Arctic Sea Ice Extent, Area, and Volume

[lookingnorth]

It looks like the Antarctic sea ice extent gap is down to 187,000 km^2.

[so_whats_happening]

On 2/11/2024 at 9:21 AM, bowtie` said:

I do not see any spaghetti lines anywhere near where we are right now.

It is no wonder with a look like this

[Typhoon Tip]

We spend all this time obsessing over the Arctic when in so far as climate change ramifications is a concern... it's the other one that's the biggest problem. 

https://phys.org/news/2024-03-scientists-fret-antarctic-sea-ice.html

 

But... I don't really think a lot of the Arctic focus in here is really about climate change per se.  More about preserving chances for cold and snow in people's winters, and having connected that to the state of north pole. Call me a 'motivational cynic' -

[Taylorsweather]

So it looks like extent in the Arctic reached 15.1M on 3/11.  Probably does not get higher than that but there is a small chance it could.  That said, that is the highest extent in winter since 2014.  Surprised no one mentioned it.

[so_whats_happening]

Probably a bit too early to know for sure but there does seem to be some see-sawing situation between the poles. Will be interesting to watch it over the next 5 years.

Thickness levels I don't think can recover meaningfully going forward but we shall what happens with extent (not that this is all too important in the long run).

[Typhoon Tip]

https://phys.org/news/2024-03-antarctic-sea-ice-historic-lows.html

[FPizz]

On 3/26/2024 at 9:37 AM, Typhoon Tip said:

https://phys.org/news/2024-03-antarctic-sea-ice-historic-lows.html

The satellites that measured the ice from say 79-90 vs the 1000s more we have today, do you think that makes a difference at all?  They are probably way more precise today with many more doing calculations than the handful we had 40 years ago.  I wonder if we were to use 1980 tech to measure today what that would have come up with.  

[bluewave]

A recent study confirms that a fundamental shift occurred with the Arctic sea ice around the 2007 season. The Arctic lost so much older ice that it makes it harder to set new extent records. This is why the 2012 low extent record has been so difficult to beat. While the 2020 season came close, it came up short of the 2012 record. This is also why no season since 2007 has been able to see a recovery to pre-2007 extents and thickness. Most seasons since then finished in the 4 to 5 million sq km range for extent since extents change more slowly with younger ice dominating the Arctic instead of older.
 

https://www.nature.com/articles/s41586-022-05686-x

Manifestations of climate change are often shown as gradual changes in physical or biogeochemical properties¹. Components of the climate system, however, can show stepwise shifts from one regime to another, as a nonlinear response of the system to a changing forcing². Here we show that the Arctic sea ice regime shifted in 2007 from thicker and deformed to thinner and more uniform ice cover. Continuous sea ice monitoring in the Fram Strait over the last three decades revealed the shift. After the shift, the fraction of thick and deformed ice dropped by half and has not recovered to date. The timing of the shift was preceded by a two-step reduction in residence time of sea ice in the Arctic Basin, initiated first in 2005 and followed by 2007. We demonstrate that a simple model describing the stochastic process of dynamic sea ice thickening explains the observed ice thickness changes as a result of the reduced residence time. Our study highlights the long-lasting impact of climate change on the Arctic sea ice through reduced residence time and its connection to the coupled ocean–sea ice processes in the adjacent marginal seas and shelves of the Arctic Ocean.

Our analysis demonstrates the long-lasting impact of climate change on Arctic sea ice through reduced residence time, suggesting an irreversible response of Arctic sea ice thickness connected to an increase of ocean heat content in areas of ice formation. The large reduction of summer ice extent in the Alaskan and Siberian sectors in 2005 and 2007 triggered intensive ice–albedo feedback^42,45 and initiated the perennial increase of ocean heat content in these areas⁴⁴. This resulted in the stepwise reduction of residence time of sea ice in the Siberian sector of the Arctic, and hence a nonlinear response of the system.

https://www.jpl.nasa.gov/news/with-thick-ice-gone-arctic-sea-ice-changes-more-slowly

The Arctic Ocean's sea ice blanket has already lost most of its old ice and two-thirds of its thickness. The younger ice is thinning more slowly and variably.

The Arctic Ocean's blanket of sea ice has changed since 1958 from predominantly older, thicker ice to mostly younger, thinner ice, according to new research published by NASA scientist Ron Kwok of the Jet Propulsion Laboratory, Pasadena, California. With so little thick, old ice left, the rate of decrease in ice thickness has slowed. New ice grows faster but is more vulnerable to weather and wind, so ice thickness is now more variable, rather than dominated by the effect of global warming.

Working from a combination of satellite records and declassified submarine sonar data, NASA scientists have constructed a 60-year record of Arctic sea ice thickness. Right now, Arctic sea ice is the youngest and thinnest its been since we started keeping records. More than 70 percent of Arctic sea ice is now seasonal, which means it grows in the winter and melts in the summer, but doesn't last from year to year. This seasonal ice melts faster and breaks up easier, making it much more susceptible to wind and atmospheric conditions.

Kwok's research, published today in the journal Environmental Research Letters, combined decades of declassified U.S. Navy submarine measurements with more recent data from four satellites to create the 60-year record of changes in Arctic sea ice thickness. He found that since 1958, Arctic ice cover has lost about two-thirds of its thickness, as averaged across the Arctic at the end of summer. Older ice has shrunk in area by almost 800,000 square miles (more than 2 million square kilometers). Today, 70 percent of the ice cover consists of ice that forms and melts within a single year, which scientists call seasonal ice.

Sea ice of any age is frozen ocean water. However, as sea ice survives through several melt seasons, its characteristics change. Multiyear ice is thicker, stronger and rougher than seasonal ice. It is much less salty than seasonal ice; Arctic explorers used it as drinking water. Satellite sensors observe enough of these differences that scientists can use spaceborne data to distinguish between the two types of ice.

Thinner, weaker seasonal ice is innately more vulnerable to weather than thick, multiyear ice. It can be pushed around more easily by wind, as happened in the summer of 2013. During that time, prevailing winds piled up the ice cover against coastlines, which made the ice cover thicker for months.

The ice's vulnerability may also be demonstrated by the increased variation in Arctic sea ice thickness and extent from year to year over the last decade. In the past, sea ice rarely melted in the Arctic Ocean. Each year, some multiyear ice flowed out of the ocean into the East Greenland Sea and melted there, and some ice grew thick enough to survive the melt season and become multiyear ice. As air temperatures in the polar regions have warmed in recent decades, however, large amounts of multiyear ice now melt within the Arctic Ocean itself. Far less seasonal ice now thickens enough over the winter to survive the summer. As a result, not only is there less ice overall, but the proportions of multiyear ice to seasonal ice have also changed in favor of the young ice.

Seasonal ice now grows to a depth of about six feet (two meters) in winter, and most of it melts in summer. That basic pattern is likely to continue, Kwok said. "The thickness and coverage in the Arctic are now dominated by the growth, melting and deformation of seasonal ice."

The increase in seasonal ice also means record-breaking changes in ice cover such as those of the 1990s and 2000s are likely to be less common, Kwok noted. In fact, there has not been a new record sea ice minimum since 2012, despite years of warm weather in the Arctic. "We've lost so much of the thick ice that changes in thickness are going to be slower due to the different behavior of this ice type," Kwok said.

Kwok used data from U.S. Navy submarine sonars from 1958 to 2000; satellite altimeters on NASA's ICESat and the European CryoSat-2, which span from 2003 to 2018; and scatterometer measurements from NASA's QuikSCAT and the European ASCAT from 1999 to 2017.

[ORH_wxman]

Slow start to the season for melt in May so far. The updates will be more interesting as we get into mid-June. The next week looks pretty slow too except up in the Laptev where some warm air could start eating into the pack there and create meltponding.

The Beaufort looks a bit vulnerable this year, so if a dipole pattern can set up, then we could see a chance to make up some ground since the Beaufort/CAA region is always crucial for trying to go big in a melt season.