Category Archives: Paleoclimatology

By Andy May This post has been translated into German by Christian Freuer here. As I noted in my earlier post, “The IPCC AR6 Report Erases the Holocene,” the IPCC does not like to discuss the correlation between CO2 and temperature during the Holocene. It destroys their hypothesis that greenhouse gases and volcanos control Earth’sContinue reading “Holocene CO2 and the earlier IPCC Reports”

By Andy May For decades We have been told that we must not let global warming exceed two degrees Celsius above the “pre-industrial” global average temperature. Recently the IPCC lowered this limit to 1.5°C. In the latest IPCC report, called AR6, pre-industrial is defined as before 1750, but they use global temperatures from 1850-1900 asContinue reading “The Two-Degree Limit”

By Andy May An interesting PNAS article discusses the deepest portion of the Camp Century Greenland Ice core. It is not paywalled. The researchers, led by Andrew Christ (Dept. of Geology, University of Vermont) found evidence of an ice-free vegetated environment at the base of the Camp Century ice core roughly one million years ago.Continue reading “What’s below the Greenland Ice?”

By Andy May The PETM or Paleocene-Eocene Thermal Maximum was a warm period that began between 56.3 and 55.9 Ma (million years ago). The IPCC AR6 report (actually a draft, not a final edited report), released to the public on August 9, 2021, suggests that this warm period is similar to what is happening todayContinue reading “The Paleocene-Eocene Thermal Maximum or PETM”

By Andy May In the last post, I discussed the problems comparing modern instrumental global or hemispheric average temperatures to the past. Ocean temperature coverage was sparse and of poor quality prior to 2005. Prior to 1950, land (29% of the surface) measurements were also sparse and of poor quality. Only proxy temperatures are availableContinue reading “How to compare today to the past”

By Andy May The concepts and data used to make temperature and climate reconstructions, or estimates, are constantly evolving. Currently, there are over 100,000 global weather stations on land and over 4,500 Argo floats and weather buoys at sea. This is in addition to regular measurements by satellites and ships at sea. The measurement locationsContinue reading “Global Warming is happening, what does it mean?”

By Andy May This is an update to a 2016 post; the original post is here. We often hear that the planet is warming faster than ever before, or at the fastest rate since the beginning of the industrial era! Is it true? We haven’t had thermometers for very long. How do thermometer readings compareContinue reading “A Review of Temperature Reconstructions”

Guest essay by David Middleton and Andy May A pdf version of this post can be downloaded here. The Geological Society of London recently published a statement on climate change: Geological Society of London Scientific Statement: what the geological record tells us about our present and future climate Geologists Andy May and David Middleton haveContinue reading “May/Middleton: Rebuttal to Geological Society of London Scientific Statement on Climate Change”

By Andy May In my last post, it was suggested that Michael Mann’s 2008 reconstruction (Mann, et al., 2008) was similar to Moberg’s 2005 (Moberg, Sonechkin, Holmgren, Datsenko, & Karlen, 2005) and Christiansen’s 2011/2012 reconstructions. The claim was made by a commenter who calls himself “nyolci.” He presents a quote, in this comment, from Christiansen’sContinue reading “Michael Mann’s 2008 Reconstruction”