Experts warn of risks from plans to change solar radiation

Experts argue that while injecting billions of sulfur particles into the atmosphere's stratosphere helps to reflect most of the Sun's rays, the consequences could outweigh the benefits.

More than 60 policy experts and scientists on January 17 called on governments to block global-scale geosynthetic systems as part of a controversial plan called Changing Solar Radiation. (SRM), which is designed to cool the Earth's surface and reduce the effects of global warming.

In an open letter, experts argue that while pumping billions of sulfur particles into the atmosphere's stratosphere helps to reflect most of the Sun's rays, the consequences could outweigh the benefits.

The letter, published in the journal WIREs Climate Change, states: 'It is not possible to globally manage the deployment of solar geoengineering in an equitable, comprehensive and efficient manner. We therefore call on governments, the United Nations (UN) and other institutions to immediately stop viewing solar geoengineering as a normal climate policy option."

An increase of 1.1 degrees Celsius above mid-19th century temperatures has increased the intensity, frequency and duration of deadly heatwaves, droughts and hurricanes.

Countries around the world have pledged to limit the increase in Earth's surface temperature to 1.5 degrees Celsius compared with the mid-19th century, but UN scientists say this limit will be exceeded, possibly possibly in the next decade.

Reducing greenhouse gas emissions has led some policymakers to rely on solar geoengineering – which was not long ago considered science fiction – to buy time while finding a solution. more sustainable.

It has long been known that injecting large amounts of light-reflecting particles into the upper atmosphere can "cool" the planet. A similar phenomenon has occurred in nature: ash from a 1991 volcanic eruption in the Philippines has reduced the average surface temperature of the Earth for more than a year.

But the open letter outlined a number of reasons for rejecting this course of action. Several studies have shown that artificially reducing solar radiation would disrupt seasonal rainfall in South Asia and West Africa, and destroy the rain-demanding crops on which millions of people depend. depend on it.

In its latest scientific assessment, the Intergovernmental Panel on Climate Change (IPCC) said: 'Injecting sulfur into the atmosphere reduces summer rainfall in Asia and Africa and causes arid forests in the forests. Amazon'. However, there are also regions that will benefit: a study last year concluded that SRM could avert drought risks in southern Africa.

Scientists are also concerned about the so-called "end shock" when this sulfur injection suddenly stops. The IPCC said that if the SRM "stops for any reason, it is likely that the Earth's surface temperature will rise rapidly".

Besides, the technology does nothing to prevent the continued increase of CO2 in the atmosphere, which changes the chemical nature of the oceans.

The open letter is also concerned that hoping too much for a climate solution 'could discourage governments, businesses and society from continuing their full efforts to achieve CO2 neutrality as soon as possible'.

Finally, there is currently no regulatory system on a global scale to monitor or implement solar geoengineering mechanisms. Scientists are calling for an international agreement to prevent countries from funding and conducting unsavory outdoor experiments and refusing to license SRM technologies. The open letter states that such an agreement 'will not preclude further research into the atmosphere or climate'.