Browsing articles tagged with " Paul Pearson"

When was CO2 last at 400 ppm? And what was the climate like?

May 13, 2013   //   by Athena   //   Blog, Earth System  //  Comments Off on When was CO2 last at 400 ppm? And what was the climate like?
Paul N. Pearson, School of Earth and Ocean Sciences, Cardiff University CF10 3AT, UK.
Email: pearsonp@cardiff.ac.uk
 
Summary Atmospheric CO2 is approaching the 400 ppm mark for the first time in human history which begs the question: when was it last that high? A recent high profile suggestion is that CO2 was that high in the Pliocene epoch (approximately 2.6-5.3 million years ago) and this is now being repeated in the press and around the internet. Here I point out that this claim is based on a few extreme estimates, mostly from sites that systematically overestimate more recent CO2 levels, while the majority of published Pliocene CO2 values are in the 250-400 ppm range. The last time we have consistent evidence for pCO2 over 400 ppm is in the Early Oligocene epoch more than 26 million years ago. This post presents the key graphs and comments on some of the methods used to calculate past pCO2.
 
Read the article
Download the article (pdf)

 
Images and graphs are subject to copyright.

Presentations, papers, and a curious case of planktonic foraminiferal evolution that may be linked to global cooling

Nov 14, 2012   //   by Athena   //   Blog  //  Comments Off on Presentations, papers, and a curious case of planktonic foraminiferal evolution that may be linked to global cooling

By Paul Pearson 

Paul Pearson, a Descent into the Icehouse participant,  made two presentations to the Geological Society of America in Charlotte, North Carolina, this month. The first was a review of the most important of all the palaeoclimate proxy methods, vital to the Descent into the Icehouse project: ‘Oxygen Isotopes in Foraminifera: Overview and Historical Review‘.

It was accompanied by a review paper of the same title published in Paleontological Society Papers, Volume 18, p. 1-38. We hope to provide a link to the pdf on this blog shortly.

The second talk was on a curious specific case of evolution in the plankton in deep pelagic niches that may be linked to the global cooling that set in during the middle Eocene: ‘Evolutionary origin of Hantkenina (planktonic foraminifera) in the middle Eocene and comments on its biostratigraphic significance’ by Paul Pearson, Helen Coxall, Bridget Wade, and Brian Huber.

The study will be submitted for publication shortly. The graphic shows a line-up of beautifully preserved ‘transitional’ hantkeninids from a core in Tanzania, in emulation of the iconic image of human evolution (via a spear-wielding Neanderthal) beloved of textbooks.