Condensed summary

While changes in the long-term mean state of climate will have many important consequences on a range of environmental, social, and economic sectors, the most significant impacts of climate change are likely to be generated by shifts in the intensity and frequency of extreme weather events. Indeed, insurance costs resulting from extreme weather events have been steadily rising since the 1970s, essentially in response to increases in population pressures in regions that are at risk, but also in part because of recent changes in the frequency and severity of certain forms of extreme. Regions that are now safe from catastrophic windstorms, heat waves, and floods could suddenly become vulnerable in the future. Under such circumstances, the costs of the associated damage could be extremely high. This chapter provides an overview of certain climate extremes that in recent years have had very costly impacts in the Swiss Alps – namely, heat waves and strong convective precipitation – and how these events may change as climate warms in response to increased greenhouse gas concentrations.

Introduction

If climate warms as projected during the course of the twenty-first century, the thermal energy that drives many atmospheric processes will be enhanced and, as a consequence, many types of extreme event may increase in frequency and/or intensity. Although this intuitive reasoning has a physical basis, current climate trends do not unequivocally show that atmospheric warming in the past century has been accompanied by greater numbers of extreme events.