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Amstrup Is Lying To The Media About Crockford’s Demolition Of His 2007 Polar Bear Paper

April 13, 2018

By Paul Homewood



Susan Crockford has responded forcefully to the latest disinformation to come from Steve Amstrup and co:


Until now, my scientific paper post at PeerJ Preprints for review, about the failure of Steve Amstrup’s 2007 USGS polar bear survival model (Crockford 2017), has been formally ignored by Amstrup and his colleagues. But now Amstrup and his colleagues have taken to lying to the media about my analysis because he can’t refute it in a scholarly manner.


Mother with cubs Russia_shutterstock_71694292_web size


Amstrup was quoted by Erica Goode in her New York Times article on the Harvey et al. (2018) BioScience attack paper published Tuesday (10 April 2018: “Climate Change Denialists Say Polar Bears Are Fine. Scientists Are Pushing Back”):

“Dr. Amstrup, however, said that according to the National Snow and Ice Data Center, the average September sea ice extent for the years 2007 to 2017 was 4.5 million square kilometers, “nowhere near the low levels projected it would be by the middle of the century.”

“To say that we already should have seen those declines now when we’re not early [sic] to the middle of the century yet is absurd,” he said.” [my bold]


And over at the online outlet Mashable (11 April 2018: “Climate scientists fight false polar bear narrative pushed by bloggers”), reporter Mark Kaufman quoted Jeff Harvey, lead author of the BioScience paper on the issue, although Harvey is hardly an authority:

“(Harvey noted Crockford misunderstood and then mischaracterized this prediction).”

Amstrup also presented a lame critique of the portion of my Financial Post 27 February 2018 op-ed that dealt with his 2007 predictions, published 2 March 2018 by Climate Feedback (self-proclaimed “fact checkers”), that is easily refuted because it’s a blatant lie. He’s saying 2015 sea ice models are relevant to his 2007 predictions that used 2005/2006 sea ice models.

Quote from my op-ed to which Amstrup responded:

“Although the extent of the summer sea ice after 2006 dropped abruptly to levels not expected until 2050, the predicted 67-per-cent decline in polar bear numbers simply didn’t happen. Rather, global polar bear numbers have been stable or slightly improved.”


Amstrup responded, in part:

“Of course summer ice availability has been reduced from earlier years, but neither observations nor models suggest that what we predicted for mid century has already happened. Here is an image that may help put this in perspective, and make it clear why our projections focused on mid century and beyond, and that we are not yet in mid-century.”

amstrup_seaice_March 2 2018 Fact check

My response to Amstrup’s comment:

The image Amstrup offers as evidence is a sea ice projection graph modified from Atwood et al. 2015.2 This is a strawman argument at best and an outright lie at worst: a sea ice projection from 2015 is irrelevant to the model developed in 2007.

The ESA decision of 2008 by the US Fish and Wildlife Service used the 2007 USGS reports Amstrup co-authored with colleagues based on sea ice projections developed in 2005/2006 for 2007 IPCC AR4 (e.g. Holland et al. 2006; Soloman et al. 2007; Zhang and Walsh 2006).

The appropriate sea ice image to discuss this issue is the one below (especially the panel on the left), found in Amstrup et al. (2007:84); Durner et al. (2007:46); and Durner et al. (2009:44):

Durner et al. 2009 FIg 12 a sea ice extent summer models

This version is taken from Durner et al. (2009:44, Fig. 9). From the original caption: (a) Mean monthly ice extent in the full study area during the summer ice seasons (left column) and expressed as percentage change (right column) relative to the respective model’s 1990–1999 mean for the 20th-century hindcasts and the satellite-observed record and the 2001–2010 mean for the 21st-century GCM projections. Mean monthly values of ice extent (panel a, right column) during 1990–1999 from the satellite observed record are shown in the ice-extent percentage-change panels to provide a baseline for assessing the effective magnitude of change. All results are plotted as 10-year running means.



Just as the badly written Harvey et al. (2017) Bioscience paper said more about the naked desperation of the authors than it did about me or my fellow bloggers, this most recent attempt by Amstrup and others to discredit me and my work reveals their frustration at being unable to refute my scientifically supported conclusion that Amstrup’s 2007 polar bear survival model has failed miserably (Crockford 2017, Crockford 2018; Crockford and Geist 2018).

Amstrup fell in love with his 2007 predictive model (Amstrup et al. 2008), a deadly sin for any scientist. Because now that it’s been shown to have failed, he’s flailing about trying to save face. His colleagues, rather than helping him let it go, are encouraging him. It’s a very sad thing to watch.

My full analysis of the Climate Feedback fact-checking fiasco, with references: Part 1 [here] and Part 2 [here].

Footnote 1: Amstrup says the graph he provides is modified from “Atwood et al. 2015.” However, there appears to be only one publication that fits that citation and the sea ice graph it contains, on pg. 39, is an anomaly graph (showing amount of change, not absolute extent). Consequently, it does not look anything like the graph provided by Amstrup, even without the snarky labels. That leaves me to ask: where did the graph Amstrup provided to Climate Feedback actually come from?



It’s a bit technical, but the gist is this:

1) Amstrup’s 2007 model was based on the predictions of Arctic sea ice shown below, and as used in IPCC AR4 in 2007:



Notice how the red ensemble line dips below 4m sq km around 2040. This is roughly the level seen in recent years, with the lowest extent barely above 3m sq km in 2012.


2) Based on the above, Amstrup predicted a large drop in Polar Bear Carrying Capacity:



His Abstract makes it totally clear:




3) Amstrup now claims that we should ignore the 2007 predictions, and use the most recent ones below, which show summer ice virtually disappearing by 2050:



Whether or not the prospect of no summer sea ice in the Arctic will have the effect on polar bear population that he surmised in 2007 is irrelevant.

The simple fact is that we already have the reduced levels of sea ice, upon which his model was based for mid-century. Yet the polar bear population has not declined in any way whatsoever.

On the contrary, it has in all likelihood actually increased, although the uncertainties of measurement mean we cannot be sure.


I can’t sum things up better than Susan:

 Amstrup fell in love with his 2007 predictive model (Amstrup et al. 2008), a deadly sin for any scientist. Because now that it’s been shown to have failed, he’s flailing about trying to save face. His colleagues, rather than helping him let it go, are encouraging him. It’s a very sad thing to watch

  1. April 13, 2018 12:05 pm

    IT would appear from Amstrup to The Times’ Goode and the gang of 14, the very health of the speciecs is threatening the very health of their reputations. Activists who are supposed to cheer the bears’ health and population growth irrespective of contradicting their failed, doomsday models. Now that’s sad, and telling.

  2. April 13, 2018 12:31 pm

    Some “scientists” lie. Do tell.

  3. Broadlands permalink
    April 13, 2018 2:12 pm

    It has been one forgotten observation that the early emphasis on polar bear declines and “global warming” was based on the fact that the decline was because of unregulated recreational over-hunting. Once that was stopped the population began to recover irrespective of “global warming” or even sea ice extent. Continued “concern” is unjustified but fits the rest of the climate alarmism?

  4. April 13, 2018 3:23 pm

    Polar bears hunt seals during the whelping period in the spring. About 85% of their total calories for the year if I recall correctly. (The rest is summer terrestrial foraging (berries, snow goose eggs, young caribou—see essay Polar Bears for the scientific references). The extent of summer sea ice is mostly irrelevant. Amstrup’s model isn’t just factually wrong in hindsight, it is biologically illogical. Susan should be harsher, IMO.

  5. April 13, 2018 4:18 pm

    I can’t get past there being 14 authors for 5 pages of work.

    Put your hand up if you think some or most of those “authors” didn’t contribute a thing except for agreeing to have their name attached to it.

    • MrGrimNasty permalink
      April 13, 2018 9:09 pm

      It’s similar to the tactic often employed by climate alarmists, publicly sending a letter to some body or politician, signed by as many ‘concerned scientists/experts’ i.e. eco dingle berries. It’s just the deployment of a political correctness enforcement mob.

  6. Keitho permalink
    April 13, 2018 4:31 pm

    If the sea ice decline was much faster than they predicted their model, and understanding, are wrong too.

    Good work Dr Crockford, you are a definite asset in these times of scientific advocacy.

  7. Tony Mckenna permalink
    April 13, 2018 4:58 pm

    So it appears that Amstrup made two predictions. The first was that by using climate models and his understanding of the effect of CO2, he could predict the time when the Arctic would be reduced to 4m sq Kilometres. It turns out he was spectacularly wrong.
    He also predicted that whenever these physical conditions occured, it would be bad for the bears.
    Unfortunately for him these conditions did not happen when he was safely retired and we can judge the effect on the bears ourselves.
    His defence seems to be that because he was wrong in the timing of his first prediction, we cannot comment on his second even though the exact test bed conditions applied. A Clintonian level of defence.
    I can remember when journalists used to spot such attempts at sophistry and make their reputations in exposing them, not being fooled by them.

    • April 13, 2018 6:59 pm

      “… not being fooled by them.” A better explanation is that they’re on the same team.

  8. Bitter@twisted permalink
    April 13, 2018 6:14 pm

    Amstrup is a mini-Mann.
    Charlatan, grant-grasper and all round arrogant to$$er.

  9. tom0mason permalink
    April 15, 2018 2:17 pm

    Of course the big problem that the Greenies, cAGW activists, advocates, UN-IPCC stooges, etc., have yet to answer is how all the animals that are here currently, including polar bears, managed to survive the last Roman and Medieval Warm Periods.

    Or were the animals so weirdly different back then?

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