11:15 AM | Global sea ice areal extent currently running near normal; northern hemisphere continues below normal, but southern hemisphere almost at record high sea ice areal extent for the date
The areal extent of northern hemisphere sea ice continues to run at below normal levels, but this is being compensated by above normal readings in the southern hemisphere so that the current global sea ice areal extent is relatively close to normal.
Sea ice occupies about 7% of the surface area of planet Earth and is especially important in polar regions. Even though sea ice is found predominately in polar regions, it does have an influence on global climate as its bright surface reflects much sunlight back into space. The North Pole region is considerably different than the South Pole in that up north there is an ocean (Arctic) that is surrounded by land whereas down south there is land (continent of Antarctica) surrounded by ocean. The Arctic responds much more directly to changes in air and sea-surface temperatures than does Antarctica.
The below normal trend for northern hemisphere sea ice began in the mid-90’s which is about the same time the northern Atlantic Ocean entered a warm (positive) phase. Northern Atlantic Ocean sea surface temperatures are tracked by meteorologists through an index called the Atlantic Multidecadal Oscillation (AMO). Specifically, sea-surface temperatures in the north Atlantic have been generally running at above normal levels since the mid 90’s and this is quite likely having an influence on the northern hemisphere sea ice areal extent. Oceanic cycles can last two or three decades and it is likely that when the AMO returns to a cold (negative) phase the sea ice in the Arctic region will return to normal or above normal levels on a consistent basis similar to what occurred prior to the mid-90’s.
Meanwhile, way down south the sea surface temperatures have been running below normal in recent times in those areas surrounding the continent of Antarctica and this is likely contributing to the above normal levels of sea ice in that part of the world. In fact, the southern hemisphere sea ice area has been generally above normal for the last several years it is very close to a record high for this time of year (second only to 2010) when compared to all years going back to 1979 which is when satellite-era data records began for global sea ice.