Arctic Sea Ice Melting at an Accelerated Rate

Reader Contribution by Richard Hilderman and Ph.D.

Arctic sea ice is at its lowest level on record!  Historically, floating summer sea ice in the Arctic Ocean has covered an area about the size of the United States. Arctic sea ice follows an annual cycle of melting during the summer and then refreezing during the winter. Summer Arctic sea ice has shown a significant decline over the past 30 years.   Using satellite records the National Snow and Ice Data Center announced that in 2012 Arctic sea ice has fallen to 1.58 million square miles (note that in the Arctic sea ice will continue to melt through September) which is 27,000 square miles below the previous record level set in 2007.  This summer the ice has been melting at an extremely rapid pace.  About 38,000 square miles have melted each day since June.  This is an area about the size of Indiana.  Should this matter to us?

Sea ice reflects the sun’s radiation and keeps the Arctic cool. But when the sea ice melts, the dark sea absorbs the sun’s radiation which increases the water temperature which triggers more melting.  Within a few decades the Arctic could be ice free in the summer for the first time in 55 million years!  The melting of sea ice will only have an indirect effect on sea level rise because Arctic sea ice is already floating in the ocean and its melting won’t affect water levels.  Think of a glass full of ice water.  When the ice melts the water doesn’t flow over the lip of the glass.   However, the lack of sea ice raises the Arctic’s atmospheric temperature and triggers the melting of glaciers which will cause the sea level to rise.  In the past 3,000 years, mean sea level rose 0.4 to 0.8 inches.  But due to global warming, during the 20th century alone, mean sea level rose 8 inches.  On a beach with a gentle slope of 1 degree, this 8-inch increase could move the shoreline inland almost 40 feet, leaving low-lying areas more vulnerable to floods and hurricanes.  

Warm air rising over the Arctic Ocean to arctic land masses will also trigger the melting of permafrost, a concrete-like combination of frozen water, soil and vegetation.  Permafrost extends over about 20% of the planet’s land mass-mainly in the subarctic and arctic regions of North America and can be up to 4,900 feet deep.  When it melts it releases methane into the atmosphere which is a greenhouse gas that is 24 times more powerful than carbon dioxide!  Methane is also stored on the floor of the ocean and there are estimates which suggest that there is more methane on the ocean floor than oil.  As the water temperature in the Arctic Ocean continues to rise methane will be released into the atmosphere.  In recent years scientists have detected methane plume rising from the floor of the Arctic Ocean.  Methane released from the ocean and from the permafrost will accelerate global warming and climate change. This acceleration is most likely already occurring because summer sea ice is melting at a rate faster than was predicted by the Intergovernmental Panel on Climate Change.

During the Paleocene Epoch 55 million years ago there was a similar global warming trend that we are experiencing today.  Then there was a sudden and massive release of carbon into the atmosphere.  Global temperatures quickly rose 9-160 F and 30 to 35% of the ocean bottom flora/fauna became extinct.  This lasted about 120,000 years and took over 40,000 years to return to cooler temperatures.  At lot of experts believe the massive carbon release was methane coming from the ocean floor and permafrost.  Are we approaching a similar crossroad that exited 55 million years ago? 

Another consequence of the loss of sea ice in the Arctic is that it could change the complex ecosystem in the polar region.  One example is the fate of polar bears, seals and fish.  The increasing loss of sea ice will force polar bears to swim longer distances to find stable ice or reach land.  This could lead to a significant reduction in the polar bear population or even to its extinction.  Some people argue that we don’t need polar bears.  This is far from true.  Polar bears are a top arctic predator and their food source is seals.  Their eating of seals keeps the seal population in check.  If the bear population declines significantly the seal population will explode.  The problem with this is that seals eat the same fish that we eat.  If the seal population goes unchecked it will put more stress on the fishing industry which is already in trouble due to overfishing.  Needless to say we will feel it in our pocket book when we go to buy fish for supper.

The increase melting of the Arctic sea ice is an indicator of human induced global warming through the burning of fossil fuels.  It is estimated that we are pumping about 90 million tons of carbon into the atmosphere each day!  When is this going to stop?