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australian tropical rainforest – Once major carbon sinks – more is being emitted carbon dioxide Scientists say this is the first recorded change of this kind anywhere in the world.
A new study was published in Nature Note that the trunks and branches of trees in the country’s humid tropical regions, known as woody biomass, are now the net source of carbon dioxide due to factors associated with rising temperatures, atmospheric dryness, and frequent droughts. climate crisis,
The research found that standing woody biomass in the wet tropics of Australia is now losing about 0.9 tonnes of carbon per hectare per year, compared with about 0.6 tonnes per hectare before the early 2000s, marking a clear transition from sink to source.
“Tropical forests are among the most carbon-rich ecosystems on the planet,” said study lead author Dr. Hannah Carle, who conducted the study at the Australian National University.
“We rely on them more than most people realize. Forests help prevent the worst effects of climate change by absorbing some of the carbon dioxide released from burning fossil fuels. But our work shows this is at risk.”
Research examining data from rainforest sites in northern Queensland found that increased tree death due to heat stress and drought outstripped new growth.
“The change described in our study is largely due to increased tree mortality due to climate change, including extreme temperatures, atmospheric dryness and drought,” Dr Carle said.
“Sadly, the associated increase in carbon loss to the atmosphere has not been offset by an increase in tree growth. This is surprising because higher carbon dioxide levels would make it easier for plants to extract carbon dioxide from the air, leading to the growth of more trees and greater carbon sink capacity.”
The findings challenge the long-held belief that tropical forests will continue to absorb more carbon as emissions increase. “Current models may underestimate the ability of tropical forests to help reduce fossil fuel emissions,” Dr Carle said.
Researchers warn that if this trend continues, it will undermine global emissions reduction targets that rely on forests to offset a portion of the carbon released from burning fossil fuels.
Although it was long feared that forests could turn from carbon sinks to sources, the findings were a surprise.
“The switch from net carbon sink to carbon source in Australian tropical rainforests appears to have occurred sooner than in other tropical regions, where rainforests have remained carbon sinks,” study co-authors Dr David Baumann and Professor Patrick Meyer said. Independent,
The study also found that tropical cyclones – already a major problem in northern Australia – are further weakening the ability of rainforests to absorb carbon.
“We found that cyclones suppress the carbon sink capacity of the woody biomass in these forests,” Dr Carle said.
“This is cause for concern as cyclones are projected to become increasingly severe under climate change and impact areas further south, potentially affecting additional stretches of forest to a greater extent.”
Study co-author Professor Adrienne Nicotra said the research is based on some of the most comprehensive and long-term forest health data ever collected in Australia.
“The rainforest sites at the center of this research provide unusually long-term and high-resolution data on forest health over time,” he said. “We need to pay attention to that data.”
The study authors said the findings underlined the importance of protecting remaining tropical forests and restoring degraded areas to maintain their role in stabilizing the climate.
“Our findings provide clear evidence that the ability of tropical forests to mitigate climate change is at risk through the action of large carbon sinks, even though these forests remain irreplaceable stores of carbon and biodiversity,” the study authors said.