A program promoted by energy secretary Steven Chu to paint roof tops white was supposed to help cool the planet by reflecting sunlight.  However a study published in the Journal of Climate found an overall warming effect: “A worldwide conversion to white roofs, accounting for their albedo effect only, was calculated to cool population-weighted temperatures by ~0.02 K but to warm the Earth overall by ~0.07 K.”

That happens because the white roofs, while perhaps lowering local temperature, cause less cloud-producing water vapor to be put into the atmosphere.  Clouds reflect sunlight over a larger area.  According to the study, the net effect is warming rather than cooling.

The paper is:

Mark Z. Jacobson and John E. Ten Hoeve. Effects of Urban Surfaces and White Roofs on Global and Regional Climate. Journal of Climate. 2011. DOI: 10.1175/JCLI-D-11-00032.1

Abstract here.

“The best laid schemes of mice and men

Go oft askew,

And leaves us nothing but grief and pain,

For promised joy!”

- Robert Burns

This entry was posted on Wednesday, October 26th, 2011 at 9:18 am and is filed under Climate change. Tags for this post: global warming, white roofs. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.