The S.S.W. in February caused a major disruption to the atmospheric jet stream of the Northern Hemisphere — the strong westerly winds that encircle the Arctic — by driving the jet stream to teeter and temporarily slow. Without westerly winds to transport weather from west to east, cold air streamed in over Europe and parts of North America from the northeast. As a result, Europe was freezing while the Arctic was extremely warm.

We don’t know yet whether the S.S.W. pattern drove warming in the Arctic this year and whether climate change influenced this weather pattern. But we do know from paleoclimate reconstructions that Arctic warming rates in the industrial era are happening faster than at any time in the past 12,000 years and that the Arctic’s sea ice decline is now greater than at any time in at least the past 1,450 years. Recent warming and ice loss are inevitably linked to climate change caused by human activity. But more research is needed to understand events this winter because the conditions were so unusual.

Both the S.S.W. and the Arctic warming were forecast with outstanding accuracy in timing and magnitude about two weeks in advance, which allowed parts of Europe hit by the unusually frigid weather plenty of time to prepare. American scientists are now developing new computer models to improve forecasts so that they go beyond two weeks by taking into account ocean temperature, circulation and sea ice cover.

Preparing for future shifts in weather extremes also requires a better understanding of how the climate is changing. This will require long-term government investment in surface-based and satellite observations, and in the continued development of new computer models for improved predictions. Even as funding for climate change research has become highly politicized and is under threat, record numbers of talented students are applying at our universities to do graduate work in climate science. Given enough support, they could improve our future by helping us prepare for it.

The extreme Arctic warming this winter is a foreshadowing of things to come. On our current greenhouse emissions trajectories, the Arctic Ocean is expected to be ice-free in late summer by about midcentury or possibly as early as 2030, depending on natural variability. The impact will extend beyond the Arctic, adding to warming and sea level rise throughout the Northern Hemisphere.