Trends in the atmospheric jet streams are emerging in observations and could be linked to tropical warming

[knocker]

Abstract

Climate models predict a weak poleward shift of the jets in response to continuing climate change. Here we revisit observed jet trends using 40 years of satellite-era reanalysis products and find evidence that general poleward shifts are emerging. The significance of these trends is often low and varies between datasets, but the similarity across different seasons and hemispheres is notable. While much recent work has focused on the jet response to amplified Arctic warming, the observed trends are more consistent with the known sensitivity of the circulation to tropical warming. The circulation trends are within the range of historical model simulations but are relatively large compared to the models when the accompanying trends in upper tropospheric temperature gradients are considered. The balance between tropical warming and jet shifts should therefore be closely monitored in the near future. We hypothesise that the sensitivity of the circulation to tropical heating may be one factor affecting this balance.

https://www.nature.com/articles/s43247-023-00792-8

[richie3846]

On 15/10/2023 at 09:58, knocker said:

Abstract

Climate models predict a weak poleward shift of the jets in response to continuing climate change. Here we revisit observed jet trends using 40 years of satellite-era reanalysis products and find evidence that general poleward shifts are emerging. The significance of these trends is often low and varies between datasets, but the similarity across different seasons and hemispheres is notable. While much recent work has focused on the jet response to amplified Arctic warming, the observed trends are more consistent with the known sensitivity of the circulation to tropical warming. The circulation trends are within the range of historical model simulations but are relatively large compared to the models when the accompanying trends in upper tropospheric temperature gradients are considered. The balance between tropical warming and jet shifts should therefore be closely monitored in the near future. We hypothesise that the sensitivity of the circulation to tropical heating may be one factor affecting this balance.

https://www.nature.com/articles/s43247-023-00792-8

Thanks for this link, it's really interesting. The authors indicate that this information may not be reflected in current climate models, and may impact regional climate modelling as a result. 

Reading between the lines, perhaps our UK climate modelling is not accurate at all, because a north shifted jet may not be in the modelling. 

This study throws a spanner in the works for anyone who thinks that climate science is 'settled'. A phrase I've heard used more than once. Changes in the position of the jets, may have an enormous impact on large populations, especially in Europe where many people live with the ever changing jet position, day in day out. 

40 years is a really short timescale, so who knows if this information is a reflection of what may happen next.