If the climate continues to change at its current pace, most emperor penguins could become extinct by the end of this century, a new study predicts. However, if countries meet the objectives of the Paris Agreement, limiting the global increase in temperature to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels, then that would give penguins a fighting chance, with one-third of their population still projected to decline, researchers say.
“If global climate keeps warming at the current rate, we expect emperor penguins in Antarctica to experience an 86 percent decline by the year 2100,” Stéphanie Jenouvrier, a seabird ecologist at Woods Hole Oceanographic Institution (WHOI) and lead author on the study, said in a statement. “At that point, it is very unlikely for them to bounce back.”
Emperor penguins (Aptenodytes forsteri), the largest of all living penguins, need stable sea ice in Antarctica to thrive. They use the ice as a breeding platform, to rear chicks, to molt, feed, and protect themselves from predators. Sea ice also influences the food that the penguins rely on, such as the Antarctic krill (Euphausia superba) and Antarctic silverfish (Pleuragramma antarctica). So fluctuations in sea ice directly affect the birds’ survival: if the sea ice breaks up early, then the chicks could struggle to live; if the sea ice cover is higher than usual, then the penguins have to move farther to get food.
Jenouvrier, who has spent more than two decades studying emperor penguins’ lives on the harsh Antarctic sea ice, and her colleagues wanted to see how all known 54 colonies of emperor penguins would respond to changing sea ice conditions under three future climate scenarios: where no action is taken and greenhouse gas emissions continue at their present rates; where the global temperature rise is restricted to 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels; and one where global temperature rise is capped at 1.5 degrees Celsius.
To get these estimates, the researchers combined a global climate model that projects sea ice formation under different climate scenarios and a model of penguin populations that predicts how penguin colonies would react to changing sea ice.
“We’ve been developing that penguin model for 10 years,” Jenouvrier said. “It can give a very detailed account of how sea ice affects the life cycle of emperor penguins, their reproduction, and their mortality.”
The model suggests that under the business-as-usual scenario, where countries fail to halt climate change, penguin numbers will decline by around 86 percent by 2100. However, if nations manage to limit emissions and the rise in global temperature to 2 degrees Celsius, then emperor penguin numbers would decline by about 44 percent. If the global temperature rise is further limited, to 1.5 degrees Celsius, that would result in a 31 percent decline in the penguin population, the model predicts.
“Our model indicates that these population declines will occur predominately in the first half of this century,” Jenouvrier wrote in the Conversation. “Nonetheless, in a scenario in which the world meets the Paris climate targets, we project that the global Emperor Penguin population would nearly stabilize by 2100, and that viable refuges would remain available to support some colonies.
“Our findings starkly illustrate the far-reaching implications of national climate policy decisions,” she added. “Curbing carbon dioxide emissions has critical implications for Emperor Penguins and an untold number of other species for which science has yet to document such a plain-spoken warning.”
Jenouvrier, S., Holland, M., Iles, D., Labrousse, S., Landrum, L., Garnier, J., … Barbraud, C. (2019). The Paris Agreement objectives will likely halt future declines of emperor penguins. Global Change Biology. doi: 10.1111/gcb.14864
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