From the Australian A warming planet is not the only impact of...

From the Australian


A warming planet is not the only impact of higher carbon dioxide levels in the atmosphere; it is a greener planet as well. This has been one of the striking, and controversial, scientific confirmations of the year.
The greening of the planet because of an increase in leaves on plants and trees is equivalent to twice the size of the continental US, a long-range study found.
It strengthens the case for changing our land use to combat human greenhouse gas emissions, and means using bioenergy — renewable energy from living organisms — may solve our energy security of supply problems. It also may help to create a billion-dollar economy based on plants that can help our energy troubles.
The findings, published in Nature Climate Change, give weight to arguments that climate change can have positive as well as negative impacts.
Some are quick to assert that the negatives of higher CO2 and climate change — rising temperatures, sea level changes and greater chance of forest fires — outweigh the positives.
Nonetheless, NASA’s report this year on the research findings of a group of 32 authors from 24 institutions in eight countries is unambiguous. Between 25 per cent and 50 per cent of Earth’s vegetated lands show significant greening across the past 27 years largely because of rising levels of atmospheric carbon dioxide.
Increased leaf cover has been the result of higher rates of photosynthesis, the process through which plants chemically combine carbon dioxide from the air with water and nutrients tapped from the ground to produce sugars, the main source of food, fibre and fuel for life on Earth.
Study co-author Ranga Myneni, a professor in the department of earth and environment at Boston University, says results show that carbon dioxide fertilisation is responsible for 70 per cent of the greening effect — higher than anticipated. Nitrogen land cover change and climate change due to temperature, precipitation and sunlight changes make up the rest.
Lead author Zaichun Zhu, from Peking University, says the extent of greening across the past 27 years “has the ability to fundamentally change the cycling of water and carbon in the climate system”.