From a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide, according to a new study published in the journal Nature Climate Change on April 25.
An international team of 32 authors from 24 institutions in eight countries led the effort, which involved using satellite data from NASA’s Moderate Resolution Imaging Spectrometer and the National Oceanic and Atmospheric Administration’s Advanced Very High Resolution Radiometer instruments to help determine the leaf area index, or amount of leaf cover, over the planet’s vegetated regions. The greening represents an increase in leaves on plants and trees equivalent in area to two times the continental United States…
Carbon dioxide fertilization isn’t the only cause of increased plant growth—nitrogen, land cover change and climate change by way of global temperature, precipitation and sunlight changes all contribute to the greening effect. To determine the extent of carbon dioxide’s contribution, researchers ran the data for carbon dioxide and each of the other variables in isolation through several computer models that mimic the plant growth observed in the satellite data.
Results showed that carbon dioxide fertilization explains 70 percent of the greening effect, said co-author Ranga Myneni, a professor in the Department of Earth and Environment at Boston University. “The second most important driver is nitrogen, at 9 percent. So we see what an outsized role CO2 plays in this process.”
“The greening represents an increase in leaves on plants and trees equivalent in area to two times the continental United States” – imagine how much less green our blue planet would be without the carbon “pollution”. This is not to say that CO2 might not be causing any problems, but just to underline the point that in real life things are rarely as clean cut as slogans suggest. As unpopular environmentalists like Bjorn Lomborg keep arguing you can’t have a sensible action unless you first examine all the trade-offs and then the costs and benefits of various approaches in order to find out the most effective way to spend scarce resources (contrary to the big “g” Greens, scarce resources include money).