Science’s Last Card Against Climate Change

 Vision Think Tank¹ - November 2022

“Climate change and science. Recent technological developments in the USSR on weather modification”. This document, released in 1975 by the famous DARPA (the Pentagon’s Defense Advanced Research Projects Agency, known for having financed the invention of the Internet in the late sixties), shows how back then there were already concerns about changes in climate  caused by industrial activities. DARPA also reported to the US Congress the hypothesis that the soviets could be the first to introduce techniques to lower the temperature of the planet. The concern was that a system designed to save the world (or at least the part of the world governed by Moscow) could turn into a weapon to induce glaciation and sudden storms elsewhere. Almost half a century later, after another UN Conference on climate change in Sharm el-Sheikh, we probably have to declare the failure of the attempt (introduced in Paris in 2015) to keep global warming within 1,5 degrees, compared to 1990 levels. And, maybe, we also have to start considering the hypothesis that the most effective way to react to men’s climate manipulation might be a counter-manipulation conducted by scientists. The adequate technology exists, but it introduces a problem as big as the one it tries to solve for good. 

The words of the UN Secretary General, Antonio Gutierrez, confirm that the climate summit that just ended in Egypt led to inadequate results: “We took – after 15 days of meetings between 40.000 delegates – a small step forward”; and yet, the problem is that the issues to be tackled are walking several kilometers, while we have advanced by only half a meter. The inadequacy of the UN conferences (COP), which have been meeting for 27 years to find a solution to global warming, is proved by a graph accompanying a previous Vision paper: since the first COP in 1995, which launched the moral imperative to reduce CO₂ emissions in the atmosphere, such emissions have increased every year, while each year new multilateral agreements were signed. 

According to scientists, if we get past this point, we will head towards scenarios whose destruction potential dwarfs even the 2020 Covid-19 pandemic. What should we do?

The possibility is that of resorting to a solution that only science fiction movies would have dared to imagine. An artificial cooling of the planet’s temperature quick enough to balance on time the effects of global warming, which is also caused by human activity. We already have the technology to make it and it belongs to - at least - four different categories of innovation. 

The first is aimed at reducing CO2 particles (carbon dioxide removal, CDR). CLIMEWORK, a spin-off of the ETH Zurich Polytechnic, has already successfully experimented the  machine capable to “seize” CO2  from air, which they then sell back to companies who produce, for instance, mineral water). At the conference on climate change that Vision organized in Trento/Bolzano right before COP27, Marco Grasso – Professor of Economics of Climate Change at the Bicocca University – underlined that costs are still high (800 dollars per ton of CO2 removed) but they would eventually decrease as a consequence of the economies of scale, provided that there is a global investment on the project. 

A second, much more natural approach is about using forest and agriculture to absorb excess CO2. It is something which governments (starting from the Brazilian one which governs the Amazonia which captures 10% of CO2 and whose deforestation may transform it into a net producers of emissions) and farmers are cultivating and that yet it is not without collateral effects. Too many trees may, for instance, also alter climate. More importantly, the problem of such methods is that results may come too late.

A third category of geoengineering techniques that has been proposed is the so-called Passive Daytime Radiative Cooling (PDRC), considered as less intrusive than the previously mentioned approaches. PDRC, in fact, dissipates terrestrial heat to the outer space without producing any pollution or consuming energy. This should happen through the installation of thermally-emissive surfaces on Earth, designed to have high solar reflectance (to absorb minimum heat in the daytime) and high longwave infrared thermal radiation heat transfer through the atmosphere’s infrared window, so as to lower the temperature during the day. PDRC differs from “solar radiation management”, the fourth category of geoengineering approaches we will now consider, as it increases radiative heat emission instead of only reflecting the absorption of solar radiation.

The most effective way to reduce Earth’s temperature, however, is about the method we just mentioned, the Solar Radiation Management (SRM). The SRM is about techniques designed to ricochet solar radiations that penetrate CO2 molecules but stay trapped when reflected by Earth. One of the most effective techniques belonging to this category is paradoxically a method using Sulphur dioxide (SO2), a pollutant which we had to reduce urgently in the past decades. The graph below compares global trends in CO2 and SO2 emissions from 1900 to 2010: as the graphs show, while annual CO2 emissions have been continuously increasing since 1900 (reaching 33.36 billion tonnes per year in 2010), SO2 annual emissions grew until 1980 (reaching the peak of 151,51 million tonnes per year) and started decreasing since that moment, becoming 97 million tonnes in 2010, as a consequence of policies followed by several countries in order to specifically lower this pollutant. This, however, had the effect of further increasing global heating, because the very IPCC’s (the UN backed Intergovernmental Panel on Climate Change) report acknowledges that without the Sulphur Dioxide the temperature of the planet would be half degree higher.

Graph 1 – Global trends in SO₂ and CO₂  annual emissions 1970-2010 (1970=100; SO₂ emissions in 1970=140 million tonnes/year; CO₂ emissions in 1970=14000 million tonnes/year) 

SOURCE: VISION on Oxford Martin School, Our World In Data 

The main source of Sulphur dioxide in the atmosphere is represented by the burning of fossil fuels by power plants and by other industrial facilities. Moreover, vehicles such as locomotives or ships – burning fuel with a high content of sulfur – also produce SO2 and, besides industrial activities, SO2 is also produced naturally by volcanoes. Since SO2 leads to the formation of small particles, it contributes to particle matter pollution which can cause severe health problems as they penetrate deeply into the lungs. The climate engineering approach using SO2 to lower global temperatures is the so-called “Stratospheric Aerosol Injection”: it consists in using small reflecting particles to reflect solar radiations into space to stop or reverse global warming, cooling down the temperature of the planet. Through this technique, reflective sulfate aerosol particles are sprayed into the stratosphere – the layer of the atmosphere between 7 and 31 miles above the ground – through airplanes, tethered balloons, high altitude blimps or artillery. The stratosphere is usually seen as an ideal target for geoengineering techniques, as it is relatively distant from human populations but still accessible through planes/delivery methods and it doesn’t have any weather condition which could make aerosol particles fall to the ground.

Even though SO2 is a pollutant, it has then the effect of slowing down global temperatures’ increase, rejecting solar radiations. This was also proved by research carried out on several volcano eruptions (for instance, Mount Pinatubo in 1991) that showed strong evidence of the cooling properties of SO2.

Moreover, simulations² conducted through the Community Earth System Model (CESM1) of the National Center for Atmospheric Research (NCAR) showed that the technique of stratospheric aerosol injection could prevent further global warming and help maintaining a relatively stable climate situation. However, even the supporters of stratospheric aerosol injection underline that this method would have potential negative side effects, such as the reduction of rainfall in some areas of the world. However, since the benefits would outweigh the costs, the technique might be used while developing measures to protect people from the potential damage.

Lowering temperatures artificially solves an issue but originates at least three further questions: what is the effect of a further artificial adjustment of a machine (that of climate) whose functioning we know only partially? Who builds and who controls a network of global protection which has, by definition, effects on everyone? And finally, does this entail the “moral hazard” of reducing the urgency of changing a system of production and energy consumption that is no longer sustainable, for reasons that go even beyond climate change? The model of the International Space Station, where in these months (it is a pity that this news did not make the headlines) Russian and American astronauts have been working together, might be the embryo of a solution.

In one of the most beautiful myths, the titan Prometheus steals the fire from Zeus and gives it to men. That gift was the start of the idea that men can tame the energy; but it was also the start of wars, made possible by weapons and iron production. However, human societies managed to survive combining the innovation of the mechanisms through which they govern their own societies to the innovation of their technologies. This time, we should be able to imagine forms of global democracy that are essential to control the machines we will need to save us from our own excesses.

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^1: The co-authors of this paper are Margherita Curti and Francesco Grillo from Vision Think Tank

^2: “NEW APPROACH TO GEOENGINEERING SIMULATIONS IS SIGNIFICANT STEP FORWARD”, L. Snider on NCAR News, 2017