1. The use of CHALLENGE data in climate change detection claims Albert Klein Tank, KNMI Source: CRU/MetOffice, 2004

2. Recent warming also observed over Europe

3. Warming dominates in all seasons, except Autumn (bottom right)

4. Climate change detection/attribution: At the global scale most of the warming observed over the last 50 years is attributable to human activities.

5. Climate change detection/attribution: At the global scale most of the warming observed over the last 50 years is attributable to human activities. At the continental scale (Europe), the attribution of the observed warming trends to human influence is not (yet) firmly settled due to the larger natural variability.

6. Climate change detection/attribution: At the global scale most of the warming observed over the last 50 years is attributable to human activities. At the continental scale (Europe), the attribution of the observed warming trends to human influence is not (yet) firmly settled due to the larger natural variability. Anthropogenic signals have not yet been positively detected at all in series of extreme events, despite their obvious relevance for society.

7. Climate change detection/attribution: At the global scale most of the warming observed over the last 50 years is attributable to human activities. At the continental scale (Europe), the attribution of the observed warming trends to human influence is not (yet) firmly settled due to the larger natural variability. Anthropogenic signals have not yet been positively detected at all in series of extreme events, despite their obvious relevance for society. We use CHALLENGE data to investigate whether changes in the frequency of modest temperature extremes in Europe (expressed by T90-T10) are a possible fingerprint of human influence.

8. European window CHALLENGE data

9. European station data

10. Spring change in T90-T10: trends (left) – natural variability (right)

11. Summer change in T90-T10: trends (left) – natural variability (right)

12. Autumn change in T90-T10: trends (left) – natural variability (right)

13. Take-away messages: 1. Some of the characteristics of the recent warming in Europe provide a possible fingerprint of human influence, because they are different from the estimated patterns associated with natural temperature variability. 2. Similar differences are seen in CHALLENGE between the patterns in the future greenhouse warming simulations and the current climate simulations. 3. The advantage of the CHALLENGE data is that natural variability is explicitly accounted for in the ensemble of 62 climate model simulations.