Hi Umbra,

Can we make small changes to increase the albedo in the Northern Hemisphere? Choose white or light-colored autos (white is safer, anyway), white or light-colored roofs. Could we float white “islands” (recycled Styrofoam) in our lakes and oceans in locations that would not disrupt transportation? Sometimes white plastic bags get caught in the branches of trees and I’ve been so angry about that litter — maybe I should appreciate them as increasing the albedo?

Thanks for all you do,
Forest Park, Ill.

Dearest Shelley,

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How generous of you to see a silver lining on litter. Alas, it is unmerited — plastic bags in trees have no redemptive qualities, save perhaps inspiring others to be more careful in bag disposal.

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Maybe a hat would help.

Photo: iStockphoto

Your albedo idea, even if you meant it in a jocular fashion, brings us to interesting topics. For those of you who don’t recall, a little refresher: albedo (reflectivity) and absorption are two important factors related to climate change. Our high-albedo (shiny white) icecaps are melting, hence they have less reflective surface area to bounce the sun’s heat away from Earth. The ice melts into the ocean, which is nicely absorptive of CO2 — but has sadly low albedo. We are bummed about losing high-albedo surfaces and absorbing more heat.

So why not add our own human-made albedo, just as you say? This brings us to the interesting topic of geo-engineering: intentionally manipulating Earth environments on a large scale. One branch of geo-engineering is concerned with possible large-scale solutions to climate change, and I hear that until recently this branch was considered quite wacky. Now it’s getting airtime, and you can read about various ideas in places like The New York Times. In the Times article, in fact, they mention one idea to increase Earth’s albedo by floating giant white plastic islands in the oceans. Somebody stole your idea, basically. Or you are a diligent newshound.

Other geo-engineering ideas include releasing huge amounts of sulfur dioxide out of airplanes to simulate volcanic eruptions and block sunlight; sticking a lot of medium-sized mirrors somewhere up there; and floating shiny balloons. These ideas are a testament to human ingenuity, but if implemented might also become a testament to our habit of preferring some new, really expensive, maybe silly, and perhaps dangerous technology (see: cane toads) over simple conservation. That’s not only my analysis — other smarter people, including other geo-engineers, see it that way. The problem with geo-engineering solutions is their side effects and expense, and the small fact that we know what to do about climate change, we’re just not doing it yet.

As to your own ideas, I don’t think small, land-based efforts to be shiny make a difference in the earth’s entire albedo (read an April fool’s article about sheep albedo for a giggle). They do, however, make a difference in our immediate climate, especially in heavily paved and urban areas. Dark surfaces absorb heat, as you know, and then when the air becomes cooler, they release that heat. Summer in New York City is a fabulous example of what is formally called an urban heat island, a nest of dark absorptive surfaces that keep a place hot long after the sun goes down. Replacing typically dark surfaces with light ones is a great way to keep the immediate environment cooler. There are all sorts of benefits, including personal comfort and reduction of ground-level ozone, which is created when some chemicals react with heat.

In the case of light roofs, there can be a significant reduction in air conditioning loads (10 to 60 percent) because the building will stay cooler. Less air conditioning means less electricity means less greenhouse-gas production. I think light cars probably stay a little cooler too, although I’m not sure they stay less cool enough to reduce air conditioning use. But a nice tree-filled, light-colored gravel parking lot would keep parked cars cooler in the summer and could reduce air conditioning loads on car engines as they leave the parking lot, increasing gas mileage.

Your ideas about cars and roofs are good, in other words. Sorry about the bags and Styrofoam, I think they are still just litter.