Will any remain by the end of the century? Satellite data shows a 22% decline in emperor penguin populations across a quarter of Antarctica over the past 15 years, due to climate instability.
One more brick in the edifice painstakingly built by penguin scientists around an intuition that is confirmed with every new publication: Emperor penguins will disappear by the end of the century if no action is taken. By nothing, meaning continuing to allow greenhouse gas emissions to rise. To provide tangible, factual evidence validated by the scientific community, Dr Peter Fretwell, a biologist specializing in the study of penguins using satellite images from the British Antarctic Survey, and his team studied the populations of this iconic bird over the quarter of Antarctica located between longitude 0 and longitude 90.
Their results published on June 10 in Communications Earth & Environment, show that models calculating the population size of this species under different emission scenarios underestimate the emperor’s decline. Over the past 15 years, while Dr. Michelle LaRue’s latest calculations predicted a 9.5% decline across Antarctica as a whole, Dr. Peter Fretwell’s findings show that the decline is actually 22% for the quarter of the continent surveyed.
From Queen Maud Land to the Weddell Sea to the Bellingshausen Sea, this stretch of coastline cuts across a variety of climatic disturbances found around Antarctica. On the one hand, the Weddell Sea is still relatively unscathed by ocean warming, and on the other, the western Antarctic Peninsula is experiencing the most drastic degrees of warming on the continent. By concentrating on this part of Antarctica, researchers were able to gain time.
“The imaging we use is expensive, but the main problem is time – analysis is time-consuming. Dr Michelle LaRue’s work, in which we were also involved, covered the whole continent and took years. The latest data used was from 2018, but it wasn’t published until 2024. We wanted our study to be more up-to-date, so we decided to take a smaller subset,” Dr Peter Fretwell explained to polarjournal.net.
Destabilized ice floes
If researchers have been in such a “hurry” to include new observations from 2019 to 2024, it’s because emperor penguins have suffered new consequences of climate change. Records for the low extension of the summer or winter pack ice have have been brloken year after year for the last five years – we’ve been chronicling this in ou articles since 2019. But why are the calculations so wrong if the effects of climate change on sea ice are known and well documented?
“To mathematically reproduce the reality for emperor penguins, you need to take more data into account. It’s not just the loss of pack ice, the flat habitat on which they breed, that affects them, but also the opening up of the ice that puts them in competition with other penguins and other animals that fish, or exposes them to predators,” explained Dr. Phil Trathan, co-author and Emeritus Research Fellow at the British Antarctic Survey.
Emperors are not very agile and are quite heavy, being totally dependent on pack ice and the underwater habitats it covers. They feed on a variety of prey including fish, krill and squid. And even if whales are coming back from near extinction for some species as a result of their hunting, this is not particularly unfavorable for the emperor, unlike penguins, which mainly fish for krill.
“Only the minke whale really ventures out there, and it was the least hunted whale in the days of the whalers,” assures Dr. Peter Fretwell. It’s not the weight of maritime history that’s unbalanced, but rather the melting ice floes, or lack thereof. The study points out that, when there’s not enough ice, penguins have to dive deeper to find prey, and when there’s too much, they have to walk a long way to be able to dive. More than warming, the authors point to climate instability as being at the heart of the decline.
“It’s important to point out that our data are measurements and do not emanate from a model. Worryingly, they are about 50% below what the population should have been in 2023 according to previous forecasts. We’re not speculating or modeling what’s going to happen in the future, but if you look at the projections that have already been made, i.e. near-extinction by 2100, and the actual data are worse… I’ll let you draw your own conclusions,” stated Dr. Peter Fretwell. “I think it’s fair to say that urgent action is needed and that the horizon for saving this species is shorter than we thought.”
Fragility now official?
Analyses often leave it at this stage, but here the researchers go a step further. There are two stages of species conservation policy on which these data could have weight. The first is the IUCN Red List of Threatened Species, and the second is the Antarctic Treaty System’s lists of Specially Protected Species. Listing the emperor penguin as “vulnerable” on the IUCN red list could take a year, says Dr Phil Trathan, but at Antarctic Treaty meetings last year, its listing was rejected.
“Our paper adds to the growing list of evidence that emperor penguins are in danger,” adds Dr Peter Fretwell. “Whether it changes anything on the Antarctic scene depends mainly on whether the current stalemate results from a lack of scientific evidence or other non-scientific reasons.” The next international Antarctic Treaty meeting will take place at the end of the month in Milan and “they could choose to file it this year or wait for further scientific data. It’s important to note that the IUCN is also reviewing the scientific evidence and once completed, this will be a key factor that could help persuade the Antarctic Treaty to reconsider its earlier decisions,” notes Dr Phil Trathan.
Recognizing the vulnerability of the species is one thing, but the other lies in the DNA. Scientists hope that emperor penguins will trigger a form of adaptation that is still silent in their genome, coming from a time that only multimillennials can know, from the last interglacial age. Like a branch on a cliff… it’s not very comfortable, but you can hold on to it.