Home » today » World » Cool the Earth by reflecting sunlight? It is a bad idea – 2024-04-21 10:40:48

Cool the Earth by reflecting sunlight? It is a bad idea – 2024-04-21 10:40:48

Recently, the United Nations Environment Assembly (ANUMA) considered a resolution on solar radiation modification, which refers to controversial technologies aimed at masking the warming effect of greenhouse gases by reflecting part of sunlight back into space.

The draft resolution initially called for convocation of a group of experts to examine the benefits and risks of solar radiation modification; However, the proposal was discarded days later as no consensus was reached on the controversial issue.

“The much better and safer option is to eliminate fossil fuels immediately”

James Kerry, Associate Senior Research Fellow at James Cook University in Townsville, Australia

Although their defenders maintain that these technologies will limit the effects of climate change, in reality, according to experts, this type of ‘geoengineering’ runs the risk of further destabilizing an already deeply disturbed climate system. Furthermore, its full impact will not be known until after its deployment.


“We already know that our climate is changing, but modifying solar radiation would not reverse the changes, but rather would introduce a new climate that would be unpredictable and uncontrollable,” James Kerry, associate principal investigator at James Cook University in Townsville, Australia, explained to Metro.

For example, “I would reduce light levels and temperature. This would change weather patterns and global and local climate. While some parts of the world could be colder, others would experience more droughts or more floods,” the expert said.

Kerry adds that man-made climate change is already a experiment on a planetary scale too many, so the world doesn’t need another.

Kerry’s vision is shared by more than 500 scientists from 61 countries who signed an open letter calling for an international agreement not to use solar geoengineering. The document, released in 2022, said that speculative technologies are detrimental to the urgent need to reduce global emissions, and that there is no global governance system that fairly and effectively regulates their deployment.

“It is important to note that even if these technologies worked, they would not address the root causes of climate change: the CO2 we have added to our atmosphere will still be there and will continue.” causing problemssuch as ocean acidification,” Kerry concludes.

A risky business

In some circles, the geoengineering Solar is gaining importance as a response to the climate crisis. However, research has consistently identified potential risks posed by technologies such as:

  • -Unforeseeable effects on climate and weather patterns.
  • -Loss of biodiversity, especially if the use of technology is abruptly interrupted.
  • -Undermine food security, for example by reducing light and increasing the salinity of the land.
  • -The violation of the human rights of several generations, which includes, among other things, the transmission of enormous risks to future generations.


Scientists signed a letter in 2022 calling for an international agreement not to use solar geoengineering.

4 questions to….

James Kerry, Associate Senior Research Fellow at James Cook University in Townsville, Australia.

Q: Where did the idea of ​​cooling the Earth by reflecting sunlight come from?

–Solar radiation modification is a set of geoengineering ideas to reflect sunlight in order to cool the Earth that have been proposed by a small number of scientists in recent decades. Are controversial technologies They aim to mask the warming effect of greenhouse gases, which cause climate change, by reflecting part of the sunlight into space.

Q: How is this plan intended to reflect sunlight?

–Among the ideas are the injection of stratospheric aerosols, the clearing of marine clouds or space shadows.

Injecting stratospheric aerosols would require injecting millions of metric tons of pollutants, such as sulfur dioxide, into the stratosphere using a purpose-built fleet of aircraft. The idea is that the particles block or reflect some of the sunlight incoming and, therefore, the heat. This technology was tested in April 2022 by a US company, without permission, in Mexico, using weather balloons.

Marine cloud clearing follows a similar logic. When pumping small particles of salt water in low clouds, these should become more reflective. It is estimated that an armada of ships would have to operate all year round pumping large quantities of seawater into the atmosphere for this to affect the climate.

The satellites would circle the Earth with space screens to reduce incoming sunlight. It is estimated that they would have to cover one million square miles (about the size of Argentina) to cool the planet.

Q: Why is this a bad idea?

–There are many reasons why it is a bad idea. Firstly, in many cases, it would mean combating decades of pollution (greenhouse gases) with other decades of pollution, since these technologies would have to be carried out over a long period of time. several generations.

Secondly, we already know that the deployment of any of these technologies will have many repercussions negative effects on our planet, such as damage to the environment and human health.

Third, we will never be able to know the full consequences of these technologies until they are fully deployed: climate systems and our planet They are too complex to understand how they would develop.

Finally, there is a great risk of a “termination shock”, that is, a technology suddenly stops working. For example, if a space screen were to break down, it would cause a rapid and catastrophic increase in temperature on our planet.

Q: What could be a better option to this plan?

The much better and safer option is to remove the fossil fuels immediately, and we already have the renewable energy and energy efficiency technologies we need to do it. What is missing is political will and investment.

It is not too late, but time is of the essence: The IPCC has made it clear that the world needs to reach a peak emissions in 2025 before halving them in 2030 to meet the Paris goal.

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