Australia’s tropical rainforests have become the first to emit more carbon dioxide than they absorb, and researchers say the trend is linked to climate change, writes the BBC.
Rainforests are usually considered carbon sinks because they absorb more carbon dioxide than they emit, and new trees also offset the carbon dioxide released by dead wood. But now a study in Queensland forests has found that extreme weather conditions have meant that the forest has more dead trees than new plants.
Hannah Carle, a scientist at the University of Western Sydney and lead author of the study published in the journal Nature, said the findings had implications for global emissions reduction targets, which are partly based on how ecosystems can absorb carbon. She said current models were likely overestimating the ability of rainforests to offset emissions from fossil fuels.
The scientist said forests can help combat the effects of climate change, but the study shows that forests are also at risk. The increased number of dead trees in recent decades is linked to climate change – extreme air temperatures, atmospheric dryness and drought periods in general. The study, based on 49 years of data collected from 20 Queensland forests, concluded that
the increasing number and strength of cyclones is also increasing the number of fallen trees
and making it more difficult for new growth.
Carla said the study shows that Australia’s rainforests are the first to show such changes in forest biomass. She added that it was very significant and could indicate wider problems.
One of the study’s authors, Patrick Meir, described the results as very worrying, and indicated that it was likely that other rainforests around the world were responding to climate change in a similar way. He also said more data and research were needed to make an assessment.
Australia has faced criticism for its reliance on fossil fuels, and the government has allowed the country’s largest natural gas project to continue for another 40 years. In September, a climate change report said Australia had already warmed above the 1.5 degrees mark, which would affect everyone.
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