Heavy snow events--a contradiction to global warming theory?
As I discussed in my previous post, record-breaking snowstorms are not an indication that global warming is not occurring. In fact, we can expect there may be more heavy snowstorms in regions where it is cold enough to snow, due to the extra moisture global warming has added to the atmosphere--an extra 4% since 1970. Snow is not the same as cold, and we have to look at global temperatures, not snowfall, to evaluate whether global warming is occurring. Heavy snow can act to bring down global temperatures, as occurred in December 2009, when the Northern Hemisphere experienced its second greatest snow extent on record (only 1985 saw greater December snow cover since reliable snow records began in 1967). Global average land temperatures, as a result, were just 31st warmest on record, even though global ocean temperatures were the 2nd warmest on record. It will be interesting to see what global temperatures did in January, when the statistics are released next week. The global temperature of the lower atmosphere as measured by satellites was the warmest on record in January, and by a considerable margin. I'll discuss this finding in more detail once the blizzard is over. It's also of interest to note that December temperatures in the U.S. were the 18th coldest in the historical record, but January temperatures were 0.3ーF above average, according to the National Climatic Data Center. As a whole, it's been a colder than average winter in the U.S., but not greatly so. However, December snow cover was the greatest on record in the contiguous U.S., and January's ranked sixth. Snow cover records go back 44 years, to 1967.