Every year, the Arctic sea ice of the north spreads from autumn until it shrinks again due to the milder spring temperatures. This turning point this year was March 7: the maximum ice surface at that time covered 14.42 million square kilometers. It reached the smallest winter extent since satellite records began in 1979, NASA reports. The record break is clearly in line with the trend: Over the past few years, there have always been minimal records. Since records began, the maximum sea ice extent has fallen by an average of 2.8 percent per decade.
Northern ice loss in trend
For the particularly weak growth of the ice this season, according to the experts, a combination of above-average temperatures, unfavorable winds and storms was responsible. "It started with a very gritty September minimum, " says Walt Meier of the NASA Goddard Space Flight Center in Greenbelt. "There was a lot of open ocean water and very slow ice growth in late October and November. The stored heat had to be broken down before the ice could grow. Ice formation had a delayed start, "explains the sea ice expert.
In the same period, the development in the south of the earth is reversed every year: during our winter months there is summer and the sea ice retreats. This year, sea ice around Antarctica shrank to a minimum of 2.11 million square kilometers on March 3. This was about 184, 000 square kilometers less than the previous record low of 1997. It was the result of a very rapid ice loss that began in September 2016, NASA reports. Since November, daily Antarctic sea ice extent has been at its lowest level ever since satellite records began.
Surprisingly strong melt in the south
In contrast to the north, development in the south is now counteracting the current trend: the current minimum record comes only two years after several monthly record highs in the Antarctic sea ice extent and after decades of moderate sea ice growth. So does climate change begin to nibble on the south ice? display
According to Meier, it is too early to say if this year will actually mark a shift in the behavior of Antarctic sea ice. "It is tempting to assume that this year's minimum record means that global warming will now also reduce Antarctic sea ice, " says Meier. "But it could just be an extreme case of year-to-year variability. We now have to wait and see the data for the coming years to say whether there is a significant change in the trend, "said the scientist.
On March 7, 2017, the maximum extent of Arctic sea ice reached a record low. The Antarctic sea ice broke again on March 3, setting a record at its annual minimum. (Video Credits: NASA's Goddard Space Flight Center)