The dynamics of extreme wave-activity events in a warming climate.

Climate change is projected to have wide ranging impacts on the atmospheric waves and mean-flow. However, it remains uncertain as to how exactly the warming climate will influence the mean-waviness of the jet stream and extreme wave-activity events in the midlatitude storm track. An objective identification of this phenomena is important as wave-activity aloft plays an important role in driving the extreme weather events over the continents. Here we use the local wave activity (LWA) metric to quantify stationary and transient wave activity during winter-time from multi-member ensembles of state-of-the-art climate model simulations including, NorESM, CESM-LENS2 and MPI-LE simulations for Historical and various SSP warming scenarios. Our analysis reveals a statistically significant decrease in the mean-waviness of the jet stream and region-specific changes in the probability of extreme wave-activity events in the midlatitudes. These changes are found to be dynamically consistent with the theoretical predictions from the non-acceleration relation and the recently proposed traffic-jam theory of atmospheric blocking.