Carbon emissions are to thank for a massive increase in plant growth over the past three decades, according to a new study.
But scientists are warning not to take the findings as evidence climate change is nothing to worry about.
Since 1982, the increased amount of carbon in the atmosphere has driven plants to grow so much, it's as if two continents the size of Australia have been added to the world's vegetation, they write in journal Nature Climate Change.
"We were able to tie the greening largely to the fertilising effect of rising atmospheric carbon dioxide concentration by tasking several computer models to mimic plant growth observed in the satellite data," says co-author Prof Ranga Myneni of Boston University.
It's estimated around 85 percent of the Earth's ice-free land is covered in vegetation; including the oceans and ice cover, green leaves cover about 32 percent.
Carbon drives plant growth through a process called carbon dioxide fertilisation. Plants use energy from the sun to turn carbon dioxide, water and nutrients into sugar -- when there's more carbon dioxide, they produce more sugar, and grow better.
While increased plant cover isn't a bad thing, scientists say it's a "fallacy" to use carbon dioxide fertilisation as an argument against cutting emissions.
"First, the many negative aspects of climate change, namely global warming, rising sea levels, melting glaciers and sea ice, more severe tropical storms, etc are not acknowledged," says co-author Dr Philippe Ciais, one of the lead contributors to the Intergovernmental Panel on Climate Change's latest major report.
"Second, studies have shown that plants acclimatise, or adjust, to rising carbon dioxide concentration and the fertilisation effect diminishes over time."
Other noted drivers of plant growth include nitrogen fertilisation and changing land use.
"While the detection of greening is based on measurements, the attribution to various drivers is based on models, and these models have known deficiencies," says co-author Dr Josep Canadell.
"Future works will undoubtedly question and refine our results."
Thirty-two scientists from eight countries took part in the research.
Newshub.
