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This study of changes in temperature and wind since 1979 met its twin aims of (i) increasing confidence in some findings of the latest IPCC assessment and (ii) identifying changes that had received little or no previous attention. It reports a small overall intensification and shift in position of the North Atlantic jet stream and associated storms, and a strengthening of tropical upper-level easterlies. Increases in low-level winds over tropical and southern hemispheric oceans are confirmed.

Observational data suggests that the extent of Arctic sea ice influences mid-latitude winter weather. However, climate models generally fail to reproduce this link, making it unclear if models are missing something or if the observed link is just a coincidence. We show that if one explicitly represents the effect of unresolved sea ice variability in a climate model, then it is able to reproduce this link. This implies that the link may be real but that many models simply fail to simulate it.

Persistent weather can lead to extreme weather conditions. One such atmospheric flow pattern, termed Recurrent Rossby wave packets (RRWPs), increases persistent weather in the Northern Hemisphere. Here, we show that RRWPs are also an important feature in the Southern Hemisphere. We evaluate the role of RRWPs and other atmospheric features during Southeast Australian heatwaves. We also study how RRWPs are related to other atmospheric features well-known for increasing heatwaves.

The Arctic is currently warming twice as fast as the global average. This results in enhanced melting and thus freshwater releases into the North Atlantic. Using a combination of observations and models, we show that atmosphere-ocean feedbacks initiated by freshwater releases into the North Atlantic lead to warmer and drier weather over Europe in subsequent summers. The existence of this dynamical link suggests that European summer weather can potentially be predicted months to years in advance.