Guest Post by Bob Vislocky, Ph.D.

Chinstrap penguin, Copyright 1993 Charles Rotter

CBS news recently reported a 50% decline in the number of chinstrap penguins residing on Elephant Island and a 75% decline of those living on Penguin Island all because of ….. drum roll please ….. global warming!

https://www.cbsnews.com/news/global-warming-cited-as-antarctica-chinstrap-penguin-population-drops-by-half/

As the article above states, the nearly 3* C of global warming over the last 50 years caused a reduction of sea ice, which in turn results in a reduction of krill that eat the algae and other organisms that live underneath in the sea ice. As the krill population declines so does that of the chinstrap penguin since krill is their favorite food.

Ironically, the journal article below from a 1991 study claimed that the chinstrap penguin population increased during the 1900s *because* of global warming. So apparently global warming can both increase and decrease the penguin population. Wish the climate community would get their story straight!

https://marine.rutgers.edu/dmcs/ms606/2011%20fall/Fraser%20et%20all%201992.pdf

Adding even more confusion, the following informational page from the Australian Department of Environment states that the chinstrap penguins have lower breeding success when there is more sea ice as it restricts access to the sea for foraging adults.

But the original CBS article says that more sea ice means more krill and a higher population of chinstrap penguins.

http://www.antarctica.gov.au/about-antarctica/wildlife/animals/penguins/chinstrap-penguins

So let’s sum this all up:

• Global warming = decline in the # of chinstrap penguins
• Global warming = increase in the # of chinstrap penguins
• More sea ice = lower breeding success of chinstrap penguins
• More sea ice = increase in the population of chinstrap penguins

So basically no matter what happens to the penguin population, climate change has all the bases covered. Expect anything different?

Back to the recent CBS article, the argument of “global warming = less sea ice = fewer krill = penguin decline” is not relevant for the Antarctic where sea ice has actually held its own or even increased over time (figure 1) based on a recent PNAS study. So if there is a local change in sea ice near Elephant and Penguin Islands, then it’s more likely due to a regional fluctuation rather than a CO2-induced global change.

Figure 1. https://www.pnas.org/content/116/29/14414

So what does better explain the decline in chinstrap penguins that the CBS article conveniently fails to mention? Overfishing!!

https://psmag.com/environment/overfishing-krill-in-antarctica