The most controversial weapons against global warming

Technologies that try to curb climate change without necessarily reducing emissions confront scientists and activists.

Geoengineering, which groups these instruments, puts the nerves to those who assume that everything that is not to allocate money to reduce emissions is to take it away and that these technologies, as pointed out by the expert Alan Robock, can cause many more problems than they promise to solve.

Until a few years ago, hostility was the consensus position of the international community. Therefore, in 2010, publications such as Scientific American were totally against and the UN Convention on Biological Diversity was signed. This convention imposed something similar to a moratorium that restricted the realization outside the laboratory of large geoengineering projects with the exception of massive reforestation. It did not help that some of those who, until recently, questioned the severity ( Bjorn Lomborg ) or human origin (ExxonMobil) of climate change said that combating emissions was only part of the solution to warming.

Among the pragmatists for and against these new techniques, the contours of the debate could be summarized as follows: some believed that, before talking about alternatives, the world leaders should concentrate their efforts in agreeing to a drastic reduction in emissions; and others said it was utopian, that this would never happen, and that it was best to recognize from the beginning that a more light emission reduction should be complemented with the advances that geoengineering could achieve.

Seen the ravages of the economic crisis and the weakness of the commitment of the States in the last decades, the second ones started with an advantage. The arrival of Donald Trump and the increase in CO2 emissions in 2018 have finally tipped the balance in his favor. The organization Global Carbon Project estimates that they increased by almost 3% last year, a record never seen since there are historical series.

Now, the international community has accepted that we must explore the possibilities of geoengineering while continuing to cut emissions. Thus, the influential UN IPCC panel recognized in October that these new techniques could be part of the warming solution. Of course, I did not put them on the same level as applying a severe snip to CO2 but admitted at least that experiments, where chemical agents had been injected into the stratosphere, were working well in the laboratory.

Polarization and paralysis

Unfortunately, the debate and the rejection of geoengineering have caused enormous delays. As a result, until the last two or three years, large research centers have not appeared in China and the United States, and although public and private funds have grown, they remain very scarce. All this has led us to believe that, according to a recent study by Nature, many of these new technologies will not reach maturity before 2050.

In spite of that, there are already great experiments outside the laboratories. One of them is SCoPEX and consists of introducing aerosols in the stratosphere. Another is the so-called Marine Cloud Brightening Project, whereby they try to increase the brightness of the clouds by spraying them with a spray of salt water in Moss Landing, California. Finally, Ice911 involves covering small ice surfaces with tiny crystals in different locations in Alaska. The objective of all of them is to increase the reflectivity of the Earth so that it absorbs less solar radiation and thus reduces the heating.
Beyond amazing experiments, the geoengineering research lines that have advanced the most are basically four. The first is to use CO2 to transform biomass into electricity, biofuels or chemical products. How does it work? For example, CO2 is captured from the atmosphere by algae (transgenic?) Which is then used to produce biofuels, or carbon dioxide is used in the production of concrete. You can also burn biomass to produce a coal that will fertilize the soil when buried. The burning of biomass to produce electricity is considered neutral from the point of view of emissions because it is assumed that the plants will grow back in the soil and that they will again capture CO2.

The second technique involves increasing the reflectivity of the Earth so that its surface 'returns' more sunlight than now and mitigates the warming that it causes. This can be done, for example, by expanding the space dedicated to the cultivation of plants such as green grass or certain foods such as grain, which could be genetically modified to make it more reflective.

The third technique that has advanced the most is to fertilize the oceans with iron to stimulate a marine bloom that captures CO2. Here the key is to pour iron sulfate or urea in areas with very little vegetation to excite the growth of phytoplankton. The latter would naturally capture CO2 and, at the same time, when dying, it would serve to nourish the sea floor, which in turn would lead to more vegetation.

The fourth technique has to do with the introduction of aerosols in the stratosphere to reduce solar radiation. The aerosols we talked about would be composed of particles of sulfur, aluminum or titanium and act as a large mirror that would repeal a part of the sun's rays. Here the big question is how would that kind of particle mirror be placed. Some advocate airplanes that dump their contents in the stratosphere, others aim at antiaircraft guns of great range and others are more inclined by the possibility that it is the particles themselves that rise 'naturally' to the stratosphere.


One of the conclusions that begin to emerge from many experiments is that it is not clear that what works on a tiny scale can work on a planetary scale. This was absolutely predictable. We have also seen that, if the rules are not clear or if the populations that may be affected by the investigations are not adequately informed, the consequence will be a resounding rejection by the people. Haida Salmon Restoration Corporation poured a hundred tons of iron sulfate into waters near Canada in 2012 and the international scandal was considerable. Sometimes, the scandals are justified, because irregularities are committed and other times they are not because they are promoted by activists who oppose geoengineering.

Another of the conclusions that are outlined with these experiments is that the large-scale manipulation of climate or solar radiation will not be free. There will be winners and losers and, therefore, some criteria and institutions are necessary so that they are not simply decided by the strongest countries. For example, there are modeled studies that indicate that the injection of aerosols into the stratosphere of the northern hemisphere could cause droughts in sub-Saharan Africa and India. If one of the dangers of climate change was the multiplication of extreme weather events that are difficult to predict, we can ask to what extent geoengineering mitigates or aggravates the threat.

In addition to creating a reliable framework for decisions, the context will require the deployment of economic and other compensation measures. It is very likely that the injection of aerosols in one place must be 'balanced' with another injection in a distant region but that it could receive an undesirable impact. We know how these spirals begin but not how they end. Climate planning, like the central planning of the economy, will involve more and more intervention if there are no strict regulations that limit it.

When we talk about the winners and losers of geoengineering, it is important to include the diversity of ecosystems and issues related to the supply of food or raw materials. It seems clear that pouring iron sulfate into the ocean increases marine vegetation, that marine vegetation becomes less diverse because the sulfate helps more to some species of plants than to others and that the increase of the vegetation reduces the oxygen that plants and fish need. It also seems clear that multiplying massively the crops of a certain type of grain (because it is very reflective) can be detrimental to the food needs of a part of humanity. To determine the success of a program like this, other variables besides the cooling of the Earth must be taken into consideration.

Geoengineering faces immense challenges and unknowns of enormous scope. Exactly the same as those who have had to face renewables until they become what they are today. As with them at the beginning, we now speak more of their difficulties than of their chances of success. But we can not remain paralyzed. Research must continue, resources must flow like a great torrent and new techniques have to show what they are capable of. There can be no excuse to justify the renunciation of a powerful weapon in the fight against global warming. We do not know if geoengineering is, but we can not afford not to discover it as long as we complement it with the reduction of emissions.