subject: The Effect of Carbon Dioxide Emissions on Earth's Climate [print this page] The Effect of Carbon Dioxide Emissions on Earth's Climate
In forecasting the effect of carbon dioxide emissions on Earth's climate, scientists may be misjudging the response to global warming from some of the planet's tiniest terrestrial in-habitants. As a result, researchers could be overestimating the average warming the planet might experience. That is the implication of a growing body of studies focusing on the release back into the atmosphere of carbon in soil, a process known as soil respiration. Respiration from plants and soils sits opposite plant absorption of carbon Breitling Bentley Replica dioxide on the terrestrial carbon-cycle teeter-totter. The latest piece in the respiration puzzle comes from a team at the University of Oklahoma in Norman, where scientists spent a year artificially warming prairie test plots at a fixed level above the ambient air and comparing the results with unheated plots.
All plots released carbon dioxide at higher rates in the summer than in the winter, as expected. But over the course of the year, the rate at which carbon dioxide was released through roots and the activity of fungi and tiny soil organisms was no greater in the warmed plots than in the unheated soils. This runs counter to a longstanding notion -- embraced in textbooks as well as climate models that the hotter it gets, the faster soils pump out carbon dioxide. For every 10 degrees C that temperatures rise, carbon dioxide, emissions from soils were thought to double.
By contrast, the team concluded that the soils' organisms quickly adjust to higher temperatures. Like Northeastern "snowbirds" moving to Florida and facing warmer temperatures year-round, they "just get used to it".
Combined with additional data suggesting that the prairie grasses in the heated plots thrived under the additional warmth, the study also suggests that the world's grasslands may soak up more carbon dioxide than they emit, according to Linda Wallace, a plant ecologist at the University of Oklahoma and a member of the team, which is Replica Breitling reporting its results in the today's edition of the journal Nature.
"This is good news on a global basis," Dr. Wallace says. "Grasslands cover such a huge proportion of the terrestrial portion of globe. We'd been kind of discounting them, saying that as things warm up, they would become carbon sources. But in reality, these grasslands could become carbon sinks." The concept of acclimatization is important in understanding how terrestrial ecosystems could respond to global change, researchers say.
Long-term experiments already have shown that, faced with increased concentrations of carbon dioxide, trees go through a relatively short "growth spurt", and Replica Watches then their growth rate slows as they become acclimatized to higher carbon dioxide levels, notes Lindsey Rusted, a soil ecologist with the US Forest Service office in Durham, N.H. .
Thus, relying on them as "sinks" for the carbon dioxide that humans are pumping into the atmosphere may be a short-term approach at best for trying to meet emissions targets set out in the 1997 Kyoto Protocols.
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