How will Emperor Penguins Respond to Changing Ice Conditions (EPIC)?

In 2021, the first full inventory of emperor penguin colonies in Antarctica was generated using satellite imagery. It is therefore not surprising that their population vulnerability to changing climate is not yet well known, with colony movements only having been observed at a small number of sites. As Antarctica responds to warming climate and ocean conditions, sea ice is likely to decline, presenting a potentially significant risk to the viability of emperor penguin colonies because they live on sea ice and rely on its stability for breeding and feeding. The extent of sea ice fell by over 2 million km2 compared to average around Antarctica between 2016 and 2018, and reductions of future sea ice loss suggest that the majority of colonies may become quasi-extinct by 2100 under current greenhouse gas emission scenarios. However, both historic and future colony responses are poorly known. For example, the models which predict future behaviour are based upon breeding factors measured at a single site and behavioural factors measured at only 9 sites over a short time period of 13 years. Thus there is a significant need to improve our understanding of past colony changes and how they link to changing sea ice habitat conditions so that we can better predict future colony vulnerability under a changing climate.
Although sea ice loss (and thus emperor penguin habitat) is controlled on a large scale by warming climate and oceans, an additionally overlooked process which may be increasingly disrupting sea ice conditions is the calving of icebergs which can push, or cause the fracturing of, sea ice, leaving an embayment sea ice free. In response to the loss of sea ice, emperor penguins may move to another region where sea ice conditions are more stable, or if no such area is available, they have more recently been observed to climb onto the glaciers themselves. This is a dramatic response, but without it the colony may cease to exist. Such observations of movement are again limited to a few local studies, and the impact of calving-induced sea ice breakout events upon emperor penguin colonies has never been measured. Our aim is to understand the past, present and future vulnerability of emperor penguin colonies to changing glacier and sea ice conditions.
We will use existing archives of freely-available satellite imagery to map past colony movements, sea ice and glacier calving conditions at each of the 61 newly identified emperor penguin colonies in Antarctica. This will allow us to establish how historic sea ice conditions have changed at each colony and will also allow us to understand the impact of specific glacier calving events over the last 30-40 years. Our work will allow us to determine whether colony ability to move onto glacier ice or to migrate to new sea ice areas is a common reaction to sea ice loss, or whether this is a new phenomena. Using this information, we will gain better understanding of colony vulnerability to sea ice changes. In areas where colonies currently appear at risk, we will use very high-resolution commercial satellite imagery to establish whether they remain viable as a breeding colony.
This understanding will be used to control and enhance numerical models of penguin population dynamics and breeding success under future scenarios of sea ice and glacier calving conditions. In particular, as air temperatures warm or as glaciers calve at a particular frequency, we will test how colonies will respond. The outcome of this work is vitally important for our understanding of the species and its survival over the next century and it expected to form the foundation for a case to establish emperor penguins as a protected species in the face of climate change.