In interviews, several scientists recalled that in the decade ending in the mid-1990s, the polar vortex seemed to be strengthening, not weakening, producing mild winters in the eastern United States and western Europe.
At the time, some climate scientists wrote papers attributing that change to global warming. Newspapers, including this one, printed laments for winter lost. But soon after, the apparent trend went away, an experience that has made many researchers more cautious.
John M. Wallace, an atmospheric scientist at the University of Washington, wrote some of the earlier papers. This time around, he said, it will take a lot of evidence to convince him that a few harsh winters in London or Washington have anything to do with global warming.
“Just when you publish something and it looks like you’re seeing a connection,” Dr. Wallace said, “nature has a way of humbling us.”
Let the humbling continue.