Arctic Sea Ice Disinformation and COP26

There isn’t a million more square kilometers of ocean covered with ice than at the same time last year. Or is there?

For our younger readers perhaps I should point out that is a reference to the genesis of the Great White Con blog way back in the mists of time in September 2013, when a Daily Mail headline proudly, but erroneously, declared that:

And now it’s global COOLING! Record return of Arctic ice cap as it grows by 60% in a year.

Almost a million more square miles of ocean covered with ice than in 2012

With the COP26 conference due to start in Glasgow on October 31st UK Prime Minister Boris Johnson had this to say to the United Nations General Assembly yesterday, amongst other things:

In the words of the Oxford philosopher Toby Ord “we are just old enough to get ourselves into serious trouble”…

It is time for humanity to grow up.

It is time for us to listen to the warnings of the scientists – and look at Covid, if you want an example of gloomy scientists being proved right – and to understand who we are and what we are doing.

The world – this precious blue sphere with its eggshell crust and wisp of an atmosphere – is not some indestructible toy, some bouncy plastic romper room against which we can hurl ourselves to our heart’s content.

Daily, weekly, we are doing such irreversible damage that long before a million years are up, we will have made this beautiful planet effectively uninhabitable – not just for us but for many other species.

And that is why the Glasgow COP26 summit is the turning point for humanity.

If all that sounds unlikely, then take a look:

As we surmised at the time of the recent G7 Summit in Cornwall:

Continue reading Arctic Sea Ice Disinformation and COP26

China’s Arctic Ambitions

Back in 2013 I sat around a table with the Chinese delegation during lunch at the Economist’s Arctic Summit in Oslo. In the evening there was a reception with the British Ambassador to Norway, where amongst other people I met Kevin Vallely.

Fast forwarding to July 2021, the Chinese icebreaker Xue Long 2 (which translates to Snow Dragon 2) set sail from Shanghai to do some research in the Central Arctic Basin:

According to a report by the China Global Television Network (CGTN):

The expedition plans to monitor sea, marine ice, atmosphere, microplastics and ocean acidification in the high seas of the Arctic through navigation observation, cross-sectional survey and satellite remote sensing to obtain hydrological, meteorological and biological data of the region.

It will also conduct scientific surveys in the Gakkel Ridge in the Arctic Ocean to learn about the formation of rocks and magma and the geomorphic features there to further enhance knowledge of the natural environment in the North Pole.

Then in August a recent United States Coast Guard press release reveals that:

The U.S. Coast Guard demonstrated its commitment to the Bering Sea and Arctic region with deployments of national security cutters Bertholf and Kimball, and a U.S. Arctic patrol by icebreaker Healy.

“Security in the Bering Sea and the Arctic is homeland security,” said Vice Adm. Michael McAllister, commander Coast Guard Pacific Area. “The U.S. Coast Guard is continuously present in this important region to uphold American interests and protect U.S. economic prosperity.”

Crews interacted with local, national and international vessels throughout the Arctic. During the deployment, Bertholf and Kimball observed four ships from the People’s Liberation Army Navy (PLAN) operating as close as 46 miles off the Aleutian Island coast. While the ships were within the U.S. exclusive economic zone, they followed international laws and norms and at no point entered U.S. territorial waters. 

The PLAN task force included a guided missile cruiser, a guided missile destroyer, a general intelligence vessel, and an auxiliary vessel. The Chinese vessels conducted military and surveillance operations during their deployment to the Bering Sea and North Pacific Ocean.

All interactions between the U.S. Coast Guard and PLAN were in accordance with international standards set forth in the Western Pacific Naval Symposium’s Code for Unplanned Encounters at Sea and Convention on the International Regulations for Preventing Collisions at Sea.

Now comes more news via CGTN, which according to YouTube “is funded in whole or in part by the Chinese government”, that:

Chinese captain Zhai Mo’s sailing boat is currently on the Northwest Passage of the Arctic Ocean.

According to the CGTN video it was “streamed live on Sep 15, 2021” from “Ilulissat, Denmark”. Then on September 16th CGTN reported that:

Canada has illegally stopped Chinese captain Zhai Mo and his crew while circumnavigating their sailboat in the Arctic Ocean near Lancaster Sound, a part of the northwest passage.

The United Nations defines the “right of innocent passage” as a vessel’s right to enter and pass through another’s territory as long as it is not prejudicial to the peace, good order or security of the other state.

Ilulissat is of course a long way from Denmark, and also a considerable distance from Lancaster Sound. Which perhaps explains why CBC reported on September 17th that:

Canadian officials are disputing reports in Chinese media that a famous sailor from that country attempting to circumnavigate the Arctic was turned back in the Northwest Passage…

Transport Canada told CBC News in an email on Friday that it was aware of Zhai’s vessel, but said “at this point, it has not entered Canada’s Arctic Waters.” The Northwest Passage has been off limits to foreign pleasure craft since March 2020 due to an interim order from the Canadian government intended to limit the risk of introducing COVID-19 in remote Arctic communities.

Transport Canada said it was in touch with Zhai via email to inform him of the rule.

“Transport Canada has since seen public reports that Captain Zhai Mo no longer plans to pass through Canadian Arctic waters and the department continues to monitor the situation,” the department said in a second statement to CBC News on Friday evening.

It seems to me that no longer planning to pass through Canadian Arctic waters is very prudent on Zhai Mo‘s part, since navigating the Northwest Passage without support from Xue Long 2 or a Canadian icebreaker is currently fraught with difficulty:

[Edit – September 21st]

By way of some additional background information, on January 26th 2018 China published a “white paper” on China’s Arctic Policy:

China is an important stakeholder in Arctic affairs. Geographically, China is a “Near-Arctic State”, one of the continental States that are closest to the Arctic Circle. The natural conditions of the Arctic and their changes have a direct impact on China’s climate system and ecological environment, and, in turn, on its economic interests in agriculture, forestry, fishery, marine industry and other sectors.

China is also closely involved in the trans-regional and global issues in the Arctic, especially in such areas as climate change, environment, scientific research, utilization of shipping routes, resource exploration and exploitation, security, and global governance. These issues are vital to the existence and development of all countries and humanity, and directly affect the interests of non-Arctic States including China. China enjoys the freedom or rights of scientific research, navigation, overflight, fishing, laying of submarine cables and pipelines, and resource exploration and exploitation in the high seas, the Area and other relevant sea areas, and certain special areas in the Arctic Ocean, as stipulated in treaties such as the UNCLOS and the Spitsbergen Treaty, and general international law. As a permanent member of the UN Security Council, China shoulders the important mission of jointly promoting peace and security in the Arctic. The utilization of sea routes and exploration and development of the resources in the Arctic may have a huge impact on the energy strategy and economic development of China, which is a major trading nation and energy consumer in the world. China’s capital, technology, market, knowledge and experience is expected to play a major role in expanding the network of shipping routes in the Arctic and facilitating the economic and social progress of the coastal States along the routes. China has shared interests with Arctic States and a shared future with the rest of the world in the Arctic.

Followed by:

The Arctic shipping routes comprise the Northeast Passage, Northwest Passage, and the Central Passage. As a result of global warming, the Arctic shipping routes are likely to become important transport routes for international trade. China respects the legislative, enforcement and adjudicatory powers of the Arctic States in the waters subject to their jurisdiction. China maintains that the management of the Arctic shipping routes should be conducted in accordance with treaties including the UNCLOS and general international law and that the freedom of navigation enjoyed by all countries in accordance with the law and their rights to use the Arctic shipping routes should be ensured. China maintains that disputes over the Arctic shipping routes should be properly settled in accordance with international law.

China hopes to work with all parties to build a “Polar Silk Road” through developing the Arctic shipping routes. It encourages its enterprises to participate in the infrastructure construction for these routes and conduct commercial trial voyages in accordance with the law to pave the way for their commercial and regularized operation.

Watch this space!

The Strange Tale of The Mail and The Snow Dragon

This article is reposted from, originally published on March 18th 2013, as historical background to a new article on the so called Polar Silk Road.

As I’ve recently been reporting over on the Arctic Sea Ice Forum, I inadvertently found myself having lunch with the Chinese delegation to the Economist’s Arctic Summit in Norway last week. Amongst other things I learned about the voyage of the Chinese research vessel Xue Long (Snow Dragon in English) right across the Arctic Basin last summer:

The summer 2012 voyage of The Snow Dragon, courtesy of the Arctic Portal
The summer 2012 voyage of The Snow Dragon, courtesy of the Arctic Portal

Then over the weekend The Daily Mail published (again?!) an article by David Rose under the strident headline:

The Great Green Con no. 1: The hard proof that finally shows global warming forecasts that are costing you billions were WRONG all along!

Needless to say the following article shows nothing of the sort. Fondly imagining that David and his loyal readership would be interested in learning about some of things I discovered on my recent trip to Oslo I posted a comment on David’s article, which included this link to the following image (courtesy of The Arctic Portal once again):

Cross-Arctic Sea Routes. Past, present and future.
Cross-Arctic Sea Routes. Past, present and future.

After a couple of hours I noticed that my learned comments seemed to have fallen foul of the Mail’s moderator(s). So too had the most popular comment on the whole story from Mark in Warwickshire, who was complaining by then that:

Mark's message is missing!
Mark’s message is missing!

My message was missing too, so I carefully read the Mail Online’s “House Rules“, which state (amongst other things) that:

We welcome your opinions. We want our readers to see and understand different points of view. Try to contribute to the thread, rather than just stating if you agree or disagree.

I figured that was exactly what I was endeavouring to do, so still somewhat baffled I read on:

You must not insert links to websites (URLs) or submit content which would be an infringement of copyright.

Figuring that I must have crossed on to the wrong side of this particular line I tried again, using the following carefully crafted form of words:

My previous comment seems to have fallen foul of the “house rules” so I’ll try again. To discover what I was on about try Googling my username along with “Arctic Summit”.

I attended the aforementioned event in Norway last week. If there was a Daily Mail reporter there they kept very quiet about it! Amongst the other matters under discussion the Russians and Chinese were obviously extremely keen on the idea of saving many billions (and hence making many billions!) of dollars by shipping many billions of tonnes of stuff across the Arctic Ocean in the very near future.

[link omitted to avoid offending the house rules]

Whatever the likes of Myles Allen and David Bellamy may have said in various locations at various times the message from the real world in Oslo last week is abundantly clear. Statements such as “No, the world ISN’T getting warmer” are extremely “economical with the truth”.

That was over 24 hours ago, but still my wisdom from the East has failed to materialise at its intended destination. Perhaps someone from the Mail Online would be good enough to explain to me where I’m going wrong? Hopefully Mark is now a happy bunny at least, because today his missing message has been miraculously restored to the top spot amongst the currently 709 comments on the Mail’s Message:

Mark's missing message is miraculously restored
Mark’s missing message is miraculously restored!

Do you suppose one or both of my messages will benefit from a similar miracle in the near future, and who is “conning” who here?

Facts About the Arctic in September 2021

A detailed dissection of the 2021 minimum of various Arctic sea ice extent metrics can be found on a dedicated thread. All other Arctic news in September will be found below.

Let’s start with a map of sea ice age at the beginning of August:

Firstly notice the absence of 3+ year old ice off the coast of north east Greenland. Also visible is a band of 4+ year old ice across the Pacific side of the Arctic Basin, which has slowed melting in the region and explains the following regional sea ice area graphs:

Next here’s the current AMSR2 concentration map:

There is currently a large area of open water in the Wandel Sea to the north of Greenland. There is also an arm of old ice across the Beaufort and Chukchi Seas which is still clearly visible, but also visible is the recent reduction in sea ice concentration in the region. By way of explanation, here’s another look at the thickness of an ice floe currently situated to the north of the Chukchi at 74.84 N, 164.29 W, as measured by an ice mass balance buoy:

As the 2021 melting season draws towards its conclusion the floe is experiencing rapid bottom melt. How much longer will this floe and others like it last? Will it survive to become an “old ice” dot on next year’s ice age maps?

[Edit – September 6th]

As Wipneus puts it on the Arctic Sea Ice Forum, “PIOMAS has updated the gridded thickness data up to the 31st of August”. Here’s the latest modelled thickness map, which shows the thickest remaining ice located north of the Canadian Arctic Archipelago rather than north of Greenland:

The accompanying volume graph shows 2021 in 7th lowest position, at 4.7 thousand km3:

Here too are the current PIOMAS volume trends for each month of the year:

The Swedish icebreaker Oden has recently been exploring the area between northern Greenland and the North Pole as part of the Synoptic Arctic Survey expedition:

Here are the measurements of water temperature it has recorded over the past few days:

Ranging between -0.4 °C and -1.0 °C it doesn’t look as though the 2021 refreeze will be starting in the Wandel Sea just yet.

[Edit – September 10th]

A picture of the sea ice at the North Pole from Ponant’s Le Commandant Charcot on September 6th:

[Edit – September 13th]

Here’s the latest NSIDC sea ice age map:

That shows plenty of old ice still left in the Beaufort Sea. However ice mass balance buoy 52460 now appears to floating free of its ice floe at 75.56 N, 165.99 W:

[Edit – September 14th]

“New ice” has started to appear in previously open water on the Canadian Ice Service charts. See area E south east of Resolute:

[Edit – September 21st]

In answer to Frozen Earth’s metaphorical prayer, Wipneus has just released the mid September PIOMAS gridded thickness numbers on the Arctic Sea Ice Forum. First of all the thickness map:

followed by the volume graph:

and the monthly volume trends:

Volume calculated from the thickness data currently show that 2021’s minimum was reached on September 7th at 4.64 thousand km3, which is the 8th lowest value in the Polar Science Center’s record.

[Edit – September 23rd]

NASA have just announced a new paper about clouds in the Arctic. Highly relevant given their recent overview of the 2021 melting season!

Clouds are one of the biggest wildcards in predictions of how much and how fast the Arctic will continue to warm in the future. Depending on the time of the year and the changing environment in which they form and exist, clouds can both act to warm and cool the surface below them.

For decades, scientists have assumed that losses in Arctic sea ice cover allow for the formation of more clouds near the ocean’s surface. Now, new NASA research shows that by releasing heat and moisture through a large hole in sea ice known as a polynya, the exposed ocean fuels the formation of more clouds that trap heat in the atmosphere and hinder the refreezing of new sea ice.

The findings come from a study over a section of northern Baffin Bay between Greenland and Canada known as the North Water Polynya. The research is among the first to probe the interactions between the polynya and clouds with active sensors on satellites, which allowed scientists to analyze clouds vertically at lower and higher levels in the atmosphere.

The approach allowed scientists to more accurately spot how cloud formation changed near the ocean’s surface over the polynya and the surrounding sea ice.

Watch this space!

The 2021 Arctic Sea Ice Minimum Extent

The results of the ARCUS Sea Ice Prediction Network August call have been released, and here is the outlook for the 2021 minimum September mean Arctic sea ice extent:

The median prediction for the mean sea ice extent during the month of September 2021 is 4.39 million km2. According to ARCUS:

As of 22 August 2021, the Arctic sea-ice extent was 5.58 (compared with 25 August 2020 value of 4.43) million square kilometers. Arctic sea-ice extent in 2021 remains well below the climatological median and has closely followed the 2012 values for much of the summer but has diverged to higher sea-ice extent starting in early August. The forecasts continue to support September 2021 mean sea-ice extent being well above the September 2020 value. July sea-ice retreat has been greatest in the Eurasian seas, particularly in the East Siberian Sea, making the 2021 ice edge well north of the long-term median edge in Eurasia. Sea ice retreated since the end of July along the northern coast of Alaska, although the ice edge is near its climatological position, which makes the Beaufort and Chukchi sea ice extent the largest at this time of year since 2006. A tongue of sea ice that has been present all summer continues to extend close to land in the Kara Sea, making the northeast passage likely to remain blocked for the first time in several years. Half the models which provide spatial data to the SIO predict that the tongue is likely to survive.

Now let’s take a look at a range of assorted extent measurements. Here’s the NSIDC’s 5 day average extent:

Continue reading The 2021 Arctic Sea Ice Minimum Extent

Facts About the Arctic in August 2021

Let’s first of all take a look at JAXA’s flavour of Arctic sea ice extent:

After reaching lowest extent for the date in early July, the weather in the Arctic Basin was stormy, cloudy and cool compared to other recent years until the last few days of the month:

Here’s the same period in 2020 for comparison purposes:

Consequently the rate of extent loss in the second half of July was significantly less than last year.

Next let’s take a look at AMSR2 concentration:

Continue reading Facts About the Arctic in August 2021

Facts About the Arctic in July 2021

The JAXA ViSHOP web site was down for maintenance over the weekend. It is now back in action, to reveal Arctic sea ice extent at the lowest for the date in the AMSR2 record:

[Edit – July 6th]

High resolution AMSR2 area is also now lowest for the date:

as indeed is extent:

[Edit – July 13th]

According to the Canadian Meteorological Centre the current cyclone has bottomed out with a central mean surface level pressure of 971 hPa:

Continue reading Facts About the Arctic in July 2021

The Polar Amplification Model Intercomparison Project

The Polar Amplification Model Intercomparison Project (PAMIP for short) is one of several Community Earth System Model (CESM for short) based climate modelling projects.

As the project’s web site points out:

Polar amplification, the phenomenon that external radiative forcing produces a larger change in surface temperature at high latitudes than the global average, is a key aspect of anthropogenic climate change but its causes and consequences are not fully understood.

PAMIP, co-led by Dr. Doug Smith, Dr. James Screen, and  Dr. Clara Deser seeks to improve our understanding of this phenomenon through a coordinated set of numerical model experiments. As one of the Coupled Model Intercomparison Project Phase 6 (CMIP6) endorsed MIPs, PAMIP will address the following primary questions:

1. What are the relative roles of local sea ice and remote sea surface temperature changes in driving polar amplification?

2. How does the global climate system respond to changes in Arctic and Antarctic sea ice?

The following article provides an overview of the PAMIP including the protocols:

The PAMIP project is thus part of the global climate modelling effort leading up to the long anticipated publication of the Intergovernmental Panel on Climate Change’s next series of assessment reports, conveniently abbreviated as simply “AR6”. The project has been in the news recently. According to an article in Science magazine:

Every time severe winter weather strikes the United States or Europe, reporters are fond of saying that global warming may be to blame. The paradox goes like this: As Arctic sea ice melts and the polar atmosphere warms, the swirling winds that confine cold Arctic air weaken, letting it spill farther south. But this idea, popularized a decade ago, has long faced skepticism from many atmospheric scientists, who found the proposed linkage unconvincing and saw little evidence of it in simulations of the climate.

Now, the most comprehensive modeling investigation into this link has delivered the heaviest blow yet: Even after the massive sea ice loss expected by midcentury, the polar jet stream will only weaken by tiny amounts—at most only 10% of its natural swings. And in today’s world, the influence of ice loss on winter weather is negligible, says James Screen, a climate scientist at the University of Exeter and co-leader of the investigation, which presented its results last month at the annual meeting of the European Geosciences Union (EGU for short). “To say the loss of sea ice has an effect over a particular extreme event, or even over the last 20 years, is a stretch.”

The idea that Arctic sea ice loss could influence midlatitude winter weather first gained traction in 2012, in a paper by two climate scientists, Jennifer Francis, now at the Woodwell Climate Research Center, and Stephen Vavrus at the University of Wisconsin, Madison. It started with a simple observation: The Arctic is warming nearly three times faster than the rest of the world. At the time, sea ice loss was thought to be the primary accelerant for this amplification: As bright, reflective ice is replaced by dark, sunlight-absorbing water, the Arctic heats up, causing more ice loss, and more warming in turn.

The warming, Francis and Vavrus proposed, would inflate the height of the polar troposphere—the lowest layer of the atmosphere and home to its weather. That would decrease the pressure differences between polar and midlatitude air that drive the polar jet stream, which separates the air masses and keeps cold air collared around the pole. The jet would grow weaker and wavier, allowing cold air to intrude farther south. In their paper, Francis and Vavrus argued such a trend was visible in weather records and worsening with Arctic warming and ice loss.

The results of the project presented at the EGU haven’t been published in an academic journal yet, but according to Science once again:

In the years long PAMIP investigation researchers ran more than a dozen climate models 100 times each. One set of model runs simulated the Arctic atmosphere without pronounced sea ice loss, using ocean temperatures and sea ice extent from 2000. The other kept the ocean temperatures the same, but reduced the ice coverage to the extent expected decades from now, after 2°C of global warming, when the Arctic could be ice free in the summer. Keeping the oceans the same should highlight the influence—if any—of sea ice loss.

In addition to finding only a tiny effect of sea ice loss on the polar jet stream, the models also found no coherent sign of a second proposed effect of reduced sea ice: more frequent disruptions of the stratospheric polar vortex—a second set of swirling winds, much higher up. Such disruptions, which occur every 2 years on average, ultimately allow cold air lower in the atmosphere to spill southward, causing extreme winter storms, including the cold that gripped Texas this past winter.

However not everyone is convinced by the modelling results:

Judah Cohen, director of seasonal forecasting at Atmospheric and Environmental Research, has long argued that increased snow cover and diminished sea ice in Siberia favor weather patterns that propagate energy into the stratosphere, making the high-altitude disruptions more frequent. He notes that the models also forecast unrealistically warm winter weather in the midlatitudes, making other predictions suspect. “There’s clearly something missing.” And Francis says the PAMIP experiment may be too simplistic, now that “we know there’s a lot more to Arctic amplification than sea ice loss.”

Whilst we wait to discover precisely what was revealed to the EGU audience, here is a list of current PAMIP publications:

In conclusion, for the moment at least, here’s an illustration of one of the issues PAMIP is endeavouring to address. The difference between the outputs of previous generation of CMIP5 global climate models and observations taken from Smith et al. (2019):

Recent Arctic and Antarctic temperature trends (C decade−1) in (a, b) observations and (c, d) model simulations. Linear trends are shown for the 30-year period (1988 to 2017). Observations are taken as the average of HadCRUT4 (Morice et al., 2012), NASA-GISS (Hansen et al., 2010) and NCDC (Karl et al., 2015). Model trends are computed as the average from 25 CMIP5 model simulations driven by historical and RCP4.5 radiative forcings.

It will be extremely interesting to discover what the working group 1 section of the IPCC’s 6th Assessment Report ultimately has to say on the topic of Arctic amplification. The current AR6 timeline states that:

The Working Group I contribution is expected to be considered at the 54th Session of the IPCC which is scheduled to take place in the 14 days from 26 July 2021. The report will be released, subject to approval and acceptance by the Panel, on or around 9 August.

Mud Wrestling with Climategate Pigs

This article started out as an addendum to my recent tale of woe in which I got banned from Anthony Watts eponymous website just as Willis Eschenbach had published an article about Arctic sea ice inspired by yours truly!

I’ll get back to that in a moment, but earlier today this happened over on Twitter:

In case you haven’t heard the shock news already, earlier today Climategate was featured on BBC News once again:

Needless to say this news caused much excitement amongst both climate scientists and the cryodenialosphere! However getting back to where I was when I went to bed yesterday, I recently had the good fortune to bump into Willis once again, only this time it was on Judith Curry’s “Climate Etc.” blog rather than WUWT. I eagerly sought to reopen our Arctic discussion, and this is how the conversation went:

Continue reading Mud Wrestling with Climategate Pigs

Month in Review – Arctic Science Edition

This month has begun with a couple of CryoSat-2 related papers. First we have one that I unexpectedly I found out about via Twitter:

Regular readers will recall that the thickness in mid April by the AWI’s CryoSat-2/SMOS metric seemed remarkably low, so I had to ask this question:

Whilst we wait on those SnowModel-LG results does the CPOM’s new analysis offer any cause for comfort concerning sea ice thickness in 2021? I’m afraid not. Here’s an extract from the conclusions:

We found that interannual variability in average sea ice thickness of the marginal seas was increased by more than 50 % by accounting for variability in the snow cover. On a seasonal timescale we find that variability in the snow cover makes an increasing contribution to the total variability of inferred sea ice thickness, increasing from around 20 % in October to more than 70 % in April.

We also observed that the trends in SnowModel-LG data propagated through to the sea ice thickness time series, amplifying the decline in regions where it was already significant and introducing significant decline where it did not previously exist. This occurred in spite of the compensating effect of enhanced interannual variability.

Next there is a preprint from Arttu Jutila et al. at the Alfred Wegener Institute. According to “Retrieval and parametrisation of sea-ice bulk density from airborne multi-sensor measurements“:

Knowledge of sea-ice thickness and volume depends on freeboard observations from satellite altimeters and in turn on information of snow mass and sea-ice density required for the freeboard-to-thickness conversion. These parameters, especially sea-ice density, are usually based on climatologies constructed from in situ observations made in the 1980s and before while contemporary and representative measurements are lacking. Our aim with this paper is to derive updated sea-ice bulk density estimates suitable for the present Arctic sea-ice cover and a range of ice types to reduce uncertainties in sea-ice thickness remote sensing. Our sea-ice density measurements are based on over 3000 km of high-resolution collocated airborne sea-ice and snow thickness and freeboard measurements in 2017 and 2019.

Some slightly strange English in there, but interesting nonetheless and an complement to Robbie Mallett’s paper above.

In addition to the paper itself Stefan Hendricks has posted an explanatory thread on Twitter:

From Stefan’s Twitter thread:

Main findings: The density values are higher than what we get with the climatology values, more so for multi-year sea ice than for first-year ice. Part of the explanation is that with the airborne data we also tried to get the bulk density of deformed ice that includes sea water.

We also found a robust relationship between ice freeboard and ice density. This will be useful for the freeboard to thickness conversion of satellite data.

If I’ve understood the 2 papers correctly Robbie’s change to estimated snow thickness implies less overall sea ice volume in CPOM’s future product, whereas Arttu’s change to estimated sea ice density implies increased sea ice volume in AWI’s version.

All in all I’m anticipating the summer 2021 high Arctic melting season with even greater trepidation than at the start of this month. Uncertainty is exceedingly unsettling!

[Edit – June 17th]


News arrives via an AWI press release, which also refers to the Ricker et al. paper we mentioned last month, of a new paper. The lead author of “Interannual variability in Transpolar Drift summer sea ice thickness and potential impact of Atlantification” is Jakob Belter. Some more famous names in the “et al.” section include Igor Polyakov, Robert Ricker and Stefan Hendricks.

According to the press release:

AWI sea-ice physicists report on the first indications that the rising ocean heat is also slowing ice formation in the Laptev Sea, which also includes measurements of the ice floe from the one-year MOSAiC expedition in late summer 2020. In it, the researchers analyse the long-term data from their sea-ice thickness measuring programme in the Arctic, ‘IceBird’, and trace the origins of the unusually thin sea ice that they observed from the research aeroplane in the northern Fram Strait in summer 2016. At that time, the ice was just 100 centimetres thick, making it 30 percent thinner than in the previous year – a difference that the researchers were initially unable to explain. “To solve the puzzle, we first retraced the ice’s drift route with the help of satellite images. It originated in the Laptev Sea,” explains AWI sea-ice physicist Dr Jakob Belter. The experts then examined the weather along the route. However, the atmospheric data for the period 2014 to 2016 didn’t show any abnormalities.

That meant the answer had to lie in the ocean – and indeed: from January to May 2015, experts from the University of Alaska Fairbanks recorded unusually high temperatures in the waters north of the Laptev Sea. We now know that the heat rose from the depths with Atlantic water masses, and slowed the winter ice growth. “Using the satellite data, we were able to show that the thin ice that we sampled in Fram Strait in July 2016 had previously passed through this unusually warm area off the Russian continental shelf,” says Belter. Furthermore, the ocean heat wave must have been so extreme that its effects on the growth in sea-ice thickness couldn’t be compensated for during its drift across the Arctic Ocean.

The conclusions from the paper itself include:

Further investigations and measurements are required to monitor the development of Atlantification in the eastern marginal ice zones. But in order to strengthen our conclusion that Atlantification is able to precondition sea ice and that this preconditioning persists far beyond the eastern Arctic, additional uninterrupted SIT time series are vital along the pathways and at the exit gates of Arctic sea ice. The presented summer SIT time series at the end of the Transpolar Drift is an important effort to establish long-term and large-scale measurements of SIT, especially during the melt season. Airborne EM measurements of SIT during IceBird campaigns provide the necessary accuracy and areal coverage that is unmatched by any other non-satellite SIT measurement approach. Russian shipborne SIT measurements show significant differences to EM-based measurements, but their regularity and spatial consistency enable the depiction of regime shifts in SIT that are hardly resolved by the presented EM SIT time series. Obtaining SIT distributions over large areas and developing and continuing long-term SIT time series will provide unique input data for modelling efforts and ultimately will improve predictions of Arctic sea ice and its thickness in the future.

Getting back to the conclusion of the press release:

The two new studies highlight the importance of long-term datasets for sea-ice research in the Arctic. “If we are to understand the changes in the Arctic sea ice, long-term observations of ice thickness using satellites and aircraft are vital. Combined with modelling data they provide an overall picture that is sufficiently detailed to allow us to identify the key processes in the changing Arctic,” explains Jakob Belter.