Global climate trends
THE main drive behind climate change is the increasing amount of carbon dioxide in the atmosphere. Its level has risen by a third since the industrial revolution started in the 1760s. As CO2 has built up, so temperature has risen. Over the past century, the Intergovernmental Panel on Climate Change estimates, the world warmed by 0.6 ĄC. In this century, says the IPCC, we can expect temperatures to increase by as much as 6 ĄC.
Warming oceans will expand, raising sea levels round the world. Some 50 million people a year already have to deal with flooding caused by storm surges. If the sea rises by half a metre, this number could double. A metre rise would inundate 1 per cent of Egypt's land, 6 per cent of the Netherlands and 17.5 per cent of Bangladesh. Only 20 per cent of the Marshall Islands would be left above water.
The main culprits behind increasing CO2 levels are burning fossil fuels, farming practices, such as ploughing, and deforestation. We have already cut down more than half the forests that existed after the last ice age. Rich nations, such as those in North America and Europe, are now reforesting about 12,000 square kilometres a year, but in South America, Asia and sub-Saharan Africa, forests are still disappearing at 10 times this rate. The biggest factor behind rising CO2 levels is burning fossil fuels. Countries such as the US and Australia emit more CO2 per person than other nations because of their high dependence on fossil-fuel power plants and high living standards. The US alone pumps out a quarter of the world's CO2 emissions.
Just how wasteful Americans are with the world's resources can be seen from their ecological footprint. This measures how much land each of us requires for our food and clothing, energy, living space and disposing of waste (measure your own footprint with our quiz). If the world's productive land were divided fairly, we would each have about 1.8 hectares. Americans have a footprint six times this area.
Sources: Deforestation, UNEP; Ecological footprint, Worldwide Fund for Nature; Global CO2, temperature and sea level, IPCC; Energy and national CO2 emissions, World Bank; Ozone, John Austin, Meteorological Office
The world's disappearing forests
Ecological footprint
CO2 levels climb
World warms up
Oceans rise
Lowest annual ozone levels
Who pumps out the most CO2?
Who uses most energy? And who gets most value for money?
http://www.newscientist.com/hottopics/climate/climatetrends.jsp