Tree Leaves Are Getting Too Hot – And They May Stop Functioning Altogether

This would only worsen the climate crisis, according to scientists.
A tree without leaves stands in the rainforest and can be seen from the tower of the Amazon Tall Tower Observatory (ATTO).
A tree without leaves stands in the rainforest and can be seen from the tower of the Amazon Tall Tower Observatory (ATTO).
picture alliance via Getty Images

The climate crisis is affecting our world in ways we might not even have realised – including making our trees so hot, they might not be able to function.

That’s according to a new international study where academics from Northern Arizona University and the University of Plymouth examines how tree temperatures in the Tropics have changed.

The study suggested “entire canopies could die” if temperatures continue to climb at their current rate.

By using a sensor also used on the International Space Station to take temperatures of the leaves every 10 seconds, the specialists found how forests are being seriously affected by the climate crisis.

For the first time ever recorded, the researchers found that leaves on trees in Australia, Brazil and Puerto Rico were reaching temperatures which they could no longer function.

University of Plymouth’s associate professor in terrestrial ecology, Dr Sophie Fauset, told the BBC that the team believe tropical trees can only manage a four degree change in temperature.

She said any higher than that and they might start to experience “temperature-induced mortality.”

Leaves can be higher in temperature than the air around them, but Dr Fauset told the BBC that in one instance they saw an 18C difference between the foliage and the surrounding air.

More than 1% of the leaves were also exceeding critical temperature thresholds at least once a year – that’s going above around 46.7C.

If leaves are too hot and there is a drought, the foliage will not be able to operate properly and cool down the tree through evaporation.

This could only make the whole tree hotter, possibly killing it – something which, in time, would only worsen the climbing temperature.

The world’s tree population is essential for reducing the amount of carbon in our atmosphere and regulating the climate. Further damage to Earth’s forests would also threaten our biodiversity.

The Amazon Rainforest, for example, has been known as the Earth’s lungs because it absorbs around so much atmospheric CO2.

However, a 2021 study suggested it was now emitting more CO2 than it could absorb, partly due to fires lit to clear large areas of land for beef and soy production, and partly because of the high deforestation rates there – and fewer trees mean hotter temperatures.

This new report into how leaves change temperature also comes after it was revealed that the ocean is getting too hot as well.

However, the forests are not beyond the point of no return yet – and the scientists suggested by tackling carbon emissions and reducing deforestations, the situation can be improved.


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