The ability of leaves to photosynthesize begins to decline as temperatures reach 46.7 degrees Celsius, and this could have devastating consequences for forests across the planet, say a group of researchers from the United States, Australia, Brazil, according to CNN.

They used temperature data collected by the International Space Station, which they combined with on-site observations from experiments where sensors were mounted right in the foliage of tropical forests.

The researchers looked at extremes, rather than using average temperatures, and found that the average in forest foliage was somewhere around 34 degrees Celsius, but there were also places where the average exceeded 40 degrees.

At this point, according to the study cited by CNN, 0.01% of the leaves have passed this critical temperature threshold, which would prevent them from starting the process of photosynthesis, the effect resulting both in the death of the leaves and the tree.