This is what makes the Earth inhabitable. Thanks to this greenhouse effect (german), the global mean temperature in the lower atmosphere increases by around 32☌, from -18 to +14☌. Greenhouse gases such as water vapour, carbon dioxide, methane and nitrous oxide absorb the heat radiation and, in turn, radiate them back again. It is essential for life on Earth that the heat radiated by the Earth’s surface does not immediately leave the atmosphere. Thirty percent is reflected back into space and is lost. A further 20 percent is absorbed by the atmosphere, which also warms. Around half the radiation is absorbed by the Earth’s surface, which then heats up. The Earth’s weather and climate are driven by incoming solar radiation. Since Switzerland is part of the land mass in the central northern latitudes, it is also subject to the second effect. The decline in snow and ice cover, which leads to greater absorption of solar radiation, is likely to play an important role here, along with increased heat transport towards the pole. The second effect is that warming increases towards the pole in the northern hemisphere. In addition, since there is an unlimited amount of water available, much of the extra heat over the oceans is used in evaporation, which is not the case on land. Conversely, land masses do not store heat as effectively, which leaves more energy available for warming the air. Water masses absorb much of the extra heat and conduct it into the deeper ocean levels. One of these is that the warming which has been taking place over land – 1.6☌ compared to pre-industrial times – is much greater than it is over the oceans. There are two main effects that readily explain the difference between the mean global warming and the warming over Switzerland.
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