[Durham INC] Urban Open Space

[Will Wilson]

All,

The Planning Department is holding an "Urban Open Space" charrette at 
5:30 p.m. on June 8 in the Neighborhood Improvement Services Department 
at 807 E. Main St. On yet another air-quality-alert day two weeks before 
the start of summer, Durham needs an Urban Open Space plan for future 
redevelopment to assure important human health benefits of "natural open 
space" in urban centers.

I think it's an important issue, and below is an Op-Ed I submitted to 
the Herald-Sun (but they didn't run it).

Thanks,
Will Wilson
-----------------------------------------------------

Cities are one big paved surface, and though a shade tree  might make  a 
sidewalk cafe more appealing, other businesses might claim trees take up 
valuable and comfortable air-conditioned building space. Put this way, 
urban trees sacrifice our downtown economic engine for the sake of 
"prettiness".

But human health, not prettying-up Durham, is the reason for urban open 
space.  As the Open Space committee of Durham's Open Space and Trails 
Commission has argued for years, it reduces urban heating effects, 
improves air quality, reduces health problems, and absorbs runoff from 
streets, roofs, and parking lots.

I show data on Durham's urban environment in my book, "Constructed 
Climates," freely available at constructedclimates.org. The problems are 
really easy to understand: We cut down trees and pave surfaces. Trees 
act like sweat glands, evaporating water that takes up the Sun's heat, 
but paved surfaces instead soak up that heat and slowly release it. 
Working with satellite data of Durham County, Joe Sexton, a former Duke 
graduate student, showed that tree coverage crucially determines 
Durham's temperatures. The result, called an urban heat island, is a 10 
to 15F summertime temperature difference between paved downtown Durham 
and surrounding treed areas.

Ok, it's hotter downtown -- so what? These higher downtown temperatures, 
combined with the emissions from cars, speed up chemical reactions in 
the air and make polluted air even worse. Bad urban air causes more 
cases of asthma and heart attacks in cities where the studies have been 
done, and Durham's no different.

High temperatures mean more cooling costs and more greenhouse gas 
emissions --- southern California data shows a 10F increase causes a 25% 
increase in peak electricity demand. One source estimates that the added 
cooling to counteract urban heat uses 10% of urban energy: Every 
downtown resident and small business owner can thank too-few-trees for 
one-tenth of their summer electricity bill.

A map of Durham County lightning strikes also reflects downtown Durham's 
heat island --- on some days the hot, humid air causes thunderstorms, 
rain, and lightning strikes just downwind. Warm rain on hot pavement 
also heats stormwater, killing downstream critters, and harms our streams.

Finally, guess who suffers most of the problems from Durham's urban heat 
island? The satellite data, combined with income maps, show that 
families making $80,000/year live where trees cover 70% of the 
neighborhoods, but families making $20,000/year live where trees cover 
just 20%. That difference means low income families experience hotter 
days, worse air, and more health problems while being less likely to 
live in air conditioned spaces.

The public charrette follows up a few meetings of an Urban Open Space 
advisory committee, on which I and other Open Space comittee members 
served, but no time was allotted for the role of urban open space on the 
heat island, air and water quality, human health, or energy demands. The 
discussion really didn't move beyond using some derelict lots for small 
parks in downtown Durham.

I urge everyone to attend the charrette. Ask about the heat island. Ask 
about air quality. Ask about stormwater. Ask about health issues. Ask 
about energy use. Ask about socioeconomic inequities. Then ask how the 
urban open space planning process addresses these concerns.



-- 
http://www.biology.duke.edu/wilson/
New Book: http://www.constructedclimates.org/