The Corner

The Hidden Resource of Rooftops

I think the first op-ed I ever thought about writing was on a quirky idea I had in college. It was back when Poppa Bush was talking about planting a hundred kabillion new trees by the end of the decade. This was back when clean air was a bigger deal than global warming, and I thought it would be super smart to take advantage of the fact that rooftops in cities are wasted space. Why not mandate that every roof be planted with air-cleaning plants that would also be a boon to birds and the like? After all if you look at a city from above, a giant amount of the cities topography is just heat trapping blacktop (and as a kid who hung out on NYC rooftops too much as a kid I can attest they are heat trapping). How cool would New York look if all those buildings had little parks on top? I still think there’s merit to the idea, in a day-dreamy kind of way, but engineer types have explained to me that there are all sorts of structural problems — soil holds water, for example. But maybe biotechnology has a solution to this. After all, it seems crazy to me that we can grow mice with human ears on their backs but we can’t make a plant that sucks up CO2 and pollutants.

Anyway, what reminded me of this was Tigerhawk’s post in response to the dirty snow story about the idea of painting all of the rooftops bright white. He writes:

This invites the question, could we easily increase the albedo of surfaces around us to slow down the warming of the climate? The answer, it seems, is yes. By one calculation, if we painted all the world’s rooftops white we would overwhelm all the anthropogenic warming to date:

The Earth has an albedo of 0.29, meaning that it reflects 29 per cent of the sunlight that falls upon it. With an albedo of 0.1, towns absorb more sunlight than the global average. Painting all roofs white could nudge the Earth’s albedo from 0.29 towards 0.30. According to a very simple “zero-dimensional” model of the Earth, this would lead to a drop in global temperature of up to 1 °C, almost exactly cancelling out the global warming that has taken place since the start of the industrial revolution. A zero-dimensional model, however, excludes the atmosphere and, crucially, the role of clouds. [But!] It would be interesting to see if more sophisticated models predict a similar magnitude of cooling.

This seems like precisely the sort of easy, non-”hair shirt” adjustment that we should all take to mitigate the impact of human activity on the climate. Unfortunately, in many American communities (including mine) restrictive covenants or zoning requirements would prevent even the ecologically-minded homeowner from taking this simple step. The obvious libertarian answer is to pass a federal law that declares that any state or local law or restrictive covenant may not be enforced to prevent the owner of property from painting his roof or driveway to reduce its albedo. The obvious Gorean answer is to require that all building owners paint their roofs (and, for that matter, driveways and parking lots) white by 2010, with an extensive government program to specify the type of paint to be used, an inspection regime to be sure that it has happened, and subsidies to be paid for by a new tax on the “rich.”

Either way, we get the albedo down with virtually no impact on our standard of living. That won’t satisfy the environmental activists who have an agenda beyond the mere reduction of global warming, but it should make the rest of us happy.

I kind of dread all the email this will elicit from engineers (the emailingest profession among my readers), but as someone who believes that geoengineering and adaptability rather than Rousseauian back-to-nature romance is the path to solving global warming, I think Tigerhawk has his head in the right place. Hey, maybe we can bioengineer a bunch of bright white plants?

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