Open Mind

33 responses so far ↓

• jonathan // Oct 30th 2007 at 10:19 pm

  Could Inhofe have used some other weather stations in Greenland which have data going back to the 1940’s?

  [Response: Of course Inhofe didn’t do any of the work; he simply found whatever he thought would discredit AGW and included it in his speech.

  I’ve looked at most of the relevant literature referenced on Inhofe’s site. One of the main sources for his claims is Chylek 2006 (Geophys. Res. Lett., 33, L11707), which clearly states “There are only two stations in Greenland with century-long temperature measurement records that contain the 1995–2005 warming period.” The tricky part is to find stations that start no later than the early 20th century *and* cover the early 21st century. However, I have found a data set (not in the GHCN, but from ECA — European Climate Assessment and Dataset Project) which appears to have the requisite time coverage, from Ilulissat; in papers referencing that station the data tend to end well before 2000, perhaps ECA has updated it.]

• windansea // Oct 30th 2007 at 11:15 pm

  Considering available station data that are continuous and begin before 1900 (Table 3), the year 2006 is not outstanding. In this longer perspective, only 2003 at Tasiilaq is outstanding in recent decades. Over the past century, years in Greenland that register as abnormally warm, 1929, 1932, 1941, 1947, and 1960 are outstanding, having temperatures warmer than observed recently. Increases in GrIS melt and runoff during this past century warm period must have been significant and were probably even larger than that of the most recent last decade (1995-2006).

  http://www.arctic.noaa.gov/reportcard/essay_hanna.html

  The Greenland coastal temperatures have followed the early 20th century global warming trend. Since 1940, however, the Greenland coastal stations data have undergone predominantly a cooling trend. At the summit of the Greenland ice sheet the summer average temperature has decreased at the rate of 2.2 °C per decade since the beginning of the measurements in 1987. This suggests that the Greenland ice sheet and coastal regions are not following the current global warming trend. A considerable and rapid warming over all of coastal Greenland occurred in the 1920s when the average annual surface air temperature rose between 2 and 4 °C in less than ten years (at some stations the increase in winter temperature was as high as 6 °C). This rapid warming, at a time when the change in anthropogenic production of greenhouse gases was well below the current level, suggests a high natural variability in the regional climate.

  Chylek P.1; Box J.E.2; Lesins G.3

  Source: Climatic Change, Volume 63, Numbers 1-2, March 2004 , pp. 201-221(21)

  We provide an analysis of Greenland temperature records to compare the current (1995–2005) warming period with the previous (1920–1930) Greenland warming. We find that the current Greenland warming is not unprecedented in recent Greenland history. Temperature increases in the two warming periods are of a similar magnitude, however, the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.

  http://www.agu.org/pubs/crossref/2006/2006GL026510.shtml

• JesusChristHimself // Oct 30th 2007 at 11:22 pm

  You did one thing that is somewhat odd to me. You’re talking about Greenland temps, and then you slide over to the Arctic Sea Ice Extent Anomaly. I have no problem with looking at Arctic sea ice and your point is valid, but why not a graph of Greenland ice?

• CraigM // Oct 31st 2007 at 12:11 am

  tam:

  “What surprised me is the size of the warming experienced in just five years; the difference between the 5-year average from 2000 and that from 2005 is somewhat startling. Not only is the latest 5-year average hotter than any of its predecessors, the change is the largest in this record.”

  60 minutes australia carried a story about greenland last sunday. The above seems to have been the experience of many greenlanders: a rapid warming period in the last few years. One guy pointed to a rapid growth spurt in pine trees from 2002-2003; more and more land free of ice for farming. people being able to sail into the harbour without ice. So…I predict Inhofe will soon drop the greenland cooling line in place of greenland is warming fast, AND ITS GOOD FOR US. Its always very easy to cherrypick.

  Of course the same story also pointed to the fact that the quicker greenland warms, the quicker sea levels rise, which is probably not such a good thing. Also the the same show pointed to wildfires in California. A fire worker there said the the intensity of fires in the last 10 years have been unlike anything previously. Fires (called megafires by the story) are so strong that they kill a tree called the pondarosa (spelling?), a tree that usually survives fires. This means that forests, once ripped by a megafire, are pretty much gone for some considerable time. Of course sceptics will say its all about fire management practices. But the firefighter put it down to both that and a shift in climate in the last ten years. But now im getting onto something that belongs in another thread.

• JesusChristHimself // Oct 31st 2007 at 1:02 am

  windansea’

  Also from that paper:

  ” To summarize, we find no direct evidence to support the claims that the Greenland ice sheet is melting due to increased temperature caused by increased atmospheric concentration of carbon dioxide. The rate of warming from 1995 to 2005 was in fact lower than the warming that occurred from 1920 to 1930. The temperature trend during the next ten years may be a decisive factor in a possible detection of an anthropogenic part of climate signal over area of the Greenland ice sheet. …”

  In 2004 they did a paper that claimed Greenland was cooling. Then they did another paper and they hung their hat on 1920 to 1930. I would think if they truly wanted to kill off AGW, they would have proven a 5-year span within 1920 to 1930 blows away 2000 to 2005.

  I’m perplexed as to why they did not administer the coup de grace.

• windansea // Oct 31st 2007 at 1:57 am

  I would think if they truly wanted to kill off AGW, they would have proven a 5-year span within 1920 to 1930 blows away 2000 to 2005.

  I’m perplexed as to why they did not administer the coup de grace.

  why bother with 2000 to 2005 when you can kill 1995 t0 2005 with faster rate of warming?

  Temperature increases in the two warming periods are of a similar magnitude, however, the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.

• Mark Hadfield // Oct 31st 2007 at 3:08 am

  Surely one of the issues here is the naivete of talking about Greenland temperatures as if Greenland were homogeneous and representative of the entire Arctic.

  As usual, RealClimate has the info:

  http://www.realclimate.org/index.php/archives/2006/11/strawmen-on-greenland/

  Gavin Scmidt and Michael Mann point out that Southern Greenland is strongly affected by the Arctic Oscillation and say:

  “western and southern Greenland is an extremely poor place to look, from a signal vs. noise point of view, for the large-scale polar amplification signature of anthropogenic surface warming.”

• dhogaza // Oct 31st 2007 at 3:59 am

  60 minutes australia carried a story about greenland last sunday.

  The US press has been carrying variants of the story, too, in the last couple of days.

  So, apparently:

  1. Greenland is cooling (disproves global warming)

  2. Greenland is warming (proves that global warming is good).

  Can’t these people get their effing story straight even in a one-week timeframe?

  Windandsea, which is it?

  #1 or #2?

• henry // Oct 31st 2007 at 1:57 pm

  “Gavin Scmidt and Michael Mann point out that Southern Greenland is strongly affected by the Arctic Oscillation and say:

  “western and southern Greenland is an extremely poor place to look, from a signal vs. noise point of view, for the large-scale polar amplification signature of anthropogenic surface warming.””

  So we shouldn’t look to half of Greenland for proof of AGW.

  “Temperature increases in the two warming periods are of a similar magnitude, however, the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.”

  So while Greenland is not cooling, a period with lower CO2 had a greater rate of change than today (with higher CO2).

  What else could cause this natural variability? Does Greenland have volcanos?

• Danny Bloom // Oct 31st 2007 at 2:21 pm

  Tamino, interested in hearing about POLAR CIITES and what part they might play in future of Earth and glo warming? google the term and email me. See my blog here linked. URGENT. Would love to hear your feedback pro or con.

  http://climatechange3000.blogspot.com

• windansea // Oct 31st 2007 at 2:56 pm

  Windandsea, which is it?

  The 2006 Chylek paper conclusions:

  [edit]

  http://meteo.lcd.lu/globalwarming/Chylek/greenland_warming.html

• John Mashey // Oct 31st 2007 at 4:12 pm

  Google: “polar cities” dan bloom
  Ardent blogflogging, although at least this thread at least has something to do with Arctic regions.

• henry // Oct 31st 2007 at 4:32 pm

  From the Chylek(06) paper:

  [16] ii) …”The summers at both the southwestern and the southeastern coast of Greenland were significantly colder within the 1955-2005 period compared to the 1905-1955 years.”

  Could this be the statement that Inhofe is referencing to?

• JesusChristHimself // Oct 31st 2007 at 4:36 pm

  From an article:

  Chylek points out that he speaks for himself on these issues and does not represent the Los Alamos nuclear weapons lab.

  “We have many people in the lab who completely disagree with me,” he said.

• henry // Oct 31st 2007 at 4:58 pm

  “JesusChristHimself // Oct 31st 2007 at 4:36 pm

  From an article:

  Chylek points out that he speaks for himself on these issues and does not represent the Los Alamos nuclear weapons lab.

  “We have many people in the lab who completely disagree with me,” he said.”

  Yeah, I imagine that there are a few people in his lab that have their own idea of what “global warming” is…

• windansea // Oct 31st 2007 at 5:03 pm

  Chyleck should not be painted as a GHG denialist, as his paper in 2005 concluded the recent large warming in Greenland can be explained only considering CO2 and aerosol (Chylek, P., and U. Lohmann (2005), Ratio of the Greenland to global temperture change: Comparison of observations and climate.
  modeling results, Geophys. Res. Lett., 32,
  L147705, doi:10.1029/2005GL023552).

  It appears he has changed his mind in the more recent paper.

  Another paper going back further in time:

  JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, D07110, doi:10.1029/2005JD006494, 2006

  Svalbard summer melting, continentality, and sea ice extent from the Lomonosovfonna ice core

  Aslak Grinsted et al

  The continentality and melt proxies are validated against twentieth-century instrumental records and longer historical climate proxies. In addition to summer temperature, the melt proxy also appears to reflect sea ice extent, likely as a result of sodium chloride fractionation in the oceanic sea ice margin source area that is dependent on winter temperatures. We show that the climate history they depict is consistent with what we see from isotopic paleothermometry. Continentality was greatest during the Little Ice Age but decreased around 1870, 20–30 years before the rise in temperatures indicated by the δ18O profile. The degree of summer melt was significantly larger during the period 1130–1300 than in the 1990s.

• cody // Nov 1st 2007 at 8:38 am

  The rants and abuses of people as members of certain classes is totally unhelpful whoever does it. Perhaps even more unhelpful when a Senator does it.

  But on the substantive point, whether there is Greenland warming or cooling, and whether it supports AGW or not, have not windandsea and henry now both cited sources which demonstrate at a minimum that the data from those two stations isn’t as compelling as it looked. Its not clear that it is representative of conditions in the Arctic as a whole, and its not clear that the present warmth in Greenland or the rate of warming really is unprecedented.

  The ice melt is much harder to argue with. Though I do have informed friends who are convinced ‘warmers’ who think it likely due to weather rather than AGW.

  Tamino’s original post thus seems to have been unfair to the factual basis for the Senator’s remarks (which does not excuse Sen’s ranting), and also arguably to have overstated the significance of the data which he cited.

  But. But. We shouldn’t leave it there, whatever we think of what the OP does or doesn’t prove.

  We need to say more. We owe Tamino sincere thanks for the way he’s conducting this site. Its very educational, and while he has a strong point of view, he’s facilitating the presentation of evidence which forcefully conflicts with it in a way that lets us make up our own minds. So few on either side of this debate are doing this, its something we should particularly value. Thanks.

• luminous beauty // Nov 1st 2007 at 11:26 am

  “Temperature increases in the two warming periods are of a similar magnitude, however, the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.”

  Does anyone besides me see something wrong with this picture?

• Eli Rabett // Nov 1st 2007 at 12:52 pm

  Well yes, but my time machine doesn’t have a forward gear.

• henry // Nov 1st 2007 at 1:28 pm

  luminous beauty // Nov 1st 2007 at 11:26 am

  “Temperature increases in the two warming periods are of a similar magnitude, however, the rate of warming in 1920–1930 was about 50% higher than that in 1995–2005.”

  Does anyone besides me see something wrong with this picture?

  I’m assuming (without seeing the charts he refers to), that where both temps reached 1 deg (est), one took the full 10 years to get there, while the other occured over a 5 year period (somewhere in that 10 year window).

  The raw data he used (not averaged or smoothed) for both 10 year periods might help (showing trend lines for both).

  Again, a link to his full paper (not just the abstract or a selected summary) would be helpful. Not a member of AGU, so would have to pay for the full paper.

  [Response: The AGU listing is here, where you can purchase the article. You can get the data from NASA GISS, here and here.]

• JesusChristHimself // Nov 1st 2007 at 2:28 pm

  I know an excellent Delorean mechanic.

  Those guys had to make a full retreat from their prior paper, and it looks to me like they are going to have to retreat rapidly from their 2nd paper. Scientists report that 2007 snow melting days at the higher elevations of Greenland were up 150% over 2006. The higher elevations are thickening, but that might not be the case if snow melting days continue to increase.

• windansea // Nov 1st 2007 at 4:03 pm

  Does anyone besides me see something wrong with this picture?

  the statement is quite clear, Henry explains it well.

  I know an excellent Delorean mechanic.

  jokes don’t explain the serious problem Greenland cooling presents for current GHG based climate models. Last time I looked, 90% of Greenland is north of the arctic circle, the region where polar amplification of the greenhouse effect is supposedly strongest.

  Those guys had to make a full retreat from their prior paper, and it looks to me like they are going to have to retreat rapidly from their 2nd paper. Scientists report that 2007 snow melting days at the higher elevations of Greenland were up 150% over 2006.

  a one year change is weather, not relevant to multi decadal trends like this:

  Since 1940, however, the Greenland coastal stations data have undergone predominantly a cooling trend. At the summit of the Greenland ice sheet the summer average temperature has decreased at the rate of 2.2 °C per decade since the beginning of the measurements in 1987.

  [Response: Was it you who took temperatures in *summer only*, from *one location*, and extrapolated to “the serious problem Greenland cooling presents for current GHG based climate models,” or was it Senator Inhofe?

  There are four Greenland stations in the GHCN which have records extending in to the early 21st century. They all show strong warming since 1987; the *slowest* is warming more than four times faster than the global average. They’re plotted in the update to this post.]

• John Mashey // Nov 1st 2007 at 6:40 pm

  But tamino, doing regressions on substantial sets of data doesn’t allow eyeballing of spikey lines and drawing strong conclusions by picking a couple points, or arguing about the great significance of whether year A is the biggest/smallest, by some tiny amount, etc

  But seriously, how about a short essay to pull together key ideas of relevant time-series analyses and common misinterpretations, using a climate example, perhaps, but emphasizing the generic issues, as opposed to discussing the specific climate case, to keep the topic focussed on the general case.

  For example:

  - start with plot of some series, and consider what conclusions people might draw from it.

  - take the same data at different resolutions (yearly, seasonally), and see if conclusions change.

  - do smoothed curves of the above, with various periods of smoothing.

  - do linear regressions, or combinations, or other regressions if that makes any sense. Talk about how important this especially is when trying to analyze data whose jiggles are large compared to the trend (like here) versus those whose jiggles are small compared to the trend (CO2 concentration).

  - do endpoint sensitivities, and difference between doing a regression and picking two endpoints and drawing straight line [the “intuitive” thing]. Compute all the slopes from each possible starting point to current endpoint, and compare distributions of regression slopes to straightline slopes.

  - Anyway, you’d know better than I what should be in this, and your blog has a fine collection of this sort of stuff, but unless I’ve missed it, it’s not in one place, focussed on the general issues, as opposed to analyzing individual topical cases.

  Anyway, it is all too easy for people to be be misled by time-series graphs, even when it isn’t on purpose. Maybe there should be a good, terse list of such mistakes and how to avoid them, akin to John Cook’s list of arguments in
  http://www.skepticalscience.com/argument.php.

  [Response: That’s an excellent idea for a post. It’s a nontrivial amount of work, and will take some time to do it right.]

• luminous beauty // Nov 1st 2007 at 10:15 pm

  windy,

  Yes, Henry is doing his best to make sense of a contradictory statement; similar temperature changes over the same length time periods differ by 50%. That is clear English, but mathematically unsound.

• windansea // Nov 1st 2007 at 10:36 pm

  [Response: Was it you who took temperatures in *summer only*, from *one location*, and extrapolated to “the serious problem Greenland cooling presents for current GHG based climate models,” or was it Senator Inhofe?

  I’m just quoting various studies done by Chylek and other scientists verbatim, and it wasn’t just one station that exhibited cooling. And it wasn’t just in the summer. The conclusion that these studies pose a serious problem for GHG models is my own, and most likely is shared by the scientists I am quoting.

  Since 1940, however, the Greenland coastal stations data have undergone predominantly a cooling trend. At the summit of the Greenland ice sheet the summer average temperature has decreased at the rate of 2.2 °C per decade since the beginning of the measurements in 1987. This suggests that the Greenland ice sheet and coastal regions are not following the current global warming trend. A considerable and rapid warming over all of coastal Greenland occurred in the 1920s when the average annual surface air temperature rose between 2 and 4 °C in less than ten years (at some stations the increase in winter temperature was as high as 6 °C). This rapid warming, at a time when the change in anthropogenic production of greenhouse gases was well below the current level, suggests a high natural variability in the regional climate.

  As I have said before, I don’t completely deny GHG theories, but I think the current GCMs greatly overstate their effect. I am all for cleaner more efficient energy production, less pollution etc etc.

  Earth’s climate system is infinitely complex, probably the most complex system we have ever tried to understand. Reducing this system to an apparent CO2/temperature correlation accompanied by alarmism is not not justifiable at this point.

• guthrie // Nov 1st 2007 at 11:10 pm

  If you’ll all excuse me for a minute.

  Quoth Windansea:
  “Earth’s climate system is infinitely complex, probably the most complex system we have ever tried to understand. ”

  Maybe so, although I understand the human body and the entire visible universe are pretty complex as well.

  Also
  “Reducing this system to an apparent CO2/temperature correlation accompanied by alarmism is not not justifiable at this point.”

  Who on earth is doing that? Have you read the IPCC report?

• windansea // Nov 1st 2007 at 11:13 pm

  This rapid warming, at a time when the change in anthropogenic production of greenhouse gases was well below the current level, suggests a high natural variability in the regional climate.

  basically, this is all I’m saying, there are natural and systemic forcings that are not understood at this point, and assuming that modern warming is global, unprecedented in recent millenia, and dominated by GHG forcings is not a logical conclusion at present. There are too many published studies by credible scientists that show equal or greater temperature anomalies before post industrial GHG increases.

• luminous beauty // Nov 1st 2007 at 11:47 pm

  windy,

  It is warmer in California than in Minnesota on average, but I can find plenty of data in particular locations where the opposite is true. Does that mean it might really be warmer in Minnesota than California? On average?

• John Mashey // Nov 2nd 2007 at 12:24 am

  re: a lot of work … yes, but in the long run, it might save work to be able to just refer back to it …
  [of course, advice is easy when someone else is doing the work :-)]

• luminous beauty // Nov 2nd 2007 at 12:37 am

  guthrie,

  May I suggest that perhaps the most complex and difficult to quantify system that humans face is the very means that we use to understand those systems; human consciousness.

• windansea // Nov 2nd 2007 at 1:12 am

  I
  it is warmer in California than in Minnesota on
  average, but I can find plenty of data in particular locations where the opposite is true. Does that mean it might really be warmer in Minnesota than California? On average?

• Hank Roberts // Nov 2nd 2007 at 1:40 am

  > assuming that modern warming is global
  Well, no, there are a few ‘blue’ spots on the maps even though most of them are yellow-orange-red. How “Global” do you insist someone believe in?

  > unprecedented in recent millenia
  Not exactly. How absolute do you insist someone be about the current conditions?

  >dominated by GHG forcings
  Works for me.

  > is not a logical conclusion at present.

  Ray Pierrehumbert’s inline responses are perhaps the best I’ve seen to this:
  http://www.realclimate.org/index.php/archives/2006/05/positive-feedbacks-from-the-carbon-cycle/

• EliRabett // Nov 2nd 2007 at 4:14 am

  Since what we are looking at is anomalies, it really does not matter to the argument whether it is warmer in CA than MN, but rather whether it is getting warmer in both CA and MN as compared to themselves.

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