March 25:Plants respond a bit better to global warming than scientists had thought, according to a new study that suggests their potential contribution to worsening global warming is not likely as bad as researcher believed.
When it gets hotter, plants breathe harder. And the greenhouse gas carbon dioxide is produced by respiration. That’s why researchers think that as Earth is warmed by CO2 from people’s activities, plants may add to the emissions and make warming worse.
Plants generally take in carbon dioxide during daytime photosynthesis and release carbon dioxide during respiration at night. But plants take up much more carbon dioxide in photosynthesis than they release in respiration.
But now “with this new model, we predict that some ecosystems are releasing a lot less CO2 through leaf respiration than we previously thought,” said co-author Kevin Griffin, a plant physiologist at Columbia University’s Lamont-Doherty Earth Observatory.
The study was published by the Proceedings of the National Academy of Sciences.
The research found that rates of increase slow in a predictable way as temperatures rise, in every region. And the newly defined curve leads to sharply reduced estimates of respiration, especially in the coldest regions.
“What we thought was a steep curve in some places is actually a little gentler,” said Griffin.
The biggest changes in estimates are in the coldest regions, which recently have seen warming far beyond that in temperate zones.
“All of this adds up to a significant amount of carbon, so we think it’s worth paying attention to,” said Griffin.
Lead author Mary Heskel, of Massachusetts’ Marine Biological Laboratory, said the study would go far toward helping estimate “carbon storage in vegetation, and predicting concentrations of atmospheric carbon dioxide and future surface temperatures.”