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”

Global Warming is happening, what does it mean?

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?”

A Review of Temperature Reconstructions

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”

May/Middleton: Rebuttal to Geological Society of London Scientific Statement on Climate Change

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”

Michael Mann’s 2008 Reconstruction

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”

Earth’s Ice Ages

By Andy May The phrase “Ice Age” is poorly defined and often abused, so let’s first define the climate state during most ice ages. It is called “Icehouse Earth.” The earth is in an icehouse state when either or both poles are covered in a thick, permanent icecap (Scotese 2015). Today, both poles are coveredContinue reading “Earth’s Ice Ages”

Oxygen-18 Stability in Foraminifera fossils, implications in paleoclimatology

By Andy May 18O is a rare isotope of oxygen. The ratio of 18O to the normal 16O in foraminifera fossils (“forams”) can be used to estimate paleo-ocean temperatures. Higher values mean lower temperatures. A recent article on geologypage.com (here) led me to Bernard, et al., 2017, which has experimental data that suggest 18O concentrationsContinue reading “Oxygen-18 Stability in Foraminifera fossils, implications in paleoclimatology”

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