The rise in atmospheric CO2 over the past 100 or so years has been having some devastating effects. From the record temperatures being observed with increased frequency, to the melting of the Arctic ice, there is little doubt that the climate is indeed changing. But it seems that there has been another impact, as the world appears to have gotten greener. Even so, the authors note that the negatives of more CO2 in the atmosphere far outweigh the benefits.
A new study published in Nature Climate Change has found a massive increase in the growth of trees and plants, and concludes that this has been driven by the increase in concentration of atmospheric CO2. Using data from the NASA-MODIS and NOAA-AVHRR satellite sensors, an international team of 32 researchers from 24 institutions found that over the last 33 years, between 25 and 50 percent of Earth’s vegetated land has shown significant greening.
The planet has actually seen a significant increase in leaf cover around the world. Prof. R. Myneni/Boston University
If all green leaves on Earth were laid out the area would cover around 32 percent of the entire planet, and the new study has shown that the dramatic increase in atmospheric CO2 from around 220 parts per million (ppm) at the start of the industrial revolution to 403 ppm has added the equivalent of enough leaves to cover the continental U.S. twice over.
But an increase in CO2 is not totally sufficient to entirely explain the observed greening across much of the land. Using computer models, the researchers calculate that while the greenhouse gas accounts for around 70 percent of the increase in growth, other factors are involved. They reckon that an increase in nitrogen in the system is responsible for around 9 percent of the growth, climate change is responsible for around 8 percent, and changes in land use clocks up about 4 percent.
Inevitably, the study has been seized upon by climate skeptics, some of whom argue that the increase in atmospheric CO2 is actually good for the planet due to this increase in growth of vegetation. Yet this effect diminishes over time, the researchers say, as plants acclimatize to the higher concentrations of CO2, and get limited by other factors such as water and nutrients. But obviously, there are other impacts from the increase in greenhouse gasses.
The increase in leaf cover would cover all of the continental U.S., twice. IVDMStock/Shutterstock
“The fallacy of the contrarian argument is two-fold,” explains Dr. Philippe Ciais, one of the co-authors of the study from the Laboratory of Climate and Environmental Sciences in Gif-sur‑Yvette, France. “First, the many negative aspects of climate change, namely global warming, rising sea levels, melting glaciers and sea ice, more severe tropical storms, etc. are not acknowledged. Second, studies have shown that plants acclimatize, or adjust, to rising CO2 concentration and the fertilization effect diminishes over time.”
Despite what many a climate denier might argue, this increase in CO2 uptake by plants is simply not going to be sufficient, and has actually already been factored in by the International Panel on Climate Change (IPCC) when they make their models. Not only that, but while CO2 is the most prominent greenhouse gas, it is not the only one we have to worry about. The warming planet has already started to thaw out the permafrost of the northern hemisphere, beginning the release of massive reserves of methane, and there is little plants can do with that.
