The role of increasing temperature variability in European summer heatwaves

Abstract

Instrumental observations and reconstructions of global and hemispheric temperature evolution reveal a pronounced warming during the past approximately 150 years. One expression of this warming is the observed increase in the occurrence of heatwaves. Conceptually this increase is understood as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small. Here we show that this framework fails to explain the record-breaking central European summer temperatures in 2003, although it is consistent with observations from previous years. We find that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account. We propose that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003. To test this proposal, we simulate possible future European climate with a regional climate model in a scenario with increased atmospheric greenhouse-gas concentrations, and find that temperature variability increases by up to 100%, with maximum changes in central and eastern Europe.

Long-term projections and acclimatization scenarios of temperature-related mortality in Europe

“…Europe emerges as an especially responsive area to temperature rise, particularly during the warm season 12 . The record-breaking 2003 heat wave in western Europe has been described as an extremely unlikely event given the observed warming, and to share similar characteristics with future summers simulated by state-of-the-art climate models for the end of the 21st century 6 (Fig. 1).…”

“…Daily temperatures 25 and numbers of deaths 13 corresponding to 187 NUTS2 regions (that is, second level of the Nomenclature of Territorial Units for Statistics 13 ) are studied here, which essentially correspond to the domain affected by the 2003 heat wave 6,8 and some neighbouring countries. Because of the extremely large differences in population between regions, they were grouped in 54 larger and more homogeneously populated areas.…”

“…In particular, increasing attention has been paid to warm extremes [6][7][8][9][10] , which are expected to become more frequent, longer and more severe 11 . Europe emerges as an especially responsive area to temperature rise, particularly during the warm season 12 .…”

Drought stress and carbon assimilation in a warming climate: Reversible and irreversible impacts

“…Additionally climate change models predict more frequent and more severe extreme events such as drought phases or heat waves (Schär et al, 2004;Fuhrer et al 2006;Mittal et al, et a., 2014;Fischer and Knutti, 2015;Teskey et al, 2015). Drought as well as elevated ambient temperature may cause considerable impacts on crop plants by disturbing essential physiological functions including photosynthesis, mineral nutrient acquisition, long-distance transport via xylem and phloem, interactions between organs as well as yield quantity and quality (Loreto and Centritto, 2008;Gilgen and Buchmann, 2009;Ji et al, 2010;Jentsch et al, 2011;Cottee et al, 2014;Molina-Rueda and Kirby, 2015;Ramya et al, 2015;Xu et al, 2015).…”

Intra- specific variation in response of Jatropha (Jatropha curcas L.) to elevated CO2 conditions

“…The impact of climate variation/climate change has been realized on the global agriculture through its impact on yields, as lower rates of increase in yields in areas of Europe with more extreme conditions have been reported (Schar et al 2004). Significant variation in the climate is attributed to increased levels of greenhouse gases viz.…”