Climate development in the last century - Global and regional

The global mean temperature increased by approximately 0.6-0.7 °C within the last century, the measured increase being quite different depending on the region under investigation. It can generally be said that the slightest temperature increases were measured at the equator but were increasing towards the Poles. Regarding precipitation, the second strongly climate-relevant parameter, the changes were regionally quite different. As a tendency, it can be said that the annual sum in regions with high precipitation sums will increase, whereas the annual sum in regions with low precipitation sums will decrease. The climatic impacts of the regions of Germany strongly at risk of tick-borne diseases result from the comparison of the previous climate in the period 1951-2003, the basic scenario, and climate changes to be expected for the period 2004-2055, the future scenario. In the basic scenario, temperature will increase between 0.6 and 1.5 °C depending on the region under investigation. With a few exceptions, an increase of precipitation is observed in winter and a decrease in summer. Regarding the changes of threshold events, we draw attention to the development of summer days (maximum temperature ⩾25 °C), of frost days (minimum temperature <0 °C), and of days with heavy precipitation (precipitation ⩾10 mm). With regard to extremes, threshold events were analysed. Hence, like in the basic scenario, this resulted in an increase of summer days and a decrease of frost days; however, an inconsistent trend can be noted for days with heavy precipitation. Due to these strong and regionally distinctly differentiated climate changes, the question arises in how far these changes have an influence on tick-borne diseases and which developments are emerging as to a further climate-related spread to be expected.