Global Warming Effect 8: Heat Waves

The deadly heat wave that swept across Europe in 2003, killing an estimated 35,000 people, could be the harbinger of an intense heat trend that scientists began tracking in the early 1900s [source: MSNBC].

This man tried to cool himself with a water bottle during a 2008 heat wave in New York City.
Spencer Platt/Getty Images
Heat waves not only make it seem difficult to function, they can be deadly as well. This man tried to cool himself with a water bottle during a 2008 heat wave in New York City.


­Extreme heat waves are happening two to four times more often now, steadily rising over the last 50 to 100 years, and are projected to be 100 times more likely over the next 40 years [source: Global Development and Environment Institute, Tufts University]. Experts suggest continued heat waves may mean future increases in wildfires, heat-related illness and a general rise in the planet's mean temperature.

El Niño
El Niño, and its opposite, La Niña, are naturally occurring fluctuations in ocean-atmosphere conditions in the tropical Pacific Ocean that, in turn, create fluctuations in weather around the world -- usually wetter weather. During El Niño, the normal trade winds that blow westerly across the tropical Pacific instead settle in the central Pacific. This leads to a rise in water temperatures and rainier weather. La Niña, on the other hand, is connected to cooler-than-normal water temperatures.