While some say it’s our obligation to utilize the science at our disposal, others believe the idea of altering our environment this way is wrong, even immoral, because of the possibility of unforeseen consequences.

It was this sort of debate that recently pushed the subject onto the agenda of the Convention on Biological Diversity (CBD) in Nagoya, Japan.  The issue has gained enough attention that many scientists now take the idea of geoengineering seriously.  Over the past few years, research in the field has exploded, and what was once a theory has become a real possibility.

Three popular geoengineering ideas have emerged.  The first proposes capturing carbon dioxide with plants, chemicals or machines.  Another idea would find ways to keep glaciers at the ice caps and prevent their slide into the ocean.  The third idea involves throwing particles into the air to reflect more sunlight back into space.

The first geoengineering idea – capturing carbon dioxide from the atmosphere and holding it where it doesn’t harm the environment – is no new concept.  Nature does this already.  Putting carbon dioxide in a storage locker is just a matter of encouraging more forest and plankton growth to pull more gas from the air.  Another variation proposes “air scrubbers” that would suck air through machines to remove the carbon dioxide and lock it in underground saline aquifers or vacated oil reserves.  Still another option involves dumping quicklime into the ocean to chemically change the dissolved carbon dioxide into ions of carbonate and bicarbonate – essentially, destroying carbon dioxide (and making the ocean more acidic) to make space for more carbon dioxide.

Each of these options presents problems – the time it takes forests to grow, the feasibility of building large air scrubbers, and the aforementioned moral issues surrounding chemically altering our environment in a major way.

The second geoengineering idea, which proposes halting glaciers, also poses a large problem.  While preventing the slide of glaciers into the oceans could avoid global sea-level rise, it does not address the issue of global warming, and looks suspiciously like plugging one hole just to have another spurt open elsewhere.

Odd as it sounds, the geoengineering solution to global warming with the most traction is to simulate a volcanic eruption.  Volcanoes throw sulfur dioxide into the stratosphere where it creates small particles of sulfate that reflect sunlight back into space.  One challenge with this proposal is that geoengineers would need to find a way to keep the sulfate up for a long time.  Also, adding sulfur dioxide to an already hazy atmosphere could create larger particles, rather than the small ones required for cooling.

The best option, according to some reports, would be to use sulfuric acid, which unlike sulfur dioxide will produce a haze of small particles.  Scientists say creating a screen of this type would require the development of a vehicle capable of dispersing ten tons of sulfuric acid 12-15 miles up.  One model for such a vehicle is the White Knight craft developed to launch Virgin Galactic’s tourist spaceships.  The proposed fleet would consist of 80 crafts delivering a million tons of sulfur each year, operating for 20 years with a cost of one to two billion dollars for the whole project.  No simple task.

Other concepts have involved blimps, guns, rockets, and a long pipe to pump sulfurous chemicals held aloft by a large balloon, though none of these have been entertained as seriously as the jet option.  All of them, though, have one criticism in common – the potential for ozone loss.  It is likely that adding sulfate to the stratosphere would erode ozone because ozone depletion occurs faster on surfaces – surfaces the sulfur would provide.  An example occurred in 1991 when Mount Pinatubo erupted – it cooled our climate but also caused a significant loss in ozone.  Still, some say the gains in climate cooling would outweigh the losses in ozone.

A host of questions about this option – health risks, the effect on clouds, on solar energy, on ecosystems, even the appearance of the sky – remain unanswered due to the difficulty of testing a global scenario.  Geoengineering has been modeled, but the full effects haven’t been assessed.  The risks extend beyond climate concerns.  Scientists have a moral obligation to consider the stability of the climate and other planetary cycles (water, nitrogen) and take into account possible effects on biodiversity, the health of plants and animals, cleanliness of air and water, food systems – to make a short list.  Geoengineering addresses global warming, but will it help solve the serious issues linked to climate change?

Let’s ask the obvious question waiting at the bottom of all this: does adding particles to our atmosphere to cool our planet solve the real problem, or does it just ignore the real problem?

Many scientists still point out that adding more and more sulfate to counterbalance more and more carbon dioxide does not remedy the fact that carbon dioxide is changing our world.  Studies show that, in this sulfate scenario, global warming would lessen but the climate would still change.  The sulfur’s cooling effects would be felt in the tropics but the poles would remain warmer, and the trouble of climate change would persist.  Hazing the atmosphere might blunt global warming’s effects, but it is not an alternative to the reduction of greenhouse gases.  As one scientist points out, it can be considered a tool to buy time so we can reduce emissions and solve the problem at its root.

This is the third camp, who say geoengineering is neither “good” nor “bad,” but simply a stalling mechanism while we solve the problem at its root.  From their viewpoint, geoengineering cannot be seen as a fix – we’re playing catch-up after greenhouse gases have already been emitted, and we should be stopping those emissions in the first place.  At this point, though, they say we may have no other choice, and geoengineering will soon become a necessity.

Brian Kahn 11am March 02 You’ve laid out the main options of geoengineering beautifully. I subscribe to the belief that in case of geoengineering, today’s soluti... View Full Comment Close Full Comment

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