Forest photosynthesis is in jeopardy

Climate change is causing many problems, nature reserves are among the most damaged. If we add to this drought and deforestation, the danger multiplies to unknown values. Global warming may prevent trees from photosynthesizing and thus the forests could become a wasteland.


High temperatures impede photosynthesis

So describes an article recently published in the journal Nature. The study was conducted in the tropical forests of Panama, Brazil, Costa Rica and Australia. It is based on satellite images collected by NASA between 2018 and 2020.

The information provided by the scientists indicates that, the critical temperature that prevents trees from photosynthesizing is 46.7 °C. From this point, photosynthesis begins to fail. Part of the leaves at the top of the trees are in danger of necrosis because the temperatures reached more than 47 °C. This process is essential for both the plant and also for the Earth, as trees transform sunlight and CO₂ into oxygen.

While this affects only a small percentage of the leaves in tree canopies, scientists predict that it could rapidly worsen. Leaves heat up faster than air. If the air warms by 2 or 3 degrees, this heat in the leaves can reach 8 degrees. According to Christopher Doughty, of Northern Arizona University and author of the paper, if the average temperature rises by about four degrees, leaf necrosis would be total.

Consequences of lack of photosynthesis.

This may, together with deforestation, lead tropical forests to become true savannas. If temperatures continue to rise as at present, by an average of 0.03 degrees per year, total leaf necrosis will occur in little more than a century.

Scientists insist that little is known about tree mortality, so more studies are needed. Gregory Chapman, an ecologist at the University of California and co-author of the study, says they need more ground observations to assess what is happening, in addition to satellite imagery.

In the Amazon, the so-called lungs of the planet, tree mortality has increased in recent years and continues to increase. The tropical rainforests are home to 45% of all the trees on Earth. They have the particularity of absorbing carbon dioxide particles and generating oxygen, something vital for nature. More than 40,000 different species of trees live in these tropical rainforests.

The photosynthesis of trees
Brazilian Amazon – National Geographic

Although the danger is not imminent, the study serves as a warning so that tree mortality does not continue to advance. It is essential to take precautionary measures worldwide, as soon as possible, to prevent the problem from becoming irremediable.

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