This month, arctic sea ice has slipped to an incredibly low extent.
The lowest point ever since satellite observations began took place in the summer of 2012. That summer had been particularly hot, so the ice melted.
This summer has been very hot as well and the ice in the Arctic has hit a second-lowest point. It almost ties with the mark for the year 2007 for second place.
Arctic Sea Ice at Its Lowest
The Arctic sea ice extent means the area where the sea surface is covered by ice at least 15 percent. This summer’s low point was 4.14 million square kilometers (or 1.598 million square miles). The statistically low point was registered this Saturday by the National Snow and Ice Data Center. The center is located in Boulder, Colorado and tracks data regarding weather.
The minimum extent for this year was one third lower than the average. An average was established from measurements taken between the years 1981 and 2010. And the data for this year falls significantly below that average.
Earlier this summer, weather conditions in the Arctic were cool and cloudy. This type of conditions normally favors the preservation of ice. So scientists were surprised by the big meltdown that took place.
Mark Serreze is the director of the National Snow and Ice Data Center. He says that the climatic event signals a very important shift. Because ice has gotten thinner it is easier for it to melt. The warm water underneath helps with the melting process, not just the warm weather.
“I think that this is telling us that the old rules are changing”, said Serreze.
This type of rapid ice loss at this late point in the melt season is something new. At this time of year, ice loss used to slow down. But this change in pattern suggests that the ice melting is about more than just the weather. Now, the temperature of the ocean plays a part too. The ocean waters have been getting warmer and warmer and have started to melt the ice from below.
The record low in sea ice extent is held by the summer of the year 2007. Weather conditions for that summer favored the ice melting. There were clear skies that let solar heat radiate down on the ice and wind patterns that helped the melt down.
Weather conditions this year were better. Serreze said that under the conditions of the year 2007, the melt would have been much bigger. It is likely that it would have set a new record.
Right now, freeze-up has just begun. Freeze-up is when the water turns into ice again and starts in mid-September. It goes on until mid-March, when melt starts again.
Summer and fall sea ice disappearing is a trend that will affect the Arctic long-term. Also, it has self-reinforcing effects. The loss of sea ice gives way to more melt and that gives way to more warming. The dark surface of the ocean absorbs solar heat as opposed to ice that would reflect it away. So less ice and more water means higher ocean temperatures. That lead to even more melt.
So we can expect temperatures to be even higher and the extent of sea ice less and less in the following years.
Image source: NASA