Is Geoengineering a Solution for Climate Change?

Could geoengineering be the solution to climate change? Are the risks worth the potential benefits?

The field of geoengineering is getting a second look from some scientists, policymakers, and tech billionaires, who wonder whether it could help fend off climate disaster. Geoengineering for climate change involves manipulating the Earth’s climate system to counteract the impacts of greenhouse gas emissions.

Below, we’ll discuss what geoengineering is, why scientists have pushed back against it, and why some are now giving it a cautious second look.

Geoengineering Could Save the World—but at What Cost?

Copernicus, the European Union’s Climate Change Service, reports a warmer year-to-date global average temperature as of July 2024, and the numbers are unlikely to drop. In August, Australia recorded its hottest winter ever, with some areas charting temperatures that were 15 degrees Celsius (59 degrees Fahrenheit) above the norm; the western US also experienced a record-breaking heat wave in October. These are some of the latest grim reminders of a climate emergency—a crisis that’s making experts take a second look at a contentious strategy to help avert a disaster: geoengineering.

What Is Geoengineering?

Geoengineering for climate change is manipulating the Earth’s climate system to counteract the impacts of greenhouse gas emissions. Also known as climate engineering, it can be divided into two strategies: solar radiation management and carbon dioxide removal.

1. Carbon Dioxide Removal (CDR)

This strategy focuses on removing CO2 from the atmosphere to directly reduce greenhouse gas concentrations that are leading to climate change. Examples of CDR are:

• Bioenergy with carbon capture and storage—producing energy from plant-based materials, trapping the CO2 emitted, and storing it underground.
• Direct air capture—trapping CO2 that’s already in the atmosphere and then storing it underground.

2. Solar Radiation Management (SRM)

This type of geoengineering aims to reflect a portion of the sun’s heat and light back into space to cool the planet. Some methods of SRM are:

• Stratospheric aerosol injection—releasing aerosols, like sulfur dioxide, into the stratosphere. It’s inspired by natural occurrences like volcanic eruptions.
• Marine cloud brightening—spraying sea salt crystals into marine clouds to make them more reflective.
• Space-based reflectors—placing mirrors or other reflective materials in space to deflect sunlight before it reaches Earth.

Combination Method: Marine Geoengineering

This method comprises both SRM and CDR strategies deployed in oceans. An example of a marine SRM tactic is cloud seeding using seawater sprayed by ships, while a marine CDR tactic is adding iron to the water. The latter process speeds up the growth of CO2-absorbing phytoplankton; some of this CO2 would then settle deep in the ocean once the phytoplankton die.

Why Opponents Are Saying

In the past, geoengineering lay on the fringes of the scientific world, with most experts not giving it any serious consideration. This is because many argue that manipulating the climate could lead to terrible consequences:

• It might disrupt weather patterns.
• It sends the wrong message and might make CO2-emitting industries complacent, disincentivizing them from cutting emissions. 
• It might have grave effects on geopolitics, putting more power into the hands of nations with more resources.
• It might lead to consequences we can’t even predict.

Citing geoengineering’s dangers, a group of 16 scholars from around the world initiated an open letter for an International Non-Use Agreement on Solar Geoengineering in 2022, with support from hundreds of other experts. Apart from academics, indigenous peoples have also opposed experimentation—in March 2024, Harvard researchers abandoned a planned geoengineering experiment in Sweden after much debate and pushback from the public, including the Saami peoples of Northern Europe. Climate activist Greta Thunberg has likewise spoken out against the technology.

What Advocates Are Saying

Despite these risks, advocates of geoengineering argue that it’s a necessary tool, given the urgency of the climate situation.

While the US was one of the countries that blocked a UN resolution in 2019 to conduct geoengineering research, it shifted its stance in 2020, with Congress allocating funding to the National Oceanic and Atmospheric Administration for a research program. Other experts stress the need for strong governance frameworks to regulate the use of geoengineering technologies.

What’s Next

The general public is similarly divided on the issue: One US survey found that 41-45% of Americans think geoengineering would be beneficial, while a little over half don’t believe it would help. The debate is complex, and there are many factors to consider. Some advocates, considering what happened to the now defunct Harvard experiment, say that researchers should quietly go ahead with research and testing without anyone’s approval. Others, including former Harvard researcher David Keith, are against going “rogue,” but wonder just how open researchers should be about their findings and plans.

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