Jun 6, 2011

Just the Tip of the Iceberg

Bringing up the topic of global warming can spark a heated debate. Dr. Kar Lee presented facts and statistics about climate change to about 50 people at the June Sustainability Forum at the CleanTech InnoVenture Center in Lynn last Wednesday.

Dr. Lee began his discussion by asking audience members about their experiences talking about climate change. Though many people reported that they had run into skeptics who didn’t believe in global warming, Dr. Lee presented compelling facts, adding that “there is no such thing as a long-term stable climate.”

It's a big issue. Here are a few more added points from Dr Lee on the subject:

Just as we came off from the record breaking Tornado month in April with 875 reported tornadoes nationwide, and just as we thought we have seen it all, then came the devastation in Joplin: entire area flattened out, death toll rose to 141 as of today.  Some people may ask: is it abnormal?  Just as some were asking, something hit home: tornadoes touched down in Springfield in Massachusetts.  Really, is it global warming?

What I did not get the chance to present during my talk last Wednesday at the North Shore Tech Council's Sustainability Forum was some statistics about tornadoes.  If we look at the number of reported tornadoes from 1950 to May of 2011, we indeed see a clear trend: it increases steadily from around 200 per year in 1950's to about 1400 per year in these several years. 

So, you may think, it must somehow relate to the global temperature increase. But to make matters rather confusing, the number of strong to violent tornadoes (EF3 to EF5) is actually flat: http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadoes.html. 

The worst year for strongest tornadoes actually happened in 1974, clearly a one-off year.  Other than that, the trend for the strongest tornadoes is pretty much flat.

So, how can it be?

There are two possible explanations.

1) The increase is not real.  More get reported simply because we have vastly expanded our monitoring network, and by having people move into previously uninhabited areas (with their camcorders and cell phones!!!)  So, more get reported gradually over the years.

Problem with this explanation is, wouldn't the same people with camcorders and cell phones moving into new territories also catch more strong and violent tornadoes and therefore reported more of them as well?

The answer to this question is probably something like, "If the tornado is so strong, then no matter whether you are near it or not, you know about it because it leaves enough destruction to prove its existence. So the strong ones always get reported and if you see no increase, then there really is no increases."

2) The increase is real. There is an increase in the # of tornadoes touched down beyond the improvement of our monitoring network, and we have reported them. However, the change in the climate condition only causes the increase in the number of milder tornadoes, just like the global warming pattern changes the arctic regions more than the equatorial regions.  The effect is not uniform.

To decipher which explanation is more accurate, we really need to do some investigative work to find out if "strong tornadoes always get reported."  Were there very strong tornadoes that people would have missed during the 1950's?

The point of doing science is to find out which explanation is more likely to be true, and to not take sides prematurely.  Or else, we could be accused of sensationalism.

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