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Choose a Project: Ph. D. Research Home Page 1. Atmospheric CO₂ & Climate Change 2. Early Land Plant Analogues 3. Conifer Forests in a Polar Environment 4. Megaherbivores and the Superbiome 5. Live Fast Die Young 6. Atmospheric CO₂ and Agriculture 7. Uprooting of Urban Trees 8. C₄ Photosyhthesis in Alloteropsis 9. Modelling Antarctic Ice Sheets 10. Herbivory in Antarctic Fossil Forests

Personnel
Graduate Student:

Supervisors:

Helen McGlashon

Professor D.J. Beerling
Dr C. Wellman
Dr M. Howe (British Geological Survey, Keyworth www.bgs.ac.uk)

Project dates: October 2002 - September 2005

Summary
The Permo-Carboniferous glaciation (310-290 million years ago) was the most severe ice age of the past 500 million years and lasted for around a 30 million years. At the time, whole continents were frozen over and ice sheets extended down to latitudes of 30º. But, the glaciation did not proceed in smooth and orderly manner. Instead it was marked by the waxing and waning of the huge ice sheets as the continents drifted and rotated clockwise so that the north pole took a distinct wander into warmer climatic regions. What was the concentration of atmospheric CO₂, an important greenhouse gas, doing at this time ? How did the terrestrial biosphere respond to major changes in climate and atmospheric composition ?

The Palaeozoic lycopsids, dominated the equatorial regions throughout the Permo-Carboniferous glaciation, and consequently left us with a legacy of rich fossil deposits in European and North American. Lycopsids are distantly related to modern clubmosses of upland regions, but the group represented by the fossils were in fact giant tree-like organisms 10s of meters tall. Studies on clubmosses with similar leaf structures (both fossil and modern species had microphyll leaves) suggest the fossils carry a signature of atmospheric CO₂ concentration at the time they grew. The isotope composition of the fossils themselves provides us with information about the state of the global carbon cycle at the time.

Building on these observations, our research aims to construct continuous CO₂ and isotopic records from careful morphological and geochemical analyses of fossil lycopsid cuticles. We will be analyzing sequences of fossil materials from both North America and Europe. Our aim is to provide the first empirical evidence documenting changes in atmospheric CO₂ during the growth and retreat of the major ice sheets. In this way we will be able to tie down more precisely the role of CO₂ in the Permo-Carboniferous glaciation. If we are lucky and achieve a sufficiently fine temporal resolution, we may even be able to determine how small wobbles in Earth's orbit (called Milankovitch cycles) influenced atmospheric CO₂ levels 100s of millions of year ago.

Check out our latest research findings in the paper below:

Beerling, D.J. (2002) Low atmospheric CO₂ levels during the Permo-Carboniferous glaciation inferred from fossil lycopsids. Proceedings of the National Academy of Sciences, 99 (20), 12567-12571. (196KB)

Reconstruction of a 300-million year old Carboniferous swamp community. The picture is a photograph of a painting held at the Field Museum of Natural History, Chicago. The tree-like structures shown are arborescent lycopsids and numerous fossil specimens of these plants that we will be studying are house there.