Today Arctic sea ice area, according to Cryosphere Today, measured 3,097,000 square kilometers. This is about 30,000 square kilometers above the third and fourth lowest level ever recorded and about 105,000 square kilometers above the record lows for sea ice area set in 2007 and 2011. With one month of melt still remaining, we are currently well within striking distance of a new record low for sea ice area this year. And when one considers that over 140,000 square kilometers of sea ice was lost during one day of last week, any similar weather event would almost certainly put us into new record territory.
For the day, sea ice area is currently at an all-time record low.
Sea ice extent, though lagging sea ice area, is also currently in record low territory. The Japanese Space Agency (JAXA) is currently showing sea ice extent at 5,020,000 square kilometers, a record low for today and about 800,000 square kilometers above the record low set for 2007. The National Snow and Ice Data Center (NSIDC) is showing sea ice area measurements that are currently at all-time lows for the date and about 700,000 square kilometers above record low values set in 2007.
Most recent values for sea ice volume from the Polar Science Center (PIOMAS) show that we are also in record low territory there as well. And a new set of research by UK scientists has made similar findings to PIOMAS scientists, noting in a recent BBC report that the Arctic may experience ice free periods during summer in as little as 10 years.
Given these recent reports on record lows and potentials, it is worth noting that the vast majority of scientists very recently believed that the Arctic might experience ice free periods during summer as late as 100 years from now. Sea ice melt model runs indicated similar results. But observations of actual melt and response to business as usual global warming has resulted in a much more rapid melt than expected.
Arctic sea ice is a kind of canary in the coal mine for global warming. The reason is that sea ice has a powerful influence on global climate. First, it reflects sunlight away from the Earth, causing the Earth to absorb less radiation and, therefore, be quite a bit cooler. Second, darker water absorbs much more sunlight, so much so that researchers have found that open areas of water are as much as 5 degrees Celsius warmer than nearby waters covered in ice. Third, the Arctic Ocean and surrounding tundra, when exposed to higher temperatures, emit high volumes of methane gas. Methane is a powerful greenhouse gas that is at least 20 times as potent as CO2. And the Arctic contains enough of this methane to drastically increase human-caused global warming.
And then there is the issue of Greenland. Sea ice serves as a kind of insulator that protects Greenland from warm air to the south. With much of the sea ice gone for longer and longer periods, Greenland will be exposed to warmer winds from the south and from within the Arctic itself. Losing the sea ice is like Greenland losing its heat shield. So one can expect more rapid melting from Greenland as sea ice continues its decline. It is also worth noting that Greenland did not retain ice in the geological past when CO2 levels reached current levels near 400 ppm. And with Greenland’s ice melting, seas would rise by as much as 23 feet.
Current scientific estimates for sea level rise by the end of this century are in the range of 50 centimeters to 2 meters. The upper range of this estimate would have dramatic consequences for cities, regions, and nations around the world. But given the rapid rate of sea ice melt, these estimates could also be as far off as the previous estimates for sea ice melt were.