Consequences of IPCC scenarios

Global warming
All mathematical models that have been studied so far foresee an overall warming of the lower layers of the atmosphere and of the planet’s surface of 1.5 to 5.8 °C and a cooling of the upper layers of the atmosphere. There will be different changes at different latitudes.
High latitudes (polar and subpolar areas). During the winter temperature increase will be greater than the global average increase and will affect the dry lands more than marine surfaces. At the poles there will be a decrease in marine ices and because ice plays a role in heat exchanges among the oceans, warming of the arctic areas and high latitudes will be greater. During the summer instead, the temperature increase will be lower than the average global one because of the strong thermal influence of the ocean.
Intermediate latitudes (mild areas). During the summer temperature increase in the northern hemisphere will be greater than the global average, whereas during the winter it will be very similar to the global average.
Low latitudes (subtropical and equatorial areas).Temperature increase in these areas will be minimal and lower than the average global heating. As opposed to other latitudes, it will be even throughout the seasons. This area is occupied mostly by the sea so surface temperature increases will only increase water evaporation rather than making the air temperature warmer.
The water cycle in the atmosphere and the ground
Precipitations will increase globally because of the rising temperature, and because there will be more evaporation which will mean more water vapor in the atmosphere, this will increase the amount and speed up the water cycle in the climate system.
Precipitations will increase particularly at high latitudes and the intra-tropical area both during the winter as well as during the summer. At intermediate latitudes instead, precipitation will increase only during the winter months. Locally some areas will have more dry spells and/or floods while others will have less. Rains will become more frequent and more intense so there will be an increased risk of floods.
At present we do not dispose of sufficient data to know if floods, hurricanes or tropical cyclones will increase or simply change the areas where they occur.
Sea levels
The average sea level will rise because of the ice melting and, according to the more pessimistic forecasts, it could rise as much as a meter higher than it is today; whereas according to the more optimistic forecasts it will rise by only 10 to 20 cm. Intermediate scenarios expect the sea level to rise  50 cm. by 2100.

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