Global warming myths debunked
MYTH: Water vapour is the most important and abundant greenhouse gas. So if we’re going to control a greenhouse gas, why don’t we control water instead of carbon dioxide (CO 2 )?
FACT: Although water vapour traps more heat than CO 2 , because of the relationships between CO 2 , water vapour and climate, nations must focus on controlling CO 2 in order to fight global warming.
Atmospheric levels of CO 2 are determined by how much coal, natural gas and oil we burn and how many trees we cut down, as well as by natural processes like plant growth. Atmospheric levels of water vapour, on the other hand, cannot be directly controlled by people; rather, they are determined by temperatures. The warmer the atmosphere, the more water vapour it can hold. As a result, water vapour is part of an amplifying effect. Greenhouse gases like CO 2 warm the air, which in turn adds to the stock of water vapour, which in turn traps more heat and accelerates warming. Scientists know this because of satellite measurements documenting a rise in water vapour concentrations as the globe has warmed. T he best way to lower temperature and thus reduce water vapour levels is to reduce CO 2 emissions.
MYTH: Global warming and extra CO 2 will actually be beneficial — they reduce cold-related deaths and stimulate crop growth.
FACT: Any beneficial effects will be far outweighed by damage and disruption.
Even a warming in just the middle range of scientific projections would have devastating impacts on many sectors of the global economy. Rising seas would inundate coastal communities, contaminate water supplies with salt and increase the risk of flooding by storm surge, affecting tens of millions of people worldwide. Moreover, extreme weather events, including heat waves, droughts and floods, are predicted to increase in frequency and intensity, causing loss of lives and property and throwing agriculture into turmoil.
Even though higher levels of CO 2 can act as a plant fertiliser under some conditions, scientists now believe the "CO 2 fertilisation" effect on crops has been overstated; in natural ecosystems, the fertilisation effect can diminish after a few years as plants acclimatise. Furthermore, increased CO 2 may benefit undesirable, weedy species more than desirable species.
Higher levels of CO 2 have already caused ocean acidification, and scientists are warning of potentially devastating effects on marine life and fisheries. Moreover, higher levels of regional ozone (smog), a result of warmer temperatures, could worsen respiratory illnesses. Less developed countries and natural ecosystems may not have the capacity to adapt.
The notion that there will be regional winners and losers in global warming is based on a world-view from the 1950s. We live in a global community. Never mind the moral implications — when an environmental catastrophe creates millions of refugees half-way around the world, everyone will be affected.
© Environmental Defense; reprinted with permission. For more information, visit their website at www.environmentaldefense.org.
