Monday, July 26, 2010

Earth Systems Scientists Highlight Biogeochemical Feedbacks

The impacts of biogeochemical feedbacks should not to be ignored in climate change studies, say EU-funded scientists. In order to understand how the Earth is likely to evolve in this century and beyond, the team believes greater emphasis must be placed on the feedbacks that exist between the terrestrial biosphere and the Earth's atmosphere. Results from the study, published in Nature Geoscience, suggest that biogeochemical feedbacks could be important in modulating future climate change.

The research was supported by the GREENCYCLES ('Biogeochemistry and climate change research and training network') project, which received EUR 2.84 million under the Marie Curie Actions - Human resources and mobility activity of the Sixth Framework Programme (FP6). The four-year project, which ended in 2008, fostered new developments in the multidisciplinary field of biogeochemical cycles research including training for a new generation of Earth system scientists.

GREENCYCLES is now continuing its work via the GREENCYCLES II ('Anticipating climate change and biospheric feedbacks within the Earth system to 2200') initial training network, backed with almost EUR 6 million under the Marie Curie Actions budget line of the Seventh Framework Programme (FP7). GREENCYCLES aims to boost our understanding of the impacts of climate biogeochemistry feedbacks on the evolution of Earth systems between now and 2200.

Although scientists are almost certain that human activity is having a formidable effect on global climate patterns and will continue to impact the future of our planet, they are still unsure of what form these changes will take - both during this century and beyond.

In their paper, the team of scientists led by Dr Almut Arneth from Lund University in Sweden explains that the terrestrial biosphere is a key regulator of atmospheric chemistry and climate. Studies of climate change periods that have occurred on Earth in the past have shown that vegetation cover and interactions between the terrestrial biosphere and atmosphere changed within decades.

According to the team, contemporary studies have shown that terrestrial biogeochemistry has a similar responsiveness to anthropogenic climate change and air pollution. It should be noted that while interactions between the carbon cycle (a biogeochemical cycle) and climate have been a focal area, other biogeochemical feedbacks could be just as important in understanding future climate change.

In fact, Dr Arneth and her team have provided a series of estimates of the significance of these unaccounted biogeochemical feedbacks. They found that the combined 'positive forcing from feedbacks associated with carbon, nitrogen and atmospheric chemistry in response to anthropogenic warming could further increase warming'.

'Indeed, biogeochemical positive forcing could potentially cancel out cooling associated with CO2 (carbon dioxide) fertilisation of the biosphere, an effect that has been proposed to mitigate warming,' they comment.

They are quick to add that the estimates serve as a very rough guide because of the limited number of quantitative experiments available. Substantial uncertainties exist, for example, in how changes to one biogeochemical cycle will impact on other cycles.

'The overall magnitude of the biogeochemical feedbacks could potentially be similar to that of feedbacks in the physical climate system, but there are large uncertainties in the magnitude of individual estimates and in accounting for synergies between these effects,' they conclude.

For more information, please visit:
Nature Geoscience:
Lund University:

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