NOAA: Future of Arctic Sea Ice and Global Impacts. Higher pressure surfaces above the North Pole are thought to impact large scale wind patterns over the Northern Hemisphere

NOAA: Future of Arctic Sea Ice and Global Impacts

Teleconnections impact mid-latitudes

[Dear Readers, sorry about the formatting issues --please go to the link at the bottom of this post to see the figures properly.]

Higher pressure surfaces above the North Pole, due to the warmer temperatures associated with greatly reduced sea ice, are thought to impact large scale wind patterns over the Northern Hemisphere. Climate models show these connections with cold air moving south, producing low pressure areas and unusually cold winters in the eastern U.S. and eastern Asia, and cooler than usual weather in late winter from Europe to the Far East^1,2,3,4,5 (Figure 1, below). This would be only one factor among many influencing U.S. and Eurasian weather.  How do we think we know this?

Figure 1. Severe winters in eastern US and E. Asia are related by teleconnections to changes atmospheric pressure and winds following loss of Arctic sea ice. Figure from NOAA.

How does Arctic ice loss impact the climate system? The diagram in Figure 2 (right) explains the Arctic climate feedback and its global implications. As the earth warms, the warming is amplified in the Arctic. More sea ice melts in the summertime, and with more open water, heat from the sun is absorbed in the ocean. With the warmer Arctic, winter freezeup is delayed, resulting in thinner wintertime ice. The heat absorbed into the ocean in summertime is released to the atmosphere in the fall, warming the atmosphere and changing the atmospheric pressure surfaces over the pole. This dome of warm air and elevated atmospheric pressure surfaces over the pole changes the Arctic atmospheric wind patterns, allowing outbreaks of cold Arctic air to the south.
		Figure 2. Arctic Climate Feedback and its Global Implications. Figure from NOAA.

Europe and East Asia have more severe winter storms Observational evidence shows that the recent significant cold anomalies over the Far East in early winter and cold temperature anomalies from Europe to Far East in late winter are associated with the decrease of the Arctic sea-ice cover in the preceding summer-to-autumn seasons. Results from numerical computer simulations using an atmospheric general circulation model support these notions (Figure 3).¹

Figure 3. Computer simulations of unusually high constant pressure surfaces in the upper atmosphere (red) over regions without sea ice and unusually low pressure surfaces (purple) over E. Asia in December. Figure from Honda, et al.1 United States has more severe winter storms Preliminary results from numerical computer simulations indicate that  the significant cold anomalies over the eastern US in winter are associated with the decrease of the Arctic sea-ice cover in the preceding summer-to-autumn seasons (Figure 4, right).2 Although there is considerable year to year variability, as summer Arctic open water area increases over the next decades, an increasing influence of loss of summer sea ice on northern hemisphere wind patterns can be anticipated, with resultant impacts on northern hemisphere weather. Link:  http://www.arctic.noaa.gov/future/impacts.html
		Figure 4. Computer simulations of unusually high temperatures (red) over regions without sea ice and subsequent unusually cold area (blue) over the eastern U.S. in the following October/November. Figure from Strey, et al.2