Update: At the suggestion of one of the readers at the cross post at WUWT, I’ve rewritten the second paragraph after Figure 3. Thanks, richard verney.
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In response to the May 19, 2013 op-ed Overheated rhetoric on climate change doesn’t make for good policies by Lamar Smith (Chairman of the House Committee on Science, Space and Technology), the Washington Post published an op-ed by Michael Oppenheimer and Kevin Trenberth on June 6, 2013. The Oppenheimer and Trenberth op-ed was titled Climate science tells us the alarm bells are ringing. Oddly, it is chock full of overheated rhetoric, which Representative Smith was cautioning against. Unfortunately, the Oppenheimer and Trenberth op-ed is typical of the responses by many climate alarmists to Representative Smith’s op-ed, as discussed in Judith Curry’s blog post Rep. Lamar Smith on climate change.
In addition, a couple of things caught my eye in the Oppenheimer and Trenberth op-ed.
It failed to mention Balmaseda et al (2013) Distinctive climate signals in reanalysis of global ocean heat content, of which Kevin Trenberth was co-author. Instead, they linked a couple of other recent papers and webpages. Their op-ed reads:
Much has been made of a short-term reduction in the rate of atmospheric warming. But “global” warming requires looking at the entire planet. While the increase in atmospheric temperature has slowed, ocean warming rose dramatically after 2000. Excess heat is being trapped in Earth’s climate system, and observations of the Global Climate Observing System and others are increasingly able to locate it. Simplistic interpretations of cherry-picked data hide the realities.
Specifically, Oppenheimer and Trenberth linked Lyman et al (2010) Robust warming of the global upper ocean, and they linked a webpage that introduced Loeb et al (2012) Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty.
Balmaseda et al (2013) is a newer paper. It was published in May 2013. Kevin Trenberth is a coauthor, yet Oppenheimer and Trenberth chose not to include it as a reference in their op-ed. Curious.
Note: After a few preliminary discussions, the uncertainties and difficulties with the Balmaseda et al (2013) paper were presented in detail in the blog post Open Letter to the Royal Meteorological Society Regarding Dr. Trenberth’s Article “Has Global Warming Stalled?”. Refer also to the cross post at WattsUpWithThat. There is also a pdf copy of the post here. The discussions including and following the heading of NORTHERN HEMISPHERE OCEAN HEAT CONTENT DATA DOES NOT SUPPORT BALMASEDA ET AL should also apply to Lyman et al (2010) and Loeb et al (2012).
Oppenheimer and Trenberth continued with more heated rhetoric (my boldface):
Contrary to Smith’s assertions, there is conclusive evidence that climate change worsened the damage caused by Superstorm Sandy. Sea levels in New York City harbors have risen by more than a foot since the beginning of the 20th century. Had the storm surge not been riding on higher seas, there would have been less flooding and less damage. Warmer air also allows storms such as Sandy to hold more moisture and dump more rainfall, exacerbating flooding.
Earlier, Oppenheimer and Trenberth complained about “cherry-picked data”, but they presented a rise in sea level since the beginning of the 20th Century. They should know very well that the IPCC claims their climate models cannot simulate the rate of warming for the last 30+ years without being forced by manmade greenhouse gases—implying that manmade greenhouse gases are responsible for global warming during the last 30+ years, while Mother Nature is responsible for the warming before then. That was the intent of Figure 9.5 in their 4th Assessment Report. Refer to Chapter 9 Understanding and Attributing Climate Change, under Heading of “9.4.1.2 Simulations of the 20th Century”, where the IPCC wrote:
“Figure 9.5 shows that simulations that incorporate anthropogenic forcings, including increasing greenhouse gas concentrations and the effects of aerosols, and that also incorporate natural external forcings provide a consistent explanation of the observed temperature record, whereas simulations that include only natural forcings do not simulate the warming observed over the last three decades.”
It appears that Oppenheimer and Trenberth presented the 12-inch-plus rise in sea level since 1900 at The Battery simply to make the assumed anthropogenic impacts appear greater. They must have felt the 6.5 inch rise in sea level since 1975 at The Battery (reference here) versus Sandy’s storm surge there of 13.88 feet or 166 inches (reference here) was not significant enough. The sea level rise of 6.5 inches since 1975 is only about 4% of the storm surge so they must’ve believed they needed to exaggerate the supposed influence of manmade global warming.
Also, a major portion of sea level rise comes from thermal expansion, but ocean heat content data and satellite-era sea surface temperature data both indicate the oceans warmed naturally. Refer to my illustrated essay “The Manmade Global Warming Challenge” [42MB].
Wisely, Oppenheimer and Trenberth avoided the subject of sea surface temperatures along Sandy’s path. The sea surface temperatures of extratropical portion of Sandy’s storm track have actually cooled since the New England Hurricane of 1938. Figure 1 is Figure 4 from the post October 2012 Sea Surface Temperatures and Anomalies Along Sandy’s Path Were NOT Unusual. I published that post within weeks of Sandy. It’s difficult for alarmists to claim manmade greenhouse gases caused the warming of the sea surface temperatures of the extratropical portion of Sandy’s storm track, when the sea surface temperatures there have cooled over the past 70+ years.
Figure 1
But Oppenheimer and Trenberth did make a statement with respect to hurricane Sandy that we can check with data. They wrote, “Warmer air also allows storms such as Sandy to hold more moisture and dump more rainfall, exacerbating flooding.” We’ll use RSS lower troposphere temperature anomaly data for Sandy’s storm track. It’s available on a gridded basis through the KNMI Climate Explorer. For those new to lower troposphere temperature data, they represent the temperature at about 3000 meters above sea level, as calculated from satellite measurements. Based on the linear trend, the lower troposphere temperature anomalies for Sandy’s full storm track (12N-40N, 80W-70W) haven’t warmed since 1990. See Figure 2. And for the extratropical portion (24N-40N, 80W-70W), they haven’t warmed since 1985, as shown in Figure 3.
Figure 2
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Figure 3
Note, the upward spikes in Figures 2 and 3 at January 2013 occurred after Sandy. The sharp drops occurred in November 2012. The October anomalies, leading up to Sandy, were not extraordinary. For Sandy’s full storm track, they were about 0.32 deg C. And for the extratropical portion they were approximately 0.56 deg C. Those values had been exceeded regularly before then.
If the lower troposphere temperature anomalies haven’t warmed in 2 to almost 3 decades, it’s difficult to claim “Warmer air also allows storms such as Sandy to hold more moisture and dump more rainfall, exacerbating flooding.” But, obviously, alarmists are more than willing to make claims that aren’t supported by data.
Granted, Oppenheimer and Trenberth did not state that manmade greenhouse gases caused the atmosphere to be warmer above Sandy’s storm track, when they wrote, “Warmer air also allows storms such as Sandy to hold more moisture and dump more rainfall, exacerbating flooding.” But they implied it. If the lower troposphere temperature anomalies above Sandy’s storm track haven’t warmed in 2 to almost 3 decades, it was pointless for Oppenheimer and Trenberth to write, “Warmer air also allows storms such as Sandy to hold more moisture and dump more rainfall, exacerbating flooding,” unless they wanted their readers to believe the atmosphere above was warmer.
Of course, Oppenheimer and Trenberth mentioned moisture in the air, so we need to address that as well. We’ll use the Specific Humidity and Precipitable Water from the NCEP/DOE Reanalysis-2, which are available through the NOAA NOMADS website. And we’ll use the coordinates of the extratropical portion of Sandy’s storm track (24N-40N, 80W-70W). Specific humidity in Figure 4 represents the ratio of water vapor to dry air and is expressed in kilograms of water vapor per kilogram of dry air—at 2 meters above the surface. Based on the linear trend, it hasn’t increased since 1990. The Precipitable Water in Figure 5 is the amount of water in the column of atmosphere if all the water in that column were to be precipitated as rain, and it is presented in kg per square meter. It shows no trend since 1985 for the extratropical portion of Sandy’s storm track.
Figure 4
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Figure 5
The NCEP/DOE Reanalysis-2 outputs do not agree with the claims made by Oppenheimer and Trenberth. No surprise there.
CLOSING
Oppenheimer and Trenberth made claims of “conclusive evidence” about Hurricane Sandy that are not supported by data and by the NCEP/DOE Reanalysis-2. They also complain about cherry-picking but don’t hesitate to cherry-pick a start year when it suits their needs. And I found it odd that they did not cite Balmaseda et al (2013), a paper that Kevin Trenberth coauthored. Please feel free to point out other inconsistencies or curiosities in their op-ed.