By Tom Konvicka Chief Meteorologist
It seems like anything related to climate change is grabbing headlines and research dollars these days. With 2008 off to a record start in the number of tornadoes, I thought it seemed like the appropriate time to do a series on tornadoes and climate change. Specifically, I want to entertain the topic of how a warmer Earth could affect tornado climatology and intensity.
Officially, the Intergovernmental Panel on Climate Change (IPCC) makes no definitive statement on the relationship between tornadoes and climate change. "There is insufficient evidence to determine whether trends exist in small scale phenomena such as tornadoes, hail, lightning, and dust storms." At this point let me digress briefly and express the feeling that the IPCC panel is off base on lightning. I've seen convincing evidence that there will be more lightning on a warmer Earth.
At the heart of the difficulty is the detection of all tornadoes (a future goal) and being content with just reported tornadoes (our current database). There is no doubt that the number of documented tornadoes has increased since 1950, a year many severe storms meteorologists consider the beginning of the "modern" or "reliable" era of tornado reporting and documentation. The High Plains Regional Climate Center at Lincoln, Nebraska has a nice bar graph presentation of annual tornado numbers for the period 1950-2007 at the following address:
http://www.hprcc.unl.edu/nebraska/U_S_SEVERE.html
One look at the graph and you can clearly see there are more tornadoes than there used to be. For example, in 1950, we barely documented 200 tornadoes. In 2004 we counted 1,600! Every year since 1990 has produced more tornadoes than 1957, the busiest year of the 1950s. Does this have a physical explanation or is it that we are better at counting tornadoes? I think there is truth in both condiderations but the second one is much more likely to explain observed trends. We'll talk more on this tomorrow.
Best,
Tom Konvicka