The amplified warming of the Arctic in recent decades has been related to extreme weather events over the mid-latitudes, but its relative importance compared to other influences is not yet well understood. A Nature Research collection highlights evidence from theoretical and observational studies, as well as implications for future extreme events.
Arctic change and mid-latitude weather
The Arctic is warming much faster than the rest of the planet, a phenomenon called Arctic amplification. The enhanced warming results in a massive loss in sea ice and snow cover, which in turn interact with the atmosphere. These changes can have consequences beyond the Arctic region and they have been related to an increased frequency and intensity of extreme weather events across the Northern Hemisphere mid-latitudes.
The possible link between Arctic change and mid-latitude climate and weather has spurred a rush of new observational and modelling studies. While there are some arguments for a causal relationship between Arctic amplification and mid-latitude weather extremes, the significance of an Arctic influence is still discussed. To reflect on this vivid debate, this Nature Research collection combines commentary and reviews articles with primary research articles published in Nature Communications, Nature, Nature Geoscience and Nature Climate Change.
Arctic warming affects weather and climate thousands of miles to the south. Scientists are split on how large this effect is.
Climate scientists cannot agree on what caused a recent spate of severe winters over North America and Eurasia. Now, a simple yet powerful physics-based approach makes it clear that record-low Arctic sea ice coverage was not the root cause.
Reviews & Perspectives
Consistency and discrepancy in the atmospheric response to Arctic sea-ice loss across climate models
Changes in Northern Hemisphere atmospheric temperature, pressure patterns and winds emerge as a consistent response to Arctic sea-ice loss in six coupled climate models.
Accelerated global warming in the Arctic might have profound impacts on mid-latitude weather particularly in winter, although the evidence for an effect also in summer is also growing. Here Coumou et al. show that these interactions could lead to more persistent hot-dry extremes in mid-latitudes.
Amplified warming in the Arctic has been linked to weather variability in the midlatitudes. This Review considers the evidence from both observations and modelling studies on this link for increasing severe winter weather, including cold temperatures and heavy snowfalls.
Understanding the thermodynamics of air-mass transformations that occur in the atmosphere at the boundary between the Arctic and mid-latitudes is key to improving weather and climate predictions, according to a literature synthesis
A reduced gradient in temperatures between low and high latitudes during the Holocene led to drier mid-latitudes.
Mid-Holocene climate was characterized by strong summer solar heating that decreased Arctic sea ice cover. Here the authors show that this sea ice loss had profound effects on the climate system, distinct from direct effects of solar heating, over North America, northern Asia, and the North Atlantic.
The connections between Arctic sea-ice loss and severe Eurasian winters are complicated by differences among studies. Correcting model underestimates reveals that 44% of the central Eurasian cooling trend is attributable to sea-ice loss in the Barents–Kara Seas.
Two independent methods, applied to observations and climate models, suggest that changes in atmospheric circulation drive cold winters in mid-latitudes and coincident mild Arctic winters. Reduced Arctic sea ice causes Arctic warming but has minimal influence on the severity of mid-latitude winters.
Variability of summertime Arctic sea-ice reduction is closely linked to transient Arctic anticyclones, which result from air mass injections into the Arctic upper troposphere associated with extratropical cyclones.
El Niño warms the tropical Atlantic, which in turn induces an anomalous Rossby wave train, triggering Arctic sea-ice growth and Eurasian warming in the El Niño decay year. This teleconnection via the tropical Atlantic and the Arctic in La Niña decay year contributes to Eurasian cold winter extremes.
The North Atlantic jet stream has become 15 per cent more sheared in the upper atmosphere since 1979, an expected consequence of climate change, and consistent with increased aircraft turbulence.
Whether accelerated Arctic warming is favorable for more frequent severe winter weather remains controversial. Here the authors present an observational analysis that links Arctic warming to severe winter weather, showing that extreme weather is 2–4 times more likely in the eastern US when the Arctic is warm.
Persistent atmospheric ridging in the North Pacific steered storms away and led to the California drought of 2012-16. Here the authors use simulations to show that sea-ice changes trigger reorganization of tropical convection resulting in drying over California.