NEW YORK - As air-conditioners sprout from windows and storefronts around the world, scientists are becoming increasingly alarmed about the impact of the gases on which they run. All are potent agents of global warming, scientists say.
Air-conditioning sales are growing 20 percent a year in China and India, as the middle classes grow, units become more affordable. Many fast-growing cities of Asia are scorching and humid -- the potential cooling demands of upwardly mobile Mumbai, India, alone has been estimated to be a quarter of those of the entire United States.
Air-conditioning gases are regulated primarily though a 1987 international treaty called the Montreal Protocol, created to protect the ozone layer. It has reduced damage to that vital shield, which blocks cancer-causing ultraviolet rays, by mandating the use of progressively more benign gases.
The oldest CFC coolants, which are highly damaging to the ozone layer, have been largely eliminated; the newest ones have little or no effect on it.
But these gases have an effect the ozone treaty largely ignores. Pound for pound, they contribute to global warming thousands of times more than does carbon dioxide, or CO2, the standard greenhouse gas.
Indeed, the leading scientists in the field have just calculated that if all the equipment entering the world market uses the newest gases currently employed in air-conditioners, up to 27 percent of all global warming will be attributable to those gases by 2050.
NEW YORK TIMES