The Weekend Wonk: Jennifer Francis on Arctic Sea Ice
September 22, 2012
Dr. Jennifer Francis of Rutger’s Institute of Marine and Coastal Sciences is featured in my sea ice wrap video, which should be out early in the week.
Here is a lecture she gave in January of 2012. Longish, but worth dipping into, as she summarizes some of the most recent research in regard to the effects of shrinking arctic ice on weather and climate in the temperate latitudes – the so-called “arctic paradox” so beloved by Fox News – “if there’s global warming, why are we having this record snow storm?”.
What she told me in a recent interview was that the sea ice record is not something that we just pay attention to in September – there will, in fact, be reverberations that will make fall and winter “very interesting” around the globe.
UPDATE: Dr Francis has a column today in the Washington Post:
As temperatures over the Arctic Ocean fall with the approach of winter, the extra energy that was absorbed during summer must be released back into the atmosphere before the water can cool to freezing temperatures. Essentially, this loads the atmosphere with a new source of energy—one that affects weather patterns, both locally and on a larger scale. In spring, a similar phenomenon also occurs, but it involves snow cover on northern land areas. Snow has been melting progressively earlier each year; this past June and July it disappeared earlier than ever before. The underlying soil is then exposed to strong spring sun, which allows it to dry and warm earlier – contributing to Arctic amplification in summer months.
The difference in temperature between the Arctic and areas to the south is what drives the jet stream, a fast-moving river of air that encircles the northern hemisphere. As the Arctic warms faster, this temperature difference weakens, as does the west-to-east wind of the jet stream. Just as a river of water tends to meander when it reaches the gentle slopes of coastal plains, a weaker jet stream tends to have steeper north-south waves. Arctic amplification also stretches the northern tips of the waves farther northward, which favors further meandering. Meteorologists know that steeper waves are slower to shift westward.
The weather we experience at mid-latitudes is largely dictated by these waves in the jet stream. The slower the waves move, the longer the weather associated with them will persist. Essentially, “hot,” “dry,” “cold,” and “rainy” are all terms to describe very normal weather conditions. It’s only when those conditions persist in one area for too long that they are dubbed with the names of their extreme alter egos: heat waves, drought, cold spells, and floods. And these kinds of extreme events are precisely what we’ve seen more of in recent years.
Global warming now has a face and a fingerprint that directly touch each of our lives. Rather than just a gradual increase in temperature, we can recognize its influence in a shift toward more extreme weather events. A warmer atmosphere also means a moister atmosphere, so any given storm will have more moisture and energy to work with, increasing the chances of flooding or heavy snows. Arctic amplification adds another mechanism to the mix, making extreme weather more likely. The loss of ice and snow in the far north may load the dice for “stuck” weather patterns, compounding potential risks for our economy, our health, and our security.