Category Archives: Paleoclimatology

The Bray Solar Cycle and AMO

Did the Bray Solar Cycle play a role in the recent warming of North Atlantic sea surface temperatures?

Musings on the AMO

By Andy May We hear a lot about the AMO, or the Atlantic Multidecadal Oscillation. How much does it influence the global mean surface temperature or GMST? Exactly what is the AMO? These are the issues we will discuss. First let’s look at various definitions of the AMO.

Plate Tectonics and Climate during the Cenozoic

By Andy May This post has been translated to German by Christian Freuer here. In this post I examine the proxies used to compare CO2 to temperature from 66 million years ago (Ma) until today and comment on the quality of the comparison. In addition, we look at the Cenozoic plate tectonic events that affectedContinue reading “Plate Tectonics and Climate during the Cenozoic”

Climate Change over the past 4000 Years

By Andy May I last wrote about Climate Change and Civilization for the past 4,000 Years in 2016. Since then, a lot has changed, and I’ve learned a lot more about the subject. First, we learned that various air and sea temperature proxies, such as ice core δ18O or tree rings, are all different. ForContinue reading “Climate Change over the past 4000 Years”

Holocene CO2 and the earlier IPCC Reports

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”

Are fossil-fuel CO2 emissions good or bad?

By Andy May This is the transcript, with minor edits to get it into blog post format, of my keynote speech to the AAPG Division of Professional Affairs, at the second International Meeting for Applied Geoscience and Energy Convention in the George R. Brown Convention Center in Houston on August 30, 2022. In the greatContinue reading “Are fossil-fuel CO2 emissions good or bad?“

The Two-Degree Limit

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”

What’s below the Greenland Ice?

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?”

The Paleocene-Eocene Thermal Maximum or PETM

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”

How to compare today to the past

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”