Earth Getting Dimmer; Air Pollution Is Prime Suspect

No, you’re not just depressed: The earth actually is getting darker. The amount of sunlight reaching the planet’s surface, researchers say, declined by as much as 10 percent between the late 1950s and early 1990s. In some regions the drop was steeper, including the U.S., Asia, and Europe. Hong Kong is 37 percent darker than it was mid-20th century. The phenomenon has been independently noted at several spots around the globe, but only now are scientists overcoming their initial skepticism and gathering to discuss the implications. U.S. and Canadian geologists will convene for a conference on “global dimming” next week. While most researchers blame the obvious culprit, air pollution — sunlight bounces off smog particles, and those particles also cause thicker, more opaque clouds — dimming has also been observed in places where the air is relatively clean, such as Antarctica. We shudder to think what a worldwide outbreak of Seasonal Affective Disorder might look like.