Paint it White to be Green!

by Christine
(Maine)

If the color white reflects the suns rays, why don't we have white roofs and driveways? Maybe not so much in the northern hemisphere (the black shingles and tar help when it's cold!) but definitely in the warmer areas of the planet. With all the rooftops and paved surfaces helping out, maybe it would be enough to help our icecaps recover.

Barry's Response - An idea worth considering. Of course its effect will be rather small, since the rooftop areas, all combined, make a very small percentage of the total area in the region.

With that noted, there has been research conducted into the possibility of this very idea working to mitigate the effects of global warming. It might help to reduce the effects in concentrated cities, for example. These areas have a good deal of asphalt, which is quite dark in colour, thereby absorbing a majority of incoming solar radiation. The net effect is air temperatures a few degrees warmer than they would be otherwise.

Scientists call this effect albedo, Latin for white. It can be quantified as the ratio of reflected energy to energy coming and may expressed as a percent. On average, the albedo of the earth is about 30%, depending on the cloud cover at any given moment.

For new asphalt it's only 4% (up to 12% for old) but maybe 85% for new snow (lower for dirty snow). Forests range from 5 to 20%, brown soil about 17, grass 25, sand about 40% and deep ocean water, https://www.stuffintheair.com/satellite-images.htmlas seen from satellites, under 10%.

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