Green Earth
A large lightning strike on Earth lights up solar panels on the International Space Station in this NASA picture taken by astronaut Kjell Lindgren released September 2, 2015. Reuters/NASA/Kjell Lindgren

New data from a report published in the Nature Climate Change has shown that the Earth is turning green at a very fast rate. The report says that due to the rising carbon dioxide (CO2) levels, plants have covered an area of the Earth that 2.5 times the size of Australian continent. The size equals approximately 18 million square kilometres in area.

Over the past three decades, global plant growth has increased exponentially due to the fertilising effects of higher carbon dioxide levels in the atmosphere. Half of the world’s surface has turned green, an international team of 32 authors from 24 institutions in eight countries agreed in the report titled Greening of the Earth and its Drivers.

The experts did a most all-inclusive modelling of remote-sensing data collected from records of past 33 years. The data was collected by three different satellite missions measuring green light reflected by photosynthesising leaves. The cause of the greening was ascertained after the remote-sensing data was run through 10 global environmental change models.

“[The greening] has the ability to fundamentally change the cycling of water and carbon in the climate system,” said lead author of the study, Peking University’s Dr. Zaichun Zhu.

Aussie scientist and CSIRO’s Dr. Pep Canadell, who co-authored the study, said the study shows how humans around the world have affected global biosphere. Humans emit approximately 10 billion tonnes of carbon each year and plants and photosynthesis soaks about a quarter of that amount. Currently, around 85 percent of Earth’s ice-free lands is covered in greenery.

“Carbon fertilisation is the dominant process for greening across the globe, particularly in the tropics because there's so much leaf area there,” Canadell said.

He added that the tremendous growth in CO2 levels in the atmosphere is primarily due to excessive deforestation and fossil fuel burning. Other causes of greening were attributed to agricultural fertilisers and nitrogen.

The findings come as a surprise to scientists as they expected to see more browning than greening due to the increase in number of droughts as a result of global warming. They found that only four percent of vegetated land has turned browner while 20 to 20 percent turned greener.

South-eastern Australia too showed signs of browning but the overall continent was greening. While greening of Earth may seem like a positive sign and “good news” for many, Canadell expressed grave concerns as such exponential increase in CO2 levels would mean severe weather and rising sea levels. Such negative aspects would easily outweigh any good the greening will have.