The Antarctic Peninsula, the northern most region of Antarctica, is one of the most rapidly warming places on the planet. The region has also experienced some of the largest temperature fluctuations over the last 25,000 years, when ice cover peaked at about double the current sea ice levels. A new study shows that while three Antarctic penguin species may have actually grown during the end of the last Ice Age around 11,000 years ago, the rapid warming now is negatively affecting at least two of them.
The study, published in the journal Scientific Reports on Thursday, says “this ‘reversal of fortunes’ for two former climate change ‘winners’ has resulted from anthropogenic impacts outside the range of natural variation that has occurred in the past.”
Rapid warming trends in the Antarctic Peninsula over the past 50 years has led to decreased sea ice, loss of winter habitat, and a reduction in krill stocks that is negatively affecting two of the penguin species — the Adélie and chinstrap penguins — but not gentoo penguins, which are apparently less reliant on krill. The scientists warn that while this is the only example of ‘reversal of fortunes’ they know of they “expect many more will be identified as global warming proceeds and biodiversity declines.”
West Antarctica is seeing dramatic ice loss particularly the Antarctic Peninsula and Pine Island regions. Ice loss culprits include the loss off buttressing ice shelves, wind, and a sub-shelf channel that allows warm water to intrude below the ice.
Lead author Gemma Clucas, from Ocean and Earth Sciences at the University of Southampton said that while we “typically think of penguins as relying on ice this research shows that during the last Ice Age there was probably too much ice around Antarctica to support large populations.” When the snow and ice began to melt new penguin nesting sites became available and all three penguin species benefited. However, this time around, global warming is reducing the availability of krill, an importance penguin food source, and as a result Adélie and chinstrap penguin populations are dropping at a precipitous rate in the Antarctic Peninsula according to several recent studies. The gentoo penguins are able to substitute some of this loss with fish and squid.
Krill are tiny, shrimp-like animals that rely on sea ice for the ice algae that they feed on. Commercial fishing is also impacting their populations. In terms of biomass, krill are probably the most abundant species on the planet. However around the Antarctic Peninsula krill populations have decreased by about 80 percent since the mid-1970s.
“Despite historic warming clearly opening up new opportunities for penguins, we should not assume that current rapid warming caused by human activity is good for penguins as a whole,” said Clucas. “Evidence from other studies shows that climate change today is creating lots of losers and few winners.”