Posted on August 6, 2020 |
Emperor penguin (Aptenodytes fosteri) populations in 2019 were found to have grown by up to 10% since 2009 – to as many as 282,150 breeding pairs (up from about 256,500) out of a total population of over 600,000 birds (Fretwell et al. 2012; Fretwell and Trathan 2020; Trathan et al. 2020) – despite a loss of thousands of chicks in 2016 when an ice shelf collapsed. Yet, biologists studying this species are currently petitioning the IUCN to upgrade emperor penguins to ‘Vulnerable’ (Trathan et al. 2020), based on models that use the implausible and extreme RCP8.5 ‘worse case‘ climate change scenario (e.g. Hausfather and Peters 2020) that polar bear biologists find so compelling. Not surprisingly, their unscientific models suggest emperor penguins could be close to extinction by 2100 under these unlikely conditions – but if we reduce CO2 emissions via political policy, the penguins will be saved!
Surprisingly, these researchers are going ahead with their petition to have emperor penguins uplisted despite the population increase and the reservations their colleagues expressed in 2018 about using climate change predictions to arrive at a classification of ‘Near Threatened’ for the IUCN Red List assessment (Birdlife International 2018), as noted below in their ‘justification’:
This species is listed as Near Threatened because it is projected to undergo a moderately rapid population decline over the next three generations owing to the projected effects of climate change. However, it should be noted that there is considerable uncertainty over future climatic changes and how these will impact the species.
Like polar bear biologists, some emperor penguin biologists just won’t give up on the prediction they developed back in the mid-2000s that climate change is sure to drive this species to near extinction. For example, Jenouvrier et al. (2009) calculated that there was at least a 36% chance of a 95% or more decline in emperor penguins by 2100 (what they called a “quasi-extinction”) due to changes in sea ice distribution. They suggested a decline of this magnitude would entail a fall from about 6,000 breeding pairs to about 400 in a single colony. The newest model (Jenouvrier et al. 2020) similarly uses the RCP8.5 ‘worse case’ scenario to predict near-extinction by 2100, as their ‘graphic abstract’ below shows.
This group are also recommending that “the species is listed by the Antarctic Treaty as an Antarctic Specially Protected Species” that would require a Species Action Plan (Trathan et al. 2020). And as co-author Peter Fretwell told the BBC last fall (9 October 2019):
“Everything we know – all the experts, all the models – tells us that Emperors are going to be in real trouble. We need to pull out all the stops to help them. That’s going to be hard because we know the one thing that’s really going to save them is stabilisation of the global climate.”
Sounds like something a polar bear specialist would say. Except that for polar bears, the catastrophe they keep predicting just won’t happen despite the fact that summer Arctic sea ice has been declining faster than anyone expected – so far, an almost 50% decline in ice has already happened yet global polar bear numbers keep slowly increasing (Crockford 2019; 2020).
I’d suggest that using far-fetched ‘worse case’ scenario predictions to propose an unlikely but scary-sounding future catastrophe isn’t likely to work any better for emperor penguins than it has done for polar bears, especially when the animals keep thriving.
However, some of the papers listed below are open access, so if you’re interested in more details I suggest you have a look. If you’d like a copy of the modelling paper (Jenouvrier et al. 2020), contact me and I’ll send it along. You’ll find more on the emperor penguin conservation issue in this essay by biologist Jim Steele.
BirdLife International. 2018. Aptenodytes forsteri. The IUCN Red List of Threatened Species 2018: e.T22697752A132600320. Downloaded on 07 August 2020. https://www.iucnredlist.org/species/22697752/132600320
Crockford, S.J. 2020. State of the Polar Bear Report 2019. Global Warming Policy Foundation Report 39, London. pdf here.
Fretwell, P.T., LaRue, M.A., Morin, P., Kooyman, G.L., Wienecke, B., Ratcliffe, N., Fox, A.J., Fleming, A.H., Porter, C. and Trathan, P.N. 2012. An emperor penguin population estimate: the first global, synoptic survey of a species from space. PLoS One 7: e33751 [open access] doi: 10.1371/journal.pone.0033751.
Fretwell, P.T. and Trathan, P.N. 2020. Discovery of new colonies by Sentinel2 reveals good and bad news for emperor penguins. Remote Sensing in Ecology and Conservation [open access], in press. https://doi.org/10.1002/rse2.176
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.
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
Trathan, P.N. and others, including Fretwell, P. T. 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