What human industry has done since 1990, pumping nearly a *trillion* tons of CO2 into the air, has no precedent. Never before in Earth’s history has so much carbon dioxide been added to the atmosphere over such a short period of time.
Now our planet is heating up fast, thanks to all these greenhouse gases in the air. That extra heat is not good for people, and it's ALSO not good for trees...
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Trees are struggling to sequester heat-trapping carbon dioxide in warmer, drier climates, meaning that they may no longer serve as a solution for offsetting humanity's carbon footprint as the planet continues to warm, according to a new study.
"We found that trees in warmer, drier climates are essentially coughing instead of breathing," said Max Lloyd, assistant research professor of geosciences at Penn State. "They are sending CO2 right back into the atmosphere far more than trees in cooler, wetter conditions."
Through the process of photosynthesis, trees remove CO2 from the atmosphere to produce new growth. Yet, under stressful conditions, trees release CO2 back to the atmosphere, a process called photorespiration. With an analysis of a global dataset of tree tissue, the research team demonstrated that the rate of photorespiration is up to two times higher in warmer climates, especially when water is limited.
They found the threshold for this response in subtropical climates begins to be crossed when average daytime temperatures exceed roughly 68 degrees Fahrenheit [20.3C] and worsens as temperatures rise further.
The results complicate a widespread belief about the role of plants in helping to draw down carbon from the atmosphere, providing new insight into how plants could adapt to climate change. Importantly, the researchers noted that as the climate warms, their findings demonstrate that plants could be less able to draw CO2 out of the atmosphere and assimilate the carbon necessary to help the planet cool down.
"We have knocked this essential cycle off balance," Lloyd said. "Plants and climate are inextricably linked. The biggest draw-down of CO2 from our atmosphere is photosynthesizing organisms. It's a big knob on the composition of the atmosphere, so that means small changes have a large impact."
Plants currently absorb an estimated 25% of the CO2 emitted by human activities each year, but this percentage is likely to decrease in the future as the climate warms, Lloyd explained, especially if water is scarcer.
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So, that's very bad. We used to think extra CO2 might make trees grow faster and absorb more CO2, but it turns that notion is wrong. It doesn't work that way.
And guess what — it also turns out that pumping a trillion tons of CO2 into the atmosphere in only a few decades was a terrible idea.
FULL STORY -- https://phys.org/news/2024-01-trees-struggle-climate.html
#Science #Environment #Climate #ClimateChange #ClimateCrisis #ClimateEmergency