Study warns of 'massive leaf die-off’ in tropical forests, 'do nothing about climate change’

A view of the treetops of the Amazon rainforest in the Adolfo Duque Nature Reserve in Manas, Amazonas, Brazil. Image by Ramesh Thadani / Tharunam / Getty Images

Tropical forests are the most biodiverse terrestrial ecosystems on the planet, as well as the greatest climate regulators. Now, a new one study An international team of researchers has found that the planet’s tropical forest canopies may be closer to critical high temperature thresholds than previously believed.

For the study, the researchers used data from warming experiments conducted in Earth’s tropical forests, as well as high-resolution thermal imaging data from an instrument located on the International Space Station, UK press release. University of Plymouth said.

Researchers have discovered that some tropical leaves begin to reach temperatures that prevent them from functioning, sometimes even higher, and as climate stress wears on, entire tree canopies may die.

„If climate change and tropical forest air temperatures rise above 4C, and we respond by doing nothing, there could be massive leaf death, potential tree mortality and species turnover in all tropical forests,” he said. Chris DoughtyAssociate Professor of Environmental Information at Northern Arizona University and lead author of the study, The Guardian reports.

The research team said their study’s findings could have dire consequences because tropical forests are one of the key climate regulators and contain all the biodiversity on Earth, the press release said.

„Leaf temperatures in West Africa, Brazil, China and the UK,” said one of the study’s authors, Dr. Data from Sophie Fauset’s work shows the temperature of individual leaves. A montane forest in Brazil can be up to 18 degrees Celsius warmer than the air temperature.

„Trees are an important part of our planet’s response to climate change, and tropical forests play an important role in achieving species diversity and regulating the planet’s climate. If they are damaged by rising temperatures, we lose an important protection and limit nature’s ability to mitigate the impacts of human activities,” said Fauset. „Other research I’ve been involved in has looked at the climate sensitivity of tropical forests and has shown that in the hottest part of the year, the maximum temperature above 32°C reduces the tree’s carbon stock. If we don’t do more to address climate change, the consequences will be severe.

The study was published in the journal „Tropical forests are approaching critical temperature thresholds.” Nature.

From their understanding of current leaf temperatures in tropical forests around the world, the research team was able to model how leaves might respond to human-caused global warming.

The researchers combined data on canopy-top leaf warming from experiments in Puerto Rico, Brazil, and Australia to estimate how much leaf mass could approach critical temperatures if air temperatures increased by two, three, and four degrees Celsius.

The results revealed that more than one percent of canopy leaves exceeded the critical temperature — estimated at 116.06 degrees Fahrenheit — at least once each year.

„We need to do everything we can to avoid high-emission scenarios. In low-emission scenarios, almost all tropical forest tree leaves can avoid heatstroke and the trees will survive,” said Simon Lewis, professor of global change science at University College London, The Guardian reported.

The researchers also simulated how tropical forests would perform under future global warming scenarios and explored the impact of warmer temperatures and more frequent droughts.

The results show that evaporation reduces the cooling capacity of plants, and that hotter, drier temperatures increase leaf temperatures and accelerate tree mortality.

„Given biodiversity and the important role of tropical forests in regulating the planet’s climate, insight into their future can inform understanding of the planet’s trajectory. But our model does not rule. This suggests that with some basic climate mitigation, this problem can be solved, and some that require further research.” „It helps pinpoint key areas,” Doughty said in the press release. „It also shows that by avoiding high emission pathways and deforestation, we can protect the fate of these important areas of carbon, water and biodiversity.”

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