Duration and size of blocking events: Future changes and the impact on weather extremes

Changes in characteristics of blocking events due to climate change can affect the impact of some types of weather extremes, such as heat waves. Much attention has been focused on changes in the frequency of blocks. However, changes in other characteristics such as size, duration, and vertical structure can also significant affect the resulting extreme events. Here, using a combination of theory, model hierarchy, and reanalysis data, we investigate potential changes in these characteristics of blocking events and the underlying mechanisms. In particular, we will discuss a robust increase in the size of the blocking events, consistent with a scaling law developed using the Buckingham-PI theorem. The duration of the blocking events, on the other hand, remains unchanged despite large changes in the the speed of the westerlies. We aim to explain these findings using a conceptual model of blocks, the traffic-jam model.