The Climate Story

1. Why is it important to consider climate?

The climatic conditions affect many aspects of our day to day life. Assessing changing climate conditions are the basis of investigating their impacts.

Various aspects of a changing climate under 2°C conditions are investigated by the IMPACT2C community. On the one hand, changes in mean climate indicators are investigated, such as temperature, precipitation and evapotranspiration. On the other hand, changes in extremes are reviewed, such as extreme precipitation, summer heat waves and tropical nights and cold spell duration. Extreme precipitation, e.g., affects directly the health sector, as flood events and landslides caused by extreme precipitation can lead to human loss.  Further temperature-related indicators were assessed, such as the number of freeze-thaw days, snow season length and the thermal growing season length. These indicators can be directly related to impacts, e.g., freeze-thaw days  can affect aviation, roadways and railways.

2. What are the key findings?

The assessment of the temperature values showed that most regions in Europe exhibit a robust warming greater than the global average. The warming is greatest in the North in winter and in the South in summer. Precipitation is projected to increase in the northern part of Europe and to decrease in the southern part. The drying in southern Europe is most pronounced in the summer months. Changes in evapotranspiration follow changes in precipitation where generally 30 to 50% of the increase in precipitation is counteracted by enhanced evapotranspiration.

Concerning heavy precipitation in Europe, an overall slight increase is projected under +2°C conditions. There are single regions which experience stronger increases in extreme precipitation than others. One of these regions is the area of North-East Italy, Western Slovenia, and Southern Austria, where an increase of up to 6 mm/day in extreme precipitation is projected. Heat waves will become more frequent, intense and will last longer. In a 2°C warmer climate, the number of heat wave days will more than double in Europe, with much larger increases in Mediterranean areas. Tropical nights are becoming more frequent in southern Europe. Also central and eastern Europe will begin to experience tropical nights. On the other hand, cold spell duration strongly decreases across Europe under a scenario of 2°C warming.

The number of freeze-thaw days decreases almost everywhere in Europe at +2°C global warming. For example, in northern Europe, the number of freeze-thaw days decreases from 30-60 days per year to over 15 days on average. The snow season length decreases overall. Some areas, especially at lower altitudes, may lose the whole snow season. At higher altitudes, the snow season length will be shortened by one to two months. On the other hand, the thermal growing season length increases everywhere at +2°C global warming. This might not mean that the actual growing season will be longer because other factors aside from temperature play a role such as water related changes. Positive impacts are likely to be limited to very specific regions in northern Europe.

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