Phil Jones is director of the Climatic Research Unit (CRU) at the University of East Anglia (UEA), which has been at the center of the row over hacked emails. The BBC’s environment analyst Roger Harrabin put questions to Professor Jones yesterday, including several gathered from climate skeptics.
Here are some of the questions. Some of Phil’s replies were surprisingly candid. I will look at and comment on six of the 23 questions.
Do you agree that according to the global temperature record used by the IPCC, the rates of global warming from 1860-1880, 1910-1940 and 1975-1998 were identical?
Phil Jones admitted the warming trends in the cyclical climate change we have seen since 1860 have been similar in magnitude. He provided these values for those periods:
Period Length Trend Significance
1860-1880 21 years 0.163 Yes
1910-1940 31 years 0.150 Yes
1975-1998 24 years 0.166 Yes
Jones left out 1880 to 1910, and 1940 to 1976, which both had negative decadal trends.
Do you agree that from January 2002 to the present there has been statistically significant global cooling?
Here Jones noted that the trend from 2002 to 2009 is negative (-0.12C per decade), but not statistically significant. He had noted earlier in the interview:
Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.
Do you agree that natural influences could have contributed significantly to the global warming observed from 1975-1998?
When considering changes over this period we need to consider all possible factors (so human and natural influences as well as natural internal variability of the climate system). Natural influences (from volcanoes and the Sun) over this period could have contributed to the change over this period.
However, Jones also noted that volcanoes should have produced cooling (and did) in the early 1980s and 1990s. He said the solar was flat. Here, it actually depends on what and whose measure of solar output you use.
Some, like Judith Lean, show flat solar output, but others like Hoyt/Schatten/Willson show an increase in line with recent decadal warming. Also, the other solar factors like ultraviolet (Shindell and Labitzke) and geomagnetic (Svensmark, Friis-Christensen), which can influence Earth’s temperature through ozone chemistry or cosmic ray cloud cover variations, were ignored by Lean and the IPCC (though they were discussed at some length in the IPCC science chapters). Scafetta and West have shown that, depending on which reconstruction is used and assuming that they are proxies for the total solar effect, you can explain up to 69% of the government (inflated) warming since 1900.