In the rainforest, trees and plants grow more densely than anywhere else on the planet, and this gigantic mass of vegetation acts as a dike sponge which sucks climate-hazardous CO2 out of the atmosphere.
But at some point the rainforest trees will no longer be able to photosynthesize. If it is too hot, the leaves will not be able to cope with this the process, which involves converting sun and CO2 into energy.
According to a study in Nature it fails when the average temperature reaches 46.7 degrees.
– The last of his tribe
Must choose
The researchers behind the study have used measurements from the space station ISS to show that the leaves of tropical trees under extreme heat come close to the limit of the heat they can withstand.
If they heat up further, they die.
– If the rainforests collapse, it is a disaster for the earth’s climate systems and biological diversity, the researchers warn.
Biologist and professor Dag O. Hessen says that the leaves in the rainforest “have to make a choice” when the temperature rises.
– They have to choose between going hungry or thirsty, he says.
When there are extremely high temperatures, the leaves close their slit openings, to reduce or avoid evaporation – that is, to dry out. But this prevents the leaves from absorbing CO2 – in other words nutrition, Hessen explains.
He also points out that there is a fear that the combination of reduced forest area and drought could lead large parts of the Amazon over a tipping point, where it becomes savannah.
RESEARCHER: Biologist and professor Dag O. Hessen. Photo: Jørn H Moen / Dagbladet Show more
– Enormous consequences
Already today there are places in the rainforests where it is occasionally warmer than 46.7 degrees at the top of the tree crowns, writes Live Science:
In total, 0.01 percent of all leaves exceed this critical temperature each year.
– Although it is a small number, it has enormous consequences, said Joshua B. Fisher, professor of environmental science at Chapman University in California when the study was presented.
– It is not going to increase from 0.01 to 0.02. It will potentially increase much faster, he elaborated.
Lost eleven football pitches a minute
The world’s largest
Rainforests are important to our planet. They cover approximately six percent of the Earth’s surface, and are home to half of the world’s animal and plant species. They are also an important storage room for the world’s fresh water supply, writes Videnskap.dk.
The CO2 is converted into carbon which becomes part of tree trunks, plants and soil, writes Rainforest Fund.
– That is why the rainforest is one of the Earth’s largest “carbon stores”, explains Professor Hessen.
BROKEN: The images show destroyed rainforests in Indonesia, linked to palm oil operations. Video: Regnskogfondet Show more
Leaf-dead
According to the study in Nature, a worst-case scenario would be if the globe gets 4 degrees warmer. Then there is a risk of “total leaf death”.
This is a factor when scientists examine the danger of a so-called tipping point where rainforest disappears and is transformed into savannah.
It will have very serious consequences both for species diversity, the environment and the climate, writes NTB. If large areas of rainforest disappear, huge amounts of carbon, which was stored in the trees, will end up in the atmosphere as CO2.
2023-09-30 17:44:28
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