Steve Connor, The Independent 27 Jan 09;
The emperor penguin is marching towards extinction because the Antarctic sea ice on which it depends for survival is shrinking at a faster rate than the bird is able to evolve if it is to avoid disaster, a study has found.
By the end of the century there could be just 400 breeding pairs of emperor penguins left, a dramatic decline from the population of about about 6,000 breeding pairs in the 1960s, scientists estimated.
The latest assessment is based on the projected increase in global temperatures and subsequent loss of sea ice due to the changes in the Antarctic climate that are expected in the 21st century, the study found.
Scientists based their pessimistic outlook on the long-term changes to the number of emperor penguins in a colony living in a part of the Antarctic Peninsula called Terre Adelie, which has been surveyed regularly since 1962 and has experienced regional warming over the past 50 years. The study, by Stephanie Jenouvrier and Hal Caswell of the Woods Hole Oceanographic Institution in Massachusetts, concluded that there was at least a 36 per cent probability of "quasi extinction" of the emperor penguin – when the population declines by at least 95 per cent – by the year 2100.
"To avoid extinction, emperor penguins will have to adapt, migrate or change the timing of their growth stages," the scientists report in the journal Proceedings of the National Academy of Sciences. "However, given the future projected increases in greenhouse gases and their effect on Antarctic climate, evolution or migration seem unlikely for such long-lived species at the remote southern end of the Earth."
Fluctuations in sea ice during the 1970s, and the effect that it had on the penguin population, were used as a model of what could happen on a larger scale during the next 100 years. Dr Jenouvrier said that if future climate change happened as predicted, the penguin population on Terre Adelie would probably decline dramatically in the coming decades. "Unlike some other Antarctic bird species that have altered their life cycles, penguins don't catch on so quickly," Dr Jenouvrier said.
"They are long-lived organisms, so they adapt slowly. This is a problem because the climate is changing very fast," she added.
Slimming odds for emperor penguin
BBC News 26 Jan 09;
Emperor penguins, whose long treks across Antarctic ice to mate have been immortalised by Hollywood, are heading towards extinction, scientists say.
Based on predictions of sea ice extent from climate change models, the penguins are likely to see their numbers plummet by 95% by 2100.
That corresponds to a decline to just 600 breeding pairs in the world.
The research is published in the journal Proceedings of the National Academy of Sciences.
Emperor penguins, the largest species, are unique in that they are the only penguins that breed during the harsh Antarctic winters.
Colonies gather far inland after long treks across sea ice, where the females lay just one egg that is tended by the male. That means that the ice plays a major role in their overall breeding success.
What is more, the extent of sea ice cover influences the abundance of krill and the fish species that eat them - both food sources for the penguins.
Hal Caswell of the Woods Hole Oceanographic Institute and his colleagues used projections of sea ice coverage from the Intergovernmental Panel on Climate Change's (IPCC) last report.
In addition, they used a "population dynamics" model describing the mating patterns and breeding success of emperor penguins.
The model has been honed using 43 years' worth of observations of an emperor colony in Antarctica's Terre Adelie.
Slow learners
While there are a number of models and scenarios in the IPCC report, the team used only 10 of them - those that fit with existing satellite data on sea ice.
They then ran 1,000 simulations of penguin population growth or decline under each of those 10 climate scenarios.
The results suggest that by the year 2100, emperor penguins in the region are likely to experience a reduction in their numbers by 95% or more.
The likelihood of this occurring, according to the researchers, is at least a one-in-three chance and possibly more than eight out of 10.
Though the penguins could avert disaster by shifting their breeding patterns with the climate, the study's lead author Stephanie Jenouvrier said that was unlikely.
"Unlike some other Antarctic bird species that have altered their life cycles, penguins don't catch on so quickly," she said.
"They are long-lived organisms, so they adapt slowly. This is a problem because the climate is changing very fast."
'Conservative approach'
Several prior studies have shown that climate change can affect the reproduction and geographic distribution of species, but this is the first that makes predictions about the ultimate fate of a species as a whole.
"I don't see any reason not to take these predictions very seriously," said Dan Reuman, a population biologist at Imperial College London.
"The study is based on a wide range of climate forecasts, it takes a conservative approach, it's based on a large amount of data on penguin demography, and the model accurately forecasts the data that already exist."
Dr Reuman suggests that more of this kind of work should be done to understand the species-by-species effects of climate change, and thereby the influence on whole communities.
It is an idea echoed by Joel Cohen, head of the Laboratory of Populations at Rockefeller University.
"The emperor penguin is an important species in its own right, but the whole communities in which it's embedded are also of importance," he told BBC News.
The penguins also serve as a species that particularly draws attention to the crisis in their region, he added.
"They are to Antarctica what the polar bear is to the Arctic.
"This study takes our knowledge, puts it together, gives us some insights, arouses concern and suggests that we ought to be understanding this situation a lot better."
