Messing with the Climate to Save It

Stabilizing the earth's climate will ultimately require zeroing out all emissions of carbon dioxide and other greenhouse gases. Some geological engineers are toying with some pretty wild ideas to counter climate change.

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ANDREA SEABROOK, Host:

From NPR News, it's ALL THINGS CONSIDERED. I'm Andrea Seabrook.

There's an obvious way to tackle global warming - cut emissions of the gases that cause it. Easy, right? Well, maybe not. To cut those emissions, we'd pretty much have to give up most oil and coal and natural gas in the next few decades. So, scientists are toying with some other wild ideas, and they're the focus of today's Science Out of the Box.

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SEABROOK: So, can technology really make a dent in global warming? NPR's Richard Harris reports.

RICHARD HARRIS: Good ole American ingenuity has solved plenty of problems and created plenty more. Ken Caldeira at the Carnegie Institution at Stanford University says the idea of a technological fix for climate change goes way back.

SEABROOK: The first time a president was warned that there might be a global warming problem was in 1965.

HARRIS: But President Lyndon Johnson's advisers did not suggest cutting back on fossil fuels. They said, why not spread reflective particles all across the Earth's oceans?

M: Reflecting sunlight back to space would offset the warming effects of increased greenhouse gases like carbon dioxide.

HARRIS: Since that time, Caldeira says scientists have thought of all sorts of other technological fixes - geo-engineering they call it - for getting us out of the global warming fix.

M: Whitening roofs or whitening roads or planting crops that are more reflective.

HARRIS: You could even whiten clouds by spraying sea water into the air over the ocean.

M: Perhaps the most radical idea was the idea that we should build huge satellites out in space between the Earth and the sun and that these huge satellites would deflect sunlight back to space.

HARRIS: One of the easy ideas of all is to spray tiny sulfur dust particles into the stratosphere. When volcanoes do this, the earth most certainly cools, and Caldeira says it wouldn't take much.

M: It's thought that a single fire hose constantly spewing out dust particles into the stratosphere would be more than enough to offset a doubling of greenhouse gas concentrations.

HARRIS: So, it's simple and it's cheap. You could do this for maybe a billion dollars a year - chump change compared with what it would take to reengineer the entire global economy so it's no longer running on coal and oil.

M: And so it gets away from the huge costs and huge difficulty of establishing global cooperation to reduce greenhouse gas emissions. And, of course, the downside is, well, you just might screw up the planet.

HARRIS: Oh yeah, that. Of course, we are already in the process of screwing up the planet with global warming. So, Caldeira and some other scientists are now saying it's time to figure out what's likely to happen if we were to try a project like this and compare that with what's likely to happen if we don't.

Simone Tilmes as the National Center for Atmospheric Research in Boulder, Colorado is not enthusiastic about the sulfur idea. Her specialty is the ozone layer, which protects the earth from harsh ultraviolet sunlight. She's just published a paper online in Science magazine showing how much ozone would be destroyed by sulfur particles.

The worst effect would be during especially cold winters and near the Earth's poles.

M: They can reduce the ozone layer by more than half what is there right now. And this can be really dangerous for life on Earth.

HARRIS: Fortunately, this ozone depletion would be mostly in the Arctic and the Antarctic and mostly at a time of year when there isn't much ultraviolet light to begin with - in the late winter and early spring.

M: You might not be in a bathing suit out there in the springtime, but it still impacts you.

HARRIS: Ultraviolet light isn't good for living things, but on the other hand it doesn't appear to be catastrophic either.

When Mount Pinatubo erupted in 1991, it put much more sulfur into the stratosphere than scientists would do if they geo-engineered the stratosphere to block sunlight. The Earth did cool as a result and organisms did cope with the loss of ozone.

M: We don't really mess up the entire chemistry in the stratosphere with doing geo-engineering. But it can, of course, change also local precipitation patterns and people can be impacted by geo-engineering.

HARRIS: For his part, Ken Caldeira doesn't minimize the effect of ozone loss, but he says if global warming continues at its alarming rate, the Arctic could soon lose all of its summertime ice, and that has consequences too.

SEABROOK: Is it better to have the sea ice but have the polar bears to get a little more ultraviolet radiation or is it better to keep the ultraviolet radiation down but let the polar bears go extinct? You know, this is the kind of question that we're going to be faced in the future if we don't greatly reduce greenhouse gas emissions.

HARRIS: That currently is feeling like a losing battle, considering the lack of international resolve. On the other hand, creating a thermostat for the globe in the form of sulfur particles would raise a whole host of other questions about international cooperation.

M: Once you put a knob on the climate system, whose hand is going to get to control that knob and that opens all kinds of potential for international conflict.

HARRIS: A Brazilian, for instance, might have a very different notion of the ideal temperature compared with someone from frozen Siberia.

Richard Harris, NPR News.

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