Marine and freshwater
environments have the potential to release more carbon dioxide into the
atmosphere in a warmer climate than their land counterparts, scientists at
Queen Mary, University
of London have found.
In the largest ever analysis of
rates of respiration, published online in Nature, scientists compared
the temperature dependence of respiration between aquatic and land ecosystems.
Lead author, Gabriel
Yvon-Durocher, PhD, from Queen Mary, University of London explained the context of the research: “In the carbon cycle, photosynthesis by plants absorbs carbon dioxide while respiration
by animals returns carbon dioxide to the atmosphere. Understanding how rates of
respiration of entire ecosystems respond to changes in temperature will be
crucial for forecasting future climate change as the planet warms in the coming
decades.”
In analyzing annual rates of
respiration across different ecosystems around the world, they found that
aquatic ecosystems had a stronger response to temperature changes than land
ecosystems.
“Respiration has a higher ‘activation energy’ than photosynthesis, meaning that it increases more rapidly
with increasing temperature. But over a longer time period, the carbon fixed by
photosynthesis limits respiration on the land. However, many aquatic ecosystems
receive additional carbon from the land, which washes into lakes, rivers,
estuaries, and the sea from rainfall. This extra carbon means that respiration
in aquatic ecosystems is not limited by photosynthesis and can have a stronger
response to temperature than ecosystems on the land,” explained Yvon-Durocher.
“These findings demonstrate that
aquatic ecosystems have a greater potential to release carbon dioxide to the
atmosphere as the climate warms, over long periods of time.”
The authors warn that there are
many other factors that need to be considered when analyzing the links between
global warming and changes in the carbon cycle.
“Our research has highlighted the
potential of aquatic ecosystems to contribute more carbon dioxide to the
atmosphere as global temperatures rise, but we can not definitively say that
this will exacerbate the effects of climate change—it merely highlights a new
mechanism that must be considered when making future predictions,” Yvon-Durocher
said.
“Further research should be done
to characterize the temperature sensitivities of the other key fluxes mediated
by ecosystems that control the levels of greenhouse gases in the atmosphere to
make more accurate predictions of future climate change.”
Source: Queen Mary, University of London
