Pijanowski is a researcher at Purdue University in Indiana, US. He used digitalised aerial images of the county taken in 2005 to measure the number of parking spaces it is home to. The result? Eleven times more than there are families, 3 times more than there are people.
There are quite a few environmental implications to this. Concrete increases the urban heat island effect because water from the ground cannot evaporate to cool the atmosphere. Plus the spaces accumulate pollutants, including oil and heavy metals leaked out by the cars that park on them.
Then there's the fact that rain runs off the concrete rather than sinking into the earth, and this can makes floods worse, and increase the erosion of land around paved areas.
"I can't help but wonder: do we need this much parking space?" says Pijanowski. A good question, to be sure. But I can't see supermarkets digging up their parking lots out of environmental concerns.
So what about rehabilitating the concrete space? A few ideas spring to mind:
- Google has installed massive solar panels over the top of its employee parking area.
- A study last year showed that more parks and green roofs in cities could counter the heat island effect. What about putting green roofs (roofs with vegetation planted on top) on stilts over the parking lots?
- In the UK, hedgerows are often touted as key ways of integrating biodiversity conservation and agricultural development. How about more hedges in parking lots to give birds a place to mate and feed?