Scheme: Dorothy Hodgkin Fellowship
Organisation: University of Birmingham
Dates: Jan 2010-Dec 2013
Summary: Writing this, at the begining of May 2013, the Earth is on the cusp of a realm it last experienced over 20 million years ago. Although symbolic, the rise above a concentration of 400 parts per million of carbon dioxide in the Earth's atmosphere, should be a time of questioning. What does the continued rise in CO2 above this value mean for the planet, biosphere and human societies? When will this rise slow in pace? And what was the world like before, when CO2 concentrations were last this high?
My research is a small part of a global effort by scientists to understand the functioning of the Earth's climate under conditions of very high atmospheric CO2, at least from the perspective of the human species to date. To do this, we typically use the chemistry and biology of fossil organisms to reconstruct ocean temperatures, atmospheric carbon dioxide concentrations and ecosystems of the Earth, millions to tens of millions of years in the past. Such reconstructions provide a critical test of our understanding of the basic "physics" of the Earth; how the oceans and atmosphere hold and transport heat around the planet.
This planetary physics is embedded within all computer models of our weather and climate. Reconstructions of modern climate and weather have dramatically improved in detail and sophistication over the past twenty years. The question for our future is how well they reproduce global climates well beyond the conditions we have seen for a millenia? Comparing climate models and climate reconstructions of the Earth tens of millions of years ago are one way to do this.
Two key results from the study of early Cenozoic warm climates (~65 to ~34 million years ago) are, first, that polar regions appear to warm significantly more under high CO2 conditions than simulated by climate models, and second, that there have been times in the past when a general warming trend has triggered positive feedbacks in the Earth system, leading to major transient warming events.