Discover the scientific facts on global climate change

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

Many observations indicate that global climate change has taken place during the 20^th century. Global climate change 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 climate change affects precipitation, cloud cover and extreme temperatures.More...

• What causes this global climate change?
• What global climate changes are expected for the future?
• Read the GreenFacts Digest on the global climate change

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

global climate change The annual mean change of the temperature (colour shading) and its range (isolines) (Unit: °C) from one SRES scenario global climate change Some extreme weather events and the damage, hardship, and death they cause are projected to increase with global climate change. There is also a potential for large-scale and possibly irreversible impacts which pose risks that have yet to be reliably quantified; their likelihood is probably very low but is expected to increase with the rate, magnitude, and duration of global climate change.More...

What causes this global climate change?

Global climate change 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 climate change processes and computer models have improved, leading the IPCC to draw the following conclusion:

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

What global climate changes are expected for the future?

To predict the future global climate change, 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 climate change is projected to persist for many centuries. The sea level should continue rising for thousands of years after the climate has been stabilized. More...