Winter in Helsinki (and the world)

As previously discussed on this blog, the first half of November 2006 was colder than normal and the second half was warmer than normal. This warmth continued through December and through half of January. Upon returning to Helsinki this weekend, it's been below freezing and snowing. We're expecting temperatures between -10 and -20 deg C in Helsinki later this week, before a possible warm up at the end of the week. It turns out that other parts of the Northern Hemisphere have been complaining about the unusual warmth, too. The rest of Europe has had ski races cancelled. The eastern US has been unusually warm, too. What's going on?

The picture is the temperature anomalies across the world for December 2006 in degrees Celsius. [For nonmeteorologists reading this post, approximately double degrees C to see the anomalies in degrees Fahrenheit. Precisely, 9 degrees F equals 5 degrees C.] Nearly all of the northern mid and high latitudes were unusually warm. As Kerry Emanuel (atmospheric science professor at MIT) said in response to me posting this map on a weather discussion list, the anomaly just north of Europe is associated closely with the loss of sea ice in this region.

A late start to the winter is consistent with the signs of climate change due to global warming. The ring of warmer temperatures in the mid and upper latitudes is consistent with the signs of global warming. Of course, identifying any particular temperature anomaly with global climate change is to be avoided, but more and more evidence is accumulating that the climate is changing in an abrupt manner. A nonscientist I talked to claims that this is the year that Finland really recognized the significance of climate change. (They had an unusually warm summer, too.) If this winter is an indication of things to come under a warmed Earth, I'm very scared.