I'll add my $0.02, not scientific, but my own observation.
I moved to Phoenix in the mid-70's and the population then was about 600,000. It's now at roughly 1.5 million. The house I purchased then was surrounded by citrus fields and the night time temperatures would drop over night dramatically from the day time highs. There were regular summer time storms (monsoons) that would produce rain from July through September.
2014 - Nearly every square inch of the valley is now paved. The population has nearly tripled, and the citrus groves are long gone. The valley has become a heat island because of all of the concrete. Night time lows in the summer rarely drop below the high 90's. And because of the heat island effect, the rains that usually come in the summer are pushed further and further away from the city.
Man made? Absolutely. But to say paving doesn't effect an area is not accurate, at least out here.
I moved to Phoenix in the mid-70's and the population then was about 600,000. It's now at roughly 1.5 million. The house I purchased then was surrounded by citrus fields and the night time temperatures would drop over night dramatically from the day time highs. There were regular summer time storms (monsoons) that would produce rain from July through September.
2014 - Nearly every square inch of the valley is now paved. The population has nearly tripled, and the citrus groves are long gone. The valley has become a heat island because of all of the concrete. Night time lows in the summer rarely drop below the high 90's. And because of the heat island effect, the rains that usually come in the summer are pushed further and further away from the city.
Man made? Absolutely. But to say paving doesn't effect an area is not accurate, at least out here.