabba-dabba-doo!
“Yabba-dabba-doo”?
I’m sorry, Steve, the seminar where those three will appear is on October 25th. Today’s the 22nd. Only the first link offers any kind of statement, and it’s from Curry only, not the other two.
Re #76,
Blair, one (again) need to be carefull with the time frame of the graph presented. The winter rate-of-change in the previous warming period was stronger between 1915-1935 (and the overall warming 1930-1940), than for the current one, as can be seen in the circumpolar stations which existed then, see Fig. 2, page 6 (3268) of the Overland e.a. papers.
What is interesting in the Nansen Centre paper, is that much of the recent summer (and partly winter) warming seems to be outside the Arctic, in the mid-latitudes.
Further, have a look at Fig. 1 of the Nansen paper: The difference between measurements and models still is large. The model underestimates the 1930-1940 warming as good for the Arctic as for lower latitudes, and underestimates the lower latitude recent warming, in my opinion as a result of overestimated influences of GHGs and aerosols at one side and underestimated solar influences at the other side. But that is more for the Modeller vs. modeller discussion…
Re # 80 (KM): Keith, I do apologize (well, sort of) for the Flintstones reference (Wilma -> Fred -> yabba-dabba-doo), but I couldn’t resist. I’m not sure what the implied problem is with the seminar being on the 25th, but in any case to see the 1000-word statement from the three of them just scroll down on the second linked page. It’s powerful stuff.
Thank you, Steve Bloom, for your links in #79. Curry, Emanuel, and Trenberth are certainly beacons in the fog!
#79 thanks Steve for the links.
There is no debate as well with the few media savy scientists taking a stance against Global Warming, it is after all their “raison D’etre”, as they themselves get funded by Groups opposing the theory . But I recently read that 66% of Americans have already made the link between fierce Hurricanes and Global Warming, the attention spotlight will eventually change to “raison d’avoir” a better understanding, there is nothing more strong then being right.
I am also ready to listen to the memories of Elders from the Gulf and Carribean about how similar 2005 is say to any year??? To counter the ‘matter of fact’ smug cycle theorists, there has to be a proper history recounted by climatologists capable of recounting that there was so called similar year(s), the “it was just as bad as in the 1940’s” ball is lobbed out, now we have to say, ho ya??? When then?? Name a year, say the horror stories (perhaps on a smaller scale). Then peers of that time can confirm or deny the veracity of it. Elders to the rescue! In the older days there were no NOAA’s, TV’s and internet, hardly any warning compared to today, frequent disatrous hurricanes like 05 would have been scarred in many memories.
If there is no resonance with a previous years somewhat similar to 2004-05, there is none in the media now, nobody is saying its like 1949 all over again, therefore this adds to the formidable pile of evidence in favor of AGW, and also shows the weaker side of those negating AGW’s influence.
Re #79 – Following is a Q & A from the Curry interview –
(Q – People can criticize the paper because you only went back to the 1970s. Can you actually see a pattern with such limited data?
A – We do not have global data prior to 1970. We have data from 1945 to 1970 from aircraft in the North Pacific and the North Atlantic. Prior to 1945, we only have statistics on landfalling hurricanes.
Now, events in the Atlantic comprise only 11% of global hurricanes, and U.S. landfalling hurricanes only comprise 1%. So trying to draw inferences about global hurricane activity from these statistics just doesn�t work. Using the sampling data from the Atlantic to understand what�s happening globally is like only sampling California voters to try and infer U.S. presidential preferences.
If you look at landfalling hurricanes, the statistics are really just looking at California voters over 65 [laughs]. It�s a sampling error.
Just to give you a counterexample, during the same time period, landfalling hurricanes in Australia have actually gone down. So if we had only relied on landfalling hurricanes we would have a different story. But clearly the Australian story doesn�t tell you anything about what is going on globally.)
—-Curry uses an example of looking at voters over 65 when talking about landfalling hurricanes. However the work she refers to dating from 1970 to the present is like using voters under 35. She can write all the refereed papers in the world but the data is not complete whan you use half of a cycle.
Re #84 – You do not need to look for deceased elders in the computer age. The following site has the 10 deadliest, 10 costliest,and 10 most intense hurricanes:- http://www.cnn.com/SPECIALS/2005/hurricanes/
RE – (To counter the ‘matter of fact’ smug cycle theorists, there has to be a proper history recounted by climatologists capable of recounting that there was so called similar year(s), the “it was just as bad as in the 1940’s” ball is lobbed out, now we have to say, ho ya??? When then?? Name a year, say the horror stories (perhaps on a smaller scale).)
—Historical records exist beyond the elders. With very little effort you can find records of typhoons into the 1700’s killing 10’s of thousands. The years are there and are included in the previously named site.
RE- (There is no debate as well with the few media savy scientists taking a stance against Global Warming, it is after all their “raison D’etre”, as they themselves get funded by Groups opposing the theory)
— Do the forecasters in Miami Hurricane Centre get paid by special interests?
Well, hello Tropical Storm Alpha! First time ever hitting the Greek alphabet.
Re #85 (GM): By that very same logic, your speculation about natural cycles is entirely without basis. Now, tell me this: While it is well-known that there are all sorts of natural climate cycles, they all have a physical basis. The science is clear about the connection between enhanced SSTs and more powerful cyclones, but the skeptic/contrarian argument then goes that those enhanced SSTs must be the result of some natural cycle. What natural cycle, and what is its cause? Let’s see an analysis. The problem is that the enhanced SSTs are easily explained by global warming, and not so easily by anything else. Occam’s Razor, Gerald?
RE # 88 – It is unfortunate that many AGW proponents are in denial of the NAO. That cause of variation in SST’s has been around for centuries – longer than the short term used in many studies. Analysis – there are many sites describing this.
[Response: Since no-one mentioned the NAO until now, it’s not clear why you think anyone is ‘in denial’ about it’s existence. There is a small influence on hurricane formation but there is no evidence that the NAO has long multi-decadal cycles (separate from a small forced response from the oceans or potentially from stratospheric processes) – it is best characterised by slightly red noise. -gavin]
#86, The question was how many year(s) were similar in nature to the 2004-05 period? Was not looking for a top 10 list, however the top ten most intense Hurricanes are from 10 individualized mostly sparsely separated years, but surprising isn’t it, none most intense were from the alleged infamous “hurricane crazy” 40’s, but at least 6 since 1960 . Distant past hurricane fear is something personal, unless you are an elder from down there you can’t connect the past with the present, it is a memory, something tangible which makes a lasting impression . Only a well studied person can give data suitable for proper comparisons. This is the time to hear from climate experts. As far as I can gather, there were no similar intense years, unless someone explains otherwise. Also cycles need to be convincing, example: El-Nino, like way more than 1 C fluctuations …..
RE #90 – For one year you can look at 1933. All the data back to 1851 are available at:
http://weather.unisys.com/hurricane/index.html
Re #81 – Ferdinand, indeed the rate of arctic winter warming from 1920-1939 seems equivalent that in the last few decades, as seen in both the Overland et al paper, and the Nansen paper, figure 2. But figure 2 shows the 1920-1939 anomoly as localized in the arctic, as if the energy was transferred there from further south, while in recent decades it is only a small part of a global warming pattern.
No explanation for the 1920-1939 warming is given other than “natural fluctuations.” The Nansen paper states “No positive correlation between arctic SAT and the NAO before 1950 is found â�� in fact, here we find that the correlation is negative (r ~ -0.39).” So it is not surprising that it is hard to model when it is not understood at all.
Re #79,
Steve, as advocate of the devil (I must admit, I like that role…), may I point to the fact that the Webster, Curry e.a. paper starts in 1970. As Curry said, because from that date on, the data gathering was more global (although most oceans have good data since 1946). Thus any comparison with earlier data simply is impossible, because there are no reliable data (except for the Atlantic) for any pre-WWII period.
But there were pretty rough hurricanes in the 1930-1940 period too, at least in the Atlantic, including the labor day 1935 hurricane which destroyed the Florida Key’s railway. That one had wind speeds up to 160 mph and the record lowest pressure (892 hPa), until hurricane Gilbert in 1988 and now Wilma (880 hPa).
It is pretty sure that there is a link between sea surface temperatures (SST), the lack of wind shear and the total surface with high temperatures at one side and the number and strength of hurricanes at the other side (that is more than SST alone! See e.g. Chan and Liu). And from Gray e.a.:
“When tropical cyclones worldwide are summed, there has actually been a slight decrease since 1995. In addition, it has been well-documented that the measured global warming of about 0.5 C during the 25-year period of 1970-1994 was accompanied by a downturn in Atlantic basin hurricane activity over this quarter-century period.”
But they largely underestimated the 2005 hurricane season. Seems that hurricane prediction is as difficult as weather and climate prediction…
It is pretty sure that the oceans – and the world in general have heated since the LIA, including rapid warming in the 1910-1930 period and the 1980-2000 period. The first increase anyway was mostly natural (solar induced) and the second was at least partly sun induced (and GHGs have helped but, in my opinion, less than what current models project).
A few points:
1. Solar indices indicate that solar activity never has been as high as in the recent period for the past 8,000 years (see Solanki e.a.). While there is little change since 1980, solar activity now is higher than in the 1930’s. Ocean temperature/heat content need a longer time to come into equilibrium.
2. The pattern of ocean warming in the past decades only roughly matches the increase in GHGs. The heat content of the oceans shows a large sinusoidal curve (see Levitus 2005 figure 1), with cooling (while GHGs are increasing) and warming. Moreover, ocean models (Barnett e.a. 2005) significantly differ from reality for any oscillation between 10-60 years (see fig S1 in the supplement – that includes the 11 and 22 year solar cycles).
3. There is a change in radiation balance 1985-2000 of the (sub)tropics, and a trend to less clouds. That induces an increase in insolation (~2 W/m2) directly absorbed in the oceanic surface, and an increase in IR radiation (~5 W/m2) back to space (from anywhere in the atmosphere or surface). The result (or the origin): an increase in SST of the tropics of ~0.08 C/decade. The change in cloud cover, neither the change in radiation balance is captured by any climate model (see Wielicki ea.
Compare that to a global average 0.7 W/m2 change since 1980, attributed by the models to GHGs.
Thus while some researchers link hurricanes to higher SSTs and global warming, others differ in opinion (btw, why are those not invited to the seminar? Would have been more interesting than a one-sided view!)
Global temperatures were the warmest of the last 545 million years at the Paleocene/Eocene Thermal Maximum (PETM 55 mya).
Between 95 and 68 million years ago, the interior of North America was covered by the Cretaceous Seaway.
I am unaware of any heavy uplifting or sedimentation over the east/south areas of the Cretaceous Seaway lake bottom between 68 mya and 55 mya.
Q: Is there any evidence that a shallow sea returned to parts of the east/south Cretaceous Seaway bottom area (FL, MS, LA, TX, OK, MO, IA, west MN, Manitoba) around the time of the PETM?
Re: #93,
There is also an apparent link between the number of Atlantic tropical cyclones and the atmospheric temperature. The following graph shows the number of Atlantic tropical storm systems from 1851-present:
http://www.nhc.noaa.gov/gifs/atlhist_hires.gif
The graph seems to match up quite well with this graph:
http://www.cru.uea.ac.uk/cru/data/temperature/nhshgl.gif
Of course, there is an apparent lag in storm numbers, but that is explained by the lag in oceanic warming compared to atmospheric warming, meaning it takes longer to warm water than it does to warm air. This leads me to think that we are nowhere near the peak of Atlantic tropical storms.
RE #89 Gavin – You note that NAO was not mentioned before. NAO and AMO have been noted in other threads or referenced. In #88 above a comment is made “The problem is that the enhanced SST’s are easily explained by global warming and not very easy by anything else”.(one denial)
Well I think the reverse is more accurate as the global warming part is difficult to measure. It is more of a statistical association. On a Florida State University site, the following note is made – “For hurricanes occurring in the North Atlantic, climate factors include El Nino, the North Atlantic Oscillation(NAO), the Atlantic Multi-decadal Oscillation(AMO), and the Stratospheric Quasi-Biennial Oscillation(QBO). Hurricane climatology also includes the role global warming may have in hurricane activity.”
There are also other sites relating the hurricane activity with the cycles.
I am not a climate scientist, I just listen to their discussions on streaming radio.
I wrote down my impressions and observations after listening to a roundtable titled “Is Global Warming Just Hot Air?”.
My comments are here:
http://www.livejournal.com/users/dpodbori/1858.html
Since I never saw an answer to my question about the Pacific Northwest, I went and did my own homework and, yes, I think we have trouble. Here is part of a note I posted to local politicians:
References:
Oregon Climate Service, “Fall & Winter Forecast 2005-2006”,
http://www.ocs.oregonstate.edu/winter_05-06/forecast.html
Oregon Climate Service web page,
http://www.ocs.oregonstate.edu/index.html
UW/NOAA Center for Science in the Earth System (CSES) Climate Impacts Group (CIG), http://www.cses.washington.edu/cig
UW Program on Climate Change, http://depts.washington.edu/uwpcc/
Re: 94
See: http://www.scotese.com/Default.htm for a closer look, but..
If I recall correctly, the time frame from 70 to 50 million years ago accomodates the opening of large chunks of the atlantic and finally the Artic ocean, allowing an ocean circulation regieme dominated by temperature difference instead of salinity differences. So in the late Cretaceous, the entire ocean would have been much warmer than today, and hence the same mass of water would occupy a greater volume. Even though the global surface/atmospheric temperatures may have been higher in the early Eocene, I don’t think this extends to the deep ocean.
Additionally, there is a relation between ocean basin volume and seafloor speading rates, the higher the spreading rate the higher sea level is for a given climate/ocean temperature. However, this is a very hard relationship to bring out, because more seafloor spreading means more subduction and hence higher CO2 volcanic emission rates. So are your higher sea levels a result of ocean basin volume changes, ocean temperature changes or both? These are non-trivial questions to answer.
Overall, direct comparisons of periods in earth history 30 or more million years apart are not simple. But it does not appear that N America was underwater during the Eocene.
#98, Another way of putting it would be “different climates”, good (nice and mild) for one zone, terrible (more rain/snow heavy winds) for another. Last few days Canadian High Arctic temperatures +11 C above normal with the monthly running mean at about +4 C, getting warmer.