Climate change risk to emperor penguins

British Antarctic Survey

British Antarctic Survey scientists have contributed to a new study published today (3 August) which provides valuable new data highlighting how emperor penguins extinction risk is increased due to rapid climate change and an increase in extreme climate events, such as glacial calving and sea ice loss. The study, published in the journal Global Change Biology led by Woods Hole Oceanographic Institution, and co-authored by an international team of scientists, policy experts, ecologists, and climate scientists, provides pivotal research and projections tailored for use by the U.S Fish & Wildlife Service (USFWS). The study recommends that emperor penguins be listed as threatened under the US Endangered Species Act and this week, the US Department of Interior/ USFWS submitted that listing recommendation.

“Scientists have a responsibility to make people aware of the need for change through objective evidence” explained lead author Stephanie Jenouvrier. “With the help of a dedicated team, we have put together this paper for the USFWS to provide additional analyses of future projections to help inform policy and protection for the species.”

The study presents the projected dynamics of all known emperor penguin colonies under different greenhouse gas emission scenarios using a climate‐dependent meta-population model that includes for the first time, the effects of extreme climate events based on the observational satellite record of colonies.

Co-author Shaye Wolfe, Center for Biological Diversity, said:

“Protection of species through legal frameworks should facilitate conservation actions that in turn should help mitigate climate change impacts.”

Co-author Judy Che-Castaldo, Alexander Center for Applied Population Biology, adds:

“The study is framed in the context of the US Endangered Species Act, one of the most progressive pieces of legislation in relation to species protection”.

Emperor penguins
Emperor penguin (Aptenodytes forsteri) colony. Credit: Peter Fretwell

The study demonstrates that extreme events impact the resiliency, redundancy and representation (3Rs) of emperor penguins. Resiliency is the ability to withstand stochastic (or random) disturbance, which may be measured through population size, growth rate and connectivity among populations. Redundancy is the ability to withstand catastrophic events, and considers the number, distribution, resiliency and connectivity of populations. Representation is the ability to adapt to changing environmental conditions, and is related to capturing the geographic, genetic, and life history variation that exists across the species’ ecological setting. Together, the 3Rs encompass aspects that contribute to species persistence (e.g. demography, spatial distribution, diversity) and are important for assessing climate threats in the foreseeable future. The study shows that if sea ice declines at the rate projected by climate models under current energy-system trends and policies, 3Rs for emperor penguins would be dramatically reduced and almost all colonies would become quasi-extinct by 2100.

Co-author Dr Peter Fretwell, British Antarctic Survey Mapping and GIS specialist explains,

“The more we learn about emperor penguins, the more we realize how dependent they are on the sea-ice. Our new models of population dynamics add in the effect of extreme events, which we have witnessed impacting penguin colonies in recent years. The models predict that if we do not act now to curb greenhouse emissions emperor penguin populations will decline by four-fifths by 2060 and be virtually extinct by the end of this century.

“If global emissions continue to increase, as they have done over the last two decades, the future for emperor penguins looks bleak. But this paper is not just about emperor penguins. We use emperors an example of a species where we can make a direct analysis based on known environmental stresses, in this case lack of sea ice, to predict future declines. For many species, the link between climate change and populations is less obvious and harder to model but still very real. The decline of the emperor could be seen a warning of the possible future of many species if we do not act to curb climate change.”

The novel results described in the paper also have important implications for assessing climate change risks to other species. According to the authors, rapid climate change is increasing stress on species and ecosystems, and the risk of extinction will accelerate with continued global warming. Emperor penguins live in the icy coastal regions of Antarctica, but current climate models project significant declines in Antarctic sea ice to which the emperor penguins’ life cycle is closely tied. The study reinforces the need for legal recognition and enhanced precautionary management, particularly given continued increases in greenhouse gas emissions. Given the species’ reliance upon sea ice for breeding, moulting and feeding, the most important threat for emperor penguins is climate change, which would lead to Antarctic sea ice losses over this century.

Dr Phil Trathan, Head of Conservation Biology at British Antarctic Survey, and co-author who has worked on Antarctic penguins for over 30 years said,

“Near-term global policy decisions under Paris Agreement objectives are intended to limit temperature increases to well below 2°C. This would ensure safe places for the emperor penguin, halting dramatic global population declines. As such, the future of emperor penguins ultimately depends upon decisions made today. The most important action is to reduce greenhouse gas emissions to limit further warming”.

He added “We echo President Biden and hope that global society will listen to the science and meet the moment”. Dr Trathan concluded “Protecting these systems requires legal frameworks that must be appropriately founded and based on the best available scientific evidence. Building an international framework will be key, but in the meantime immediate efforts should focus on those tools already in place, such as the ESA”.

“This study provides the best available science for projecting emperor penguin populations in the context of future climate change and informs policy makers about whether the emperor penguin warrants listing under the ESA,” said Che-Castaldo. “The future of this iconic species depends on immediate actions to decarbonize society and increased protections for species endangered by climate change.” concluded Jenouvrier.

Dr Trathan added

“The international team that carried out the study highlighted how this work cuts across the boundaries between different science disciplines, and how such interdisciplinary science was key for unravelling the future of this iconic species”. He emphasized “That projecting climate change impacts for species is technically challenging, and only by working together can progress be made”.

The call of the emperor penguin: Legal responses to species threatened by climate change by Jenouvrier , Stephanie., Che-Castaldo, Judy., Wolf, Shaye., Holland, Marika., Labrousse, S., LaRue, Michelle., Wieneck, Barbara., Fretwell, Peter., Barbraud, Christophe., Greenwald, Noahd., Stroeve, Stroeve, Julienne. & Trathan, Philip is published in Global Change Biology: https://onlinelibrary.wiley.com/doi/10.1111/gcb.15806

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