Air chemistry and climate (NCAR Research) How do we know Earth is warming now?
But a few researchers believed that pollution from burgeoning postwar industry was shielding sunlight and shading the planet, causing the observed cooldown. Some even theorized that a “snow blitz” could accelerate the cooling and bring on the next ice age. Their statements got major play in the media. Starting in the 1970s, new clean-air laws began to reduce sulfates and other sunlight-blocking pollutants from U.S. and European sources, while greenhouse gases continued to accumulate unchecked. Global temperatures began to warm sharply in the 1980s and have continued rising since then. Increasingly detailed models suggest that the more recent warmup can be attributed to greenhouse gases overpowering the effect of sunlight-shielding pollution. Computer simulations also suggest that today’s atmosphere would be even warmer still, were it not for that air pollution.
