MSO Climate Variability and Extremes (VAREX)

We aim to better understand future changes in climate variability and extremes in Europe, and will contribute to the climate knowledge used in the KNMI climate scenarios.

To achieve this, in the VAREX project we have developed a new large ensemble data set (Muntjewerf et al. 2023), which in the remaining time of the project will be used for analyses of different climatic extremes.

Many climate change studies aim to quantify and explain changes in mean climate. This overlooks somewhat the importance of climate variability, a fundamental aspect of the climate system that is also subject to forced trends. Understanding climate variability, and the relative size of forced changes in the mean to this variability, is necessary for quantifying climate extremes and hence for designing adequate local adaptation strategies. In the KNMI climate scenarios (2014) one of two axes of uncertainty depicts the direction and magnitude of changes in large-scale circulation, i.e. the change in climate variability.

The work in this project builds on recent work from KNMI scientists. For example, Bintanja et al. (2020) showed that long-term trends in Arctic climate variability are different from those in the mean climate, and attributed this difference to the specific physical processes leading to changes in climatic variability and those leading to changes in mean climate. Furthermore, for climatic extreme events, splitting the effects of a changing mean climate and changing climate variability as in Van der Wiel and Bintanja (2021), provided new insight on the relative importance of the two processes of change.

We will assess future trends in climate variability/extremes over Europe, and elucidate the governing climate feedbacks and processes behind these changes. The new information will be used to explain and constrain process-based uncertainty in future climate projections. The project is part of KNMI’s Multi-year Strategic Research (MSO) and is expected to start in September 2021.