Paul Homewood reminded me of the EPA graph below, which shows that heatwaves during the 1930s were much worse than recent years.
Hansen is of course undaunted by facts, and is claiming that bad heatwaves never used to happen.
The distribution of seasonal mean temperature anomalies has shifted toward higher temperatures and the range of anomalies has increased.
An important change is the emergence of a category of summertime extremely hot outliers, more than three standard deviations (σ) warmer than climatology.
This hot extreme, which covered much less than 1% of Earth’s surface in the period of climatology, now typically covers about 10% of the land area.
We conclude that extreme heat waves, such as that in Texas and Oklahoma in 2011 and Moscow in 2010, were “caused” by global warming, because their likelihood was negligible prior to the recent rapid global warming. We discuss practical implications of this substantial, growing climate change.
This is complete nonsense. According to the EPA graph below, the heatwaves of the 1930s were more than three standard deviations warmer than climatology.
Heat waves occurred with high frequency in the 1930s, and these remain the most severe heat waves in the U.S. historical record (see Figure 1). Many years of intense drought (the “Dust Bowl”) contributed to these heat waves by depleting soil moisture and reducing the moderating effects of evaporation.
• There is no clear trend over the entire period tracked by the index. Although it is hard to see in Figure 1 (because of the extreme events of the 1930s), heat wave frequency decreased in the 1960s and 1970s but has risen since then (see Figure 1).
GHCN HCN records show that the summer of 2011 in Oklahoma was not as hot as 1934, and that the summer of 2012 wasn’t even in the top ten.
Hansen knows that what he is saying now isn’t true. He wrote the text below in 1999.
Empirical evidence does not lend much support to the notion that climate is headed precipitately toward more extreme heat and drought. The drought of 1999 covered a smaller area than the 1988 drought, when the Mississippi almost dried up. And 1988 was a temporary inconvenience as compared with repeated droughts during the 1930s “Dust Bowl” that caused an exodus from the prairies, as chronicled in Steinbeck’s Grapes of Wrath…..
in the U.S. there has been little temperature change in the past 50 years, the time of rapidly increasing greenhouse gases — in fact, there was a slight cooling throughout much of the country