The following is a letter received on Jan. 3, 2007 from Miranda, a sixth grade student at Jackson Middle School here in the Twin Cites.
I would like to know why winters are getting warmer. I would also like to know if global warming is real or not. I have heard a lot of opinions about global warming, and I don't know which one I believe. I used to live in Tennessee and the winters there were very mild. The first year I lived up here in Minnesota the winters were horrid. Now there's not much snow. I would like to know why.
Please take my questions into serious consideration. Please write back.
-Miranda
My Response:
January 17, 2007
Dear Miranda,
Global warming is certainly a popular topic and with the winter we're having so far many folks are convinced that Global Warming is here and we are experiencing it.
When I was growing up winters were much colder than what they have been since 1997. Looking at December alone in the 1970's the average December temperature was 17.7. For the period 1997 to 2006 the average December temperature was 23.2. So the "horrid" winters you have experienced since moving to Minnesota from Tennessee have been mild to those of us who grew up in the 1970's.
Looking at the long term average (LRA) temperatures, 1820-1970, verses the most recent climatological period of 1971-2000 (30yr avg) we see that the warming that has occurred here in the Twin Cities has come during our winter months. As much as 5 degrees warmer in February. I'm sure that is welcomed news to you. Warmer winters. Maybe your classmates are wishing for more cold and snow?
Summers here in the Twin Cities have changed very little, although a bit wetter, temperatures have remained virtually steady and unchanged when comparing the LRA to the 30 yr average.
Answers to questions regarding Global warming are very tricky. There is no doubt when comparing the LRA to the 30 yr average the Twin Cities has warmed. Dependable temperature measurement has only been around since the early 1700's, not a long time of recorded history. Temperature measurement here in the Twin Cities started in 1820 at Snelling. The Twin Cities has the 3rd longest period of temperature data of any city in the United States, 183 years.
A 183 is a long period but what I feel not long enough to make bold states about what is causing global warming. Which is really what people want to know, what is causing Global Warming?
You asked in your letter, "Why winters are getting warmer?" A simple answer is more warmer air over us than cold. Why do we have warmer air over us? The Jet Stream, flow of air 30,000 feet above us, brings us our weather systems and flows from west to east. Once in awhile a kink will appear in the Jet Stream, this "kink" could either bring us colder air from the Arctic or milder air from the south(west). The Jet Stream moves north and south over the course of the year, in summer its north of us and in winter it's moves south, bringing colder weather.
This past winter the Jet Stream has be relatively flat, flowing west to east, this bring us Pacific air, mild and dry. This past week a "kink" developed in the Jet Stream and the flow turned north to south bringing us colder temperatures.
The biggest factor that controls the Jet Stream is the great oceans that cover 3/4 of the Earth surface. You might have read about El Nino, a warming of the Pacific off the west coast of South America. During an El Nino Year the Jet Stream is pushed further north in the winter months. Pushing the Jet Stream north, as you would guess it brings us here in Minnesota, warmer weather. Not a bad deal for a kid from Tennessee.
The causes of the Pacific Ocean warming are unknown, what is known it does seem to oscillate every other year. The intensity of the warming varies so you can not depend on it every other year. Is this the cause of Global Warming?
CO2 is widely blamed for creating a warmer globe. CO2 is produce when you burn fossil fuels. Gas, oil, and coal are fossil fuels. CO2 traps heat which causes higher temperatures. 7 billion tons of CO2 are released into the air yearly. CO2 is absorb by the Oceans, is stored in the ground and some escapes into space. Computer models predict the more CO2 that is put into the air the global temperature will raise. As the global temperature rises Polar Ice caps are predicted to melt raising Ocean water levels that could flood coastal cities.
Is CO2 responsible for our warmer winters? Hmm, I feel it's a bit premature to say it is the biggest and sole factor.
Should be we take steps to lessen the input of CO2 into the air? I think it is a good idea to do whatever we need to do to lessen the out put of CO2. Continuing the burning of fossil fuels, gas most in particular, is bad. Finding alternatives like fuel based on corn or better yet grass would appear to me a wise investment in the future of the United States as well as the environment. Look at the trouble we're in Iraq, trying to secure a peaceful middle east where vast amounts of oil are stored.
It's not hard to turn the issue of Global Warming into a political debate.
One thing we can do is remove the issue of burning fossil fuels by using alternative sources of power such as corn, grass, wind, solar, hydro and others.
I hope what I have written makes some sense to you. I could go on for another 10 pages but I'll end it here and save you from my babbling.
Sincerely,
Frank Watson
Weathermanwatson.com
