It’s a proven fact: forests, by absorbing some of the carbon dioxide released by the combustion of fossil fuels such as oil or coal, help mitigate the worst effects of climate change. As they grow, trees store CO2 in their trunks and branches, then release it back into the atmosphere when they die.
But research now shows that extreme temperatures have caused more of their deaths, particularly in the tropical forests of northern Australia, which have become net emitters of carbon.
Tree Mortality Outpaces Growth
Researchers examined records tracing the growth of tropical forests in the Australian state of Queensland, in the northeast of the country, over nearly 50 years. The results, published in the scientific journal Nature, show that extreme temperatures and severe droughts linked to climate change have made tree growth, and therefore their ability to store carbon, more difficult. Cyclones, whose intensity is expected to increase with climate change, have also had an impact.
Another lesson: the increase in tree mortality has contributed to the release of CO2 into the atmosphere, a release that has not been offset by tree growth, which is itself affected by climate change.
“Very worrying” results
“This is the first analysis to show that this phenomenon occurs in undisturbed natural forests and persists for many years,” Professor Patrick Meir, lead author of the study, told Agence France-Presse, describing the results as “very worrying.”
The study suggests that other tropical forests could experience the same change, but the authors caution that more data and research are needed. These results are consistent with research conducted in the Amazon showing that the gradual death of trees weakens the forest’s carbon storage capacity, notes David Bauman, a researcher at the French National Institute of Research for Development (INRD) and second author of the study.
This major upheaval illustrates Australia’s growing vulnerability to the effects of climate change. Despite the increasing number of natural disasters on the island continent, the country remains one of the world’s largest coal exporters and continues to heavily subsidize its fossil fuels.
