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Deserts impact on climate change

RESEARCH into deserts and their response to climate change has won two MMU academics the Royal Geographical Society's most prestigious prize.

The 2008 Royal Geographical Society Peter Fleming Award was won by Dr Andrew Thomas and Dr Steve Hoon of Environmental and Geographical Sciences to develop research they have conducted over the past few years in the Kalahari Desert.

Andrew and Steve are quantifying gaseous soil fluxes of carbon dioxide and nitrous oxide to determine how the Kalahari responds to moisture and temperature, to help identify how desert regions are affected by climatic change and their impact on the atmosphere.

Dr Thomas said: "Deserts cover one third of the world’s land surface, yet our understanding of their contribution to atmospheric carbon dioxide and nitrous oxide balance is poor.

Concern

"We know there is a huge exchange of carbon and nitrogen between the atmosphere and the soil and, as average global temperatures rise, scientists are concerned that bacteria will break down organic matter in soils more rapidly, releasing more CO2 and N2O into the atmosphere."

Extreme conditions in the Kalahari mean that specialist instruments have to be designed and built by the team to control the experimental micro-environment.

The pair also presented some of their research at the recent annual conference in Edinburgh of the Society for General Microbiology.

"We have recently discovered that even after light rainfall, the gains and losses of carbon dioxide through the sands of the Kalahari Desert were similar in size to those reported for more organic rich grassland soils. Despite being short lived, these raised pulses of activity are a significant and previously unreported contributor to atmospheric carbon dioxide. Global climate change models have forgotten them."

Carbon release

Dr Thomas and Dr Hoon found that in some conditions, cyanobacteria in the surface crust were taking net amounts of carbon dioxide out of the atmosphere as they photosynthesised. But after heavy rainfall other types of bacteria deeper in the subsoil became active and their activity masked the uptake of carbon by the surface cyanobacteria by consuming the organic matter in the soil, releasing large quantities of carbon dioxide.

"We also discovered that the fluxes of carbon dioxide from the soil were highly sensitive to temperature. Warmer air but similar soil moisture levels caused greater losses of carbon from the desert soils to the atmosphere. These desert soils are contributing significantly to the global carbon dioxide budget. Until recently they have been ignored," added Dr Thomas.

The £9,000 prize will enable the research team to gain further insight into the role of temperature and rainfall on desert soil gas fluxes.

The research is also informing teaching in the Department and four lucky final-year undergraduates and a Masters student will take part in the next field trip in july and August.

For more about research by the Earth System Science Group, please go to www.egs.mmu.ac.uk/users/ess/index.htm.

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