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. Currently, the northern hemisphere sea ice content is below normal while the southern hemisphere is above normal and the combination of the two has produced a global sea ice content that is very close to normal.
The below normal trend for northern hemispheric sea ice began in the mid-90’s at which time the Atlantic Ocean entered a warm (positive) phase. Atlantic Ocean sea surface temperatures can be tracked through an index called the Atlantic Multidecadal Oscillation (AMO). Specifically, sea-surface temperatures in the north Atlantic have been running at above normal levels in recent years and this is having an influence on the northern hemisphere sea ice content. Oceanic cycles can last two or three decades and it is quite possible that when the AMO returns to a cold (negative) phase the sea ice in the Arctic region will return to normal or even above levels on a consistent basis. 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 contributing to the above normal levels of sea ice in that part of the world.