Climate change and extreme weather

Strong storms

Photo credit: NASA

While large swaths of land are drying out, some areas are getting wetter. Rising temperatures mean more evaporation of water into the atmosphere, from oceans, lakes and rivers. That means more clouds holding more moisture—leading to more extreme downpours. With warmer ocean water also comes stronger hurricanes.

Recent extremes: During October 2012, Hurricane Sandy wreaked havoc across the Atlantic seaboard, leading to at least 190 deaths. Massive storm surges flooded New York and New Jersey, causing widespread power outages and damage. As the storm moved west, blizzard conditions led to a foot of snow blanketing six states.

Heat waves

A spell of weather that is hotter than normal recorded conditions is known as a heat wave. Summer heat waves are becoming more frequent, prolonged and intense as the planet’s atmosphere heats up.

Recent extremes: A nationwide June heat wave broke 3,215 high temperature daily records across the U.S. But things didn't cool off quickly: July 2012 was the warmest July on record in the U.S., and the all-time warmest month of any on record going back to 1895 records.

Drought

Shifting weather patterns mean that many areas are experiencing prolonged, severe droughts.

Recent extremes: In July 2012, more than half of the U.S. was experiencing drought conditions. By September, nearly two-thirds of the country was suffering moderate-to-exceptional drought. This is expected to last into 2013.

Blizzards

While it may seem counter-intuitive that increasing global temperatures would also lead to extreme winter weather, Earth's poles still tip away from the sun for part of its annual orbit, bringing winter. As long as temperatures fall below freezing, what would have been a heavy rainfall or bad thunderstorm becomes a blizzard.

Recent extremes: In late January 2011, one of the worst snowstorms on record struck several Northern U.S. cities. It was the "snowiest January on record" for New York City, breaking the 1925 record. In 2009-2010, a series of three winter storms socked the mid-Atlantic—a record breaking 79.9 inches of snow fell in Baltimore within a few weeks.