Guia Covid-19
Imprimir Republish

Polemic

The owners of rain

Interventions on global climate may already be feasible, but carry huge risks

MARIANA ZANETTITwo new expressions – climate management and geoengineering – are appearing more often in international debates on science and the politics of climate change. One of the reasons is the failure of attempts to implement effective policies to reduce the emissions of greenhouse gases. What is new is that it is not longer utopian to think about intervening in the regional or the global climate to avoid the ongoing rise of the average global temperature, and the heavy floods or droughts that have become more frequent as climate change increases. It may be feasible to use aircraft, balloons, or cannon to spread particles of aerosols in the stratosphere or to increase the nebulosity of the planet by seeding clouds. These interventions might reflect part of the solar radiation back into space and cool down the Earth to reduce the rising impact of the concentration of greenhouse gases, such as carbon dioxide (CO2).

However, experts warn that this might be quite dangerous – and not only because the effects of these interventions on global climate are unforeseeable. “A single country or a single millionaire might try to change the Earth’s climate, with unforeseeable consequences,” the physicist Paulo Artaxo commented, a professor at the University of São Paulo (USP), during a debate held in June at USP’s Institute of International Relations. “I hope a competition between countries, major enterprises, or billionaires from the United States, England or the Arab world wanting to save the planet doesn’t start, changing the climate on purpose. The possibility does exist; all it takes is to make a decision.”

It is estimated that pouring tons of sulfur into the upper atmosphere to produce aerosol particles would cost US$ 10 billion a year, far less than the US$ 1 trillion required to reduce CO2 emissions. Geoengineering or climate engineering, as deliberate climate intervention on a broad scale is called, offers other possibilities. The simplest are to include the reflectivity of the surface of buildings and wide-scale reforestation, as plants absorb a lot of CO2 as they grow. More refined possibilities include spreading iron ions in the ocean to increase the fertility of sea algae, which would sequester CO2, carrying it down to the seabed.

Debated in the academic world since the 1960’s, geoengineering gained public visibility through George W. Bush, the United States president from 2001 to 2009. Bush preferred betting on this type of strategy to deal with the effects of the problems caused by global warming rather than reducing emissions to avoid their impact. Those who embrace geoengineering “a group that comprises the fossil fuel industry and some scientists who believe that the climate problem is so urgent that it requires drastic interventions – argue that it might be possible to lower the planet’s temperature on purpose, not as a panacea, but as a mitigating measure, while other measures, that take longer, are put into practice.

Risks
Alan Robock, a researcher at Rutgers University in the United States, has been warning that geoengineering risks might outdo the benefits, even if the measures were to work as expected. According to him, deliberate changes in the global climate might mitigate social pressure to institute measures to reduce the emission of greenhouse gases, besides disrupting the weather even further. One of the expected effects is reducing annual rainfall, known as the monsoons, over Asia and Africa, thus threatening the production of food for hundreds of millions of people.

In 2008, in Science, Robock stated that geoengineering might be used as a weapon of war by a country against its enemies, causing droughts or floods with catastrophic consequences in hostile territories. A number of questions for which there is no answer yet also arise: who would control the climate and say when it was time to stop? Robock voiced the following scenario: what if Russia wanted a slightly higher global temperature and India wanted it slightly lower? Eduardo Viola, a sociologist from the University of Brasília (UnB), who took part in the debate at USP, fears that the more powerful countries, such as China, Russia and the United States, might take unilateral decisions to benefit themselves, which could harm many other countries.

“We don’t have any global governance to deal with these problems. What would a US president like Sarah Palin do?” questioned Jason Blackstock, a researcher from the Center for International Governance Innovation (Cigi), Canada, during his presentation at USP. “We must have a clear understanding of all the implications.” Each strategy has serious side effects. According to him, increasing the amount of sulfur in the atmosphere might cool the Earth down, but it would also change rainfall and the balance of direct and diffuse radiation, with a serious effect on the functioning of ecosystems. Inversely, the proposal to cut by 0.5% the sulfur content of fuel used in ships by 2020, as a means of avoiding the death of 35 thousand people, especially near ports, might increase the incidence of sunlight on the surface – and the planet would warm up slightly.

“Scientists in general are favorable to geoengineering research and can plan small scale experiments in forthcoming years,” says Artaxo, based on the international meetings that he has attended. “The problem is that the effect isn’t only local.” Because of the winds, part of a load of sulfur released, for example, in the central area of the United States might easily, within one day, reach the Atlantic or the Pacific, with unforeseeable consequences for the balance of the Earth’s climate.

The intentional discharges of aerosol particles would have a similar effect to that of volcanic super eruptions. The most-often mentioned example is Pinatubo, the volcano in the Philippines that erupted in June of 1991. Within a few days, it released 20 megatons (each megaton equals 1 billion kilograms) of sulfur dioxide. The particles spread in the atmosphere and the temperature of the air on the surface of the northern hemisphere countries dropped by two degrees. After one year, the particles settled and the temperature rose again.

In 2002, in Science, Robock observed that the spreading of particles from a volcanic eruption is not an innocuous phenomenon: it can reduce solar radiation and consequently evaporation and rainfall for a year or two. Artaxo points out another consequence of the accumulation of aerosols in the atmosphere: “We would never get blue skies as we have today and the optical telescopes on the surface of the Earth would become useless.”

For him, the best solution against the impact of global warming is to reduce the consumption of fossil fuels and the greenhouse gas emissions fast and to change the way in which we use the planet’s natural resources. “If we are intelligent,” he says, “we will be able to use the planet’s natural resources more efficiently and sustainably, without having to engage in mind-blowing experiments that put our fragile terrestrial system at an even greater risk.”

Republish