The Unforeseen Consequences of Geoengineering

Category Technology

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Policymakers are exploring geoengineering to alter Earth's climate by removing carbon dioxide from the air or reflecting solar energy away. However, solar radiation management may have unforeseen consequences such as increasing the chance of extreme weather and exacerbating ocean acidification.

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When soaring temperatures, extreme weather and catastrophic wildfires hit the headlines, people start asking for quick fixes to climate change. The U.S. government just announced the first awards from a US$3.5 billion fund for projects that promise to pull carbon dioxide out of the air. Policymakers are also exploring more invasive types of geoengineering − the deliberate, large-scale manipulation of Earth’s natural systems.

The White House Office of Science and Technology Policy released a research plan in July 2023 for investigating potential climate interventions.

The underlying problem has been known for decades: Fossil-fuel vehicles and power plants, deforestation and unsustainable agricultural practices have been putting more carbon dioxide into the atmosphere than the Earth’s systems can naturally remove, and that’s heating up the planet.

Geoengineering, theoretically, aims to restore that balance, either by removing excess carbon dioxide from the atmosphere or reflecting solar energy away from Earth.

The study in Nature from 2022 predicted stratospheric aerosol injection could alter rainfall patterns and leave parts of the world drier.

But changing Earth’s complex and interconnected climate system may have unintended consequences. Changes that help one region could harm another, and the effects may not be clear until it’s too late.

As a geologist and climate scientist, I believe these consequences are not yet sufficiently understood. Beyond the potential physical repercussions, countries don’t have the legal or social structures in place to manage both its use and the fallout when things go wrong. Similar concerns have been highlighted by the Intergovernmental Panel on Climate Change, the United Nations Environment Programme, the National Academy of Sciences and the National Oceanic and Atmospheric Administration, among others.

Other solar radiation management methods proposed include cirrus cloud thinning, cloud brightening, and space mirror arrays.

The White House Office of Science and Technology Policy also discussed these concerns in its July 2023 research plan for investigating potential climate interventions.

Risks of solar radiation management .

When people hear the word "geoengineering," they probably picture solar radiation management. These technologies, many of them still theoretical, aim to reflect solar energy away from Earth’s surface.

Geoengineering aims to restore the balance between the amount of carbon dioxide being put into the atmosphere and natural removal.

The idea of stratospheric aerosol injection, for example, is to seed the upper atmosphere with billions of tiny particles that reflect sunlight directly out to space. Cirrus cloud thinning aims to reduce the impact of high-altitude, wispy clouds that trap energy within the atmosphere by making their ice crystals larger, heavier and more likely to precipitate. Another, cloud brightening, aims to increase the prevalence of brighter, lower-level clouds that reflect sunlight, possibly by spraying seawater into the air to increase water vapor concentration.

Fossil-fuel vehicles, power plants, deforestation and unsustainable agricultural practices contribute to the underlying problem of climate change.

Some scientists have suggested going further and installing arrays of space mirrors that could reduce global temperature by reflecting solar energy away before it reaches the atmosphere.

While theoretically capable of cooling the planet, solar radiation management could have drastic side effects by shifting patterns of global atmospheric circulation that can lead to more extreme weather events. It also does nothing to reduce harms of excess greenhouse gases, including ocean acidification. A 2022 study published in the scientific journal Nature predicted that stratospheric aerosol injection could alter rainfall patterns and potentially leave parts of the world drier.

Climate interventions promising to pull carbon dioxide out of the air have received US$3.5 billion in funding from the U.S. government.

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