The approximate stand-still of global temperature during 1940-1975 is generally attributed to an approximate balance of aerosol cooling and greenhouse gas warming during a period of rapid growth of fossil fuel use with little control on particulate air pollution, but quantitative interpretation has been impossible because of the absence of adequate aerosol measurements.

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But especially with hybrids such as the C-Max, he says, variables such as temperature, a driver's behavior and the engineering choices Ford makes to balance mileage and performance can make a big difference.

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Altering the balance of energy has created what Bornstein calls "urban heat islands" where the temperature is 5 to 10 degrees hotter than outlying areas and generate their own rain.

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