*

Global warming is due to strengthened greenhouse effect*Greenhouse effectThe Earth has a natural temperature control system. Certain atmospheric gases are critical to this system and are known as greenhouse gases. On average, about one third of the solar radiation that hits the earth is reflected back to space. The Earth's surface becomes warm and as a result emits infrared radiation. The greenhouse gases trap the infrared radiation, thus warming the atmosphere. Naturally occurring greenhouse gases create a natural greenhouse effect. However, human activities are causing greenhouse gas levels in the atmosphere to increase.

Earths energy budget*Source: Nasa, Atmospheric Science Data Center

Strengthening of greenhouse effect is due to increase of greenhouse gases in the atmosphereThe six greenhouse gases under the Kyoto Protocol:

Carbon dioxide or CO2Methane or CH4Nitrous oxide or N2OPerfluorocarbons or PFC compoundsHydrofluorocarbons or HFC compoundsSulphur hexafluoride or SF6 Other greenhouse gases:Ozone or O3Bromine compounds or halogens, e.g. CF3BrFreons or chlorofluorocarbons or CFC:sWater vapour or H2O (g)Global atmospheric concentrations of greenhouse gases have increased markedly as a result of human activities!

*Source: IPCC Fourth Assessment Report

Different greenhouse gases have different meaning to global warming*Source: IPCC Fourth Assessment Report

Meaning of carbon dioxide to global warmingCarbon dioxide is the most important anthropogenic greenhouse gas.The primary source of the increased atmospheric concentration of carbon dioxide results from fossil fuel use in power and heat production as well as transport.The change of land use provides another significant but smaller contribution.The atmospheric concentration of carbon dioxide exceeds by far the natural range over the last 650,000 years.*Source: IPCC Fourth Assessment Report

Atmospheric concentration of greenhouse gases correlates with temperature*

According to researches earths mean temperature has risen in the 20th and the 21st century *Source: IPCC Fourth Assessment Report

*According to measurements the temperature is rising

Sea level is rising*

****Source: IPCC Fourth Assessment Report***Annual averages of the global mean sea level (mm). The red curve shows reconstructedsea level fi elds since 1870 (updated from Church and White, 2006); the blue curve shows coastal tidegauge measurements since 1950 (from Holgate and Woodworth, 2004) and the black curve is basedon satellite altimetry (Leuliette et al., 2004). The red and blue curves are deviations from their averagesfor 1961 to 1990, and the black curve is the deviation from the average of the red curve for the period1993 to 2001. Error bars show 90% confi dence intervals.