Influence of heat waves on ischemic heart diseases in Germany – present situation and climate change

The impact of heat waves on ischemic heart disease (IHD) mortality and morbidity in Germany during 2001-2010 is analyzed. Heat waves are defined as periods of at least 3 consecutive days with daily mean temperature above the 97.5th percentile of the temperature distribution. Daily excess mortality and morbidity rates are used. All calculations were performed separately for 19 regions to allow for the investigation of regional differences. The results show that IHD mortality during heat waves is significantly increased (+15 % more deaths on heat wave days). In stark contrast, no heat wave influence on hospital admissions due to IHD could be observed. Regional differences in heat wave IHD mortality are present, with the strongest impact in Western Germany and weaker than average effects in the Southeastern and Northwestern regions. The increase in mortality during heat waves is generally stronger for females (+19 %) than for males (+11 %), and for chronic ischemic diseases (+18 %) than for myocardial infarctions (+12 %). Longer and more intense heat waves feature stronger effects on IHD mortality, while timing in season seems to be less important. Furthermore, the influence of future climate change on the occurrence of heat waves in Germany is studied. Simulations of 19 regional climate models with a spatial resolution of 10-25 km are analyzed. All of the models use a moderate green house gas forcing according to the SRES scenario A1B. Three model time slices of 30 years are evaluated, representing present climate (1971-2000), near future climate (2021-2050) and remote future climate (2069-2098). Heat waves are identified by the above mentioned heat wave definition, each time using the present climate 97.5th percentile temperature threshold. Based on the model simulations, future heat waves in Germany will be significantly more frequent and longer lasting. By the end of the 21st century, the number of heat waves will be tripled compared to present climate. Additionally, the duration of heat waves will increase by 25 %. Altogether, the number of heat wave days will be four times higher in the period 2069-2098. Regional analyses show that stronger than average climate change effects are observed particularly in the Southern regions. Even though the used methodology does not imply possible adaptations to climate change, it is most likely that the individual heat burden will increase considerably. The obtained results point to public adaptation strategies to reduce the vulnerability of the population to heat waves.

Acknowledgments: This work was funded by the Federal Environment Agency and the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety as part of the project UFOPLAN-371161238 “Climate change, bioclimatology and health effects” (2012-2014), embedded in the German Adaptation Strategy to climate change.