This year has been unusually cold. Here in Richmond, Virginia, after a warm fall, a cold spell hit in November, causing it to average below normal. Warm days came back in December, but now in January we have been hit by a major arctic blast of cold air. It has caused low readings all over the place in the Northeast, and the temperature dropped to 8 degrees here at my house. So does this refute the global warming theory?
One place to look is the Arctic itself, especially the ice there. In 2007 about a third of the Arctic Ocean melted into open water. This was a record melt. September ice cover has been declining steadily the last couple of decades. The Northwest Passage opened up for 2 months. You could have sailed or steamed from London to Tokyo by going through the passage instead of all the way around the Panama Canal or Cape Horn. In 2008, the weather was colder than usual, but the ice still melted, to the second lowest level on record, beaten only by the previous year. The entire Arctic ice sheet became an island, and both the Northwest Passage (Canadian Arctic islands) and the Northeast Passage (Russia) opened.
This year Hudson Bay froze up in the middle of December, which was about the same as it has been the previous few years. In January, the Great Lakes began to freeze. This is unusual. Usually they don't freeze until February. Already, Lake Erie is nearly frozen over, there is a sizable chunk of ice on Lake Ontario which usually remains ice-free, and the other lakes have substantial ice sheets on them. The ice on the Arctic Ocean is about the same as last year, and parts of the ice sheet are not expanding.
So it looks like we are having a colder than usual winter. This is something to observe, but it does not refute the global warming theory. The record September melts probably increased precipitation in the Arctic, and if that is snow, there is more of it to reflect light back into space. This may have caused the cool down. The theory is still supported. There have been extremes, such as Nenana, Alaska going from -52 F to 54 F in just three days; this is one effect of global warming. If you look at the graph of Arctic ice amounts for the past few years, you see a zigzag line going down. 2007 was one of the low points, and 2008 rebounded from that and was a little warmer.
So I predict a record melt this summer in the Arctic Ocean - perhaps half of the Arctic Ocean ice will be gone by September 2009.
Global warming is still a problem, and it may cause dramatic climactic changes, as well as forcing coastal cities to build floodwalls. It therefore helps to control carbon emissions, and by the way, this will also delay the ill effects of Peak Oil as well.