But another major cause was global warming, which is melting polar icecaps to expose vegetation. And that type of greenery might actually be doing more harm than good.
In a study published in Nature Climate Change, a team of scientists at the University of New South Wales used a novel technique of examining satellite data for naturally emitted radiation to gauge the amount of vegetation around the globe. They found a net increase in the amount of greenery since 2003, reversing a negative trend over the previous decade.
As they expected, the scientists found increased forestation in China — where billions of trees have been planted since the 1980s — and Eastern Europe, where industry and logging have generally declined since the fall of the Soviet Union.
Researchers were surprised, however, to find an increase in vegetation in savannas and shrublands in Africa, Australia and South America.
Overall, the study found a 4 billion ton increase in vegetation since 2003. But the news is mixed.
“From this research, we can see these plants can help absorb some carbon dioxide, but there’s still a lot of carbon dioxide staying in the atmosphere,” the study’s lead author, Yi Liu, told Reuters. In fact, during that decade, a total of 60 billion tons of carbon was added to the atmosphere, Liu said.
There are other reasons to keep the fight-against-climate-change champagne in the fridge. First of all, the increases in vegetation could be short lived. Some experts have serious doubts about the longevity of reforestation programs in China, for example. And Liu admitted that recent improvements in Africa, Australia and South America could be fleeting. “Savannas and shrublands are vulnerable to rainfall — one year can be very wet, and more carbon will be fixed in plants, but the next year can be very dry, and then we will lose the carbon fixed in previous years,” he told Reuters.
But the biggest reason to keep the bubbly on ice — if it hasn’t melted already — is that climate change is actually driving much of the reforestation.
“We know that the ice is melting in the north and it’s being replaced by vegetation,” Louis Verchot, a researcher at the Center for International Forestry Research in Jakarta, Indonesia, told The Post. “As permafrost melts and ice cover decreases, it’s replaced by vegetation.”
Things get worse. Verchot says this type of vegetation in the north actually worsens climate change.
“It’s going to have a negative impact because vegetation in the north is dark and absorbs more heat,” he explained. “Forests have a dual role. Dark vegetation absorbs heat compared to ice, for example, which is bright and reflects a lot of light back into the atmosphere. So increased vegetation in northern latitudes increases the amount of energy retained in the climate system. So where the vegetation is increasing, which is in the north as that study shows, is negative for the climate system. It creates what we call a positive feedback: something that reinforces the current climate forces that we have going on.”
This is called the Albedo effect, and it’s bad news.
Verchot says increased vegetation in savannas isn’t going to help the planet much. What would have been good news is a boom in tropical forests, but Liu’s study found those were still shrinking, particularly in the Amazon.
“We need to understand things for what they really are,” Verchot said. “The devil is in the details.
“The big thing that people could take away from this [study] is that even if vegetation is increasing, it doesn’t mean we are solving problems,” he warned. “It could be a sign that things are getting worse.”