A shifting jet stream in a changing climate. Exploring the response of the polar jet stream in the Northern Hemisphere to various climate futures.

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Earth's climate system is projected to experience significant changes into the 21st Century, but these changes have not expected to happen in a uniform way. While outputs from the current generation of climate models suggest surface temperatures in the Arctic are projected to warm faster than other parts of the planet into the 21st century, the Hadley circulation in the Tropics is expected to expand pushing both the sub-tropical dry zones and storm tracks further polewards (Serreze et al., 2009, Hu et al., 2018). These types of climatic shifts would considerably influence the current thermodynamic relationships that exist in the Northern Hemisphere, altering both the positioning and characteristics of weather systems there. Despite this, there is a general lack of agreement between climate models and observations on the current dynamics controlling changes in weather regimes, in part owing to granularity of the simulated upper atmosphere (in previous generation of climate models) and a lack of consensus over which proxy can be used study this phenomena (CMIP5, Cohen et al., 2020). The main aim of this PhD is to explore the response of the jet-streams, one such proxy, in state-of-the-art climate models across various future climate scenarios - making use of outputs from the latest Coupled Model Intercomparison Project (CMIP6). Using CMIP6 simulations, this project will search for emergent and observational constraints to evaluate the accuracy of, and constrain projections for, future jet-stream behaviour across the climate model ensemble.