Analyzing Internal Variability and Forced Response of Subdaily and Daily Extreme Precipitation Over Europe.

At regional to local scales internal variability is expected to be a dominant source of uncertainty in analyzing precipitation extremes and mean precipitation even far into the 21st century. A debated topic is whether a faster increase in subdaily precipitation extremes can be expected. Here we analyzed seasonal maximum precipitation in various time steps (3 hr, days, and 5 days) from a high‐resolution 50‐member large‐ensemble (CRCM5‐LE) and compared them to changes in mean precipitation over Europe. Our results show that the magnitude of change in extreme precipitation varies for season and duration. Subdaily extremes increase at higher rates than daily extremes and show higher scaling with temperature. Northern Europe shows widespread scaling above Clausius‐Clapeyron of subdaily extremes in all seasons and for daily extremes in winter/spring. Scaling above Clausius‐Clapeyron is also visible over Eastern Europe in winter/spring. For most regions and seasons the forced response emerges from the internal variability by midcentury. Plain Language Summary: The knowledge on how and why the intensity and frequency of extremes changes is critical to a resilient society. Our adaptive measures that are currently in place are based on observed extremes of the past. We know that observations are only one realization of a chaotic system and that the climate system is altered by natural variations, and anthropogenic contributions. Since we can only measure one realization of the world, we need climate models to investigate the influence of natural variability and anthropogenic factors. In this study we focus on the contribution of natural variability and the detection of regional patterns of changes in extreme precipitation. We used regional climate simulations, driven by multiple runs of global climate simulations under the same emission scenario, but with slight changes at the start of the simulation to imitate the butterfly effect of the climate system and simulate natural variability. We have found that natural variability plays a dominant role in the first half of the 21st century. But we have also found that subdaily extreme precipitation is increasing at a higher rate than daily extremes and that some of this change can be attributed to the warming of the atmosphere. Key Points: Subdaily extreme precipitation intensifies faster than daily extremes and mean precipitationOn regional scales internal variability remains a dominant source of uncertainty until the end of the 21st centuryWidespread scaling rates of subdaily extremes above Clausius‐Clapeyron over Northern and Eastern Europe [ABSTRACT FROM AUTHOR]