The World - Climate change in the 21st century
Atmosphere and climate change
978-3-14-100890-6 | Page 20 | Ill. 3
Overview
Due to global climate change, average temperatures and precipitation will change significantly worldwide by the end of this century. However, the different world regions and climate zones will be affected by this change to varying degrees.
Global warming considerations
On the basis of a moderate further increase in climate-impacting greenhouse gases, the model calculations predict a strong rise in temperature, especially for the polar regions of the northern hemisphere. There, an increase in average temperatures of over 7 degrees Celsius, in some cases, is predicted by the year 2100 - not least because of the decreasing average duration of snow cover and melting ice. The snow- and ice-free ground surfaces will warm up more than before due to their decreased albedo (i.e. their reduced reflectivity due to the melting of the ice). Such a self-reinforcement of the global temperature increase is called a positive feedback process. In the Antarctic region, the expected temperature increase is significantly lower than in the Arctic. Here, on the one hand, the isolated location of the continent and the associated atmospheric circulation conditions and, on the other hand, the powerful inland ice masses contribute to a significantly weaker or delayed temperature increase.
In large parts of the tropics, subtropics and Mid-Latitudes, a temperature increase of 3 to 4 degrees Celsius can be expected by 2100. In the interior of the continents, the temperature increase will in many places be 1 to 2 degrees Celsius higher than in maritime regions due to the faster and stronger warming of continental masses. Above the oceans, the thermal inertia of the water masses will result in the lowest warming rates of 1 to 3 degrees Celsius. Due to a possible weakening of the Gulf Stream and the Antarctic Ocean currents as a result of global warming, the temperature increase in these regions is partly limited to less than 1-degree Celsius.
Indirect consequences of global warming
One of the most important indirect consequences of global warming is the regional change in precipitation. For example, a decrease in precipitation is predicted for large parts of the tropical-subtropical drylands, such as in eastern Brazil and Mexico. In the central and polar regions, on the other hand, precipitation is expected to increase because the increased warming there is accompanied by a greater moisture and thus precipitation potential of the air masses. In addition, a greater energy contrast between the equator and polar regions in the higher atmospheric layers contributes to increased circulation. This stimulates the formation of dynamic low-pressure areas. This is accompanied by a meridionalisation of weather patterns, which will lead to an increase in extreme weather phenomena such as droughts and hot spells, as well as floods and storms, especially in the Mid-Latitudes.
