News of a study linking death rates caused by the weather to the mean income of a neighborhood was just published here in Arizona:

“[The] link between money and the ability to cope with extreme weather emerged clearly in the research. Among the startling revelations: For every $10,000 an area’s income rises, the average outside temperature drops one-half degree Fahrenheit.

‘It’s an environmental-justice issue,’ said Darren Ruddell, a geographer who led the study. ‘The people who are most vulnerable are also living in the worst conditions. It’s a double whammy.'”

Read the full article here.

The study looked specifically at a heatwave back in 2005 during which something on the order of 31 people died here in Phoenix because of heat related stress.

The major finding is that wealthier neighborhoods are able to afford the sort of landscaping, grass, and shade trees that allow the overnight temperature to lower more quickly than it does in a neighborhood with mostly asphalt, concrete and dirt lots. Add to that the financial resources in the wealthier neighborhoods that allow the residents to use their air conditioners when it’s 100 degrees or higher outside. (Which in Phoenix can be our summertime overnight low temperature.)

Local people have reacted with programs like the water stations that are set up around town during heat advisories. Trinity Cathedral has a group of volunteers called our “Hotshots” that work with the Salvation Army in our neighborhood to staff one such site that serves the urban homeless during high heat days.

The interesting finding in the studies is that xeric landscaping (which is a design which attempts to create a local landscape as much like the original desert environment as possible) may be making things worse. The motivation behind xeric landscapes is water conservation. But by not using water on landscapes, we are losing the evaporative cooling that vegetation enables overnight.

Twenty years ago the area where I now live was pretty much just citrus orchards. I live about 3 miles from downtown Phoenix. I imagine that miles and miles and miles of trees right up against the urban setting of the city had a major effect on the temperatures. It was less the desert landscape that kept things cool and more the trees.

Perhaps it’s time to rethink what we do outside?