|
|
Climate change is one of the greatest environmental, social and economic threats facing the planet. During the last century, the Earth’s average surface temperature rose by around 0.6°C (1.08° F). Warming occurred in both the Northern and Southern hemispheres, and over the oceans. Most of the global warming that has occurred over the last 50 years is attributable to human activities and particularly to the burning of fossil fuels and deforestation, both of which result in the emission of carbon dioxide (CO2), the main greenhouse gas responsible for climate change. During the 150 years of the industrial age, the atmospheric concentration of carbon dioxide has increased by 31%. Prior to the start of the Industrial Revolution, the levels of carbon dioxide in the atmosphere were about 280 parts per million by volume (ppmv). Current levels are about 370 ppmv. The concentration of CO2 in our atmosphere today is higher than at any time in the past 420,000 years, and probably in the last 20 million years.
In its fourth Assessment Report (2007), the Intergovernmental Panel on Climate Change (IPCC) projects that global average surface temperatures will rise by a further 1.1 to 6.4°C (1.98 to 11.52°F) by the end of this century. This global temperature increase is likely to trigger serious consequences for humanity and other life forms alike. Climate change is already having pronounced environmental, economic and social impacts. The economic costs are projected to be heavy and will increase the more we allow the temperature to rise. An example of the current economic and social impacts of climate change is the lack of snow suffered by European ski resorts after an abnormally warm autumn and early winter in 2006. The deadly summer 2003 heat wave in Europe is also typical of what experts consider is likely to occur increasingly frequently as a result of climate change.
 During that event more than 20,000 people in the EU died prematurely from a combination of heat stress and increased air pollution from ozone and particulates. Southern Europe suffered large-scale forest fires, and European farmers lost over € 10 billion in income due to crop damage and other effects. There has also been an increase in weather-related natural catastrophes, such as floods and windstorms. It is projected that climate change will have severe impacts on certain ecosystems, with some species and habitats disappearing. Global food production is likely to decline, infectious diseases such as malaria and dengue fever may spread, and water scarcity and poor water quality will become problems in many regions. Over the last 30 years the extent of Arctic sea ice has decreased by around 7% and the ice has thinned by about 40%.
By 2100, sea levels are expected to rise by between 9 cm and 88 cm if global greenhouse gas emissions are not reduced. This would drown some low-lying islands such as the Maldives and many coastal regions like the Bangladesh delta, and cause widespread salt water intrusion. Weather impacts are likely to include higher maximum temperatures, more heat waves, increased summer dryness with the risk of drought and fires, or, in other regions, increases in precipitation, storms and floods. Such impacts might trigger what are termed “secondary effects”: regional conflicts, poverty, famine and migration.
|
|
|