On the one hand, a world thermostat which is carried away; on the other, greenhouse gas emissions that are still not pointing in the right direction. We are on the razor’s edge, again warn the experts of the Intergovernmental Panel on Climate Change (IPCC) in a new report which will be unveiled on February 28. By dint of inaction, will humanity one day have to rely on technology to stop global warming?
Little by little, the idea made its way into the heads of heads of state, entrepreneurs and even certain scientists. In recent years, several prototype factories capable of sucking CO2 into the atmosphere have emerged in Europe and the United States. “COP 26 in Glasgow also indirectly endorses the use of certain technologies, analyzes Roland Séférian, climatologist at Météo France. Indeed, the States undertake to no longer subsidize fossil fuel power plants which do not have a capture solution. and carbon sequestration (CCS).This agreement also paves the way for the construction of factories equipped with sorts of “catalytic converters”.
Is this really good news? Not sure. “We will undoubtedly need this kind of solution to fight against global warming,” said climatologist Olivier Boucher, research director at the CNRS. In particular to decarbonize certain branches of industry such as steelworks. On the other hand, equipping factories or power stations with capture solutions also risks prolonging the use of fossil fuels!
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Inequalities between countries
“CCS technologies have clearly gained notoriety,” notes David Keller, CO2 capture expert at the Geomar marine research center in Kiel (Germany). They no longer fall into the famous category “climate geo-engineering”, which includes unconventional and controversial solutions intended to modify temperatures on a large scale. However, these installations will only have an effect on the global thermostat if they become widespread.
However, this raises a number of problems. “Currently, the Canadian company Carbon Engineering burns cheap natural gas to capture atmospheric CO2, inject it into the subsoil and thus extract less carbonaceous oil, but it is certainly not an ideal model”, notes Olivier Butcher. In Iceland, its competitor Climeworks takes advantage of a geothermal energy source to extract CO2 from the atmosphere, but at a cost of 1,000 dollars (880 euros) per tonne harvested – ten times the price of European carbon quotas -, the installation is not profitable. And no one knows how many years it would take to become that.
Finally, not all countries have the same opportunities for CO2 burial. “The United States, Australia and China have extremely deep and vast geological reservoirs located away from populations. On the other hand, some nations are clearly limited by the characteristics of their territory. They are therefore not going to be able to cancel part of their emissions, unless a device is found to transport and store the carbon outside their borders. These inequalities are not the subject of any discussion. They do not appear in any agreement”, deplores Roland Séférian.
“CCS technologies, whether they relate to CO2 leaving the factory or the atmosphere, should above all not be considered sufficient. Reducing our emissions remains essential”, concludes Olivier Boucher. But in case it takes too long, scientists are exploring more controversial techniques such as solar radiation management (SRM).
More reflective clouds over the poles
Here, it is a question of spreading sulfur particles in the stratosphere, of injecting salt into the sea clouds or of installing mirrors in orbit above the poles in order to reflect part of the solar radiation. For David King, founder of the Climate Repair Center at the University of Cambridge (United Kingdom), modifying the composition of the clouds over the Arctic already seems necessary, because this zone is warming much more faster than the rest of the planet. But, within the scientific community, opinions differ.
“There are good reasons to believe that by intervening on such a large scale, potentially devastating unintended effects will manifest themselves” – Stefan Schäfer, professor at the Institute for Advanced Studies in Sustainable Development in Potsdam (Germany)
“The most solid track, from a theoretical point of view, is to use aerosols at altitude, because we know that large volcanic eruptions have cooled the entire planet in this way in the past”, explains Olivier Boucher. However, the effect of such a measure would be temporary: “Regularly, it would be necessary to reinject a quantity of particles into the stratosphere. Beyond the technical difficulties that this poses, side effects could appear”, adds Roland Séférian.
Impossible indeed to control this kind of technique in a very fine way. Some regions would see their situation improve. But the presence of aerosols would alter precipitation patterns in other parts of the world. It could also lead to a thinning of the ozone layer. “There are good reasons to believe that by intervening on such a large scale, potentially devastating unforeseen effects will manifest themselves”, warns Stefan Schäfer, professor at the Institute for Advanced Studies in Sustainable Development in Potsdam (Germany).
And then, who would take control of the global thermostat? This question alone would plunge the world into political chaos. “For all these reasons, we really cannot put the management of solar radiation on the same level as the capture of CO2, believes Olivier Boucher. Certainly, we can imagine a scenario with SRM over a period of a few decades, in order to ‘avoid going too far beyond the 2 degree warming target, but this is above all a plan B. David Keller confirms: “I don’t think we will go as far as putting it into practice.”
The ocean as the ultimate carbon sink
The ocean, on the other hand, could hold the key to our climatic future, believe several scientists. In the past, the latter have already tried to fertilize it by spreading iron over large areas. This substance acts as a fertilizer, by stimulating the plankton. This can then capture more CO2 in the atmosphere before taking it with it to the seabed when it dies. However, the tests carried out so far have proven to be disappointing.
Today, hopes rest on alkalinization. This process consists of adding natural substances, such as olivine or basalt, in order to reverse the acidification process and increase the absorption capacities of the ocean. “Under certain conditions, CO2 is able to dissolve three times in the same body of water. Because of this possibility, the capacity of the ocean to store it is theoretically infinite”, details Roland Séférian. This technique would not require much effort: “It would be enough to extract mineral compounds which are found in abundance in the earth’s crust and to spread the whole in the ocean.”
Another advantage: since the level of alkalinization is maintained for several hundred or even several thousand years, we would only have to do this once, unlike the dispersion of aerosols at altitude. Too good to be true ? “This is one of the most promising techniques to date,” corrects David Keller, one of the most advanced researchers on the subject. But, to find out for sure, the scientist is conducting aquarium tests in his laboratory to detect and measure any side effects.
“On paper, it can be great. But the idea of modifying the properties of the ocean is also a transgression of an unprecedented scale”, warns Roland Séférian. Should we therefore encourage research into geo-engineering? “Yes, believes Olivier Boucher. If we give the impression that technology can solve everything, the effort to reduce emissions is likely to weaken. But, on the other hand, if we do not carry out the research, that means say that we are depriving future generations of certain options.”
American experts no longer ask themselves the question. “They recommend investing 2.5 billion dollars in ocean-related solutions, notes Roland Séférian. In France, climate geo-engineering remains poorly understood. A debate on this issue would undoubtedly be useful.”
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