Plan B: Hacking the climate
Los Angeles - In a laboratory in the US Pacific north-west, scientists are working on what could one day become a new, and controversial, weapon to fight global warming: clouds.
Misting ocean clouds with salt water could multiply the water droplets inside, the theory goes, "brightening" clouds to make them reflect more sunlight away from the earth.
"If you can reflect away some of that radiation and not allow it to be absorbed, you will cool the planet," said atmospheric scientist Tom Ackerman, who directs the research at the University of Washington's Joint Institute for the Study of the Atmosphere and Ocean.
The phenomenon has been observed over cargo ships, as microscopic particles in smokestack effluent collect water droplets, leaving trails of "brightened" clouds in their wake. Ackerman's team believes it could be recreated using tiny salt particles to reduce the solar radiation absorbed by the ocean.
Initial computer models have shown promise. But Ackerman said no funder is willing to back field tests, and environmental activists have threatened to disrupt them if they do.
Other researchers in the US, United Kingdom and Germany working on high-tech climate hacks from dimming the sun's rays with stratospheric aerosols to growing phytoplankton to suck carbon dioxide from the seas have hit similar roadblocks.
The point of contention isn't whether humanity could one day use so-called geo-engineering to cool the earth - but whether we should.
"People have this sort of innate response that somehow we're tinkering with Mother Nature, and we shouldn't be doing that," Ackerman told dpa - even though, he pointed out, by burning fossil fuels "we are already adding carbon dioxide to the atmosphere and nobody objects to that."
Earth's temperature is currently on course to rise at least 4 degrees this century as a result of increasing amounts of carbon dioxide and other greenhouse gasses in the atmosphere.
Starting November 30, representatives of nearly 200 countries intend to make the final push in Paris for a new climate agreement that for the first time will include carbon emission reductions by developing countries.
Moral hazard of climate intervention
The goal is to stop the global temperature from rising more than 2 degrees centigrade over pre-industrial times, in order to avoid catastrophic loss of human life from rising sea levels and severe weather.
Many observers fear that even the whisper of a Plan B to confront climate change could weaken political will for the hard work of Plan A, reducing emissions by cutting use of fossil fuels.
Australian ethicist Clive Hamilton wrote of the moral hazard of climate intervention in the Scientific American monthly, saying "technical solutions to social problems ... are appealing when we are unwilling to change ourselves and our social institutions."
Researchers agree that emissions reduction remains key to the climate's long-term health. Even if there were a proven, safe way to reduce solar radiation, continuing carbon emissions would eventually cancel it out, limiting its use to a quick fix to buy time at cooler temperatures.
Larger, and perhaps thornier, questions involve the ethics of "playing god" with the earth's climate, and the potential pitfalls of interfering in complex systems.
"People are concerned about the unknown unknowns," Stanford geo-engineering pioneer Ken Caldeira told dpa. "There's only one planet, and you start spraying something all around the stratosphere and, obviously, bad things could happen."
But as global temperatures continue to rise, support may be growing for at least finding out whether it can be done at all.
The US National Research Council (NRC) in February gave its first green light for research into geoengineering to capture carbon from the atmosphere, as well as a lukewarm go-ahead for research into - but not use of - solar radiation management.
"That scientists are even considering technological interventions should be a wake-up call that we need to do more now to reduce emissions," NRC committee chair Marcia McNutt said. "But the longer we wait, the more likely it will become that we will need to deploy some forms of carbon dioxide removal to avoid the worst impacts of climate change."
Some supporters of research into geo-engineering say if emissions reductions efforts fail to contain global warming, there may be no other choice.
In an interview with The Atlantic, Oliver Morton, author of a new book on geo-engineering, The Planet Remade, said the belief "that with just a bit more political will, you can suddenly go to a zero-carbon world" was unrealistic.
He wondered if future generations will say "that it's kind of a pity that people in the 21st century didn't very slightly cool the planet to give themselves more time, so that the horrible thing that happened in 2055 didn't happen."