Loss of Arctic Sea Ice Creates Long-Period Atmospheric Waves That Enhance Extreme Weather

A number of recent articles and reports from Geophysical Research Letters, WeatherUnderground, Climate Progress, and Climate Central have highlighted how loss of Arctic sea ice helps to create extreme weather events over the northern hemisphere. In short, the loss of ice moves the polar wind patterns and changes temperatures there in such a way as to create giant, lumbering atmospheric waves.

Now imagine a huge wave of air swooping down from the Arctic, digging deep into the mid-latitudes, and then swooping back up toward the poles again. This is what is happening with greater and greater frequency as Arctic sea ice continues to fade.

The wave patterns created are not only deeper, moving air through zones that typically have a variety of temperature and moisture conditions, they are also longer-lasting. The result is that you get an increasing number of zones of extreme, non-typical conditions parked over regions of the world for longer and longer time-periods. This summer’s drought is one example of a persistent weather condition caused by these atmospheric waves.

But other extreme events, including floods and long periods of colder weather, could be caused by these waves or, what meteorologists have tended to call ‘blocking patterns.’

One issue that researchers have raised is that these blocking patterns tend to establish themselves consistently over similar regions. What this means is that it is more likely for certain zones to experience a certain kind of blocking pattern. This is one feature that has helped to enhance drought and drying conditions in the central US throughout the past decade.

These blocking patterns have another dark side. They transport warmer air into the Arctic, pushing temperatures  closer to those of surrounding regions and further amplifying melt and carbon feedback. One typical pattern is a flow that pulls heat and moisture from as far south as the Gulf of Mexico and deposits that air near or over Greenland. This kind of flow had an influence on the extreme melt conditions that occurred there this year. If these kinds of flows are to become more common, we can expect to experience similar, or possibly more extreme, melting over Greenland in the years to come.

This strange elongating of atmospheric wave patterns creating persistent weather and increasing the likelihood for extreme, long-lasting conditions, overlaps a long-term regime of increasing temperatures. So more extreme weather is combining with hotter weather overall to create a very volatile brew.

A recent paper from the 2012 Geophysical Research Letter entitled ‘Evidence Linking Arctic Amplification to Extreme Weather in Mid-Latitudes‘ provides the scientific basis for these conditions. The following video essay is provided by one of the study’s authors, Jennifer Francis, and gives a very in-dept explanation for these events:

It is certainly worth watching if you have the time.

In any case, changes to the Arctic caused by global warming are leading to more extreme weather patterns. This impact shows that the climate response to a warming world is non-linear. It creates unexpected changes and extremes that severely alter our world. This change has happened in a world that has warmed, on average, about 1 degree Celsius since the 1880s. If such large atmospheric changes can occur with relatively ‘small’ temperature changes, one can imagine how much more strange and severe the weather may become with 1, 2, 4 or 6 degrees of additional warming.

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