With their natural ability to absorb carbon dioxide, trees are an important player in combating Earth's warming. But research detailed by SciTechDaily has found that in several places, increasingly warmer temperatures are preventing this critical process from happening.
What's happening?
A group of researchers at Penn State compared several preserved tree samples from around the globe, measuring how much carbon dioxide they were able to absorb through photosynthesis. The team found that trees in hotter, drier climates are struggling to absorb the same amount of carbon as they've previously been able to.
Instead, these trees are seeing an uptick in something called photorespiration, a process when a tree under stressed conditions fails to absorb carbon and instead re-releases it into the atmosphere.
"[These trees] are essentially coughing instead of breathing," Max Lloyd, the lead author of the study, said to SciTech Daily. "They are sending CO2 right back into the atmosphere far more than trees in cooler, wetter conditions."
Specifically, the study found that photorespiration occurs twice as frequently in warmer climates than in cooler ones. The threshold begins when average daytime temperatures are greater than 68 degrees Fahrenheit, and the effects worsen as temperatures climb higher.
Why is photorespiration so concerning?
The levels of carbon in the atmosphere are already greater than they've been at any time throughout the last 3.6 million years, according to the National Oceanic and Atmospheric Administration.
Trees are a crucial part of mitigating those levels. A single tree will absorb an average of 25 kilograms of carbon in one year; in turn, this keeps temperatures down and prevents Earth from overheating. This is why the new increase in photorespiration rates is worrying scientists.
"We have knocked this essential cycle off balance," Lloyd said. "Plants and climate are inextricably linked. The biggest drawdown 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."
Unfortunately, these hotter conditions aren't going anywhere. The winter of 2023-24 was the hottest on record, and human-driven pollution has led to an increase in extreme weather events.
What's being done to fight rising temperatures?
There are many ways to help combat human-driven overheating, from the large to the small.
From switching to plant-based meats — even just occasionally — to supporting circular brands, your consumer choices can help lower your carbon footprint.
Your choices at home matter, too. Installing a heat pump, solar panels, or hydropanels will help reduce your pollution.
Want to take it one step further? Make your next car an EV.
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