Follow Up On Today’s AP Article By Seth Borenstein Entitled “Study: Antarctica Joins Rest Of Globe In Warming”, by Roger Pielke Sr
Climate Science, Jan 21, 2009
An AP article was released today which reports on a Nature paper on a finding of warming over much of Antarctica. I was asked by Seth Borenstein to comment on the paper (which he sent to me). I have been critical of his reporting in the past, but except for the title of the article (which as I understand is created by others), he presented a balanced summary of the study.
My reply to Seth is given below.
I have read the paper and have the following comments/questions
1. The use of the passive infrared brightness temperatures from the AVHRR (a polar orbiting satellite) means that only time samples of the surface temperature are obtained. The surface observations, in contrast, provide maximum and minimum temperatures which are used to construct the surface mean temperature trend. The correlation between the two data sets, therefore, requires assumptions on the temporal variation of the brightness temperature at locations removed from the surface in-situ observations. What uncertainty (quantitatively) resulted from their interpolation procedure?
2. Since the authors use data from 42 occupied stations and 65 AWSs sites, they should provide photographs of the locations (e.g. as provided in http://gallery.surfacestations.org/main.php?g2_itemId=20) in order to ascertain how well they are sited. This photographs presumably exist. Do any of the surface observing sites produce a possible bias because they are poorly sited at locations with significant local human microclimate modifications?
3. How do the authors reconcile the conclusions in their paper with the cooler than average long term sea surface temperature anomalies off of the coast of Antarctica? [see http://www.osdpd.noaa.gov/PSB/EPS/SST/data/anomnight.1.15.2009.gif]. These cool anomalies have been there for at least several years. This cool region is also undoubtedly related to the above average Antarctic sea ice areal coverage that has been monitored over recent years; see http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.anom.south.jpg].
4. In Figure 2 of their paper, much of their analyzed warming took place prior to 1980. For East Antarctica, the trend is essentially flat since 1980. The use of a linear fit for the entire period of the record produces a larger trend than has been seen in more recent years.
In terms of the significance of their paper, it overstates what they have obtained from their analysis. In the abstract they write, for example,
“West Antarctic warming exceeds 0.1C per decade over the past 50 years”.
However, even a cursory view of Figure 2 shows that since the late 1990s, the region has been cooling in their analysis in this region. The paper would be more balanced if they presented this result, even if they cannot explain why.
Please let me know if you would like more feedback. Thank you reaching out to include a broader perspective on these papers in your articles.
Regards
Roger
Thursday, January 22, 2009
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Scientists, Data Challenge New Antarctic ‘Warming’ Study. By Marc Morano
ReplyDeleteThe Inhofe EPW Press Blog, Jan 21, 2009
http://epw.senate.gov/public/index.cfm?FuseAction=Minority.Blogs&ContentRecord_id=fc7db6ad-802a-23ad-43d1-2651eb2297d6
Excerpts:
Washington, DC: A new study on Antarctic temperatures – which is contrary to the findings of multiple previous studies - claims "that since 1957, the annual temperature for the entire continent of Antarctica has warmed by about 1 degree Fahrenheit, but still is 50 degrees below zero.”
Despite the fact that the study was immediately viewed with major skepticism by scientists who are not skeptical of anthropogenic global warming claims, many in the media pounced on the study as a chance to attack those skeptical of man-made climate doom. According to the release of the study (http://uwnews.org/article.asp?articleID=46448) , “The researchers devised a statistical technique that uses data from satellites and from Antarctic weather stations to make a new estimate of temperature trends. […] The scientists found temperature measurements from weather stations corresponded closely with satellite data for overlapping time periods. That allowed them to use the satellite data as a guide to deduce temperatures in areas of the continent without weather stations.” [...]
[...]
UN IPCC lead author, Dr. Kevin Trenberth, who is not in any way a climate change skeptic, said of the study, "I remain somewhat skeptical… It is hard to make data where none exist.” Echoing Trenberth’s analysis were several other scientists.
Climatologist Dr. John Christy of the University of Alabama in Huntsville questioned the study. "One must be very cautious with such results because they have no real way to be validated," Christy told the AP. “In other words, we will never know what the temperature was over the very large missing areas that this technique attempts to fill in so that it can be tested back through time,” Christy added.
Former Colorado State Climatologist Dr. Roger Pielke, Sr., senior scientist at the University of Colorado in Boulder said the authors of the Antarctic study “overstated” their results. “In terms of the significance of their paper, it overstates what they have obtained from their analysis,” Pielke told the AP. “In the abstract they write, for example, ‘West Antarctic warming exceeds 0.1C per decade over the past 50 years.’ However, even a cursory view of Figure 2 shows that since the late 1990s, the region has been cooling in their analysis in this region. The paper would be more balanced if they presented this result, even if they cannot explain why,” Pielke wrote. Pielke also questioned how the authors “reconcile the conclusions in their paper with the cooler than average long term sea surface temperature anomalies off of the coast of Antarctica.” Pielke added, “These cool anomalies have been there for at least several years. This cool region is also undoubtedly related to the above average Antarctic sea ice areal coverage that has been monitored over recent years.”
A critical analysis of the paper from December 21, 2008, accused the authors of the Antarctic study of making questionable data “adjustments.” (See: Scientist adjusts data -- presto, Antarctic cooling disappears - December 21, 2008) The analysis concluded, “Looks like [study author] Steig 'got rid of' Antarctic cooling the same way [Michael] Mann got rid of medieval warming. Why not just look at the station data instead of 'adjusting' it (graph above)? It shows a 50-year cooling trend,” the analysis concluded.
[...]
Alarmists Play Both Sides
The BBC’s Richard Black filed a report on the new study that included this claim: “'It's hard to think of any situation where increased greenhouse gases would not lead to warming in Antarctica,’ said Drew Shindell from NASA's Goddard Institute for Space Studies (GISS) in New York.”
Sadly, Black of the BBC does not report that the promoters of man-made global warming fears had already concocted explanations for the failure of Antarctica to warm as models predicted. [See: Antarctic temperatures disagree with climate model predictions – February 15, 2007 http://www.eurekalert.org/pub_releases/2007-02/osu-atd021207.php]
The warming partisans at RealClimate.org have claimed that a cooling Antarctica is just what the models predict! “A cold Antarctica is just what calculations predict,” stated a February 12, 2008, post on Real Climate titled “Antarctica is Cold? Yeah, We Knew That.” ((http://www.realclimate.org/index.php/archives/2008/02/antarctica-is-cold/)
[...]