Decrease of the dynamical and spatial variability of the Euro-Atlantic eddy-driven jet stream with global warming

The atmospheric eddy-driven jet stream is one of the main features of the mid-latitude circulation. Although mostly zonal in climatological mean, the jet stream meanders at meteorological time scales. The jet and its variability have been under great scrutiny in the past years for their role in the triggering of extreme events (e.g. heat or cold waves) in mid-latitudes regions. Because of the large variability of the jet, the impact of climate change remains elusive. Here we study the eddy-driven jet stream over the Euro-Atlantic sector and assess its dynamical properties in ERA5 and ERA20C reanalysis data set using indicators from dynamical system theory. We then use a causal framework to disentangle the impact of global warming from the impact of natural variability of the climate system on the jet. We find that over the period 1900-2010, global warming decreased the spatial and dynamical variability of the jet. This decrease in variability is connected to an increase in jet persistence and speed. We additionally observe a poleward shift of the jet. Our results suggest a zonalisation of the jet under global warming