Discover the scientific facts on global warming

The annual mean change of the temperature (colour shading) and its range (isolines) (Unit: °C) from one SRES scenario

Many observations indicate that global warming has taken place during the 20^th century. Global warming has resulted in a increase of the average surface temperature, a decrease in snow cover and ice extent and a rise of the sea level. Moreover, global warming affects precipitation, cloud cover and extreme temperatures.More...

• What causes this global warming?
• What global warming are expected for the future?
• Read the GreenFacts Digest on the global warming

Variation of the Earth's surface temperature for the past 140 years

Natural reasons will always affect global warming. However, human activities are increasing significantly the concentrations of greenhouse gases, mainly CO₂) in the atmosphere, resulting in global warming. Although more research is needed, understanding of global warming processes and computer models have improved. global warming models conclude that most of the warming over the last 50 years is likely to have been due to man-made activities. Scenarios are developed to predict what global warming are expected for the future and what the likely consequences will be. More...

What causes this global warming?

global warming has and will always vary for natural reasons. However, human activities are increasing significantly the concentrations of some gases in the atmosphere, such as greenhouse gases (mainly CO₂), which tend to warm the earth surface, and anthropogenic aerosols, which mostly tend to cool it.

Although more research is needed, understanding of global warming processes and computer models have improved, leading the IPCC to draw the following conclusion:

Most of the global warming over the last 50 years is likely to have been due to man-made activities. More...

What global warmings are expected for the future?

To predict the future global warming, several greenhouse gas emission scenarios were developed and fed into computer models.

They project for the next century that, without specific policy changes:

• global mean temperature should increase by between 1.4 and 5.8°C (2.5 to 10°F).
• the Northern Hemisphere cover should decrease further, but the Antarctic ice sheet should increase.
• the sea level should rise by between 9 and 88 cm (3.5" to 35").
• other changes should occur, including an increase in some extreme weather events.

After 2100, human induced global warming effects is projected to persist for many centuries. The sea level should continue rising for thousands of years after the climate has been stabilized. More...