What is geoengineering – and can it save the planet?

The failure of world leaders to reach key agreements at Cop27 has spurred scientists’ efforts to develop radical methods to limit global warming.

Geoengineering is “one of the most controversial and consequential climate change-fighting tactics yet”, said The Daily Beast’s science writer Tony Ho Tran, and refers to “technologies and innovations that can be used to artificially modify the Earth’s climate”.

Countries worldwide including the US are exploring different forms of geoengineering. The White House last month announced a five-year research plan to explore solar radiation management.

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What is geoengineering?

Geoengineering “sounds futuristic”, wrote Robert Litan for Foreign Affairs. But the basic concept has been around since 1965, when scientific advisers to then US president Lyndon Johnson “suggested that some kind of tinkering with the planet’s mechanics might be necessary”.

Since then, this tinkering has included developing methods to suck carbon dioxide out of the atmosphere, and fertilising the ocean to stimulate phytoplankton growth. Other projects range from influencing the weather to reflecting solar heat.

The concept of geoengineering is becoming more mainstream “as the pace and destructiveness of extreme weather events seem to be quickening beyond even some of the most pessimistic forecasts”, said Litan. “Geoengineering might finally have its moment.”

The US is investigating a geoengineering technique that “essentially involves spraying fine aerosols into the atmosphere to reflect sunlight away from the Earth”, said Ho Tran on The Daily Beast. Although that “sounds a bit bonkers”, he wrote, the world has witnessed “inadvertent solar radiation management” before. The 1816 eruption of the Tambora volcano in Indonesia resulted in temperatures dropping by as much as 3C in Europe and North America that summer.

Unesco last week held a panel on the scientific advancement and ethical challenges of climate engineering at Cop27 . The UN agency said that arguments were “increasingly being made for the consideration of other actions to counter the heating effect of greenhouse gases”.

“The consideration of such methods, however, raises a host of ethical concerns and questions,” Unesco added.

Why is it controversial?

Countries worldwide are “increasingly using technology to change conditions in the atmosphere, oceans and ice to improve weather to their advantage or lessen global warming”, said Tracy Raczek, former climate advisor to the UN secretary-general. But in an article for London-based think-tank Chatham House, Raczek warned that the “results of these interventions can cross borders, and what may be good for one country may not be good for its neighbours”.

“This is not a hypothetical problem,” Raczek wrote. Iran has accused Israel of stealing its water through cloud-seeding, and China’s success in artificially altering weather over some of its cities has alarmed India and other nearby nations.

Experts say that more research is needed into many forms of geoengineering. David Keith, director of Harvard University’s solar geoengineering research programme, told the BBC’s Discovery podcast that “nobody doubts” that global temperatures could be lowered by spraying substances into the atmosphere to reflect sunlight back into space. But a question mark hangs over the potential unintended side effects and risks.

Former BP chief John Browne, now chair of climate growth equity venture BeyondNetZero, described geoengineering for climate change as “Plan C”. This approach is “not desirable, is fraught with risk, and does not need to be done immediately”, he said in the Financial Times (FT). “But it does merit greater thought and consideration.”

Can it save the planet?

Browne fears that neither emissions reduction or climate change mitigation will be enough in the battle against climate change, because they generate “returns which are long-term, unquantifiable and indirect”. So geoengineering represents our best shot at a sustainable future, he argued in the FT, although “it will take at least a decade to establish the scientific and bureaucratic institutions needed to govern this activity”.

The biggest opponents to geoengineering point to problems associated with methods such as releasing sulphur into the atmosphere to form clouds.

But “air pollution deaths from the added sulphur in the air would be more than offset by declines in the number of deaths from extreme heat, which would be ten to 100 times larger”, wrote Harvard’s Keith for The New Yorker. Geoengineering is also “cheap and acts fast”, he said, adding: “If I were asked which method could cut mid-century temperatures with the least environmental risk, I would say geoengineering.”

That sentiment was echoed by science journalist and astrophysicist Graham Phillips in The Sydney Morning Herald. Geoengineering methods such as spraying sulfur into the skies “sound insane”, he said.

“But the voice to explore them has been steadily growing louder, and serious scientific research is starting to be done on this terrestrial tinkering – because not tinkering may be even more insane,” Phillips concluded.