[Global sea ice anomaly versus the 1979-2008 mean; recent spike pushes sea ice areal extent to nearly 1 million square kilometers above the norm)
Overall summary The Great Lakes has received a lot of attention lately for its tremendous build-up of ice this winter – and it still stands at historically high levels for ice coverage (below) for this time of year - but the northern hemisphere as a whole remains at below-normal levels for sea ice areal extent by about 566,000 square kilometers (versus 1979-2008 mean). On the other hand, the southern hemisphere sea ice areal extent continues to be at or near record high levels for this time of year at around 1,342,000 square kilometers above the norm and this has boosted global sea ice to above-normal levels on the order of 1 million square kilometers. In fact, there has actually been a spike in recent weeks (above) with respect to global sea ice areal extent to these levels which have been seen only rarely in the past several years.
[Great Lakes ice coverage remains above 50%; well above all years back to the winter season of 1980/1981]
Northern Hemisphere Sea Ice The northern hemisphere sea ice areal extent is still below-normal for this time of year although it has gained significantly in the past several weeks relative-to-normal and remains well above the lowest points of the past few years. The northern hemisphere sea ice areal extent has generally trended lower since the mid 1990’s to mostly below-normal levels since the turn of the century. In the past several years, however, there has been a leveling off of the trend line in terms of sea ice areal extent at those below-normal levels. In the time period before the mid 1990’s, the sea ice extent was generally above-normal dating back to 1979.
This directional change in trend that developed during the mid 1990’s correlates quite well with a northern Atlantic Ocean sea surface temperature cycle that is tracked by meteorologists through an index called the Atlantic Multidecadal Oscillation (AMO). Indeed, the Atlantic Ocean has a significant impact on northern hemisphere sea ice and the AMO index flipped in phase during the mid 1990’s from negative (cold) to positive (warm) and the trend changed at that point in time. Once the northern Atlantic Ocean sea surface temperatures flip back to cooler-than-normal values – perhaps in the next few years - the northern hemisphere sea ice areal extent should return to the normal or above-normal levels seen prior to the mid 1990’s.
Southern Hemisphere Sea Ice The southern hemisphere sea ice areal extent continues its recent impressive run at record or near record high levels for this time of year when compared to all prior years in the satellite record-keeping era which began in 1979. This remarkable period of increasing sea ice areal extent in this part of the world has actually been occurring for the past few years with only a few brief exceptions to that overall upward trend. Back in 2011, the southern hemisphere sea ice areal extent was at below-normal levels, but it is currently running well above-normal at levels seen only a couple of times dating back to the late 1970’s (all data courtesy University of Illinois "cryosphere" web site with data originating from NOAA/NCEP Snow and Ice Data Center).
The video discussion (below) details the current ice coverage situation in the Great Lakes, the northern and southern hemispheres and across the globe.