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Furnace Cities

COPENHAGEN -- It’s possible to see, right now, what global warming will eventually do to the planet. To peek into the future, all we have to do is go to Beijing, Athens, Tokyo, or, in fact, just about any city on Earth.

Most of the world’s urban areas have already experienced far more dramatic temperature hikes over the past few decades than the 2.6°C increase expected from global warming over the next hundred years.

It’s simple enough to understand. On a hot day in New York, locals sprawl out on the grass fields of Central Park, not on asphalt parking lots or concrete sidewalks. Bricks, concrete, and asphalt – the building blocks from which cities are made – absorb much more heat from the sun than vegetation does in the countryside.

Across an entire city, there’s much more tarmac than there is grass. So the air above the city heats up. This effect, called an “urban heat island,” was discovered in London in the early 1800’s.