How are geoengineering fixes for climate change like seatbelts in an automobile? According to top climate scientist Ken Caldeira, tinkering with the climate might help keep us safe, but we’d better be sure the geoengineering “seatbelt” actually works before we start driving.

The top priority for dealing with climate change, though, still rests with cutting greenhouse gas emissions, Caldeira told US House members of the Committee on Science and Technology during a hearing on “Geoengineering: Assessing the Implications of Large-Scale Climate Intervention.”

“The best, surest, and clearest way to reduce environmental risk associated with greenhouse gas emissions is to reduce greenhouse gas emissions,” said Caldeira, a scientist with the Carnegie Institution’s Department of Global Ecology. “If you take the risk of climate damage seriously, you want to take action to diminish risk by reducing greenhouse gas emissions, but you would not want to limit yourself to only one risk-reduction approach.”

Geoengineering involves such strategies as injecting particles into the upper atmosphere to reflect incoming sunlight or using technologies to “scrub” carbon dioxide out of the atmosphere. While some sunlight-reducing proposals appear to be affordable, quick to deploy and effective, however, they don’t solve the root cause of global warming — rising levels of greenhouse gases — or related impacts like ocean acidification.

Geoengineering fixes could also create political risks or unpredictable environmental problems like decreased rainfall. While Caldeira acknowledged the need for urgent and focused research to make sure geoengineering would work if we actually need it, he compared the strategy to using seatbelts in an automobile.

“Just because we wear seatbelts, that does not mean we will drive more recklessly,” he said. “Seat belts can remind us that driving is a dangerous activity.”

Caldeira added: “We do not want our seat belts to be tested for the first time when we are in an automobile accident. If the seat belts are not going to work, it would be good to know that now. If there is something really wrong with thoughtfully intervening in the climate system, we should try to find that out now, so that if a crisis occurs, policy makers are not put in the position of having to decide whether to let people die or try to save their lives by deploying, at full scale, an untested system.

“We need the research now to establish whether such approaches can do more good than harm,” he said. “This research will take time. We cannot wait to ready such systems until an emergency is upon us.”

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