SOLAR TODAY - June 2009

Any method
that reduces
sunlight does
nothing to re-
duce the build-
up of carbon
dioxide in the
atmosphere
and the oceans.

in the atmosphere will go unchecked. And the planet will quickly cook.

This leads us to another geoengineering proposal aimed at addressing the carbon dioxide problem more directly. The idea is to use more than a dozen supertankers at a total cost of $25 billion to spread iron in the oceans for the purpose of fertilizing plankton. The hope is that the plankton would remove CO via photosynthesis and eventually sink

2

to the bottom, where the carbon would be theoretically sequestered. But it's a long way to the bottom of the ocean, and there are plenty of bacteria and animals that can eat that plankton on its way down, so it's not clear how much of that carbon actually would get sequestered. As with any geoengineering proposal, there is a large potential for unintended consequences.

Clearly it is much safer to solve the carbon dioxide problem by not emitting it in the first place, that is, by reducing energy use and switching to carbon-free energy sources. Geoengineering solutions not only have known disadvantages and unknown consequences, but even putting them out there as options can have the effect of undermining the commitment to change our energy system. The conundrum

is that by studying geoengineering, we could make it more likely that we will actually need it.

So why are highly respected scientists like Tom Wigley at the National Center for Atmospheric Research and David Keith at the University of Calgary advocating research on geoengineering? For one thing, they are understandably unimpressed by the progress we humans have made to date in addressing climate change. Combining geoengineering with whatever carbon emissions reductions we can achieve could buy us time and might result in less total damage to the environment than would an approach that relies on emissions reductions alone. Also, what if China or India decides to pursue geoengineering? Shouldn't we understand it as best we can, so we will be prepared to develop informed international treaties?

While the prospect of geoengineering might provide some people with an excuse to continue business-as-usual, perhaps the thought of another uncontrolled, planetary-scale experiment will motivate the rest of us to finally get serious about deploying renewable energy. Because regardless of the rationales some scientists may come up with, Plan B just doesn't look so hot. ST