Earth getting greener due to high level of carbon dioxide

 

According to a new study, rising carbon dioxide levels in the environment of the earth have increased the growth of plants and trees all over the earth in past thirty years.

Key points of the study

A few areas on Earth have browned but the major parts have become green
In last few years, overall plant coverage has grown by 18 million square kilometers
The main reason for the greener planet is increasing level of CO2(carbon dioxide)
Apart from CO2, nitrogen from agricultural fertilizers has also contributed to the cause

According to the scientists, up to half of the world’s vegetated areas are now showing signs of increased leaf cover. The comprehensive data shows the area on Earth covered by plants in this time has raised by 18 million square kilometers — about 2.5 times the size of the Australian continent — majorly because of the fertilizing effect of carbon dioxide (CO2).

Increasing level of carbon dioxide

The new discovery come from examining of data from the last 33 years. Researchers have analyzed the pictures taken by three different satellite missions that measured the green light reflected by photosynthesizing leaves.

Dr. Zaichun Zhu, from Peking University in China and lead author of the new study, which appears in the journal Nature Climate Change said, “(The greening) has the ability to fundamentally change the cycling of water and carbon in the climate system.”

 

Co-author CSIRO’s Dr. Pep Canadell of the Global Carbon Project said, “This is a snapshot of humans’ global influence on the functioning of the entire global biosphere.”

Dr. Canadell said that the remote sensing data was run through 10 global environmental change models to identify the cause of the planet becoming greener. It shows that about 85 per cent of Earth which is not covered by ice is covered by plants.

Drs Zhu, Canadell and his team observed that the 46 parts per million increase in atmospheric CO2 between 1982 and 2009 were responsible for 50 to 70 per cent of the greening.

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

Scientists have long pointed humans as a key source of atmospheric CO2 through the use of chemical signatures that differentiate carbon from other sources.

“The growth of CO2 in the atmosphere is almost exclusively due to fossil fuel burning and deforestation,” said Dr. Canadell.

The new study also found other factors which help in the growth of the greening, including nitrogen from agricultural fertilizers.

 

 

‘Surprising’ discovery given increase in droughts

According to Dr. Canadell, scientists are surprised when they found earth greener when they were expecting more browning, because of increase in droughts associated with global warming. In fact, researchers noted that between 25 to 50 per cent of all vegetated areas of the land have become greener and only 4 per cent have become browner, including Mongolia, Argentina and areas of North America close to Alaska.

Dr. Canadell added that south-eastern part of Australia also showed browning but overall the Australian continent was greening.

He said greener Earth may look like a positive effect. The global warming has brought warmer winters and longer growing seasons, he said. He also added that there were many negative impacts — including rising sea levels and severe weather.

“These will eventually outweigh by far any benefit from the greening,” said Dr. Canadell.