Extreme events

Determining the likelihood and severity of extreme events for the past, present and future.

Extreme weather events have the capability to severely affect our lives and it is probably through changing extremes that we will first experience or notice a changing climate. However, the area of extreme events is one of the most challenging areas of climate change to address. By definition such events are rare and so we do not have many to study. Furthermore they push climate models to the limits of their design. Many extreme events are not well captured by climate models, either because they are too small in size or the physics of such events are not well captured. We, therefore, use the most advanced statistics and climate models to tease out changes for both the past and the future.

Key aims

  • To quantify how and why extreme events have changed in the past.

  • To quantify the present day risk from extreme events.

  • To quantify how the risk from extreme events may change in the future.

  • To understand the processes causing extreme events and how these are represented in climate models.

Current projects

  • Detecting how extremes have changed in the past and attributing to causes, for example increased greenhouse gasses — Nikos Christidis.

  • The European 2003 summer heatwave possibly caused up to 30,000 premature deaths. How might these events change in the future? To what degree do proposed targets for limiting global mean warming limit the future risk of such events occurring? Will the weather patterns that cause such severe heatwaves become more frequent , thereby increasing the occurrence of 2003 type heatwaves? — Robin Clark.

  • England very nearly ran out of water in the summer of 1976 mainly due to the lack of rainfall over the previous 18 months. Will such long dry spells become more frequent and severe? Will we have to build more reservoirs to keep the taps running? How does increased CO2, plant photosynthesis and transpiration, increased atmospheric drying and changing rainfall all interact and alter future drought? — Eleanor Burke.

  • Extra-tropical cyclones, such as typical UK winter storms, have, in the past, caused extensive damage resulting in large insurance claims, yet how they might change in the future is still unclear. Many climate models have been analysed to see what the future brings but, as yet, there is no consensus in what the UK and Europe should expect in the future. Why do climate models disagree and what are the dominant driving factors for future changes in extra-tropical cyclones? — Ruth McDonald.

  • For many costal communities and insurers the biggest threats come from Tropical Cyclones. They  are too small to be properly resolved by most climate models so alternative techniques are needed to predict future changes — Joo-Hong Kim.

  • As the climate changes, the probability of an extreme event also changes. How can we characterise this change in the most robust way? New applications of non-stationary extreme value theory are being developed to allow the changes to be quantified year on year taking account of uncertainties in modelling the climate — Simon Brown.

Last updated: 4 November 2010