Climate Change is topic at brown bag lunch

09/14/07 Seán Kinane
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This afternoon at the US Geological Survey (USGS) in St. Petersburg, the monthly Community, Science, and Environmental Policy brown bag discussion focused on global climate change.

The event featured local experts on two aspects of climate change. Dick Poore is a geologist with the USGS and studies climate variability over the last few thousand years, especially in the Gulf of Mexico. Gary Mitchum is a professor with the USF College of Marine Science who studies sea levels.

Poore: “We have pretty good evidence now that climate in the area has actually been quite variable over the few thousand years, maybe a total temperature swing of about 3 degrees centigrade in terms of mean annual surface temperature in the Gulf. Which is actually a fairly large signal.”

And how does that compare to recent, say over the last 150 years or even the last 30 years?

“Over the last 150 years, the change has been about 1 degree, maybe one and a half, something like that.”

Poore spoke about both natural and human caused sources of variability in climate change. An example of natural variability is the 11-year sunspot cycle and the most important human caused example is an increase in atmospheric carbon dioxide concentrations.

“I would argue that when it comes to policy and trying to prepare for the future, that climate variability may be just as important as climate change. So again earth’s climate is dynamic, it’s not static. There’s climate change, but there’s also climate variability and I think you need to pay attention to both of those.”

Mitchum is a professor with the USF College of Marine Science and studies sea level rise. He said that in some cases upward land movement might compensate for rising sea level.

Mitchum said he is less concerned with coastal flooding due to sea level rise, possibly 30 centimeters over the next 50 years, than the flooding that would result if climate change causes hurricanes to become more frequent.

“The potential impacts of climate change are very serious. But I did say that the direct sea level rise impact is the important one. The important one is - is the climate warming? I think there’s good evidence for that - is a warmer climate going to be a stormier climate? Are we going to have more hurricanes? Are we going to have fewer? We have a perpetual El Nino. Well, we love El Nino because it suppresses the Atlantic hurricane season. Are we going to have fewer?”

Mitchum says that even though he doesn’t expect sea level rise to be the most catastrophic affect of climate change, he studies sea level because it has predictive value to determine which of the many climate models can be believed and which should be thrown out.

Mitchum and Poore were asked if they feel that humans are contributing to climate change and whether people should take action to try to reverse it. They both said humans are contributing to climate change.

The next USGS Brown Bag on Global Change is Oct. 12 at noon in the USGS conference room in St. Petersburg.

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