A couple of weeks ago, Energy Secretary Steven Chu said painting roofs white and brightening tarred surfaces (roads/parking lots) would offset a large part of the warming blamed on human carbon dioxide emmissions.  The reasoning behind this is that brighter surfaces have a higher albedo, which means they reflect more sunlight back into space.  This is good, sound reasoning.

Think about it, on a hot summer day, asphalt is much hotter on your bare feet than a concrete sidewalk.  But here’s the kicker.  Only a relatively small portion of the world is urbanized, in fact most data suggests that portion to be about 1%.  Remember, not all of that urbanized portion needs to be “brightened” since those areas include trees, concrete parking garages, sidewalks, greenspaces, etc.  Then the 1% is dwarfed by the rest of Earth’s land area which is about 30% of the planet. The rest is water and ice.  Speaking of that water, the oceans are dark, and absorb a large amount of heat.  We can’t necessarily brighten those can we?  :D

The albedo part of the discussion is sound.  It is indeed true that more sunlight, ie heat energy, would be reflected into space, however, it would likely be a very small amount.  I’m just not sure if the economic costs would be worth the small amount of heat that would be reflected back into space. 

If I were making the decision to paint my roof white, I probably would not.  But who cares what I think, what do you think?  Would you paint your roof white?

Stew on this one for a few days.  I’m going on vacation so I will leave this one up for a few days.  I’ll see you guys again next week!