National Geographic : 2009 Dec
do when we need to get rid of the reﬂectors because of an impending ice age? BILL MOULTON Port St. Lucie, Florida Bad idea. We can’t even begin to clean up the space junk already around Earth. Of course, parking billions of reﬂectors somewhere like the inner Lagrangian point may sound slyly techy, but it could also interfere with the way we measure and learn about solar emissions, particularly storms that could kill our astronauts, damage our communications satellites and GPS, and fry our electrical grid. Intelligent use of what we already have on Earth is the wise way forward. A. CANNARA Menlo Park, California If a cloud of reﬂectors is implemented to reduce the use of fossil fuels, what will we use to heat our homes on this cooler Earth? The cloud will reduce the effectiveness of solar energy, making it even more expensive. Cooler temperatures and less light will also reduce vegetation, reducing the biomass available for biofuels, not to mention food for the world’s population. What’s the big idea? TIM AND JUDY NELSON Jamestown, Tennessee I was surprised that your article did not even mention ocean acidiﬁcation, the evil twin of climate change. While it is true that there may be schemes to temporarily mask increasing temperatures, they will do nothing to combat the problem of increasingly acidic oceans. About a third of our carbon dioxide emissions is absorbed by the oceans, making them more acidic. As ocean acidity increases, many species are threatened, especially those that build shells and skeletons out of calcium carbonate, such as corals, oysters, and mollusks. In fact, some scientists predict that coral reefs could be extinct by the end of the century if we do not reduce our carbon dioxide emissions. So, while geoengineering ﬁxes like the one in your article might seem like an easy solution to this problem, the only true solution is to mitigate our carbon dioxide emissions. ELLYCIA HARROULD KOLIEB Washington, D.C. ©2009 Discover Bank, Member FDIC 1-800-DISCOVER Discover.com Discover® gives you a Cashback Bonus® on every single purchase. What you do with it is up to you. What will you get back with your cash back?