The amount of summer sea ice in the Arctic fell this year to the second-lowest ever recorded by satellite.
NASA and the National Snow and Ice Data Center in Boulder, Colo. announced Thursday that the Arctic has reached its summer season low extent.
The 4.14 million square kilometers of ice measured on Sept. 10 is statistically tied with the minimum ice extent during the summer of 2007 for second place on the historic minimum list. This year’s minimum ice cover is more than two million square kilometers below the 1981-2010 mean.
Arctic Summer Minimum Sea Ice Extent Record, 2007-2016
|YEAR||EXTENT (millions of km2)||DATE MEASURED|
|1979-2000 mean||6.70||Sept. 13|
|1981-2010 mean||6.22||Sept. 15|
A statement released by NSIDC starkly described the conditions in the Arctic this summer:
“This year’s minimum extent is 750,000 square kilometers (290,000 square miles) above the record low set in 2012 and is well below the two standard deviation range for the 37-year satellite record.”
Cloudy skies and atmospheric pressure conditions slowed ice melt in June and July, which may have prevented this season from becoming the most ice-free summer ever observed from space.
“June and July are usually key months for melt because that’s when you have 24 hours a day of sunlight – and this year we lost melt momentum during those two months,” Walt Meier, a scientist at NASA’s Goddard Space Flight Center, said in a statement.
The pace of melting accelerated in August when two cyclones crossed the Arctic Ocean.
Meier explained that these may have especially impacted the speed with which ice in the Chukchi and Beaufort seas melted.
The three-and-one-half decade long satellite record shows a marked decline in the mean extent of Arctic sea ice during each month of the year.
In fact, a paper published on Sept. 15 in the journal Remote Sensing of Environment concluded that no record for maximum Arctic sea ice extent has been set since 1986, while during the 37 years of satellite monitoring there have been 75 new minimum ice extent records set.
“The record makes it clear that the ice is not rebounding to where it used to be, even in the midst of winter,” Claire Parkinson, the lead author of that study and a senior climate scientist at GSFC, said.
Arctic sea ice ordinarily reaches its maximum reach for the year in March, late in the winter. The sun is not visible in the region during the winter and does not contribute much to warming of land and sea surfaces during that season.
NSIDC’s statement cautioned that the estimate released Thursday could be revised if late-summer winds or other factors causing ice melt impact the sea ice cover during the remaining days of summer.
The monitoring record dates to 1978.
Earth’s poles are the two regions of the planet that are most sensitive to warming of the atmosphere. As sea ice melts, more solar energy is absorbed by the Arctic Ocean. The deep and dark waters absorb about 90 percent of the sun’s energy that reaches them.
By contrast, expansion of sea ice during the colder autumn and winter months causes about 80 percent of the solar energy that hits the frozen surface of the region’s marine environment to be reflected to space.
Scientists have found a planet about the size of Jupiter orbiting two stars in a nearby solar system, marking the largest known example of a world with multiple suns.
The circumbinary planet, which has been named Kepler-1647b, is in the constellation Cygnus, about 3,700 light years from Earth. Astronomers used the Kepler Space Telescope to discover it.
“It’s a bit curious that this biggest planet took so long to confirm, since it is easier to find big planets than small ones,” Dr. Jerome A. Orosz, an astronomer at San Diego State University and a co-author of a paper documenting the discovery, said. “But it is because its orbital period is so long.”
Kepler-1647b’s orbital period is 1,107 days, which means it takes longer to orbit its stars than any other known exoplanet takes to orbit either one star or two.
The planet’s circumbinary orbit made it more difficult to find than would be the case with an exoplanet that circles one star.
“The transits are not regularly spaced in time and they can vary in duration and even depth,” Dr. William F. Welsh, another SDSU astronomer and co-author of the paper explaining the discovery, said.
A gas giant, Kepler-1647b is has a similar age as Earth – about 4.4 billion years. The two stars it orbits are similar to our sun, with one being a little larger than the Sun and the other slightly smaller than Earth’s star.
The discovery of Kepler-1647b is described in a paper to be published in Astrophysical Journal.
Earth’s north polar ice cap was smaller this past winter than at any time since measurements began to be obtained by satellite, breaking a record set only last year.
NASA and the National Snow and Ice Data Center announced March 28 that the maximum extent of ice during the season was reached on March 24 and that it covered 14.52 million square kilometers.
That beat last year’s mark of 14.54 million square kilometers and continued a stretch in which the 13 most ice-free winters in the Arctic have occurred in the past 13 years.
“It is likely that we’re going to keep seeing smaller wintertime maximums in the future because in addition to a warmer atmosphere, the ocean has also warmed up. That warmer ocean will not let the ice edge expand as far south as it used to,” Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said. “Although the maximum reach of the sea ice can vary a lot each year depending on winter weather conditions, we’re seeing a significant downward trend, and that’s ultimately related to the warming atmosphere and oceans.”
During the most recent winter season the Arctic experienced record high temperatures in December, January, and February. Air temperatures were as much as 10 degrees Fahrenheit higher than average at the edge of the ice pack, Meier said.
Warm air from the south was brought by winds to the Arctic, which also would have contributed to a lessened sea ice cover.
Less winter sea ice causes the air temperature over the Arctic ocean to increase because the unfrozen ocean waters are warmer than the overlaying air mass. As the ocean water evaporates, more water vapor accumulates in the atmosphere and that, in turn, causes clouds to form. Increased cloudiness causes an increase in surface warmth.
Satellite measurements of Arctic winter ice extent began in 1979.
Since that time the Arctic has lost nearly 1,606 square kilometers of winter sea ice. That is an area twice the size of Texas.