Technologies to reflect some of the sun's rays away from Earth, as a way to cool future runaway climate change, are moving closer to becoming a reality, and rules are needed now to govern them, scientists and other experts said Monday.
"There is no risk-free path at this point" in dealing with climate change, said David Morrow, research director for the Forum for Climate Engineering Assessment at the Washington-based American University.
Around the globe, research is pushing forward on potential cooling techniques such as spraying particles into the upper atmosphere to mimic volcanic eruptions or artificially brightening sea clouds, experts said in a report.
Such sun-dimming technology is designed to reduce the risks associated with accelerating warming in coming decades, from fiercer storms to harsher heat waves.
But the report by a group of international climate and governance experts warned the technology could create new risks — "including climatic, environmental, social, geopolitical and ethical risks."
For example, it might dissuade countries from curbing their climate-changing emissions, in the hope a technological fix is on the way.
Or a single nation might deploy the technologies in its own interests, without international rules in place, in an effort to quell a political outcry at home or shift scarce rainfall to drought-hit farmers, the experts said.
"Desperate people do desperate things," warned Andy Parker, who runs a governance initiative on solar engineering technologies backed by Britain's Royal Society, the World Academy of Sciences and the Environmental Defense Fund.
The report aims to guide research and policy on "solar radiation management" (SRM) through 2025 with a set of principles.
It recommends that efforts to curb climate change and adapt to its impacts must remain the top priority, ahead of technological fixes.
The report also calls for the risks and benefits of SRM to be "thoroughly and transparently" evaluated, and for research to focus on the social needs of the world's poor.
It says "robust" governance, including a mechanism to resolve conflicts, must be in place before any deployment of the technologies is considered.
"The starting point was that research is happening and we need to talk about it," said Aarti Gupta, an expert on governance of technological risk at Wageningen University in the Netherlands and one of the report authors.
The 14-member panel that developed the principles included academic experts in fields such as policy and governance, social sciences, international relations and conflict resolution.
The group "fundamentally disagreed" on whether research on the technologies should even be allowed to go ahead but accepted the need to discuss them publicly, said Simon Nicholson, co-head of the Forum for Climate Engineering Assessment.
The paper comes ahead of the release of a report on Oct. 8 by the world's leading climate scientists, who will say the world is not on track to meet its emissions-cutting goals.
If global warming continues at the same pace, it will exceed 1.5 degrees Celsius — the most ambitious goal set in the Paris Agreement — by 2040, the report is expected to say, threatening everything from world food supplies to economic growth.
Growing fears of an "overshoot" of climate targets are one reason research is expanding on efforts to dim the sun and suck carbon dioxide back out of the atmosphere.
Such research, once confined to laboratories, "is beginning to move outdoors," the report noted.
"Whether or not this [technology] is part of our toolbox ... the debate has to be had" on whether it should play a role, said Janos Pasztor, executive director of the Carnegie Climate Geoengineering Governance Initiative.
The report recommends that a code of conduct should be created governing research on the technologies, and that researchers make public the sources of their funding.
Intellectual property around the technologies would not have to be in the public domain, "but it should be in the public interest," said Prakash Kashwan, a University of Connecticut political science professor and report author.
Governing bodies charged with making decisions about the technologies should put in place "foresight" capabilities to predict how and where they might be researched or used rather than reacting after the fact, he said.
Poorer countries on the frontline of climate impacts — from worsening water shortages to crop failures — must have a significant say in how the technologies are researched and potentially used, the authors added.
Both pushing ahead with research on sun-dimming technologies or rejecting them present significant risks, the report warned, ranging from investors in the technology having a financial incentive to see it used, to banned research moving underground.