Misconceptions about climate change
A 1996 survey of 99 ninth-grade high-school students in Oklahoma and Honolulu showed five common misunderstandings about climate change (1), as follows:
- Students exaggerated the extent of the warming likely within 50 years, say. They reckoned about 10°C change, whereas the Intergovernmental Panel on Climate Change quotes a range of 1.0 - 2.5 K (2). Of course, the warming will not necessarily stop after 50 years, and might be more within the lifetimes of children now at school. In addition there is the possibility that warming beyond some threshold precipitates positive feedback which accelerates warming. There is considerable uncertainty amongst scientists, but also the risk of the public being too short-sighted.
- Students confused the ozone-hole problem with the greenhouse effect. They are not the same, though they overlap a little. They became well known at about the same time, and chlorofluorocarbons (CFC’s) are implicated in both. It is now known that CFC’s are the chief cause of polar ozone holes, but only a minor cause of greenhouse warming - much less important than carbon dioxide, which has a far higher concentration. On the other hand, greenhouse gases also cause cooling in the lower stratosphere, which may facilitate the catalytic reactions that destroy ozone. The now-diminished production of CFC’s by international agreement will reduce the ozone hole problem during the next century, but greenhouse warming will continue. The warming will not be affected by changing the composition of aerosol propellants and refrigeration fluids.
- Many students believed that their personal experience of recent warm weather was evidence for global warming. This is to overlook the great variability of weather conditions. Any warming can be detected only by comparing averages over decades.
- There was a prevalent tendency to blame climate change on a wide range of quite irrelevant factors such as garbage disposal. The prime cause of the enhanced greenhouse effect is carbon dioxide from the combustion of fossil fuels.
- Climate was confused with weather. The main difference is the time-scale of variability. Climate is defined by average and extreme (near-surface) atmospheric conditions over a period such as 30 years, whereas weather is the instantaneous condition, or the range over a few days at most.
(1) Gowda, M.V.R., J.C. Fox & R.D. Magelky 1997. Students’ understanding of climate change. Bull. Amer. Meteor. Soc. 78, 2232-40.
(2) IPCC 1996. Climate Change 1995: The science of climate change (Cambridge Univ. Press) 572pp.