What Happened to Global Warming?
An experienced climatologist explains how extreme winter weather may or may not be related to climate change.
Feb. 29, 2008
By Peyton Baldwin
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Extreme winter weather doesn’t signal a reversal in global warming trends.
ISTOCKPHOTO/BILL GROVE
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Brrr, it’s cold outside! Frigid temperatures and record snowfall in many areas may leave some people wondering what happened to global warming. Given the whiter-than-normal winter, is the Earth really still heating up?
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For insight, we turned to Brenda Ekwurzel, a climate science expert with the Union of Concerned Scientists, who has studied climate change for 17 years. Her research has stretched from the arid U.S. Southwest to icebreaker ship expeditions to the North Pole. She stays abreast of the latest science to help inform the public and policymakers.
Q: Could colder temperatures and more snow be signs that global warming is not happening?
A: No singular weather event or even a colder year represents a change in global warming. Weather is the temperature or precipitation over a couple of days. Climate refers to the average temperature or weather patterns over a decade or more. Global warming occurs over a long period of time, therefore gradual shifts to a warmer climate represents global warming. One event, such as increased snowfall or a heat wave, will not significantly change the climate pattern from the last decade. You have to look at what has happened over time, not in the past month or two, to determine if there is general trend of warming.
Q: Could some extreme weather events signify a shift in climate patterns?
A: Yes, actually. Because the Earth is heating up, the air is warmer and more humid and evaporation occurs faster, leading to an intensification of precipitation. This means that during the winter months, in many parts of the United States, we’re more likely to experience intense snowfall and in the summer months intense rainfall. If you look at these events over a long period of time though, the total annual volume of rain may not change as significantly as it may appear. There are just more occurrences of heavy rain events. The increase in intense rain can lead to flooding and longer dry periods in between.
Q: Other than more intense precipitation, what are some indicators that global warming is actually occurring?
A: The timing of spring and fall are indicators that global warming is happening. The spring season is coming earlier and fall is happening later. This makes for a shorter winter season and a longer summer season. Other evidence includes the accelerated melting of glaciers in Greenland and West Antarctica, and the diminishing habitat for some wildlife species, placing them at risk for extinction.
