The Sceptical Recycler

Geoengineering may be a Hot Topic, but just how new is it ?

California's Cool Cities initiative makes microclimate modification  with paint and shade trees sound like a  cutting edge discovery , but dig around and you'll find the first such municipal ordinance was drafted by Solon The Lawgiver circa 780 BC, , and  that in 1498, Christopher Columbus complained that Jamaica  was getting hotter because trees were being cut down.

I didn't have to dig that far to uncover a certain lack of novelty in Bjorn Lomborg's  last Guardian article, though I'm in no position to complain of his choice of subject -- I've invited Bjorn to dig around in Adamant 's Geoengineering sidebar for some more columns 

   FORBES    08.21.00                      GUARDIAN  11.18.07

PAINT THE TOWN WHITE           PAINT  IT WHITE

     RUSSELL SEITZ                          BJORN LOMBORG           
the greenhouse effect is not driven by fossil fuel burning, but by the power of the sun..The real problem is Earth's low albedo--it reflects only a small fraction of the sun's energy because most of its surface is dark compared to a snowfield or a coat of white paint.

Although it may seem almost comically straightforward, one of the best temperature-reducing approaches is very simple: paint things white.

Such white surfaces reflect three times as much as bare rock or desert soil, and up to ten times as much as deep water or black asphalt paving.

Cities have a lot of black asphalt and dark, heat-absorbing structures. By increasing reflection and shade, a great deal of heat build-up can be avoided.

we could lighten up the hundreds of thousands of square miles of roofs and roadways that already exist, starting with those expanses of asphalt that already contribute to cities being warmer than the countryside.

By increasing reflection and shade, a great deal of heat build-up can be avoided. Paint most of a city and you could lower the temperature by 10C.

this "White House Effect"...can suffice to raise the reflectiveness of most natural surfaces from 25% or less to 75% or more, at a materials cost on the order of around $250,000 per square mile. America's annual per capita share of such a global solution would cost as much as a couple of gallons of gas.... some things are cheaper than energy conservation.

These options are simple, obvious, and cost-effective. Consider Los Angeles. Reroofing... would lower air conditioning costs by about $170m and...lower LA temperatures by about 3C - or about the temperature increase envisioned for the rest of this century...we don't hear much about the smartest choices when it comes to addressing global warming.

Comments

[jens]

Of course the pitifully small ratio of urban/rural land area might create a bit of a headache.

Should we put our Americorp workers or graduate/undergrad students to the task of spraypainting white vast expanses of grassland. The resultant loss of photosynthesis would likely halt the release of millions of tons of CO2 per year which would help to increase the rate of reflection(until decay begins anyway).

Similarly I imagine farmers might be convinced, with large government subsidies of course, to add large amounts of titanium dioxide, calcium carbonate, or other similar compounds to their lands to "lighten" the dark color of plowed fields. The resultant lack of crop growth again would prevent millions of tons of CO2 release, further increasing reflectivity.

There is similarly a correlation between topography and reflection. The more "rough" a surface the more opportunities a bouncing photon has to hit an absorbant surface.

Were the earth as flat as the Gravity Probe B gyroscopes (http://tinyurl.com/2rzlb6
), varying no more than 12 feet from sea level, the reflectivity of the earth would increase significantly. I say we start with the Himalyas and work down to the coasts.

We would see an increase in farmable land, another positive result of this plan.

Perhaps a slick of light oil on the surface of the oceans would help as well. Oil tends to decrease rippling of water and might increase the reflectivity of the ocean slightly. Also, it's iridecent sheen would help in reflecting more light while only killing a large percentage, not all, of the phytoplankton and riparian vegetation which produce so much troubling CO2 anyway. Again an unexpected but welcome positive feedback loop helping to increase reflectivity of the planet.

So, c'mon over to my place. I've got plenty of room for your SUV under my reflective yard shade. Sorry, you'll have to just park on the dirt, the trees and grass won't grow under the darn thing.

I'll buy a barrel of crude (a bargain at $87 today) and we can roast marshmallows over the bubbling vat of flames just to celebrate our wonderful idea. I'll leave all the lights on in the house and yard so we can see through the acrid smoke.

What a great idea! We've just saved the planet from a hot, humid and highly undesirable fate. Best of all, we can sit in the shade while we bask in our own self importance.

Posted to my blog as well (jenshegg.blogspot.com).
RESPONSE

Lighten Up , Jens. Start with a white hat and polishing the rocks in your back yard. No need to paint the lawn- just switch from grass ( R ~ .16) to saltwort ( R~ .30).
And please paint the roof white to make up for your photovoltaics ( R~.02)

[Russell]

Thanks for drawing my attention to the missing link- it is now op on Adamant
http://www.forbes.com/forbes/2000/0821/6605036a.html

You have picked the wrong point of departure - the Earth's area is not at issue, because the CO2 forcing to which warming is attributed is measured as a fraction of the average solar flux of 342watts per square meter.

As the total man made greenhouse forcing is about 2.24 watts M2, it equals the solar energy falling on ~ 3 million Km2. Increasing the reflectivity of 6 million Km2 by 50% may therefore approximately offset radiative forcing and climatic change from geerhouse gases .

If you consider the daily rate of change of greenhouse forcing- about 3 microwatts/M2, you can see that keeping pace with current climate forcing rates involves very small areas on a per capita basis.

10:47 PM