Rising temperatures pose very specific threat to tropical rainforests. What a new report shows.

Sara Chernikoff, USA TODAY
Thu, August 24, 2023 

Tropical forests ranging from South America to South East Asia face a new threat; leaves may not be able to photosynthesize when their temperature gets too hot. Without this essential process, the world’s forests face threatening potential consequences, according to a recent report published in Nature.

A group of scientists from the U.S., United Kingdom, Brazil, France and Australia found that photosynthesis begins to fail when leaves’ temperatures reach 116 Fahrenheit. Although this temperature seems steep, leaves can heat up much more than the air temperature, according to the report.

Tropical forests play an essential role in sustaining life and regulating the global climate. They are home to half of all species found on land.

During photosynthesis, plants use sunlight, water and carbon dioxide to create oxygen and energy. Most life on earth depends on photosynthesis. It is the number one source of oxygen in the atmosphere and forms the base of Earth’s food web.

Here’s what the report found

The report found that 0.01% of leaves are passing the critical temperature threshold, meaning their ability to photosynthesize fails. Although this percentage is small, it’s expected to increase as temperatures continue to climb due to global warming.

Tropical forests can handle about 7.2 degrees Fahrenheit of increased temperatures before they reach a turning point.

If warming exceeds this threshold, the percentage of leaves passing the critical temperature threshold could rise to 1.4%. This could potentially cause major leaf loss and death to the entire tree.