Global warming may have another victim in its sights: the penguin.
According to newly released report, penguins are facing an intangible threat that may ultimately decimate the population.
A study produced by several Boulder researchers notes that penguin populations could decline by as much as 60 percent. The team noted that a series of recent observations showed that the penguin population is already witnessing a steep decline in numbers.
“Over the last century, we have already observed the disappearance of the Dion Islets penguin colony, close to the West Antarctic Peninsula,” says Stephanie Jenouvrier, WHOI biologist and lead author of the study. “In 1948 and the 1970s, scientists recorded more than 150 breeding pairs there.”
She notes that within the past ten years the population has nearly vanished, a disturbing sign that global warming may be forcing the birds to migrate elsewhere.
“By 1999, the population was down to just 20 pairs, and in 2009, it had vanished entirely,” said Ms. Jenouvrier.
Like in Terre Adélie, Ms. Jenouvrier thinks the decline of those penguins might be connected to a simultaneous decline in Antarctic sea ice due to warming temperatures in the region.”
Current predictions note that the penguins could nearly vanish by the end of the coming century.
“Our best projections show roughly 500 to 600 breeding pairs remaining by the year 2100,” said Ms. Jenouvrier, a biologist at the Woods Hole Oceanographic Institution in Massachusetts and lead author of the study. “Today, the population size is around 3,000 breeding pairs.”
Unlike other sea birds, Emperor penguins breed and raise their young almost exclusively on sea ice. If that ice breaks up and disappears early in the breeding season, massive breeding failure may occur, says Jenouvrier. “As it is, there’s a huge mortality rate just at the breeding stages, because only 50 percent of chicks survive to the end of the breeding season, and then only half of those fledglings survive until the next year,” she says.
Disappearing sea ice may also affect the penguins’ food source. The birds feed primarily on fish, squid, and krill, a shrimplike animal, which in turn feeds on zooplankton and phytoplankton, tiny organisms that grow on the underside of the ice. If the ice goes, Ms. Jenouvrier says, so too will the plankton, causing a ripple effect through the food web that may starve the various species that penguins rely on as prey.
Local researchers then went to work evaluating the roughly 20 climate models available for scientists to use to see which ones did the best job of representing historic changes to sea ice.
“You want to work with models that can reproduce the historical representation of the sea ice,” said Julienne Stroeve, an NSIDC scientist and a co-author of the study.
Researchers chose to use five models for the study. When researchers ran the models they found that the results varied depending on which climate model they match population against, said NCAR researcher Marika Holland, a co-author of the study.
While some showed better than expected results, in the end every model resulted in some decline in the area used by the penguins.