Global warming: dire warning

Barbara Sibbald

Violent floods, pestilence, melting glaciers, vanishing coral reefs. This almost sounds like a passage from the Old Testament, but the words appear in the third report on global warming prepared by the UN's Intergovernmental Panel on Climate Change (IPCC).

The IPCC warns that global temperatures could rise an additional 1.4°C to 5.8°C over the next century, depending on what political choices are made. Canada may experience the world's biggest increase in temperature, which could bode well for agriculture, but IPCC Chair Robert Watson says Canada has a moral obligation to reduce greenhouse-gas emissions because of their impact around the world. The panel of 2000 scientists, established in 1988, concludes that human action and inaction are largely responsible for the warming trend.

Although the technology exists to switch to less harmful fuels, the political will to do this does not, Watson says. The 800-page study, Climate Change 2001: Mitigation (www .ipcc.ch), concludes that switching to clean energy sources needn't be prohibitively expensive. It estimates that the average country could reduce greenhouse gases to an acceptable level with only a 0.2% decline in annual economic growth.

The IPCC's second report, Climate Change 2001: Impacts, Adaptation and Vulnerability, concluded that global warming is already costing world economies at least $36 billion a year because of “weather events” and other weather-related disasters, and these costs could escalate to $300 billion.

The panel says man-made climate change will cause tropical diseases to spread and glaciers to melt, and the number of people facing water shortages to increase from 1.7 billion today to 5.4 billion by 2026 (see McCally M. Environment and health: an overview. CMAJ 2000;163[5]:533-5).

According to the as-yet unratified Kyoto Protocol, Canada would be required to cut emissions of greenhouse gases by 6% from 1990 levels. There are fears that the recent decision by the US to back out may scupper the deal. In the meantime, emission levels in Canada have risen by at least 13.5% over 1990 levels.