[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2014/07/EW-07-14-14-Warm-Pacific.mp3|titles=EW 07-14-14 Warm Pacific]
Last winter was one of the coldest on record in the American Midwest. Northeastern cities were buried in snow. Meteorologists kept talking about the “polar vortex”. And meanwhile, western states were unseasonably warm and were stricken by drought. By all accounts, it was a weird winter.
A number of scientists attributed all of this to warming in the Atlantic and melting of sea ice, leading to changes in the jet stream. However, a climate expert at the University of Oxford has offered a different explanation: unusually warm waters in the Pacific.
During the past winter, abnormally warm western Pacific waters lead to enormous thunderstorms that reached high into the atmosphere. The result of all this upper atmospheric energy was a rerouting of the jet stream. That, in turn, sent warm air north toward Alaska and allowed cold air to drop south and freeze large parts of North America. The same warm waters provide an explanation for the strength of the supertyphoon that struck the Philippines in November.
Whether the unusual winter weather was the result of Arctic melting or warm Pacific waters is a matter of considerable debate among climate scientists. The Pacific warming is more likely to be a natural climate variation that was only somewhat amplified by global climate change rather than a trend. The arctic melt, on the other hand, appears to be an ongoing phenomenon. If the warm Pacific theory is correct, wild winters like the last one might not necessarily become the new normal.
**********
.
Web Links
Weird Winter: Is the Pacific to Blame?
Photo, posted April 10, 2009, courtesy of Wouter Kiel via Flickr.
.
Earth Wise is a production of WAMC Northeast Public Radio.