Science Cafe in St. Pete debates causes of Climate Change listen01/26/11 Matthew Cimitile
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In his State of the Union address, President Barack Obama didnâ€™t mention climate change. But the topic was at the forefront last night at the Pier Aquariumâ€™s science cafÃ© meeting in St. Petersburg.
More than a year removed from the stalemate at the climate conference in Copenhagen and another two months after a follow-up meeting in Cancun, there is still no binding global agreement to cut greenhouse emissions. Without those cuts, the Intergovernmental Panel on Climate Change predicts that man made activities will raise temperatures by 1 to 4 degrees Celsius or more by the end of this century. David Hollander is a chemical oceanography professor at the University of South Florida and moderated the Science CafÃ©.
â€œThe concept of climate change is a highly charged word. If climate change is actually occurring, the impacts to the world can be severe. Not only is the idea that large climate changes or large levels of sea levels will cause great changes but relatively modest changes are going to cause significant changes to our business as usual scenario. We realize that greenhouse gases, carbon dioxide specifically generated from fossil fuels is primarily the driving force, than one has to believe we have to alter that. But it is a debate whether that is driving the climate and I think our story today comes back to the Al Gore question of whether climate change is actually happening or not?â€
According to NASA and the National Climatic Data Center, 2010 was tied as the warmest on record. Nine of the 10 hottest years have been in the past decade. Benjamin Flowers is a USF paleoceanographer who studies the role of ocean circulation in past global climate change.
â€œThere is well demonstrated evidence from thermometers that the entire Earthâ€™s surface has warmed by .7 degrees since the beginning of the 20th century. So since 1900 the entire globe has warmed on average by .7 degrees Celsius, which is about 1.1 degrees Fahrenheit. This doesnâ€™t sound like a large temperature change but it amounts to 10 to the 22nd joules. That turns out to be about 40 times the mean global energy consumption."
Gene Shinn, a Courtesy professor of Geology at USF, countered that the Earth has naturally gone through climatic changes, where temperatures and sea levels fluctuated tremendously. He cited that through geologic history, Florida was either mostly underwater due to higher sea levels from a warmer climate or of much greater landmass due to lower sea levels from a colder climate.
â€œAbout 125,000 years ago we probably would see water way up here, when Florida was in its peninsular form. 16,000 years ago sea level was down maybe 400 feet and 70 miles offshore, so those are extreme changes and extreme temperature changes and there werenâ€™t any SUVâ€™s around so it is hard to blame that on the usual suspects. Yes it is getting warmer, we have been coming out of the little ice age and before that out of the last glacial period so naturally it is getting warmer.â€
An overwhelming majority of climate scientists fear that this new climatic change is something different, because of the rate and the nearly unprecedented amount of CO2 in the atmosphere. They believe that the jump in temperature in the past century is largely due to the burning of fossil fuels that emit greenhouse gases and trap greater amounts of heat into the climate system. Flowers said that the last century saw an increase in CO2 in the atmosphere greater than the last 10,000 years preceding it.
â€œTodayâ€™s measurement as you may know is greater than 390 ppm by volume in the atmosphere. At the last glacial maximum it was 190 and prior to the Industrial Revolution it was 280. So the total range from glacial to interglacial is about 90 ppm. And we have exceeded that range just in the anthropogenic era. Keep in mind the scale here, were not talking about .7 degrees, were talking about a magnitude greater than glacial to interglacial changes.â€
However, using proxy data such as ice cores and other geologic information, Shinn cited data confirming that the relationship between CO2 and temperature is not as straight forward as people claiming manmade climate change may think.
â€œIf you look at the data from the ice cores, the Vostok core and so on, it shows a rapid rise in temperature, it is like a saw tooth. And most recent data shows that temperature precedes the rise of CO2. Iâ€™m old fashion and like cause and effect. So if temperature is going up faster than CO2 by about 1,000 years, than I worry about that. Now the global warmists, they donâ€™t have a problem with that because there is a lot of feedback going on, but Iâ€™m just old fashioned. I need to see this causes this and that does that and so on, very simple.â€
At the end of the talk, Flowers reiterated the direct effect carbon dioxide has on the climate system that has been recognized for over a hundred years.
â€œThere is no argument what Gene mentioned that temperature may preceded CO2 change in the past, but that is not the experiment we are conducting right now. When we pump CO2 in the atmosphere we know it is a very strong greenhouse gas and it has the effect of enhancing water vapor in the atmosphere and doubling its effect right there. So CO2 has its own positive feedback, the biggest one being the enhancement by other greenhouse gases, especially water vapor. 96 is when the first paper was published on this, that quantified this effect, that is 1896, when Arrhenius was the first to quantify the relationship between CO2 and temperature change.â€
That effect has been well documented and measured ever since. So too has the debate over the science of man-made climate change.