Global Warming Climate Change Concept

Tropical trees are dying twice as fast due to climate change

Global warming climate change concept

According to a new study, trees live about half as long as they did before. This trend was discovered to be widespread throughout species and places throughout the region.

According to new research, climate change may have caused rainforest trees to die faster since the 1980s

The results of a long-term international study published in Nature May 18, 2022 shows that tropical trees in Australia’s rainforests have died twice as high as before since the 1980s, probably due to climate change. According to this study, as the dehydration effect of the environment has increased due to global warming, the mortality rate for tropical trees has doubled in the last 35 years.

Deterioration of such forests reduces the storage of biomass and coal, making it more difficult to comply with the Paris Agreement’s requirement to keep the global peak temperature well below the 2 ° C target. The current study, led by experts from the Smithsonian Environmental Research Center and Oxford Universityas well as the French National Research Institute for Sustainable Development (IRD), has analyzed very extensive data records from Australia’s rainforests.

It finds that the average death toll for trees in these forests has more than doubled in the last four decades. Researchers found that trees live about half as long, which is consistent between species and locations throughout the region. According to researchers, the effects can be observed as far back as the 1980s.

North Australian tropical rainforest

Northeastern Australia’s relatively tropical rainforests, one of the oldest and most isolated rainforests in the world. Death rates for trees have increased markedly between species in northeastern Australia’s tropical rainforests, threatening the critical climate limitation and other functions of these ecosystems. Credit: Alexander Schenkin

Dr David Bauman, a tropical forest ecologist at the Smithsonian, Oxford and IRD, and lead author of the study, argues: “It was a shock to discover such a marked increase in tree mortality, let alone a trend consistent across the diversity of species and places we studied. “A lasting doubling of the risk of mortality would mean that the carbon stored in trees returns twice as fast to the atmosphere.”

Dr. Sean McMahon, senior researcher at the Smithsonian and senior author of the study, points out, “Many decades of data are needed to detect long-term changes in long-lived organisms, and the signal for a change can be overwhelmed by the noise of many processes.”

Drs Bauman and McMahon emphasize, “A remarkable result from this study is that not only are we seeing an increase in mortality, but this increase seems to have begun in the 1980s, suggesting that the Earth’s natural system may have responded to climate change for decades. . “

Oxford professor Yadvinder Malhi, co-author of the study, points out: “In recent years, the effects of climate change on corals in the Great Barrier Reef have become well known.

“Our work shows that if you look at the beach from the reef, Australia’s famous rainforests are also changing rapidly. The probable driving factor we identify, the increasing drying power of the atmosphere caused by global warming, also suggests that similar increases in tree death rates may occur in the world’s tropical forests. “If that is the case, tropical forests could soon become sources of coal, and the challenge of limiting global warming well below 2 ° C will be both more acute and more difficult.”

Susan Laurance, professor of tropical ecology at James Cook University, adds, “Long-term data sets like this are very rare and very important for studying forest change in response to climate change. This is because rainforest trees can have such long lives and also that tree death does not is always immediate. ”

Recent studies in the Amazon have also suggested that the death toll from tropical trees is increasing, weakening the carbon sink. But the reason is unclear.

Intact tropical rainforests are large stores of carbon and have so far been “carbon sinks”, which acted as moderate brakes on the pace of climate change by absorbing about 12% of carbon dioxide emissions caused by humans.

By examining the climate areas for the tree species that show the highest death rates, the team suggests that the main driving force for the climate is the increased drying power of the atmosphere. When the atmosphere warms up, it draws more moisture from plants, which results in increased water stress in trees and ultimately increased risk of death.

When the researchers keyed in the figures, it further showed that the loss of biomass from this increase in mortality in recent decades has not been compensated by biomass gains from tree growth and recruitment of new trees. This means that the increase in mortality has been translated into a net reduction in the potential of these forests to compensate for carbon dioxide emissions.

The research group included colleagues from Oxford University, James Cook University (Australia) and other institutions (UK, France, USA, Peru).

Reference: “Mortality in Tropical Trees Has Increased with Rising Atmospheric Water Stress” by David Bauman, Claire Fortunel, Guillaume Delhaye, Yadvinder Malhi, Lucas A. Cernusak, Lisa Patrick Bentley, Sami W. Rifai, Jesús Aguirre-Gutiérrez, Imma Olivera’s Menor, Oliver L. Phillips, Brandon E. McNellis, Matt Bradford, Susan GW Laurance, Michael F. Hutchinson, Raymond Dempsey, Paul E. Santos-Andrade, Hugo R. Ninantay-Rivera, Jimmy R. Chambi Paucar and Sean M. McMahon, 18 May 2022, Nature.
DOI: 10.1038 / s41586-022-04737-7

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