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Simulations of Climate Change for IPCC AR4

The following figures and animations show first results of the simulations for the IPCC Assessment Report No. 4 (AR4). The simulations have been realised at DKRZ by scientists of MPI-M and the “Model and Data” Group using the climate model ECHAM5-MPI-OM developed at MPI-M.
 

The future development of the emissions determines considerably the concentrations of CO2 and other greenhouse gases that are found in the future atmosphere. A short description of the SRES scenarios is found on the last page of the Summary for Policymakers of the last IPCC report (IPCC TAR).

  

Increasing concentrations of CO2 and other greenhouse gases change the radiation budget of the earth. As a consequence the global mean temperature rises. The grey curve illustrates the response of the climate model to the observed greenhouse gas concentrations; the multicolored curves show the reaction to different emission scenarios.

The direct comparison of the projected temperature changes for the rather pessimistic scenario A2 with those for the much more optimistic scenario B1 illustrates the variety of possible future developments. According to the new simulations a mean global warming between 2.5 and 4.1 degrees Celsius until the end of this century (relative to the mean temperature between 1961-1990) is expected - dependent on how much greenhouse gases are emitted into the atmosphere during that time.

As a consequences the seasonal varying sea ice decreases. If emissions will not be reduced, the arctic could become ice free during late summer till the end of this century ...

2-Meter Temperature

The different presumptions for emissions of greenhouse gases and aerosols according to the different scenarios result in different projected changes of the 2-meter temperature. The warming varies regionally. The warming over the continents is, for example, much stronger compared with the temperature increase over the oceans. This typical warming pattern appears within a few decades, with different strengths for the different scenarios, though. Consequently, the warming over land is much stronger compared with the global mean temperature increase.

The animations show the running 5- years mean of the "Ensemble Mean" for the IPCC SRES scenarios A2, A1B and B1.

Animation: Simulated temperature change relative to the mean temperature between 1961-1990 for the scenarios A2 and B1. Projected is the period between 1980 and 2100. (Mpeg1, 4 MB)

Animation: Simulated temperature change relative to the 1961-1990 mean for the scenario A2. (Mpeg1, 3 MB)

Animation: Simulated temperature change relative to the 1961-1990 mean for the scenario A1B. (Mpeg1, 3 MB)

Animation: Simulated temperature change relative to the 1961-1990 mean for the scenario B1. (Mpeg1, 3 MB)

Visualisation: Michael Böttinger, DKRZ

Precipitaion

Due to climate change, the cycle of precipitation and evaporation is going to be intensified. Within the next hundred years, the global mean precipitation might increase by several percent. For scenario A1B for example, our simulations show an increase of approximately 7 percent until 2100. The spatial and temporal distribution of the rainfall, though, is also going to change: increases are shown with red colors, decreases are shown in blue.

In order to evaluate the simulated percentual precipitation changes for January and July shown above, it might be helpul to know the "normal" mean rainfall in the different regions in the respective seasons. The following images and the animation show at the same time the simulated precipitation for 1961-1990 and the changes at the end of this century simulated for IPCC scenario A1B.

The simulated mean precipitation over land in the summer season (June, July, August) for the period 1961-1990 is shown by the height of the bars. The percentual changes of the mean precipitation for scenario A1B, simulated for 2070-2100, is given by the colors. (JPEG, 130 kB).

The simulated mean precipitation over land in the winter season (December, January, February) for the period 1961-1990 is shown by the height of the bars. The percentual changes of the mean precipitation for scenario A1B, simulated for 2070-2100, is shown by the colors. (JPEG, 130 kB).

This animation shows the simulated "normal" monthly precipitation during the term of a year, being visualised by the height of the bars.The percentual changes of the mean precipitation for scenario A1B, simulated for 2070-2100, are shown by the colors. (MPEG, 2.7 MB).

It can be expected, that a strong decrease of the precipitation (yellow to red) will have a strong impact on the vegetation and on the agriculture, especially in areas with naturally little preciptation (short bars).

Visualisation: Michael Boettinger, DKRZ

Sea ice and snow

The developement of sea ice and snow represents an important climate indicator. A decrease of the sea ice and snow cover due to a warmer climate will result in a darker surface. As a consequence more solar radiation will be absorbed at the surface and thus contribute to a further warming and melting (ice-albedo-feedback).

Development of the mean annual sea ice cover for the three scenarios A2, A1B and B1.

The following figures illustrate the seasonal cycle (green) and the annual mean (blue) of the sea ice area on the northern hemisphere. When the green field reaches the bottom line of the diagram, the sea ice melts completely during late summer.

Animation: Comparison of the northern hemispheric sea ice and snow cover in March and September for the scenarios A2 and B1. While for A2 the sea ice in summer melts completely, the arctic remains partly covered with ice for B1. (Mpeg1, 2.4 MB)

Animation: Development of the norther hemispheric sea ice and snow cover in March and September for the scenario A2. (Mpeg1, 2.7 MB)

Animation: Development of the norther hemispheric sea ice and snow cover in March and September for the scenario A1B.(Mpeg1, 2.7 MB)

Animation: Development of the norther hemispheric sea ice and snow cover in March and September for the scenario B1.(Mpeg1, 2.7 MB)

Visualisation: Michael Böttinger, DKRZ

Sea Level

The sea surface height is affected by many different processes, acting on different time scales: short term changes due to wind or tides as well as long-term global changes due to variations of the climate and earth system. The fundamental factors for long-term changes are:

The following simulations consider steric and dynamic changes, but do not account for eustatic or tectonic effects.

Changes of the mean global sea level are strongly influenced by the level of greenhouse gas concentrations in the atmosphere. The simulations show that - depending on the IPCC-SRES emission scenario - a global mean sea level change of 21 to 28 cm (compared to the period 1961-1990) can be expected.

  
Since the ocean is able to store large amounts of heat, the sea level will still continue to rise even when the concentrations of the different greenhouse gases in the atmosphere are not increasing any more. For the scenarios A1B and B1 the simulations have been continued with constant concentrations (values of 2100) for the period between 2100 and 2200.

Regional differences in the sea level changes are caused by changes of the ocean circulation and the hydrologic cycle (precipitation minus evaporation). In the high southern latitudes changes of the sea level during the 21st century are comparatively small; in the Arctic Ocean, however, sea level rises more than twice as much relative to the global mean, due to an increasing fresh water influx from rivers and precipitation. Shifting ocean circulation patterns can also result in deviations of regional sea level changes from the global mean - e.g. in the North Atlantic.

Animationen
Bilder
  

Comparison of th sea level changes of the scenarios A2 and B1 for the period between 2000 and 2100. Changes occur particularly in the end of the century. (Mpeg1, 2.4 MB bzw. JPEG 100 kB)

Sea level changes of the scenario A2 for the period between 2000 and 2100. (Mpeg1, 2.5 MB bzw. JPEG 100 kB)

Sea level changes of the scenario A1B for the period between 2000 and 2100. (Mpeg1, 2.5 MB bzw. JPEG 100 kB)

Sea level changes of the scenario B1 for the period between 2000 and 2100. (Mpeg1, 2.5 MB bzw. JPEG 100 kB)

Sea level changes of the scenario A1B for the period between 2000 and 2200. (Mpeg1, 5 MB bzw. JPEG 100 kB)

Sea level changes of the scenario B1 for the period between 2000 and 2200. (Mpeg1, 5 MB bzw. JPEG 100 kB)

Mor information about sea level rise can be found in the FAQs on the homepage of the Max-Planck-Institute for Meteorology.

Felix Landerer from the Max Planck Institute for Meteorology investigates the connection between regional sea level changes and climate relevant ocean processes in reponse to a global climate change.

Visualisation: Michael Böttinger, DKRZ

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