With so much snow in North America and Europe in the Winter of 2009 and 2010, How can Global Warming be real?

By Dave Pittman

To understand global warming it is important to make the distinction between weather and climate.  We identify events like rain, snow, tornadoes, and hurricanes as weather in the short term while patterns of weather events and average temperature over the long term as climate.   Global warming does not eliminate the probability of heavy snowfall and under the right circumstances may actually increase it in some areas of the world.  It’s not about weather events;  it is about long term climate change.  The difference between heavy rain and heavy snow is only a few degrees, which any particular weather pattern will influence.

The heavy snow events on the East coast and in Europe this year came because colder temperatures combined with moist air from the ocean.  The cold air came from the Arctic, which at the same time was experiencing dramatically warmer temperatures.  [This is called the Arctic Oscillation and may or may not have anything to do with global warming.]  Record warm temperatures in January and February 2010 led to in increase in water evaporation from the oceans providing the moist air needed for the heavy snowfall.

Scientists and climatologists have shown that over the past 100 years, there has been a 5% increase in water vapor caused by warmer temperatures.  Most of that increase has been since 1970.  January 2010 was the hottest January in the University of Alabama at Huntsville satellite record and February was the second hottest February ever in their satellite data records.  The warming temperatures result in extra water vapor that increases the chances of more extreme precipitation events – like heavy snows.  However, the heavy snows and rains of the past winter in Europe and Eastern North America do not directly prove or disprove anything about long term climate change.  The evidence of climate change and global warming are in long term patterns of weather events, so scientists must use more than single events like heavy snows or even Hurricane Katrina to support their conclusions.

Scientists hypothesize that climate change impacts will not only include an increase in droughts in some areas but an increase in rainfall in others.  Take a look at a global view of recorded precipitation for the past 100 years. NASA (National Aeronautics and Space Administration) has extensive records in its updated global climate change website, and you can take a look at page 114 -115 of the book An Inconvenient Truth by Al Gore for the same information displayed in a different visual format. Note the huge recorded drought areas across most of Africa, the Middle East, Southern China, Southeast Asia and Chile. Check out the big wet area covering much of North America with the exception of the far Western US. These patterns, in general, will probably continue. Welcome to the 21^st century.

The first decade of the 21^st century had twice as many record setting high temperatures than record low temperatures but that does not mean record low temperatures now no longer exist. The world’s climate is changing, most glaciers are melting, the summer Arctic ice is rapidly melting, and the Greenland glaciers are indeed accelerating their rates of melting. However winter will not vanish, and all snowfalls will not turn into rain. The realities of weather are complicated and certainly will present many more surprises in our lifetimes and our children’s lifetimes. It is very likely that weather patterns will demonstrate increasingly dramatic cycles with an average increase in annual precipitation across much of North America.

For more information, I suggest the Australian website by John Cook, SkepticalScience – Getting Skeptical About Global Warming Skepticism.

[Editor’s Note:  You may also want to check out our Science page on this web site to learn more about the science behind global warming.]