The tropical trees of the world can become so hot that their leaves stop photosynthesizing. Actually, it is possible that a small part of them have already exceeded the maximum temperature threshold, says a new study published in the journal Nature. The scientists behind the study say there is still time, but stress that the discovery is another clear sign of why climate change needs to be stopped urgently.
Tropical trees are accustomed to temperate and warm climates. However, according to a study, its leaves they begin to die when exposed to temperatures close to 46.7 °C.. This level of heat does not allow them to carry out photosynthesis, the main metabolic mechanism that allows them to convert sunlight into energy. The study shows that these forests could approach the dangerous temperature limit sooner than expected.
Researchers led by Northern Arizona University scientist Christopher Doughty combined a series of analyzes to study leaf temperatures in tropical tree canopies in unprecedented detail. One of the instruments used was ECOSTRESS, an instrument aboard the International Space Station that measures tree canopy temperatures. This information was supplemented by direct analysis from the field.
The results showed that the temperature of the tropical canopy usually reaches maximum around 34°C. However, in some regions there is heat above 40°C. And a small fraction 0.01% of all leaves are already registering warmer temperatures up to the threshold of 46°C. If nothing is done, the situation could worsen significantly in the coming decades.
The warming limit of tropical trees
As temperatures rise, tropical trees will become more susceptible to death. The researchers built a computer model to predict how quickly heat could kill these trees. According to research, this tipping point will come when the average local temperature rises by about 4°C.
The planet has already warmed more than 1°C since the pre-industrial era. A report by the Intergovernmental Panel on Climate Change estimates that global average temperatures will rise by 1.5℃ in the first half of the next decade. In the worst case scenario, if greenhouse gas emissions continue at the same rate, the Earth by 2100 it will warm by about 4 °C.
The models in this new study predict that once we reach a global temperature rise of 3.9°C, these forests could experience massive leaf damage. An impact that will affect much of the biodiversity and global climate. Although they occupy only 6% of the planet, more than 100 different tree species can live in one kilometer of tropical forests.
The study explains that climate change in these forests is so minimal that even a small change in temperature can have a big impact. Experiments have shown that leaves can become even hotter than the surrounding air. This is what suggests that the temperature limit may be exceeded earlier than expected.
Ecosystem under threat
“It gave very accurate numbers to what we already intuitively know is too hot for trees and rainforests,” said Stephanie Pau, a global change ecologist at Florida State University who was not involved in the new study.
The researcher spoke about this in an interview with the publication Scientific Americanthat the photosynthesis of these trees will slow down with rising temperatures even before their leaves die off. “This study has provided some hard numbers on what we should expect going forward,” Pau said.
In addition to the heat, rainforests are also threatened by deforestation. Activity up 10% last yearwhen 4.1 million hectares were cleared or burned. The increase comes a year after the leaders of 145 countries pledged to stop deforestation worldwide.
Source: Hiper Textual
