The Dutch Approach 121 Dutch Climate Scenarios

The Dutch Meteorological Institute developed four climate scenarios for the Netherlands (KNMI, 2006). The scenarios for 2050 are based on two variables, which influence the Dutch weather in particular: changing air patterns and temperature rise. Thus, four scenarios are defined (Fig. 1.2): G (no change in air patterns and 1°C rise of temperature), G+ (changed air patterns and 1°C rise), W (no change

Luchtstromings-patronen

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G +

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+ 1°C

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G

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Wereld-. temperatuur in 2050 t.o.v. 1990

C Gematigd

W Warm

1°C temperatuurstijging op aarde in 2050 ten opzichte van 1990 geen verandering in luchtstromingspatronen in West Europa

VC temperatuurstijging op aarde in 2050 ten opzichte van 1990 -f winters zachter en natter door meer westenwind + zomers warmer en droger door meer oostenwind

2*C temperatuurstijg'mg op aarde in 2050 ten opzichte van 1990 geen verandering in luchtstromingspatronen in West Europa

2°C temperatuurstijging op aarde in 2050 ten opzichte van 1990 + winters zachter en natter door meer westenwind + zomers warmer en droger door meer oostenwind

Fig. 1.2 Climate scenarios for the Netherlands (KNMI, 2006)

Fig. 1.3 Average temperatures French cities equal 2006 and 2007 temperatures in the Netherlands (Source: KNMI, 2008)

Fig. 1.3 Average temperatures French cities equal 2006 and 2007 temperatures in the Netherlands (Source: KNMI, 2008)

in air patterns and 2°C rise) and W+ (changed air patterns and 2°C temperature rise). The changed air patterns imply a more moderate and wet winter caused by a dominant western wind as well as increased dry and warm summers, caused by a dominant eastern wind.

Recent climate in the Netherlands has been analysed by KNMI (2008). In 5 recent years warming continued. 2006 and 2007 are the warmest years since the Dutch started to measure temperature. These years represent the temperatures in the Netherlands can be compared with average temperatures in French cities, about 600-800 kilometres southward (Fig. 1.3). It is perfectly clear that the last 10-15 years most of the seasons are much warmer than normal (Fig. 1.4).

Fig. 1.4 Relative seasonal warmth since 1900 (Source: KNMI, 2008)

Fig. 1.4 Relative seasonal warmth since 1900 (Source: KNMI, 2008)

Fig. 1.5 Recorded trends in temperature rise between 1950 and 2007 (local temperature rise per centigrade rise of world average) (Source: KNMI, 2008)

The warming of the Netherlands takes place at a faster pace than expected. Since 1950 the Netherlands heated up twice as fast as the global average. Even if this is taken into account, 2006 (autumn) and 2007 (winter and spring) show extraordinary results. And if we compare the recorded trend in temperature in four seasons with the world average, the rise of temperature above North-Western Europe is evident in all seasons (Fig. 1.5).

The Dutch coast is in (late) summer wetter than the rest of the country. This is caused by the warming of the North Sea, resulting in heavy precipitation and water annoyance in the coastal provinces.

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