Emperor penguin ESA listing in 2022 used Antarctic sea ice models known to be flawed

While Arctic sea ice has declined remarkably since 1979, Antarctic ice has been unexpectedly stable. Experts acknowledge that existing climate models–which assume that CO2 emissions drive global sea ice loss–had predicted Antarctic sea ice would have declined over the last several decades–and would decline even more in the future. They’ve finally admitted they were wrong.

John Turner (British Antarctic Survey) and Josifino Comiso (NASA) in a NATURE paper in 2017:

Current climate models struggle to simulate the seasonal and regional variability seen in Antarctic sea ice.

A new model released earlier this year suggests the virtually stable Antarctic sea ice cover that has existed over the last four decades can now be expected to continue for almost another three decades, until at least 2050, and decline only slowly after that (Rackow et al. 2022).

However, emperor penguin researchers used the old flawed models to get the species listed as ‘threatened’ in the US just a few months ago due to predicted sea ice loss (Jenouvrier et al. 2009; Jenouvrier et al. 2020; Trathan et al 2020; USFWS 2022).

In other words, it’s not just that penguin researchers picked the most pessimistic and totally implausible ‘worst case’ scenario to make their case, as polar bear specialist so love to do (Crockford 2019; Hausfather and Peters 2020): sea ice experts now say those old sea ice models are quite useless for predicting future sea ice conditions and have known this for more than a decade (Blanchard-Wrigglesworth et al. 2021, 2022; Comiso et al. 2017; Turner and Comiso 2017; Turner and Overland 2009; Turner et al. 2013).

Sea ice experts knew the models were wrong about Antarctic sea ice and CO2–and wrote about their concerns in the scientific literature–yet penguin biologists ignored that evidence and continued to insist that penguins are doomed to near-extinction by future sea ice loss in the Southern Ocean. See graphic below, from Jenouvrier et al. 2020:

ESA protection for emperors was granted by US Fish & Wildlife on 25 October 2022, even though a new Antarctic sea ice model was published more than eight months earlier, on 2 February 2022. This means both the petitioners for the ESA listing and the USFWS ignored years of evidence provided by trusted experts that Antarctic sea ice models were not fit for purpose plus a more plausible option offered, then called it all “best available science.”

The new model may also be crap but that doesn’t warrant ignoring solid evidence that the old one was seriously flawed.

The graph below is from the Turner and Comiso paper and shows the discrepancy of concern: summer Arctic ice vs. Antarctic winter ice (September for both) from 1979-2017, with max for Antarctic ice hitting 20.11mkm2 in 2014 (when Arctic ice was its 6th lowest at 5.02mkm2):

That graph ends in 2017, now five years ago. Below was the extent at 19 September 2022, near the maximum for that year, eventually reaching 18.19 mkm2. Plenty of ice for emperor penguins, who uniquely lay their eggs and raise hatchlings over the winter/spring, primarily on land-fast ice:

As an aside, I couldn’t help but notice that emperor penguin researchers working in the Antarctic focus on winter sea ice with regard to future health and survival while polar bear specialists and other Arctic biologists are most concerned about summer sea ice loss. In both cases, the ice-dependent species of concern require sea ice in the winter/spring for reproducing and/or feeding. The difference is that summer sea ice in the Antarctic has always virtually disappeared over the summer (down to 15% or less than winter extent) and no one pretends that any Antarctic animal requires summer sea ice for survival. Odd, that.


BirdLife International. 2020. Aptenodytes forsteri. The IUCN Red List of Threatened Species 2019: e.T22697752A132600320. Downloaded on 26 October 2022. https://www.iucnredlist.org/species/22697752/157658053

Blanchard-Wrigglesworth, E., I. Eisenman, S. Zhang, et al. 2022. New perspectives on the enigma of expanding Antarctic sea ice, Eos 103. https://doi.org/10.1029/2022EO220076.

Blanchard-Wrigglesworth, E., Roach, L.A., Donohoe, A. and Ding, Q. 2021. Impact of winds and Southern Ocean SSTs on Antarctic sea ice trends and variability. Journal of Climate 34(3):949–965. https://doi.org/10.1175/JCLI-D-20-0386.1.

Hausfather, Z. and Peters, G.P. 2020. Emissions – the ‘business as usual’ story is misleading [“Stop using the worst-case scenario for climate warming as the most likely outcome — more-realistic baselines make for better policy”]. Nature 577: 618-620

Jenouvrier, S., Caswell, H., Barbraud, C., Holland, M., Stroeve, J. and Weimerskirch, H. 2009. Demographic models and IPCC climate projections predict the decline of an emperor penguin population. Proceedings of the National Academy of Science USA 106: 1844-1847. Available here: https://www.researchgate.net/publication/23951047_Demographic_models_and_IPCC_climate_projections_predict_the_decline_of_an_Emperor_penguin_population

Jenouvrier, S. et al. 2020. The Paris Agreement objectives will likely halt future declines of emperor penguins. Global Change Biology 26(3): 1170-1184. [paywalled] https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14864

Rackow, T., Danilov, S., Goessling, H.F. et al. 2022. Delayed Antarctic sea-ice decline in high-resolution climate change simulations. Nature Communications 13:637. https://www.nature.com/articles/s41467-022-28259-y

Trathan, P.N. et al. 2020. The emperor penguin – Vulnerable to projected rates of warming and sea ice loss. Biological Conservation 241:108216. [open access] https://doi.org/10.1016/j.biocon.2019.108216

Turner, J. and Comiso, J. 2017. Solve Antarctica’s sea-ice puzzle. Nature 547:275-277. https://www.nature.com/articles/547275a

Turner, J. and Overland, J. 2009. Contrasting climate change in the two polar regions. Polar Research 28(2):146-164. https://doi.org/10.3402/polar.v28i2.6120

Turner, J., Bracegirdle, T.J., Phillips, T. et al. 2013. An initial assessment of Antarctic sea ice extent in the CMIP5 models. Journal of Climate 26(5):1473-1484.

USFWS 2022. ‘Endangered and Threatened Wildlife and Plants; Threatened Species Status for Emperor Penguin With Section 4(d) Rule.’ Federal Register 87(206):64700-64720.

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