Eco-News: Cool Roofs and Shiny Plants

Well we are finally back in business! It seemed to take months to fix the virus that had infiltrated our website. In the meantime, Ros had a barrage of email questions about a wide variety of topics. Here’s a recent one about the reflective properties of white and its impact on the earth.

-Jean Ann

Hi Rosalind,

For awhile now I’ve been fascinated with the notion of “cool roofs”. I’ve read (though this has been disputed) that much like glaciers it could reflect sunlight back into space and lowering the impact of sunrays. I also read this crazy article about Peruvians painting rocks. Now maybe my idea has already been tested and shot down. I have no idea. I’m a huge fan of yours so I thought I would start my research with you.

My idea is this, given that the US has vast acres of pastures for cattle and corn, is there a white plant that could take their place? Maybe food for live stock? What are the white plants and grains available to us? I know people may not be interested converting their lawns but I do wonder if some would. There are also acres of landfill that could grow something white. Again maybe this is all crazy but I have to look into it.

Any information would be greatly appreciated, again I’m a huge fan of all of your wonderful work!

Thanks,
J.

Ros responds:

Hi J.,

It great to think outside of the box but I think there is a problem with your premise. Plants need chlorophyll in their leaves to convert sunlight into to energy and thus live, and of course, chlorophyll is green. “White” plants are few and far between, mostly limited to desert areas. They are white because white absorbs less heat as you stated. If memory serves me, I believe these plants are also not efficient at converting sunlight to energy. Inefficient conversion is not a problem in desert areas because of the intense and constant sunlight. I can think of no white food or grain plants and I’m guessing that white versions wouldn’t be productive in areas with frequent clouds or cooler weather. However, some folks interested in this subject have suggested we breed more reflective shiny-leaved plants. What do you think of that idea?

Thanks for making me think and why don’t you ask a few other folks and see what they say. Let me know if you make much progress in your research, it’s certainly an interesting premise.

Best, Ros Creasy

Picture via http://www.energysavers.gov