Can geoengineering fix the climate? Hundreds of scientists say not so fast

 The Biden administration is developing a controversial solar geoengineering research plan to the dismay of many experts

As global heating escalates, the US government has set out a plan to further study the controversial and seemingly sci-fi notion of deflecting the sun’s rays before they hit Earth. But a growing group of scientists denounces any steps towards what is known as solar geoengineering.

The White House has set into motion a five-year outline for research into “climate interventions”. Those include methods such as sending a phalanx of planes to spray reflective particles into the upper reaches of the atmosphere, in order to block incoming sunlight from adding to rising temperatures.

The work is required by Congress. It is “not new research, but a report that highlights some of the key knowledge gaps and recommendations of priority topics for relevant research”, said a spokesperson for the White House’s office of science and technology policy, adding Joe Biden’s administration wants “effective and responsible CO2 removal” as well as deep cuts to greenhouse gas emissions.

Several American researchers, somewhat reluctantly, want to explore options to tinker with the climate system to help restrain runaway global heating, even as they acknowledge many of the knock-on risks aren’t fully known. “Until recently, I thought it was too risky, but slow progress on cutting emissions has increased motivation to understand techniques at the margins like solar geoengineering,” said Chris Field, who chaired a National Academies of Sciences report last year that recommended at least $100m being spent researching the issue.

“I don’t think we should deploy it yet and there are still a ton of concerns, but we need to better understand it,” Field said. “Climate change is causing widespread impacts, it’s costing lives and wrecking economies. We are in a tough position; we are running out of time, so it’s important we know more.”

Previous attempts at running experiments for what is known as solar radiation management (SRM) have faced staunch opposition. Last year, an exploratory flight in Sweden of a high-altitude SRM balloon, led by Harvard University researchers, was halted after objections by environmentalists and Indigenous leaders.

But at least one US startup is now hoping to leap ahead with solar geoengineering.

Make Sunsets, backed by two venture capital funds, launched in October. It claims to have already run two internal test flights for its plan to inject sulphur via balloons into the stratosphere, more than 20km above the Earth’s surface.

The venture, named after the deep red sunsets that would occur if particles were seeded into the stratosphere, says its “shiny clouds” will “prevent catastrophic global warming” and help save millions of lives. “Any human-caused release of carbon dioxide is geoengineering,” it argues on its website, which asks people to buy “cooling credits” to fund its work. “We screwed up the atmosphere, and now we have a moral obligation to fix things!”

Edward Parson, an expert in environmental law at University of California, Los Angeles, says Make Sunsets’ claims that it could return the world to its pre-industrial temperature for just $50bn a year are “absurd”. He explains that most researchers are wary of deploying what they consider to be a desperate, last-ditch option.know more.”

But Parson says the risks in researching solar geoengineering have been overblown and that the US “is probably the bold leader on this. It would be a big step forward if we have a research program.”