Galleries / 5 Most Radical Ways to Squelch a Climate Crisis

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Lizzie Buchen; published February 25, 2008

Global Boiling

Send CO<sub>2</sub> to Sleep With the Fishes

Build CO<sub>2</sub>-Guzzling Supertrees

Deploy a Planetary Parasol

Increase the SPF of Earth's Natural Sunblock

Welcome to Planet Seattle

<p><i>How it works: </i>Oceans already play a key role in climate moderation, naturally taking up about 3 billion tons of CO<sub>2</sub> per year. One possible way to increase that amount is to boost the growth of photosynthetic plankton, which absorb carbon from the air. When they die, they sink to the ocean floor and are buried for up to thousands of years. The limiting factor is that about a third of the ocean's surface is short on iron, which limits phytoplankton's growth. Dumping tons of soluble iron sulfate into the sea could stimulate massive plankton blooms (a natural bloom is pictured here) and whisk our CO<sub>2</sub> cares away.</p><p><i>Pros:</i> Iron's cheap, and we know that it can cause spikes in phytoplankton populations. Iron seeding is also associated with the best biogeochemical quote ever: "Give me half a tanker of iron, and I will give you an ice age," a boast from iron-seeding supporter John Martin (in what he calls his "best Dr. Strangelove accent"). </p><p><i>Cons:</i> Dumping large amounts of acidic compounds into an <a href="http://www.nature.com/nature/journal/v437/n7059/abs/nature04095.html" target="_blank">ocean</a> that's already suffering from <a href="http://en.wikipedia.org/wiki/Ocean_acidification" target="_blank">acidification</a>, causing a population explosion for a single type of marine organism? Not surprisingly, environmental groups like Greenpeace <a href="http://www.greenpeace.to/publications/iron_fertilisation_critique.pdf" target="_blank">aren't in favor (pdf)</a> of this option. The effects of polluting the oceans with soluble iron are unknown, and phytoplankton blooms are likely to consume lots of other nutrients as well, possibly putting their fellow ocean residents in danger. And it might not even work--many climatologists are <a href="http://news.nationalgeographic.com/news/2002/01/0108_020108oceaniron.html" target="_blank">skeptical of the impact</a> extra phytoplankton would actually have on the concentration of greenhouse gases.</p>

<p><i>How it works:</i> Sure, real trees are pretty. But when it comes to sucking CO<sub>2</sub>, we could do so much better. In a system designed by Klaus Lackner, a physicist at the Earth Institute at Columbia University, giant treelike filters would bind airborne CO<sub>2</sub> molecules with a chemical like sodium hydroxide or calcium hydroxide. The solution would then pass through a filter, where CO<sub>2</sub> would be removed and disposed of or recycled in some way, perhaps even as synthetic gasoline or diesel fuel.</p><p><i>Pros:</i> Lackner has calculated that one of his synthetic trees, measuring 200 feet high and 165 feet wide, could remove about 90,000 tons of carbon dioxide in a year--a thousandfold improvement on the natural behavior of a real, living tree. Take that, nature.</p><p><i>Cons:</i> The technology isn't completely worked out--it may not be easy to separate CO2 from the binding chemicals, and the process may even require energy from fossil fuels. Even with the acceleration of global warming, CO2 is pretty dilute in the air, so the scale of the project would have to be large (though a couple of orders of magnitude smaller than what would be required to completely replace fossil fuels with wind or solar energy). In order to capture enough CO2 to offset human production, you'd need to blanket these "wind scrubbers" over an area at least the size of Italy. Mama mia!</p>

<p><i>How it works: </i>This idea dates back to the 1980s, when scientists pondered how to make Venus (pictured) <a href="http://en.wikipedia.org/wiki/Terraforming_of_Venus" target="_blank">habitable for humans</a>. Now the plan for creating the luxury real estate of the future may be necessary just to keep ourselves alive on Earth. To deflect the sun's rays, shields would be deployed to a point referred to as L1, where an object can remain balanced between the gravity of Earth and that of the Sun (about 1.5 million kilometers from Earth). In order to deflect enough sunlight, the shields would need to cover just under two million square miles, an area about the size of Greenland. Two options are being considered: single giant shield, 1,100 miles in diameter and 10 microns thick (about 1/30 the thickness of a sheet of paper), or a fleet of 16 trillion lenses or mirrors, each weighing about a gram and covering about three square feet. Estimated cost: $1 trillion to $10 trillion.</p><p> </p><p><i>Pros:</i> The easiest plan to understand and visualize, it <a href="http://i.treehugger.com/files/solar-shield-01.jpg" target="_blank">looks awesome</a> in speculative diagrams.</p><p><i>Cons:</i> Exorbitantly expensive, complicated, and impractical in every way. Sending a nearly million-square-mile structure--weighing about 100 megatons on Earth--out to L1 is not a small feat. The alternative of 16 trillion small lenses is no more feasible; in order to mitigate the effects of excess atmospheric CO2, 20 launchers would each need to propel 800,000 lenses every five minutes for 10 years.</p>

<p><i>How it works:</i> Atmospheric scientists have long known that volcanic eruptions cool the local climate by releasing billions of tiny sunlight-reflecting particles. We can recreate these volcanoes (without the <a href="http://en.wikipedia.org/wiki/Pompeii" target="_blank">catastrophic consequences</a>) by injecting sulfur particles--which happen to be the perfect size--into the atmosphere. There, they float around for a couple of years before being used up in chemical reactions and slowly returning to the surface of the earth. The quickest way to get the particles up there is releasing them out the back of a plane; a properly equipped 747 could do this today. Other options include carrying sulfur into the atmosphere via balloons and using artillery to blow them up (think giant carnival game), and shooting sulfur into the sky via a long hose--a smokestack to the stratosphere. </p><p><i>Pros:</i> Fast acting, long lasting, and proven to work--all the components of a good emergency-response system. The cooling effect could be apparent in a few months, would last for up to two years, and would probably cost "only" in the low billions of dollars. What's more, it's technologically simple, making it the most practical scheme. Most <a href="http://globalecology.stanford.edu/DGE/CIWDGE/home/main%20page/caldeira.php" target="_blank">supporters</a> propose injecting sulfur only above the Artic, at least at first. This would prevent the catastrophic loss of ice in the Arctic and Greenland and minimize the impact of unintended environmental or health consequences. If it works, the program could expand to encompass the rest of the planet.</p><p><i>Cons:</i> Sulfur reacts with chlorine from those <a href="http://discovermagazine.com/1995/mar/unintendedconseq487/" target="_blank">pesky CFCs</a>, so it may be bad for the ozone layer--although Paul Crutzen, who won a Nobel Prize for his research on ozone depletion, <a href="http://www.springerlink.com/content/t1vn75m458373h63/fulltext.pdf" target="_blank">doesn't think it will be an issue</a>. The reduced sunlight might also disrupt plants, particularly tropical plants that have adapted to high levels of sunlight, throwing the biosphere out of whack. The sulfur particles may also have an effect on cloud formation, leading to unexpected droughts. But hey, there's no such thing as a free lunch.</p>

<p><i>How it works:</i> Marine stratocumulus clouds blanket about a third of the world's oceans, mostly around the tropics, reflecting sunlight and shading the seas. To give clouds a boost in reflectivity, University of Edinburgh engineer Stephen Salter and John Latham, an atmospheric physicist based at the National Center for Atmospheric Research in Colorado, have designed a fleet of vessels that would continuously spray a fine mist of saltwater into the air. As the ships moved through the ocean, <a href="http://en.wikipedia.org/wiki/Flettner_ship">Flettner rotors</a> would draw seawater into the spraying system and geyser the droplets at high speed from the tops of the rotors. The water droplets would evaporate as they rose to the clouds; water vapor in the clouds would then condense on the remaining salt, making the clouds thicker and more reflective. Latham and the appropriately named Salter estimate that about 1,000 ships would be required to make the plan effective.</p><p><i>Pros:</i> Effects are short-lived, so if there's some deleterious effect, the process could be stopped immediately. It's a relatively cheap system to maintain (no one's put a price on seawater yet), and the ships would be wind-powered, radio-controlled, and unmanned.</p><p><i>Cons:</i> Effects are short-lived, so you'd have to spray continuously. Another fear is that salt particles could, ironically, impede the formation of rain clouds, causing droughts.</p>

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