Emperor penguin populations in Antarctica rapidly declining

By Lauren Beavis

Antarctica's emperor penguin population may be decreasing faster than thought, and they are expected to be extinct by the end of the century, according to the British Antarctic Survey.

Computer-modeled projections point to the species approaching extinction by 2100, assuming current rates of global warming continue and are maintained.

New analysis of up-to-date satellite imagery suggests the birds' numbers have declined by a staggering 22 percent over a 15-year period (from 2009 to 2024) in a key sector of the continent, encompassing the Antarctic Peninsula, Weddell Sea and Bellingshausen Sea.

Dr. Peter Fretwell, who studies wildlife from space at BAS, said: "There's quite a bit of uncertainty in this type of work and what we've seen in this new count isn't necessarily symbolic of the rest of the continent.

"But if it is - that's worrying because the decline is worse than the worst-case projections we have for emperors this century."

An earlier estimate saw a nine-and-a-half percent reduction in the species, from 2009-2018, across Antarctica as a whole.

Experts at the British Antarctic Survey (BAS) are now checking to see whether their latest assessment in this narrower geographic range reflects the same story across Antarctica.

Dr. Fretwell and colleagues have published their latest work in the journal Nature Communications: Earth & Environment.

Experts explain how a rapidly warming climate poses a particular challenge for emperor penguins because of their dependence on seasonal sea ice.

The species uses the frozen sea ice around the Antarctic coastline as a platform on which to mate and bring up their young, and this ice needs to be stable for about eight or nine months of the year.

Unfortunately, the recent trend has seen sea ice in many parts of the continent become patchy and unreliable, likely harming breeding success.

The last global census of emperors found the total population had declined by 9.5 percent.

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It covered the 10 years up to 2018, and included what appeared to be a slight uptick in numbers towards the end of the period.

The latest work extends the count up to 2024, but does so only for the limited area running between 0 degrees to 90 degrees West longitude - from Dronning Maud Land to the Bellingshausen Sea, taking in the entire Antarctic Peninsula.

The quadrant, which at 2.8 million square kilometres is more than 11 times the size of the UK, is significant as it contains about 30 percent of the global emperor population.

In this narrower geographic range, the team finds that the decline in the number of birds continues through the extended time period.

It has revealed an average reduction of 1.6 percent per year, or 22 percent over the full 15 years.

Counting penguins from space is not straightforward and relies on estimating the number of individuals in the large huddles of birds detected in high-resolution satellite imagery.

The approach is, however, the only way scientists can really gauge the emperors' status because many of the breeding sites are so remote they would be extremely difficult, even dangerous, to reach in person.

A collection of satellite pictures is now being assembled to update the global population of emperors.

Experts explain how the report highlights the complex interplay of climate-related factors beyond just unreliable sea-ice conditions that appear to be making life harder for the penguins.

These include changing storm, snow and rainfall patterns; increased competition for food resources as other wildlife shift their ranges; and the increased disturbance and predation coming from petrels, seals and killer whales, which are exploiting a more open ocean.

Dr. Phil Trathan, co-author and emeritus fellow at BAS, added: "The fact that we're moving to a position faster than the computer models project means there must be other factors we need to understand in addition to loss of breeding habitat.

"The only way we'll see a turnaround for the population is if we stabilize greenhouse gas emissions.

"If we don't, we'll probably have relatively few emperor penguins left by the turn of this century.”