4.2 million square kilometers – record low Arctic Sea Ice (ASI) coverage on August 24th
3.6 million sq km – latest (and new) low in ASI coverage this week
Half a million sq km melted in the past 2 weeks
75% of all ASI volume has disappeared in the past 20 years
50% higher than predicted – rate of ASI melting
Source: NOAA/National Snow & Ice Data Center
Arctic Sea Ice: Record melt in 2012
We’ve already reported on the new record low in Arctic Sea Ice coverage observed by NOAA on August 24th. The melting has continued the past 2 weeks, and now a new, new low has been achieved in the Arctic.
As of August 24th just 4.2 million square kilometers of ice coverage was observed by satellite in the Arctic Ocean at the top of the world. This week that number is closer to 3.5 million sq km…and still falling.
What’s even more troubling may be the volume of ice that’s disappearing. A full 75% of the volume of ASI has vanished in the past 20 years. Just 25% of that ice volume remains today.
And it’s not just the extent of the ice. It’s now much thinner: new figures of modeled data from PIOMAS show the volume on 25 August was around 3,600 cubic kilometers. This is just one-quarter of the volume twenty years ago. This fits with data from the first purpose-built satellite launched to study the thickness of the Earth’s polar caps showing that the rate of Arctic summer sea ice loss is 50 per cent higher than predicted.
As the ice becomes thinner and vulnerable to break-up from more severe Arctic storms, there are predictions of a summer Arctic Ocean free of sea-ice as early as 2015-16. A week ago ReNew Economy reported on the “big call” of the Cambridge Professor and Arctic expert Peter Wadhams who predicts Arctic summer sea ice “all gone by 2015”, except perhaps for a small multi-year remnant.
Other Arctic specialists are now saying we will see an ice-free Arctic in summer within a decade or so. Some, relying on global generalised climate models which have a poor record for modelling and projecting Arctic sea-ice loss, are sticking to a 2030-2040 projection, but lament that “We just don’t know exactly why this (sea-ice loss) is moving so fast”.
Credit: Ted Scambos, NSIDC
Why it matters: The “Arctic Refrigerator” is broken
The fact that ASI is disappearing at a more rapid rate than IPCC and other projections has consequences.
-Less ice in the Arctic means summer sunlight is absorbed by a warmer Arctic Ocean.
-A warmer Arctic Ocean means air masses coming south into the USA and across the Northern Hemisphere are not as cold as in years past. That in turn means hotter summers and may mean fewer rain producing “temperature contrasts”…weaker cold fronts with less rain which may lead to bigger droughts such as the Drought of 2012.
-Cold fronts that used to drop temperatures below average are now…”normal fronts.”
-A warmer Arctic Ocean warms waters around Greenland, which leads to faster melting of the largest land based ice sheet in the northern Hemisphere. As Greenland sees record ice melt, sea levels rise accordingly.
-A warmer arctic may fuel more extreme weather in the USA and Europe.
The “Lake Effect” analogy:
One way to think about the impact of less ASI is to think of the “lake effect” you feel near Lake Superior and other Great Lakes in summer. As breezes blow over the much colder waters, temperatures fall over otherwise warm land near the lakes.
Credit: The Weather Doctor
The air above the chilly water is cooled from below…like the air pouring out of your freezer when you open the door on a hot day.
One way to think of the vast Arctic Ocean is like a huge saltwater “Great Lake.”
Source: NOAA/National Snow & Ice Data Center
Less Arctic Sea ice means sunlight warms the Arctic Ocean more efficiently. As air masses ride over now warmer the Arctic Ocean water instead of ice, the do not cool as much. The “lake effect” is reduced…and the planet’s ability to cool off from spring to fall is also reduced.
The air masses that do come south from the Canadian Arctic into Minnesota and the USA just don’t pack the punch they once did. That can mean hotter summers like 2012, the 3rd hottest summer on record in Minnesota. It may also be one reason that 3 of the 6 hottest summers in Minnesota have occurred in the past 6 years.
Source: Twin Cities NWS
Weaker cool fronts may also produce less precipitation. The result can be growing areas of drought.
We are just staring to connect the dots on how climate is affected by shrinking ice cover in the Arctic. The story is unfolding faster than many climate scientists had anticipated, and we’re seeing, and feeling the effects right before our eyes in our lifetime.