Living in New York, I sometimes notice that I'm walking on what appears to be a leopard-spotted sidewalk, littered with months' -- years'? -- worth of discarded chewing gum and other tasty treats, melted and turned black by the sun to become near-permanent fixtures, not to mention landmines in hot months.
Should we have maybe taken a hint from this earlier? Greengeek.ca writes that U. of Manchester wiseguys stared at data long enough to tell us this: a small increase in green spaces in cities could go a long way toward making said cities suck less in the summer.
More scientifically, "a mere 10% increase in the amount of green space in cities would reduce average urban surface temperatures by as much as 4°C," or 7° or 8° Fahrenheit.
It's kind of like those fancy jackets with the airholes in the armpits: Green spaces collect water and release it, like so many magicians' doves, back into the air via the, er, magic of evaporation. Then lovely assistants come out and spread the cool air around the audience -- OK, it's not like a jacket, it's like a magic show!