a new study published Monday in the journal Nature Climate Change is likely to re-energize the debate over the consequences of pumping CO2 into the atmosphere … for about a week. Then the newest round of temperature records will be reported for april, and we’ll probably be back to freaking out.
But for now, in this one significant study by 32 authors from 24 institutions in eight countries, we can see a bright, green lining in the clouds: Plants are growing more leaves to absorb more carbon and that’s great.
In “Greening of the Earth and its drivers,” the researchers write:
Here we use three long-term satellite leaf area index (LaI) records and ten global ecosystem models to investigate four key drivers of LaI trends during 1982–2009. We show a persistent and widespread increase of growing season integrated LaI (greening) over 25% to 50% of the global vegetated area, whereas less than 4% of the globe shows decreasing LaI (browning).
Factorial simulations with multiple global ecosystem models suggest that CO2 fertilization effects explain 70% of the observed greening trend, followed by nitrogen deposition (9%), climate change (8%) and land cover change (LCC) (4%). CO2 fertilization effects explain most of the greening trends in the tropics, whereas climate change resulted in greening of the high latitudes and the Tibetan Plateau.
Wow. Except … as phys.org reports:
The beneficial aspect of CO2 fertilization in promoting plant growth has been used by contrarians, notably Lord Ridley (hereditary peer in the UK House of Lords) and Mr. Rupert Murdoch (owner of several news outlets), to argue against cuts in carbon emissions to mitigate climate change, similar to those agreed at the 21st Conference of Parties (COP) meeting in Paris last year under the UN Framework on Climate Change (UNFCCC).
“The fallacy of the contrarian argument is two-fold. 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,” says co-author Dr. Philippe Ciais, associate Director of the Laboratory of Climate and Environmental Sciences, Gif-suvYvette, France and Contributing Lead author of the Carbon Chapter for the recent IPCC assessment Report 5.
But the greening of the Earth is still good news.
If the world cuts back on CO2 emissions enough to keep the temperature of the planet down, there are natural mechanisms that humans can exploit to cut the carbon load even more, such as growing more plants to capture more carbon.
We have lots of options, but so far none of them preclude cutting back CO2 emissions.