LiveScience posted a short article
the other day on potential schemes for dealing with extreme climate change, and the list of possibilities is a wonderful primer on how wild eyed people can be about this issue. The article reported on testimony from climatologist Ken Caldeira of the Carnegie Institution in Washington, D.C., following a report Dr. Caldiera gave to the British Parliament.
Climate change is a big issue, to say the least. In the last 150 years humanity has managed to bootstrap itself from an agrarian species to a technological one, principally through exploiting the stored chemical energy in fossil carbon compounds. The Earth's carbon cycle laid away a small buried surplus of reduced carbon compounds over the last 350 million years (give or take), and we've used that geologic nest egg to prodigious benefit. In the last few decades we've also come to realize that there is no free lunch, and the waste generated from burning megatons of fossil hydrocarbons - specifically carbon dioxide waste - has ratcheted up the size of our planet's atmospheric infrared-radiation buffer. Result: a warming climate.
I'm a pretty strong environmentalist. I might as well get that out of the way, in the name of full disclosure. But I'm also an environmental scientist, and I value an evidence-based approach to problems. Anthropogenic climate change is now unequivocal, after decades of slow and steady data accumulation. In fact not only is it clear that humans have changed the climate, it has become increasingly clear that climate is an amazingly complex machine governed by different control systems operating on wildly different scales of space and time. Before people started examining climate with a careful eye, no one understood (for example) that tectonics + plankton + erosion could function as a planetary thermostat on multi-million year timescales. But they do. Studying climate empirically - as opposed to the arch-conservative approach of ignoring reality in favor of reading the memoirs of pre-soap goat herders - has taught us a great deal.
But apparently one of the things studying the planet has not taught us is humility. In Dr. Caldeira's report to Parliament, a number of alternate ideas were floated for dealing with climate if it starts to get too weird in the next century. Ideas for dealing with potential runaway greenhouse warming might be:
* Inject dust or sulfur into the atmosphere to scatter sunlight.
* Construct a "sun shade" with an artificial ring of small particles or a spacecraft that would block some of the sun's rays.
* Inject iron into oceans to stimulate the growth of plankton, which consume carbon dioxide.
* Bury carbon underground to sequester it for millennia.
To his credit, these are not Dr. Caldeira's ideas. He was just reporting on their existence. But that list reveals something interesting about people's response to the threat of a planetary climate out of control. When faced with a looming Earth-sized problem, people badly want quick dramatic fixes, as if life is a science fiction movie. When in doubt, build a giant machine.
Take dust/sulfur injection. The idea here is to somehow (the method isn't clear) pollute the Earth's lower atmosphere with megatons of dust or sulfate aerosol particles, more or less as a volcano does... or perhaps a Chinese coal-burning power plant. Reflective dust scatters sunlight back to space, and cools the planet's surface. It also returns to Earth as acid rain, in the case of sulfur. It's also difficult to get dust to shroud the entire planet evenly, unless we resort to globally democratic means of dispersal, such as a thermonuclear war. Next idea?
A sun shade. To make that work, you'd need to construct a device in space, and that device would need to be tens of thousands of kilometers across, in a synced orbit between the Earth and the Sun. If built correctly, it would undoubtedly cost several trillion dollars, and would give whoever controls it absolute power over the Earth's fate. If built incorrectly, it would either 1) bankrupt the world, 2) cause the planet to freeze, or 3) both. Next?
Inject iron into the oceans. The idea here is that iron is a limiting planktonic nutrient, which it is, and that seeding the oceans with iron wholesale would result in a bloom of planktonic activity that would send a torrent of organic carbon to the seafloor as generation after generation of plankton use up CO2 to make themselves. One problem with this is cost, as in the cost of sending megatons of iron powder to Davy Jones' locker. Another problem is anoxia. When one over-fertilizes a water body, what typically happens is an algal bloom, followed by oxygen starvation as waves of senescent algae decompose. Without oxygen every fish, crustacean, mammal and sea slug dies. Then they decompose, making matters worse. Result: an oceanic dead zone, a lifeless black void in the water, from which issues a lethal miasma of hydrogen sulfide and other toxic gases. Next?
Carbon sequestration. This is the idea of taking CO2 from the exhaust of a coal-burning power plant and capturing it, then sending it down into the Earth, where it will remain. I actually know geologists who are working on this, mostly through Congressional earmark funding because the idea is too harebrained to pass peer review at NSF. Injecting CO2 into the ground isn't harebrained in itself. Oil companies do it from time to time, as a technique to expand cracks in deep rock and force out more oily dregs. But the scale of trying to sequester all the CO2 from all the coal plants in the country (or the world) is another thing altogether. How much will it cost to pay all those workers to build the CO2 sequestration apparatus, to keep it running, to truck the CO2 from the plants to the injection sites, and to monitor the injection sites for leakage? How much will a kilowatt of electricity cost after all that laborious Rube-Goldberging? If it's more than the cost of a kilowatt of solar or wind electricity, it's not worth the trouble. And in case you think that only nuclear plants can have accidents that kill thousands overnight, imagine what would happen if a wellhead breaks and billions of cubic feet of CO2 escape from an injection well, blasting up and out under geologic pressure to blanket the ground with heavy, suffocating gas. Actually you don't have to imagine. A natural version of exactly that happened one night in 1986, at Lake Nyos
in Cameroon. Seventeen hundred people died in seconds.
Instead of crazy schemes, perhaps we ought to consider that climate is a tricky thing that is very large. Unlike getting to the Moon, manipulating climate is not a simple matter of calculating where to shoot a missile and having it land on target. Climate change is now a fact of life, and the most direct thing we can do to stop it from getting out of hand is to try and produce less CO2. Instead of gigantic Wile E. Coyote schemes, perhaps we should first concentrate on straightforward aims, such as greater energy efficiency, and better ways of getting at renewable energy sources such as wind, solar and biomass. Right now we don't need to waste energy on grandiose scenarios from the mind of a James Bond villain.