Arctic sea ice melted rapidly in July

The total extent of the Arctic sea ice shrank rapidly in July, causing the extent to fall below the level recorded in July 2007, the year that saw the lowest ever Arctic sea-ice minimum, according to the National Sea and Ice Data Center. The minimum extent normally occurs in September, as the summer ice melt transitions into the winter freeze up — presumably the question of whether a new minimum extent record will be set this year will depend on weather conditions in August and September.

NSIDC attributes the rapid July melt to persistent high pressure over the northern Beaufort Sea, a phenomenon that led to above average temperatures over much of the Arctic Ocean. Air temperatures over the North Pole have been 11 F to 14 F above average for the time of year, although temperatures over the Kara Sea were lower than average during the first half of July, NSIDC said.

The sea ice extent is particularly low in the Barents Sea, the Kara Sea, the Laptev Sea, Hudson Bay and Baffin Bay, NSIDC said. NSIDC also said that satellite data is providing evidence that the annual ice melt is starting earlier than normal in some regions, with the subsequent formation of water pools on the ice surface accelerating further melting.

There may also be a new trend for relatively high snow falls in the Northern Hemisphere in late autumn, winter and early spring, followed by a rapid snow melt in May and June. Following this year’s snow melt, summer snow cover in the Northern Hemisphere is the second lowest on record, NSIDC said.

—Alan Bailey