With some extreme winter weather taking place in some parts of the world, discussions about global warming would seem to fall on deaf ears. It can be challenging to gain the attention of a U.S. senator regarding warming ocean temperatures when he or she is shoveling several feet of snow to get to the U.S. capitol!
In United States alone, we have had some flip-flopping of "normal" weather patterns: heavy rains in southern California, record snow levels in the northeast, and a cold snap in Florida that has caused the deaths of over 100 manatees and triggered an extensive coral bleaching event. Even with an unusual warm spell in Vancouver, British Columbia as the Winter Olympics are about to begin, it doesn't sound much like global warming, does it?
However, one must look beyond micro-weather patterns and look at the big picture, at annual or decadal trends, and even longer, to determine what is a natural cycle or an anomaly or a man-made trend.
As an example, NASA's Goddard Institute for Space Studies recently declared 2009 to be the second warmest year on record, next to 2005. This first decade of the 21st century has been the warmest on record, warmer than the previous decade which was the former record holder. With changes in macro-weather patterns over a long period of time, there are disruptions to the typical wind, temperature, and ocean current patterns. In the Pacific Northwest, changing climate conditions are being considered responsible for steadily increasing wave height over the past several decades, posing greater flooding and erosion potential. Ironically, these major weather disruptions can manifest themselves regionally in ways that would seem to run counter to the idea of global warming.
One seasonal weather event that occurs in the Pacific is the El Nino - a change in the usual sea temperature patterns that warms the Pacific and disrupts weather patterns across much of North and South America. Research that has studied the El Nino over several centuries have shown that it has been occurring more frequently, with over 40% of the extreme events taking place in the 20th century, with 30% of those occurring after 1940. There is an El Nino in place right now and is considered the source of much of the current abnormal weather patterns in the North America.
There are some scientists who propose that all of this represents a normal macro-weather pattern, that this is all nature's doing and not man-made. But as research continues, we are beginning to see that the rate of change seems to be much greater than from any other previously recorded or extrapolated natural cycle - another accelerant would appear to be at work here. Hence, the issue of man's impact through CO2 and other greenhouse gas emissions and the use of fossil fuels.
Opponents of global warming have characterized it in various ways, from a natural-occurring event to a massive global conspiracy by maniacal scientists. While I don't buy into the Machiavellian plots, I would propose that if all the research were to ultimately point to a natural shift, I for one would choose not to simply sit back and enjoy the ride, proclaiming there's nothing we can do and watch ecosystems shift and species (including homo sapiens) disappear in many parts of the world. I just can't sit on my hands.
However, having reviewed the continuing stream of research studies, my inclination is that man-made activities have been the primary cause behind climate change. We did it and we can do something about it.
Read SeaWeb article on recent cold temperatures, El Nino, and northeast Pacific wave height.