Warmer ecosystems could absorb less atmospheric carbon dioxide

June 30, 2010, Queen Mary, University of London

(PhysOrg.com) -- Research by scientists at Queen Mary, University of London has found that a predicted rise in global temperature of 4°C by 2100 could lead to a 13% reduction in ecosystems' ability to absorb carbon dioxide (CO2) from the atmosphere.

Writing in Philosophical Transactions of the Royal Society B, the scientists describe a new model to predict how the capacity of ecosystems would respond to future global warming. They tested their predictions against data collected from experimental ponds which were warmed to simulate global warming, revealing a 13% reduction in the amount of CO2 absorbed by the warmed ecosystems.

Lead author of the Philosophical Transactions paper, Gabriel Yvon-Durocher from Queen Mary's School of Biological and Chemical Sciences said: "The beauty of this model is in its simplicity. We made our prediction based on just two parameters - the 'activation energies' for photosynthesis and respiration, and the increase in temperature which exactly predicted the changes observed in our experiment."

He explains: "Photosynthesis by plants absorbs CO2 while respiration by animals returns CO2 to the atmosphere. Respiration has a higher 'activation energy' than photosynthesis meaning that it increases more rapidly with increasing temperature. So if climate change raises environmental temperatures, the balance between respiration and in the ecosystem will change, favouring more and less CO2 absorption."

The work is complemented by another paper published this month by Dr Guy Woodward and other Queen Mary colleagues in the journal Global Change Biology. This research compared animals living in 15 similar Icelandic streams, a rare long-term 'natural experiment' in which geothermal activity heats some streams up to 45°C. The unique situation meant researchers could study how temperature affects Arctic ecosystems, where is predicted to cause a rise of around 7.5°C within the next century.

Dr Woodward says: "We found dramatic changes in the type and number of species in cold streams compared with the warmer ones. It was notable that fish and other larger predatory animals were absent from the coldest streams. We saw longer food-chains, with predators becoming bigger and more abundant as temperatures increased from 5°C to 25°C. We also have more recent (as yet unpublished) data collected from the Icelandic streams by colleagues at the Macaulay Institute that show similar patterns to those seen in the experimental ponds: namely the warmer streams emitted far more CO2 than the cooler streams and acted as sources of carbon, rather than sinks."

Explore further: Corralling the carbon cycle

More information:
-- Gabriel Yvon-Durocher, J Iwan Jones, Mark Trimmer, Guy Woodward and Jose M Montoya, "Warming alters the metabolic balance of ecosystems" is published in the journal Philosophical Transactions of the Royal Society B DOI:10.1098/rstb.2010.0055
-- Guy Woodward, John B. Dybkjær, Jón S Ólafsson, Gísli M Gíslason, Elísabet R Hannesdóttir, Nikolai Friberg, "Sentinel systems on the razor's edge: effects of warming on Arctic geothermal stream ecosystems" is published in the journal Global Change Biology DOI: 10.1111/j.1365-2486.2009.02052.x

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not rated yet Jun 30, 2010
Yet another article from the Annals of Improbable Research. Metabolism of living things increasing with temperature is common knowledge. Warmer climates host incredible abundance and diversity of life forms. Significant C02 absorbing ecosystems such as Amazon rain forest are located in warmer climates. One can care less about alleged O2/CO2 consumption/production relative rate changes influenced by temperature, as long as absolute values grow and, more importantly, the number of living things multiplying.
5 / 5 (2) Jun 30, 2010
And how much CO2 is exchanged through the ice of a frozen lake when sunlight can't reach the algea for photosynthesis to occur? I think they need to rethink the methodology of the experiment. Once again, using a unique location that isn't typical of real world conditions will yield results different than those seen elsewhere. Claiming that warmer temperatures will lead to less carbon consumption is patently absurd. The lowest possible level of carbon consumption HAS to be when the water is frozen, so cooler climate is worse than warmer. Even a pro-AGW nutball can't argue with that one.
4 / 5 (1) Jun 30, 2010
Oh, and the same thing goes for carbon consumption on land. Plants covered in snow and ice can't be doing much photosynthisis, not to mention the fact that many trees shed their leaves when it gets cold. If it stays warm all year long, then there's going to be more photosynthis, especially if temperate climate broadleaf trees move north to replace cold climate connifers.

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