According to a recent study, in the next two decades, at the current rate of temperature increase, the Earth’s ability to absorb nearly one-third of the anthropogenic carbon emissions absorbed by plants will be halved. science progress This was done by researchers from Northern Arizona University, Woodwell Climate Research Center and Waikato University in New Zealand. The research team used more than two decades of data from measurement towers in every major biological community in the world to determine a critical temperature, beyond which the ability of plants to capture and store carbon in the atmosphere is called “terrestrial carbon sink.” . -Decrease as the temperature continues to rise.
The terrestrial biosphere (the activities of land plants and soil microorganisms) completes the “breathing”
However, as record temperatures continue to spread across the globe, this situation may not continue. Researchers at NAU, Woodwell Climate, and Waikato have detected a temperature threshold above which the carbon absorption of plants will decrease and carbon release will accelerate.
Lead author Catherine DuffyNAU’s postdoctoral researchers noticed that even after removing other effects such as water and sunlight, the photosynthesis of almost every biome in the world dropped sharply above this temperature threshold.
Duffy said: “The earth’s fever has been steadily increasing, just like the human body. We know that every biological process has the best performance within a certain range of temperature, and the temperature will deteriorate if the temperature exceeds this range.” “So, we thought Ask, how much can plants bear?”
This research is the first to detect the temperature threshold of photosynthesis from global observational data. Although the laboratory has studied the temperature thresholds of photosynthesis and respiration, the Fluxnet data provides a window into the actual ecosystems on the entire planet and how they respond.
Duffy said: “We know that the optimal temperature for humans is about 37 degrees Celsius (98 degrees Fahrenheit), but our scientific community does not know what the optimal temperature is for the terrestrial biosphere.”
She worked with researchers at Woodwell Climate Corporation and the University of Waikato, who recently developed a new method to answer this question: Macromolecular Rate Theory (MMRT). MMRT is based on the principles of thermodynamics, enabling researchers to generate temperature profiles for each major biological community and the world.
The results are shocking.
The researchers found that nature has exceeded the temperature “peak” of carbon absorption (18 degrees Celsius for the more common C3 plants, 28 degrees Celsius for C4 plants), but no respiration temperature was observed. This means that in many biological communities, continued warming will lead to a decline in photosynthesis and an exponential increase in the rate of respiration, which will shift the balance of the ecosystem from carbon sinks to carbon sources and accelerate climate change.
NAU co-authors said: “Different types of plants vary in the details of temperature response, but when the temperature is too high, the photosynthesis of all plants will decline.” George Koch.
Currently, less than 10% of terrestrial biospheres experience temperatures that exceed the maximum temperature of photosynthesis. However, at current emission rates, by the middle of this century, as many as half of the terrestrial biosphere may experience temperatures above this productivity threshold-as well as some of the world’s most carbon-rich biomes, including the tropical rainforests of the Amazon and Southeast Asia, and Russia Canada’s Taiga will be the first country to reach this tipping point.
Vic Alkus, a biologist at the University of Waikato and co-author of the study, said: “Our analysis shows that the most amazing thing is that the optimal temperature for photosynthesis in all ecosystems is very low.” “Combined with the increase in the respiration rate of the ecosystem in the temperature range we have observed, our findings indicate that a temperature increase of more than 18 degrees Celsius may have an adverse effect on terrestrial carbon sinks. If warming is not suppressed to keep it at or At the level set by the Paris Climate Agreement, land carbon sinks will not continue to offset our emissions and buy us time.”
Picture of Victor O. Leshyk, Center for Ecosystem Science and Society
Kate Peterson | Ecosystem Science and Society Center