China Helps Reverse Global Forest Loss, With a Little Bit of Luck

With a little bit of luck, China has helped to reverse global forest loss despite ongoing large-scale deforestation in the tropics, according to recent research.

The findings, published in the journal Nature Climate Change, reveal that worldwide vegetation has increased nearly a staggering 4 billion tons of carbon since 2003.

"The increase in vegetation primarily came from a lucky combination of environmental and economic factors and massive tree-planting projects in China," lead author Dr. Yi Liu from the University of New South Wales (UNSW) said in a news release.

"Vegetation increased on the savannas in Australia, Africa and South America as a result of increasing rainfall, while in Russia and former Soviet republics we have seen the regrowth of forests on abandoned farmland. China was the only country to intentionally increase its vegetation with tree planting projects," he added.

However, at the same time, massive vegetation loss is still occurring in many other regions around the globe, with the greatest declines seen on the edge of the Amazon forests and in the Indonesian provinces of Sumatra and Kalimantan.

To better assess the impact China's tree-planting projects have had on global forests, Yi and his colleagues analyzed 20 years of satellite data from natural radio waves emitted from the Earth's surface. This novel technique allowed them to more accurately map changes in vegetation biomass over time.

"Previous analyses of vegetation biomass focused on forest cover change," noted fellow lead author, Professor Albert van Dijk of The Australian National University. "With our approach we found unexpectedly large vegetation increases in the savannas of southern Africa and northern Australia. The increase in Australia occurred despite ongoing land clearing, urbanization and big droughts across other parts of Australia."

Though deforestation continues in these regions, the main cause of this strong growth over the savannas is higher rainfall in recent years, coupled with higher levels of atmospheric carbon dioxide (CO2), which may have also helped plants there to grow more vigorously. The increased greening means the total amount of carbon captured in Australia's vegetation has increased.

However, this is a delicate balance, and the situation could rapidly reverse if the savannas were to experience extended dry periods, according to the study team.

"This study shows this capture of carbon is very sensitive to year-to-year changes in rainfall over savanna regions, both for Australia and for the global CO2 budget," explained Dr. Pep Canadell, a co-author of the study and director of the Global Carbon Project. "It's important to recognize that global warming would be happening faster if some of our CO2 emissions were not captured by this vegetation growth."

In fact, Earth's tropical forests can help fight carbon build-up better than we hoped. A NASA-led study recently revealed that tropical plant life is somehow absorbing more CO2 than experts thought possible, taking the harmful greenhouse gas from our atmosphere at unprecedented rates.

In total, forests and other land vegetation currently remove up to 30 percent of human CO2 emissions from the atmosphere during photosynthesis - that's a whopping 1.4 billion metric tons of CO2 out of a total global absorption of 2.5 billion metric tons.

But deforestation threatens this natural carbon uptake, and could prove to be just as costly as man-made carbon pollution from activities such as the burning of fossil fuels.

So even with the good news of nature helping to regulate Earth's climate, this latest study concludes that there is still only one way to reduce the impacts of global warming.

"We know about 50 percent of emissions from human activities stay in the atmosphere even after the other half is removed by terrestrial vegetation and oceans. The only way to stabilize the climate system is to reduce global fossil fuel emissions to zero," Canadell said.

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