(ORDO NEWS) — With an average annual air temperature of two degrees Celsius, 71 percent of the species of living organisms that inhabit the tropical forests of the planet will be outside their temperature tolerance. According to a study published in the journal Science, this will lead to a decline in biodiversity, a decrease in biomass, and a weakening of the role of rainforests in carbon sequestration and the management of climate change.
The long-term response of tropical forests to climate change is a key uncertainty in existing climate models. Their most important role in the carbon cycle, and therefore in climate regulation, is beyond doubt, but it is rather difficult to predict changes in the biogeochemical flows of these ecosystems for many years to come.
Short-term observations of rainforests have shown that increasing air temperature and drought inhibits tree growth and enhances their respiration, leading to a general decrease in productivity and carbon sequestration.
More than 100 scientists from several dozen countries led by Martin JP Sullivan from Leeds University have come together to make a long-term forecast of the rainforest’s response to climate change.
To do this, they laid a network of 590 sites in South America, Africa, Asia, and Australia (273, 239, 61, and 17 sites, respectively). At each site, overground biomass, carbon fixation rate, and retention time were evaluated for several years.
After receiving data on the current state of forests, the authors of the study calculated the forecast for its long-term change using mathematical modeling. The key variables described the biogeographic features of forests on the continents, as well as differences in soil properties.
According to scientists, increasing the average annual temperature by one degree Celsius will lead to an average loss of 9.1 megagrams of carbon per hectare of rainforest, and an increase of two degrees will push 71 percent of the inhabitants of these forests beyond their temperature tolerance.
The authors noted that the thermal stability of tropical forests in the long run turned out to be higher than previously stated in a number of studies conducted over short periods of time: nevertheless, an increase in the concentration of carbon dioxide in the air to a certain threshold stimulates photosynthesis in plants.
Nevertheless, the negative impact of current trends in climate change on the productivity of the tropics has been confirmed: the stronger the temperature rises, the worse the trees will be able to absorb carbon dioxide from the atmosphere, and its retention period in the system will also decrease. To prevent this, people should protect the rainforests from deforestation for economic use, as well as focus on the international regulation of anthropogenic greenhouse gas emissions.
Rainforests are not the only biome that could be affected by climate change. For example, experimental warming in the taiga area led to a break in ties between ecosystem elements and attracted more invasive species to the forest.
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