On so-called climate plantations, fast-growing plants are supposed to extract the greenhouse gas carbon dioxide from the air on a large scale and thus slow down global warming. But it’s not quite that simple, as a study now shows. According to this, climate plantations would be needed on an area three times the size of the USA in order to produce effective amounts of CO2 to fish out of the atmosphere. The researchers therefore recommend placing greater emphasis on reducing emissions from the outset.
There are large amounts of CO in our atmosphere2 and other greenhouse gases that contribute to planetary warming. The search is therefore underway worldwide for technologies that reduce CO2 can pull out of the air again, at full speed. One possibility would be so-called climate plantations. The idea: Very fast-growing plants bind CO there2 from the air and are then burned in biomass power plants. The CO released in the process2 is separated, chemically bound and stored; the energy generated can be used by us humans.
The potential of climate plantations has been overestimated
The Intergovernmental Panel on Climate Change (IPCC) assumes that climate plantations produce 11.3 billion tons of CO every year2 could be pulled out of the atmosphere. Reforestation could contribute another 10.1 billion tons. Together, this would correspond to more than half of annual anthropogenic emissions. But is that really realistic? Researchers led by Alexandra Deprez from the Institute for Sustainable Development and International Relations in Paris have now scientifically verified the Intergovernmental Panel on Climate Change’s estimates. To do this, they brought together data from various studies and, among other things, included assumptions about available space and the conversion efficiency of biomass into energy.
The result: To meet the Intergovernmental Panel on Climate Change’s estimates, climate plantations would have to cover an area of around 29 million square kilometers – three times the size of the USA. “It is obvious that this cannot be achieved under any circumstances,” explains senior author Felix Creutzig from the Berlin climate research institute MCC. And even if it were possible to create climate plantations on such a huge area, it would probably cause more harm than good, according to the researchers. They assume that the extensive plantations would both harm biodiversity and contribute to water scarcity. They would also be in competition with arable land on which food is grown.
A return to less CO2-Emission necessary
Are climate plantations inherently bad? Not necessarily. They can still play a role in mitigating climate change – just a smaller one than the Intergovernmental Panel on Climate Change had hoped. Deprez and her colleagues assume that climate plantations that are largely environmentally friendly emit at least 0.7 to 2.8 billion tons of CO annually2 could absorb from the atmosphere. When it comes to afforestation and reforestation, researchers estimate a further 3.8 billion tonnes. However, anything beyond that could do more harm than good to the planet.
Deprez and her colleagues therefore also criticize the exaggerated values that the Intergovernmental Panel on Climate Change has set so far. Just because something is technically feasible in theory doesn’t mean it has to prove sustainable in practice. “From a purely technical point of view, what is feasible in the climate models is helpful information in order to represent the maximum range of possibilities, for example to limit global warming to 1.5 degrees. But politicians are increasingly deriving carte blanche from this to the CO2-Too little emissions and would rather do big things with CO2“To promise removal,” says Creutzig. The researchers therefore recommend that in the fight against climate change we should focus more on limiting emissions and not neglect other factors such as species protection.
Source: Mercator Research Institute on Global Commons and Climate Change (MCC) gGmbH; Specialist article: Science, doi: 10.1126/science.adj6171