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. 

Watts Up With That Koonin Hypocrisy?

Our regular reader(s) must have noticed by now that in the dim and distant past we had the occasional debate with Anthony Watts, proprietor of the self proclaimed “world’s most viewed climate website”, catchily entitled “Watts Up With That”?

You may even have noticed that more recently we managed to engage in an admittedly brief debate with the suddenly world famous American Physicist Steven Koonin?

Now in a world exclusive we bring you the shock news that we are suddenly unable to debate with either of them!!!

In a recent article on the Watts Up With That web site Anthony wrote:

I was sent this by email, apparently “Scientific American” doesn’t believe in fairness. I stopped subscribing to SciAm years ago because they’ve turned into a socialist cesspool of opinion, with science as an afterthought. Steve Koonin writes:

I attach a response that I submitted yesterday to Scientific American.  Not surprisingly, they declined to publish it.  

Please do distribute my response freely among your contacts or websites.

Steve Koonin

Needless to say Anthony did as he was asked. Since I consider myself by now as something of an expert on the deficiencies of Professor Koonin’s alleged “science” I replied to Steve’s response to Scientific American on WUWT as follows:

Needless to say two days later I have received no reply and my pertinent comment is still languishing underfoot on the Watts Up With That cutting room floor. Paraphrasing Dave Yaussy only slightly, and bolding for emphasis:

The greatest danger posed by Steve and Tony isn’t their ideas, it’s the attempt to silence all dissent.

That, and their corruption of science.

By way of one further example of his hypocrisy, Anthony did of course advertise his article on Twitter:

Of course he also stifled any anticipated dissent:

Q.E.D? As some scientists have been known to write from time to time.

Oreskes, Mann, Dessler et al. versus Koonin

Earlier today Scientific American published an article entitled “That ‘Obama Scientist’ Climate Skeptic You’ve Been Hearing About“. The climate skeptic in question being of course Steven E. Koonin. If you click that last link it will be immediately obvious that I’ve recently been critical of Professor Koonin’s new book “Unsettled” in several more ways than one! The article in Scientific American is authored by several more people than one. Twelve to be precise, including the famous names of Naomi Oreskes, Michael E. Mann and Andrew Dessler. That team takes a largely different approach to my own criticism, making no mention of the cryosphere for example, although sea level rise does get a mention. Rather than going into the science in detail, Oreskes et al. take a different approach. Here’s the introduction to the article:

If you’d heard only that a scientist who served in the Trump administration and now regularly appears on Fox News and other conservative media thinks climate change is a hoax, you’d roll your eyes and move on. But if you heard that someone associated with former President Barack Obama’s Democratic administration was calling the climate science consensus a conspiracy, the novelty of the messenger might make you take it a little more seriously.

The latter is what Steve Koonin is using to sell his new book, which is being billed as the revelation of an “Obama scientist” who wants you to think that climate change isn’t a big deal. But unfortunately, climate change is real, is caused primarily by burning fossil fuels, and is already hurting people all over the world, including here in the United States. 

For example, a study published recently found that because climate change has caused sea levels to rise, Superstorm Sandy flooded an additional 36,000 homes, impacting 71,000 people who would’ve been safe otherwise, and caused $8 billion in additional damage.

A little later the article suggests that:

Steve Koonin is hoping you’ll see Obama’s name and trust him when he tells you that he’s better equipped to summarize major climate reports than the authors of the U.N.’s IPCC report and the U.S. government’s National Climate Assessment, who wrote at length about the already sizable and growing costs of climate change. He’s hoping you won’t recall that each president appoints thousands of people, and Koonin, it turns out, was hired at the Energy Department specifically for his contrarianism. His boss at the time, Stephen Chu, said he “didn’t want to have a department where everybody believed exactly as everybody else” and added that Koonin “loves to be the curmudgeon type.”

Curmudgeon or not, Steve’s science certainly leaves a lot to be desired, as has been proved here! Oreskes et al. put it this way:

When it comes to the science, Koonin cherry-picks and misrepresents outdated material to downplay the seriousness of the climate crisis…

He wants you to believe that, as an Obama hire, he knows better about what you should take away from these reports than the scientists who wrote them.

That sums things up quite nicely, although the article doesn’t actually contain a whole lot of evidence for the first assertion, what Steve refers to as “The Science”. Instead it prefers to link to the Climate Feedback article mentioned here at the Great White Con back at the beginning of May and two articles by Marianne Lavelle in Inside Climate News.

However towards the end of the article, in true “Merchants of Doubt” style, following the money trail behind the promotion of “Unsettled” is mentioned:

The misrepresentations cited as appearing in Koonin’s book are being amplified in right-wing media and beyond. A recent Washington Post column by conservative contributor Marc Thiessen repeats several points Koonin makes… 

Thiessen is a fellow at the American Enterprise Institute. For those unfamiliar with the tangled world of organized climate denial, a recent study paints a pretty clear picture: of all the conservative, climate-denying think tanks that get Koch and other industry funding, AEI has gotten the most. It received some $380 million to peddle industry-friendly denial like Koonin’s, much of it through dark money pass-throughs to conceal that it’s coming from conservative and dirty-energy donors. 

Be all that as it may, in conclusion let’s get back to the cryospheric science. Here’s how I first found out about the Scientific American article, and Steve Koonin and/or Judith Curry still haven’t answered my pertinent questions about the unsettling lack of Arctic scientific expertise evident in “Unsettled”:

Facts About the Arctic in June 2021

Let’s begin the month with a “true colour” image from the Terra satellite of the Laptev Sea and thereabouts:

The blueish tinge that indicates the appearance of melt ponds almost everywhere over the land-fast ice currently covering the majority of the Laptev Sea.

Let’s also take a look at the high resolution AMSR2 metrics for the end of May 2021:

Thanks to the recent “brief hiatus” in areal decline, Arctic wide compaction is no longer in record territory:

Finally, for the moment at least, here is the Danish Meteorological Institute’s high Arctic temperature data in the form of a graph of freezing degree days:

For some reason the data file still doesn’t include data to the end of May, but things won’t change much by then. Over the winter as a whole only 2016/17 was significantly warmer.

Let the 2021 Arctic sea ice summer melting season officially begin!

[Edit – June 4th]

Perhaps unsurprisingly the GFS forecast from four days ago hasn’t quite worked out as predicted. The Arctic as a whole is certainly on the warm side, with a +2 C anomaly at this moment:

However the 966 hPa MSLP cyclone predicted for Monday is now forecast to be a mere 978 hPa:

With 3 days to go there is a reasonable chance of it verifying in the “New Arctic” of 2021. As you can see from the map above a large area of the Central Arctic has now lost its snow cover. This is confirmed by the Rutgers Snow Lab northern hemisphere data for May:

A new Sentinel 3 melt pond fraction product from the University of Bremen confirms that on the fast ice in the Laptev & East Siberian Seas snow cover has departed and melt ponds have arrived:

In other news Wipneus has released the latest PIOMAS gridded thickness and volume data on the Arctic Sea Ice Forum:

For some strange reason 2021 volume at the end of May is almost identical to 2012 and 2020! Plus of course there’s the modelled volume export from the Central Arctic via the Fram Strait:

[Edit – June 6th]

This “false colour” image reveals that there’s virtually no snow cover left on land, and this “false colour” image reveals that the land-fast ice in the East Siberian Sea is now awash with melt ponds:

[Edit – June 8th]

The forecast low pressure area appears to have bottomed out near the Severnaya Zemlya islands with a 978 hPa MSLP:

High resolution AMSR2 Arctic sea ice area is now 2nd lowest for the date after 2016:

Laptev sea ice area is still lowest for the data, and looks as though it will retain that position for a while:

[Edit – June 9th]

The effect of the recent heat and wind on the remaining sea ice in the Laptev Sea is now all too apparent:

It’s also evident in the DMI >80N temperature graph, which has now reached sea ice “melting point” ahead of the climatology:

Note that the blue line is actually above the “freezing point” of salty Arctic sea water.

[Edit – June 13th]

Fairly clear skies over the Laptev Sea and the western East Siberian Sea, revealing wall to wall melt ponds and the land-fast ice starting to break up near the coast as well as on the edge of the now open ocean:

Plus yesterday’s view of the Beaufort Sea, revealing fast ice breaking up in the western entrance to the McClure Strait:

[Edit – June 18th]

A clearish view of the Laptev Sea today, revealing assorted cracks in a variety of locations:

[Edit – June 20th]

The latest mid-month PIOMAS thickness/volume numbers have been released:

[Edit – June 23rd]

The skies over the Vilkitsky Strait have been cloudy for a few days. However a fairly clear view yesterday reveals that breakup is well under way in what is usually one the last areas along the Northern Sea Route to become navigable:

Watch this space!

Unsettling Koonin Critiques Continue

We have previously mentioned assorted reviews of Steven Koonin‘s new book “Unsettled”, but today we bring news of a novel variation on that theme. In an article on the Union of Concerned Scientists web site Ben Santer writes:

Lawrence Livermore National Laboratory (LLNL) has invited Professor Steven Koonin to give a seminar on May 27, 2021. Professor Koonin’s seminar will cover material contained in a book he published on May 4. His book is entitled “Unsettled”. Its basic thesis is that climate science is not trustworthy.

Professor Koonin is not a climate scientist. I am. I have worked at LLNL since 1992. My primary job is to evaluate computer models of the climate system. I also seek to improve understanding of human and natural influences on climate.

Please read Ben’s article in full, but I expect you can already see what’s coming?

Continue reading Unsettling Koonin Critiques Continue

Unsettling Defence of the Undefensible?

As mentioned in a previous episode of my series of reviews of Steven Koonin’s new book “Unsettled”, he published an allegedly “detailed point-by-point rebuttal of the fact check” of his book by Climate Feedback on Medium.

I politely enquired in a comment on Medium “Why does ‘Unsettled’ fail to address the issue of declining Arctic sea ice?”, and Steven was gracious enough to reply that:

All writers have to make choices. I didn’t (couldn’t) write an assessment report…

My focus is on significant points where the popular perception about climate and energy is very different from what the science says. In that way, this book is about more than what’s scientifically correct and what isn’t; it’s also about how the science, with all of its certainties and uncertainties, becomes The Science — how it gets summarized and communicated, and what’s lost in the process…

So limited space (and time writing the book) meant arctic sea ice didn’t get much mention. The topic is also somewhat distant from ordinary folks’ perception (unlike storms, heat waves, SLR, …).

Even so, on page 85 you can find a discussion of the ice-albedo feedback, although I don’t use that term. (no need to introduce technical lingo when it’s not convenient)

However Steven then rather ungraciously chose to ignore my follow up question:

Regarding “the topic somewhat distant from ordinary folks’ perception”, that is largely my point. Is Arctic sea ice decline really any more distant to the average (wo)man in the street than sea level rise?

Etc. etc. For 8 days and counting…


Since Steve is evidently unable and/or unwilling to respond to my enquiry perhaps somebody else might be willing to do so in the space provided for that purpose below?

Meanwhile here’s news of a brand new paper documenting the evidently inexorable decline of the sea ice cover across the Arctic Ocean:

Steve Koonin’s Unsettled History of US Temperature

Regular readers will no doubt have noticed by now that here at the Great White Con we are publishing a series of reviews of Steven E. Koonin‘s new book “Unsettled”? Today we move on to the topic of Land-Surface Air Temperature (LSAT for short). Here is an extract from the very first page of the book:

Yes, it’s true that the globe is warming, and that humans are exerting a warming influence upon it. But beyond that—to paraphrase the classic movie The Princess Bride: “I do not think ‘The Science’ says what you think it says.”

For example, both the research literature and government reports that summarize and assess the state of climate science say clearly that heat waves in the US are now no more common than they were in 1900, and that the warmest temperatures in the US have not risen in the past fifty years. When I tell people this, most are incredulous. Some gasp. And some get downright hostile.

Here once again is an extract from page 23 of the Kindle edition of Steve’s book:

The [IPCC] assessment reports literally define The Science for non-experts. Given the intensive authoring and review processes, any reader would naturally expect that their assessments and summaries of the research literature are complete, objective, and transparent—the “gold standard.” In my experience, the reports largely do meet that expectation, and so much of the detail in the first part of this book, the science story, is drawn from them.

First of all let me remind Steve that the United States does not constitute the entirety of our planet. In particular the Arctic is warming a lot faster than mid latitudes in general and the US in particular. Using WRIT once again to produce our own time series, we can compare and contrast longer term temperature records between the Continental United States and the Arctic (including both land and ocean above the Arctic circle):

Also note that for some reason Steve makes no mention of US “coolest temperatures” and/or “cold waves” since 1900. I don’t know about you, but the top graph certainly suggest to me that “the warmest temperatures in the US have risen in the past fifty years”.

Let’s see how Steve explains himself. For that we have to wait until Chapter 5, catchily entitled “Hyping the Heat”. Therein no mention is made of recent temperature increases across the Arctic, but we are able to read in the introductory paragraphs that:

We can all agree the globe has gotten warmer over the past several decades. Here’s another summary statement from the IPCC’s AR5:

[S]ince about 1950 it is very likely that the numbers of cold days and nights have decreased and the numbers of warm days and nights have increased . . . there is medium confidence that globally the length and frequency of warm spells, including heat waves, has increased since the middle of the 20th century. (IPCC. AR5 WGI Section 2.6.1.)

Then there is a long discussion about what Steve apparently perceives to be shortcomings in the “The US government’s most recent assessment report, the 2017 Climate Science Special Report (CSSR)”. Steve is apparently well qualified in physics, so presumably he is able to comprehend these equations?

  • US ≠ Global
  • CSSR AR5

For those of you less familiar with the arcane language of mathematics and physics that translates to “the climate of the continental United States is not identical to Arctic climate or typical of the climate of Planet Earth as a whole” and hence “US Governmental climate reports are not necessarily typical of ‘Intergovernmental’ climate assessments”.

Next let’s check what Steve’s “gold standard for The Science” has to say on this topic. According to section 2.6.1 of the Intergovernmental Panel on Climate Change’s fifth Assessment Report, as cited by Steve:

A large amount of evidence continues to support the conclusion that most global land areas analysed have experienced significant warming of both maximum and minimum temperature extremes since about 1950 (Donat et al., 2013c). Changes in the occurrence of cold and warm days (based on daily maximum temperatures) are generally less marked (Figure 2.32):

Figure 2.32 | Trends in annual frequency of extreme temperatures over the period 1951–2010, for (a) cold nights (TN10p), (b) cold days (TX10p), (c) warm nights (TN90p) and (d)
warm days (TX90p) (Box 2.4, Table 1). Trends were calculated only for grid boxes that had at least 40 years of data during this period and where data ended no earlier than 2003.
Grey areas indicate incomplete or missing data. Black plus signs (+) indicate grid boxes where trends are significant (i.e., a trend of zero lies outside the 90% confidence interval).
The data source for trend maps is HadEX2 (Donat et al., 2013c) updated to include the latest version of the European Climate Assessment data set (Klok and Tank, 2009). Beside
each map are the near-global time series of annual anomalies of these indices with respect to 1961–1990 for three global indices data sets: HadEX2 (red); HadGHCND (Caesar et al., 2006; blue) and updated to 2010 and GHCNDEX (Donat et al., 2013a; green). Global averages are only calculated using grid boxes where all three data sets have at least 90%
of data over the time period. Trends are significant (i.e., a trend of zero lies outside the 90% confidence interval) for all the global indices shown.

To paraphrase The Princess Bride once again: “I do not think ‘The Science’ says what Steven E. Koonin says it says in ‘Unsettled’”.

Unsettling, is it not?

The Northwest Passage in 2021

Prompted by a comment on the Northwest Passage thread from last year I’m opening the 2021 equivalent earlier than usual, in part because there’s already a lot going on of interest. First of all let’s get our bearings with the help of this map of the area:

and another map detailing the routes through Canadian Arctic Archipelago that have previously been successfully traversed:

The forecast high pressure has arrived and the skies have cleared over the Beaufort Sea, which reveals that the land-fast ice off the Mackenzie Delta has started breaking up:

In addition the snow has been melting along the valley of the Mackenzie River, and the resulting increased flow at the mouth of the delta is flooding the fast ice:

Further east Barrow Strait and Lancaster Sound are also crumbling:

But what about the sea ice in the Canadian Arctic Archipelago that isn’t already falling apart at the seams? To get a feel for what might happen during the coming melting season let’s take a look at the Canadian Ice Service’s “stage of development” charts. Here’s the most recent one, from May 10th:

Several of the assorted routes along the Northwest Passage are currently clear of multi-year ice, so let’s also try and check the thickness of the ice along those routes. Here is the latest available merged CryoSat-2/SMOS thickness map for the Canadian Arctic Archipelago :

All in all it looks to me as though the Northwest Passage will open earlier than “normal” this year, but as always everything depends on the summer weather.

[Edit – May 28th]

The skies were clear over the Canadian Arctic Archipelago yesterday, which revealed several patches of open water across the CAA and a long stretch of Route 1 already “open for business”:

Watch this space!