Steve Amstrup is lying to the media about my critique of his 2007 model

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?


Amstrup, S.C., Marcot, B.G. & Douglas, D.C. 2007. Forecasting the rangewide status of polar bears at selected times in the 21st century. US Geological Survey. Reston, VA. Pdf here

Amstrup, S.C., Marcot, B.G., Douglas, D.C. 2008. A Bayesian network modeling approach to forecasting the 21st century worldwide status of polar bears. Pgs. 213-268 in Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications, E.T. DeWeaver, C.M. Bitz, and L.B. Tremblay (eds.). Geophysical Monograph 180. American Geophysical Union, Washington, D.C. and

Atwood, T.C., Marcot, B.G., Douglas,D.C., Amstrup, S.C., Rode, K.D., Durner, G.M. and Bromaghin, J.F. 2015. Evaluating and ranking threats to the long-term persistence of polar bears. USGS Open-File Report 2014–1254. Pdf here.

Crockford, S.J. 2017. Testing the hypothesis that routine sea ice coverage of 3-5 mkm2 results in a greater than 30% decline in population size of polar bears (Ursus maritimus). PeerJ Preprints 2 March 2017. Doi: 10.7287/peerj.preprints.2737v3 Open access.

Crockford, S.J. 2018. State of the Polar Bear Report 2017. Global Warming Policy Foundation Report #29. London. pdf here.

Crockford, S.J. and Geist, V. 2018. Conservation Fiasco. Range Magazine, Winter 2017/2018, pg. 26-27. Pdf here.

Durner, G.M., Douglas, D.C., Nielson, R.M., Amstrup, S.C. and McDonald, T.L. 2007. Predicting 21st-century polar bear habitat distribution from global climate models. US Geological Survey. Reston, Virginia. Pdf here.

Durner, G.M., Douglas, D.C., Nielson, R.M., Amstrup, S.C., McDonald, T.L. and 12 others. 2009. Predicting 21st-century polar bear habitat distribution from global climate models. Ecological Monographs 79:25-58.

Harvey, J.A., van den Berg, D., Ellers, J., Kampen, R., Crowther, T.W., Roessingh, P., Verheggen, B., Nuijten, R. J. M., Post, E., Lewandowsky, S., Stirling, I., Balgopal, M., Amstrup, S.C., and Mann, M.E. 2017. Internet blogs, polar bears, and climate-change denial by proxy. Bioscience. DOI: 10.1093/biosci/bix133 pdf here. Supplementary info here.

Holland, M.M., C.M. Bitz, and B. Tremblay. 2006. Future reductions in the summer Arctic sea ice. Geophysical Research Letters. 33:L23503. DOI: 10.1029/2006GL028024 Open access, pdf here.

Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor, and H.L. Miller (Editors). 2007. Summary for policymakers. In Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, United Kingdom. Available at Pdf here.

Zhang, X. & Walsh, J.E. 2006. Toward a Seasonally Ice-Covered Arctic Ocean: Scenarios from 991 the IPCC AR4 Model Simulations. Journal of Climate 19: 1730-1747. Open access, pdf here.

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