Higher sea levels
The polar regions are particularly vulnerable to a warming atmosphere. Average temperatures in the Arctic are rising twice as fast as they are elsewhere on earth, and the world's ice sheets are melting fast. This not only has grave consequences for the region's people, wildlife, and plants; its most serious impact may be on rising sea levels. By 2100, it's estimated our oceans will be one to four feet higher, threatening coastal systems and low-lying areas, including entire island nations and the world's largest cities, including New York, Los Angeles, and Miami as well as Mumbai, Sydney, and Rio de Janeiro.
There's no question: Climate change promises a frightening future, and it's too late to turn back the clock. We've already taken care of that by pumping a century's worth of pollution into the air nearly unchecked. "Even if we stopped all carbon dioxide emissions tomorrow, we'd still see some effects," Haq says. That, of course, is the bad news. But there's also good news. By aggressively reducing our global emissions now, "we can avoid a lot of the severe consequences that climate change would otherwise bring," says Haq.