For years, certain climate contrarians and self-styled skeptics have suggested that the temperature records have been contaminated by illegitimate adjustments, poor siting of instruments and the Urban Heat Island (UHI) effect, such that the increase in temperature observed during the past century is due, not to greenhouse gas associated warming, but to non-GHG factors, fudging and poor data. These so-called “skeptics” have made careers out of spreading this misinformation around the blogosphere, giving it credit it does not deserve.
For example, Anthony Watts has made quite a name amongst the skeptical crowd because of his claims that the temperature record is contaminated by bad siting of weather stations (Watts Bunk #1) and the Urban Heat Island effect or UHI (Watts Bunk #2).
Here’s the description of the Watts D’Aleo paper Surface Temperature Records: Policy Driven Deceptions?
The startling conclusion that we cannot tell whether there was any significant “global warming” at all in the 20th century is based onnumerous astonishing examples of manipulation and exaggeration of the true level and rate of “global warming”.
That is to say, leading meteorological institutions in the USA and around the world have so systematically tampered with instrumental temperature data that it cannot be safely said that there has been any significant net “global warming” in the 20th century. (my emphasis)
In a recent post responding to Menne 2010, he claims that unlike Elvis, UHI is not dead.
One of the most ridiculous claims recently related to Menne et al 2010 and my surfacestations project was a claim made by DeSmogBlog (and Huffington Post who carried the story also) is that the “Urban Heat Island Myth is Dead“.
To clarify for these folks: Elvis is dead, UHI is not.
For disbelievers, let’s look at a few cases showing UHI to be alive and well.
It must be difficult for Mr. Watts and other so-called climate skeptics, what with the debunking of their bunk. All he can do in response to the recent debunking is to complain that the work has not been peer reviewed.
*picks self up off the floor*
Pot? Meet Kettle.
With respect to Watts Bunk # 2 The Berkeley Earth Surface Temperature group has released its pre-publication reports including this paper: “Influence of Urban Heating on the Global Temperature Land Average Using Rural Sites Identified from MODIS Classifications”. The other reports are available here.
The effect of urban heating on estimates of global average land surface temperature is studied by applying an urban-rural classification based on MODIS satellite data to the Berkeley Earth temperature dataset compilation of 39,028 sites from 10 different publicly available sources. We compare the distribution of linear temperature trends for these sites to the distribution for a rural subset of 16,132 sites chosen to be distant from all MODIS-identified urban areas. While the trend distributions are broad, with one-third of the stations in the US and worldwide having a negative trend, both distributions show significant warming. Time series of the Earth’s average land temperature are estimated using the Berkeley Earth methodology applied to the full dataset and the rural subset; the difference of these shows a slight negative slope over the period 1950 to 2010, with a slope of -0.19°C ± 0.19 /100yr (95% confidence), opposite in sign to that expected if the urban heat island effect was adding anomalous warming to the record. The small size, and its negative sign, supports the key conclusion of prior groups that urban 2warming does not unduly bias estimates of recent global temperature change. (my emphasis)
In terms of Watts Bunk #1 — bad siting — a number of researchers, including Menne et al 2010, debunked the issue of poor siting biasing the temperature record.
Here’s Menne et. al. 2010:
Results indicate that there is a mean bias associated with poor exposure sites relative to good exposure sites; however, this bias is consistent with previously documented changes associated with the widespread conversion to electronic sensors in the USHCN during the last 25 years. Moreover, the sign of the bias is counterintuitive to photographic documentation of poor exposure because associated instrument changes have led to an artificial negative (“cool”) bias in maximum temperatures and only a slight positive (“warm”) bias in minimum temperatures. These results underscore the need to consider all changes in observation practice when determining the impacts of siting irregularities. Further, the influence of nonstandard siting on temperature trends can only be quantified through an analysis of the data. Adjustments applied to USHCN Version 2 data largely account for the impact of instrument and siting changes, although a small overall residual negative (“cool”) bias appears to remain in the adjusted maximum temperature series. Nevertheless,the adjusted USHCN temperatures are extremely well aligned with recent measurements from instruments whose exposure characteristics meet the highest standards for climate monitoring. In summary, we find no evidence that the CONUS average temperature trends are inflated due to poor station siting. (my emphasis)
Elvis, UHI and Poor Siting.
Dead. Dead. Dead.
The science on these issues has already been done sufficiently that only those with a bias against action on climate change question the findings. More research is always welcome to provide clarity on the issue and I am glad that BEST has supported what the best science already concluded — UHI is not a significant contrubution to observed warming in the temperature record.
Sadly, while this confirmation is welcome, and will help us debunk the bunk, a lot of precious time has been wasted and much unfounded doubt raised – about science and about scientists — around the temperature record.
Being skeptical of research findings and wanting to dig deeper and replicate research is the foundation of science. A skeptical stance towards data and theory is the hallmark of a good scientist. However, non-scientists with political biases promoting unfounded speculation and passing it off as legitimate research is just plain corrupt and morally vacuous.
Luckily, we can write off Watts Bunk and associated dreck, so thank you to BEST for further supporting what the best science already found. UHI is of no significance in the temperature record.
From around the climate blogosphere:
Peter Gleick in Forbes: Breaking News: The Earth Still Goes Around the Sun, and It’s Still Warming Up
Shawn Lawrence Otto in The Huffington Post: Another Climate Denial Argument Bites the Dust
Greg Laden in Science Blogs: Urban Heat Islands as Explanation for Hockey Stick Global Warming Curve
Joe Romm at Climate Progress: Hot Dog Bites Skeptical Man: Koch-Funded Berkeley Temperature Study Does “Confirm the Reality of Global Warming.
Andrew Revkin at Dot.Earth: Skeptic Talking Point Melts Away As An Inconvenient Physicist Confirms Warming
Brian Angliss at Scholars and Rogues: Watts Wrong With This Picture?