final_program_abstracts[1]

11 IMSC Session Program
Monitoring information on weather and climate extremes in
support of climate change attribution studies
Friday - Plenary Session 7
Albert Klein Tank
Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands
Changes in weather and climate extremes are among the most serious challenges to
society in coping with a changing climate. The sustainability of economic
development and living conditions depends on our ability to manage the risks
associated with extreme events. According to the latest IPCC report, ‘confidence has
increased that some extremes will become more frequent, more widespread and/or
more intense during the 21st century’. But what changes in weather and climate
extremes do we observe already over recent decades, how certain are we about these
changes, and are our monitoring systems adequate to address these questions?
In this talk, some examples of available observational evidence for changes in
extremes will be shown from the European Climate Assessment & Dataset project
(ECA&D; http://eca.knmi.nl). This project provides vital ingredients for successful
monitoring of weather and climate extremes across Europe, even reporting online
during emerging extreme events. ECA&D is embedded in worldwide activities that
monitor extremes on the basis of station data using standardized descriptive indices.
Each index describes a particular characteristic of climate change, both changes in the
mean and extremes. Observed changes in mean state inevitably affect extremes.
Moreover, the extremes themselves may be changing in such a way as to cause
changes that are larger or smaller than would simply result from a shift of variability
to a different range.
The core set of temperature and precipitation indices in ECA&D follows the
definitions recommended by the joint CCl/CLIVAR/JCOMM Expert Team on
Climate Change Detection and Indices (ETCCDI). This team has helped to design and
implement a system of indices and tools that enable a consistent approach to the
monitoring, analysis and detection of changes in extremes of temperature and
precipitation by countries and regions across the globe. An additional set of indices in
ECA&D highlights other characteristics of climate change in Europe (including snow
depth, sunshine duration, etc.). Latest developments include the use of extreme value
theory to complement the descriptive indices of extremes, in order to evaluate the
intensity and frequency of more rare events. Changes in return values for events that
occur up to once in 50 years are compared to the trends in the indices for more
moderate extremes.
Abstracts 296