It’s suddenly extremely cold today in Ohio. When I got up this morning, it was 0 degrees with 35 mph wind gusts. Just looked at thermometer again, and it is now -1 degree F, and the forecast is for falling temperatures today. You may hear some folks ask, “So where’s the global warming we’ve been hearing about?” Of course, you are probably aware of the differences between climate and weather, weather being a more short-term experience, which can include considerable volatility. Climate is the long-term picture.
However, a longer-term pattern of suddenly colder and then suddenly warmer weather in the middle latitudes, according to climate scientists, is likely an effect of general global warming. Here’s why.
Global warming is causing the polar regions to warm twice as fast as the middle latitudes. This is due to the fact that ocean ice in the artic is being reduced quite rapidly. Thus, the reflective white surface is being replaced by the dark ocean surface, which causes more heat to be absorbed, and yet more ice to melt, and warming to accelerate in the arctic from this feedback loop.
This accelerated warming in the arctic is causing a reduction in the temperature gradient, the contrast between the temperatures of polar regions and those of the middle latitudes being reduced. This reduction in temperature gradient affects the jet stream, weakening it, reducing its speed, and causing it to dip more north and south rather than remaining a mostly west-east direction.
This dipping can bring colder air down from the artic or bring unusually warm air up from southern regions. So, for example, the end of January could be much colder than normal with a sudden change in a week to several weeks later to much warmer than normal. (Just saw forecast for warming to around 50 degrees four or five days from now.) Once in a while this large temperature swing happens within the normal climate range, but the pattern seems to be repeating more than normal, probably as a result of global warming that especially affects the polar regions. So watch the rest of the winter. What will February and March be like? You might be able to detect yet more evidence of this global warming effect.