The Earth’s ability to absorb nearly a third of human-induced carbon emissions through plants could halve within the next two decades, according to current heating rates. science Progress It was led by researchers from Northern Arizona University, Woodwell Climate Research Center and the University of Waikato, New Zealand. The team has used more than two decades of data from measurement towers in all major living organisms around the world.The team has identified critical temperature tipping points beyond which plants can capture and store carbon in the atmosphere, a cumulative effect. The so-called – will decrease as the temperature continues to rise.
Terrestrial biosphere, which is the activity of terrestrial plants and soil microorganisms, performs the Earth̵7;s “breathing” function by exchanging carbon dioxide and oxygen. Ecosystems around the world draw carbon dioxide through photosynthesis and release it back into the atmosphere through microbial and plant respiration. Over the past few decades, biospherees generally have received more carbon than those released to mitigate climate change.
But as record-breaking temperatures continue to spread throughout the world, this may not continue.NAU researchers, Woodwell Climate, and Waikato have detected a higher temperature threshold at which plants slower to absorb carbon and accelerate carbon release. up
Lead author Katharyn DuffyNAU postdoctoral researchers noticed a rapid drop in photosynthesis above this temperature threshold in almost every biome around the world, although other effects such as water and sunlight have been eliminated.
“The world is getting more and more fever, and like the human body, we know that every biological process has a range of temperatures that are working optimally.” We would like to ask how well plants tolerate it? ”
This study is the first to detect the temperature threshold for photosynthesis from global observational data. While the temperature criteria for photosynthesis and respiration are being studied in the laboratory, Fluxnet data provides a window into how ecosystems around the world are experiencing and how they respond.
“We know the optimal temperature for humans is about 37 degrees Celsius (98 degrees Fahrenheit), but we in science don’t know what those optima are for the terrestrial biosphere,” Duffy said.
She collaborated with researchers at Woodwell Climate and the University of Waikato, who recently developed a new approach to answer that question: MacroMolecular Rate Theory (MMRT) .Based on the principles of thermodynamics, MMRT allows researchers to create temperature curves for all living things. Important and worldwide
The results were shocking.
The researchers found that the “highest” temperature for carbon uptake – 18 ° C for the more widespread C3 plants and 28 ° C for the C4 plants – were already beyond natural. But did not see the respiratory temperature monitor This means that in many organisms, sustained heat degrades photosynthesis, while the rate of respiration is exponentially increasing, balancing ecosystems from carbon sinks to carbon sources and accelerating transformation. Climate
“Plants differ in detail in their response to temperature. But they all show that photosynthesis decreases when it gets too hot, ”said a co-author of NAU. George Koch.
Now less than 10 percent of the terrestrial biosphere experiences temperatures above this photosynthetic maximum. But at current emissions rates, up to half of the terrestrial biosphere may have exceeded the production threshold by the middle of the century – and some of the world’s most carbon-rich organisms, including the tropical rainforests in Amazon and Southeast Asia, and The taiga in Russia and Canada will be among the first to be popular.
“The most striking aspect of our analysis shows that the optimum temperature for photosynthesis in all ecosystems is very low,” said Vic Arcus, a biologist at the University of Waikato and co-author of the study. Increasing ecosystems throughout the temperatures we observe, our findings suggest that temperature increases above 18 ° C may be detrimental to terrestrial carbon basins. If the heat is not kept at or below the Paris Climate Accord, the onshore carbon sink will not compensate for our emissions and continue to buy time for us. “
Graphic by Victor O. Leshyk, Center for Ecological Sciences and Society
Kate Petersen | Ecological Science and Society Center