Is the climate changing? Of course! It is always changing, and it always will. The big question is: Are humans affecting the ways in which climate is changing? Are we making the globe warmer?
There's no doubt that our civilization's addiction to fossil fuels is adding "greenhouse gases" to the atmosphere. Here's what happens: Burning gasoline--and other fuels, too, such as coal--generates a lot of carbon dioxide. The world added 5 billion tons of carbon dioxide to the atmosphere in 1990, 186 million tons of which came from Florida (Henry, 1998). Carbon dioxide and other "greenhouse" gases trap heat, and scientists have quite precise estimates of how much more heat can be trapped by given concentrations of these gases.
A scientist measures methane, one of the "greenhouse gases." Copyright University Corporation for Atmospheric Research/photo by Patrick Zimmerman.
Coastal erosion (photo by Karla Brandt)
But will these atmospheric accumulations change the planet's climate? Scientists do not agree. Here we present both arguments.
Evidence for global warming
Some scientists have built computer models that show that increased greenhouse gases will cause increased temperatures. The U.S. Environmental Protection Agency (1997) lists the following possible effects on Florida of the buildup of greenhouse gases:
- rising temperatures, which would melt glaciers, icebergs, and the polar ice caps, flood coastal areas, and cause saltwater intrusion in aquifers
- rising sea levels, which would destroy structures, accelerate erosion, wreck wildlife habitat, and increase salinity of estuaries and aquifers;
- more extreme weather patterns (more intense droughts and storms) and worse air pollution;
- lower crop yields;
- expansion of the range of disease carriers (such as mosquitoes);
- more frequent blooms of marine algae, contaminating fish and shellfish
It's a long list, and not a pretty one.
Evidence against global warming
Other scientists think we're being self-important when we claim that our actions are changing global climate because climate is affected by much larger forces (on the scale of the sun, the planets, and the oceans) that work on much longer time-frames than mere centuries. They say that no definitive conclusion about climate change can be drawn from computer models. Schmidt (2002) looked at weather data, which suggest that the climate might actually be cooling off:
- the bottom five miles of the atmosphere has cooled by an average of 0.19 degrees F since 1979
- models use data collected around cities, which reflect more heat from their buildings and roads than do forests and grasslands
- 90% of the increased average temperatures was recorded before 1940, before the huge increases in emissions of greenhouse gases
- from 1946 to 1975, cities cooled off, leading the media to predict a new Ice Age
Which way will climate change? No one knows for sure. The proof will be in the pudding. Let's hope it's not overcooked.
Henry, J.A. 1998. Weather and climate. Pp. 16-37 in Fernald, E.A., and E.D. Purdum (eds.). 1998. Water resources atlas of Florida. Institute of Science and Public Affairs, Florida State University, Tallahassee.
Schmidt, W. 2002. Facts, myths, misconceptions, and media misrepresentations about global warming. Florida Geology Forum 16(1), March. Available at Florida Geological Survey.
U.S. Environmental Protection Agency. 1997. Climate change and Florida. EPA 230-F-97-008i. Office of Policy, Planning and Evaluation (2111), Washington, D.C.
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