Burning fossil fuels release gases, notably carbon dioxide (CO2) to the atmosphere; this extra CO2 absorbs infra-red radiation that would otherwise escape into space, thereby heating the atmosphere – the greenhouse effect – and possibly causing changes in climate. The following are likely effects of any doubling of CO2 concentration: average earth temperature would increase by 2 to 3 degrees C; precipitation would increase in some regions, though the change in rainfall patterns is uncertain (some scientists suggest that regions between middle and high latitudes would be affected, which is where most developing countries are located); and evaporative tendencies would increase in parts of the world, perhaps more than rainfall.
Trends documented by the the World Bank and Worldwatch Institute, and reported to the Rio+5 conference in 1997, at that emissions of CO2, the main contributor to global warming, have increased by 10 to 40 percent in many developing countries since 1990. In 1993, the rapidly expanding economy of China already ranked third in CO2 emissions, behind the USA and the former Soviet Union (when Soviet emissions are split among the newly independent republics, China may well be second). Chinese energy and environmental officials expect coal consumption to rise from the current level of 1.1 billion tonnes a years to more than 1.4 billion tonnes by the year 2000, despite the fact that energy growth has been held to half the rate of economic growth. One projection even suggests that China would pass the USA in carbon emissions by the year 2025.
In 1990, Canadians emitted 461 megatonnes of CO2, most of it from the combustion of fossil fuels. The transport sector accounted for the largest part of the CO2 emissions (34%), followed by: electricity production (20%), industrial sources (17%) and miscellaneous heating and industrial processes.
Research revealed that on the basis of bubbles of atmospheric gass contained in ice cores extracted from the Antarctic ice sheet, the levels of Carbon Dioxide in the atmosphere is higher in 1998 than at any other time in the last 420,000 years. at 360 parts per million, the levels are 20% higher than in any previous warm period between the ice ages, and double the particular concentrations during an ice age.
In the late 1990s, annual emissions of carbon dioxide were almost four times the 1950 level and atmospheric concentrations of carbon dioxide had reached their highest level in 160,000 years.
Annual global emissions of carbon dioxide from the burning of fossil fuels, cement manufacture and gas flaring reached a new high of nearly 23 900 million tonnes in 1996 (CDIAC 1999). This was some 400 million tonnes more than in 1995 and nearly four times the 1950 total. Only in some countries in Europe and Central Asia has there been a significant drop in emissions during the past decade, mainly as a result of the economic crises in Eastern and Central Europe. Atmospheric concentrations of CO2 in 1997 reached more than 360 parts per million (ppm), the highest level in 160 000 years (Keeling and Whorf 1998).