Some people wonder if Michael Mann is simply an activist masquerading as a scientist, this lends credence to that idea. I wonder if Dr. Mann has ever visited weather stations in China to understand what is going on there? I have.
I had to laugh when I saw this quote from Mann in Seth Borenstein’s most recent AP article:
“The study is important because it formalizes what many scientists have been sensing as a gut instinct: that the increase in extreme heat that we’ve witnessed in recent decades, and especially in recent years, really cannot be dismissed as the vagaries of weather,” said Pennsylvania State University climate scientist Michael Mann.
The study he is referring to is this one, press release below. I’ll explain why Mann and Borenstein made me laugh (besides the “gut instinct” nonsense) after the press release:
Greenhouse-gas emissions raise extreme temperatures in China
9 April 2013 AGU Release No. 13-12 For Immediate Release
WASHINGTON – Humans are responsible for increasingly warm daily minimum and maximum temperatures in China, new research suggests. The study is the first to directly link greenhouse gas emissions with warmer temperature extremes in a single country, rather than on a global scale, according to the paper’s authors.
“There is a warming in extreme temperatures over China, and this warming cannot be explained by natural variation,” said Qiuzi Han Wen, an author on this paper and a researcher at the Institute of Atmospheric Physics in Beijing, China. “It can only be explained by the anthropogenic external forcings. These findings indicate very clearly that climate change is not just an abstract number for the globe; it is evident at regional scale.”
The study was recently published in Geophysical Research Letters—a journal of the American Geophysical Union.
To identify the human influence on temperatures, researchers from Beijing and Toronto compared data from climate change models with actual observations from 2,400 weather stations in China gathered between 1961 and 2007.
“The climate model produces historical simulations to mimic what would have happened under different influences—such as human-induced greenhouse gas emissions and volcanic activities—and produces many possible outcomes”,” said Xuebin Zhang, an author on the paper and a researcher in the Climate Research Division of Environment Canada in Toronto. “If we average these possible outcomes, the day-to-day weather noise cancels out, leaving us with a general trend.”
The climate model reproduces China’s present reality only if human emissions are included, indicating that global warming is indeed the culprit for China’s warmer day and nighttime temperatures and not natural weather fluctuations, Zhang said.
“Actually seeing a warming trend in a single location is hard,” Zhang said. “It’s like trying to see the tide change when you’re in a rowboat going up and down on the waves. You need a lot of data to distill the day-to-day weather noise from the general trend.”
But the key to cracking the warming trend in China, Zhang said, was the vast amounts of data that the research team distilled from the thousands of weather stations, over more than four decades. The researchers estimate that human emissions likely increased the warmest annual extreme temperatures—the daily maximum and daily minimum for the hottest day and night of the year—by 1.7 degrees Fahrenheit (0.92 degrees Celsius) and 3°F (1.7°C), respectively. They also found that human emissions likely raised the coolest annual extreme temperatures—the daily maximum and daily minimum for the coldest day and night of the year—by 5.1°F (2.83°C) and 8.0°F (4.44°C), respectively.
In addition to calculating the overall trend, Wen, Zhang and their colleagues separated the effect of each anthropogenic input. Carbon dioxide emissions had the highest impact on warming, explaining 89 percent of the increase in the daily maximum temperatures and 95 percent of the daily minimum temperatures.
Wen asserts greenhouse gases already in the atmosphere will continue to affect China’s climate for years to come, regardless of mitigation measures taken to reduce future emissions. “As a result, we expect warming in China will continue into the future, and consequently warming in extreme temperatures will also continue,” Wen said. “This will have huge implications for China, as heat waves and drought have already become more and more of an issue in our country. We would expect more hardship for dry-land farming as water supply is already stressed, higher demand on energy for cooling, and increasing heat-induced health issues.”
Zhang stresses that the results of this study highlight that climate change is an urgent issue for China and that warming is already taking a toll on the country.
“There are heat waves almost everywhere in China and we’re seeing more droughts,” Zhang said. “China is getting much warmer, and people are very concerned.”
This study was funded by the National Basic Research Program of China and benefited from a collaboration between the Meteorological Service Canada and the China Meteorological Administration.
Paper: “Detecting human influence on extreme temperatures in China”
Journalists and members of the public can download a PDF copy of this accepted article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/grl.50285/abstract
 This study compares observed and model-simulated spatiotemporal patterns of changes in Chinese extreme temperatures during 1961–2007 using an optimal detection method. Four extreme indices, namely annual maximum daily maximum (TXx) and daily minimum (TNx) temperatures and annual minimum daily maximum (TXn) and daily minimum (TNn) temperatures, are studied. Model simulations are conducted with the CanESM2, which include six 5-member ensembles under different historical forcings, i.e., four individual external forcings (greenhouse gases, anthropogenic aerosol, land use change, and solar irradiance), combined effect of natural forcings (solar irradiance and volcanic activity), and combined effect of all external forcings (both natural and anthropogenic forcings). We find that anthropogenic influence is clearly detectable in extreme temperatures over China. Additionally, anthropogenic forcing can also be separated from natural forcing in two-signal analyses. The influence of natural forcings cannot be detected in any analysis. Moreover, there are indications that the effects of greenhouse gases and/or land use change may be separated from other anthropogenic forcings in warm extremes TXx and TNx in joint two-signal analyses. These results suggest that further investigations of roles of individual anthropogenic forcing are justified, particularly in studies of extremely warm temperatures over China.
The full paper is open and available here: http://onlinelibrary.wiley.com/doi/10.1002/grl.50285/pdf
So what did they do?
Here, we use a newly compiled and quality-controlled extensive Chinese daily temperature data set and ensembles of model simulations under different forcings, conducted with the second-generation Canadian Earth System Model (CanESM2) [Arora et al., 2011], to investigate possible causes of the observed changes in extreme temperatures.
China’s National Climate Center has recently compiled
and quality controlled an extensive daily temperature data
set [Wu and Gao, 2012]. Records of daily maximum, daily
minimum, and daily mean temperatures were collected from
2416 observation stations from 1961 to 2007.
They compared surface data to a model, and drew inferences from that:
We used optimal detection method to compare the observed China annual extreme temperatures for 1961–2007 with those simulated by the CanESM2 under different external forcings. Our analyses include one-signal analysis using climate responses to ALL, NAT, ANT, and individual anthropogenic
forcing, and two-signal analyses using various combinations
of responses to different forcings.
But the only forcing they considered was GHG’s. Nary a word exists in the paper about UHI, urban heat island, station siting, or heat sink effects.
We also found that the influence of anthropogenic forcing can be separately detected from that of natural forcings. These clearly indicate that among known external forcings, only anthropogenic influence can explain observed changes in China’s extreme temperatures.
That statement is ludicrous, and made me laugh, especially when the physics of heatsink effects is staring them right in the face by their own observations in the press release:
The researchers estimate that human emissions likely increased the warmest annual extreme temperatures—the daily maximum and daily minimum for the hottest day and night of the year—by 1.7 degrees Fahrenheit (0.92 degrees Celsius) and 3°F (1.7°C), respectively.
A larger nighttime signal than daytime signal is exactly what you would expect in the influence of poor station siting and UHI. The EPA says:
In contrast, atmospheric urban heat islands are often weak during the late morning and throughout the day and become more pronounced after sunset due to the slow release of heat from urban infrastructure. The annual mean air temperature of a city with 1 million people or more can be 1.8–5.4°F (1–3°C) warmer than its surroundings.3 On a clear, calm night, however, the temperature difference can be as much as 22°F (12°C).3
I find big differences in Watts et al 2012
But never mind the exponential growth of China’s infrastructure during their industrial revolution in the last 30+ years adding heat sinks near weather stations, let’s go with our “gut feelings” rather than investigate any other avenues.
I’ll have more on this flawed study later.