Climate projections, including regional projections and sea level

1. Climate projections, including regional projections and sea level U. Cubasch M&D at the Max-Planck-Institut für Meteorologie Hamburg, Germany

2. The information chain leading to a climate projection

3. A1: A world of rapid economic growth and rapid introductions of new and more efficient technologies A2: A very heterogenous world with an emphasis on familiy values and local traditions B1: A world of „dematerialization“ and introduction of clean technologies B2: A world with an emphasis on local solutions to economic and environmental sustainability IS92a „business as usual“ scenario (1992)

4. IS92 a IS92 a IS92 a IS92 a The SRES marker emission scenarios and the resulting change in concentration concentrations emissions

5. IS92 a The change in temperature resulting from the SRES emission scenarios

6. The projected sea level change

7. The annual mean change of temperature (map) and the regional seasonal change (upper box: DJF; lower box: JJA) for the scenarios A2 and B2

8. The annual mean change of precipitation (map) and the regional seasonal change (upper box: DJF; lower box: JJA) for the scenarios A2 and B2

9. The CO2-emissions, the CO2-con- centration and the temperature evolution for various stabilization scenarios

10. The evolution of the sea level for two stabilization scenarios, simulated by various models 2xCO2 4xCO2

11. Summary 1/5 • The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C. • The projected rate of warming is much larger than the observed changes during the 20th century and is very likely to be without precedent during at least the last 10,000 years. • Global mean sea level is projected to rise by 0.09 to 0.88 metres between 1990 and 2100. • Global mean surface temperature increases and rising sea level from thermal expansion of the ocean are projected to continue for hundreds of years after stabilisation of greenhouse gas concentrations (even at present levels).

12. Summary 2/5 • Global average water vapour concentration and precipitation are projected to increase during the 21st century. • At low latitudes there are both regional increases and decreases of precipitation over land areas. Larger year to year variations in precipitation are very likely over most areas where an increase in mean precipitation is projected. • For a number extreme phenomena, climate models currently lack the spatial detail required to make confident projections. Very small-scale phenomena, such as thunderstorms, tornadoes, hail and lightning, are not simulated in climate models.

13. Summary 3/5 • Changes of extremes * For other areas, there are either insufficient data or conflicting analyses;** Past and future changes in tropical cyclone location and frequency are uncertain. # For more details see Chapter 2 (observations) and Chapter 9, 10 (projections).Footnote (12): Heat index: A combination of temperature and humidity that measures effects on human comfort.

14. Summary 4/5 • Monsoon: The warming associated with increasing greenhouse gas concentrations will cause an increase of Asian summer monsoon precipitation variability. • Thermohaline circulation: Most models show weakening of the ocean thermohaline circulation, but there is still a warming over Europe due to increased greenhouse gases. The current projections do not exhibit a complete shut-down of the thermohaline circulation by 2100. • Current projections show little change or a small increase in amplitude for El Niño events over the next 100 years.

15. Summary 5/5 • Northern Hemisphere snow cover and sea-ice extent are projected to decrease further. • Glaciers and ice caps are projected to continue their widespread retreat during the 21st century. • The Antarctic ice sheet is likely to gain mass because of greater precipitation, while the Greenland ice sheet is likely to lose mass because the increase in runoff will exceed the precipitation increase.