The Paris Agreement in 2015 recognized the necessity to drastically reduce greenhouse gaz emissions, in order to protect ecosystems and associated biodiversity at the global scale. Polar regions are extremely impacted by global warming, and the species adapted to these ecosystems are among the first threatened by environmental change. Many of these species, like the emperor penguin (Aptenodytes forsteri), have complex life cycles, spanning different marine and terrestrial ecosystems, to achieve different biological functions: growth, reproduction, parental care. Yet the change in the environment, such as higher sea cover, implies higher energetic cost for foraging and reduces breeding success. Alternatively, complete absence of sea ice increases predation risks. Additionally, the emperor penguin distribution is composed of distant populations, which can exchange individuals (i.e., a metapopulation), thus possibly providing a resilient mechanism against environmental variation and local extinction (rescue effect).
Scientists from our LTSER have been studying emperor penguin for a long time, and are therefore able to estimate the relationships between climate, ice cover, and demographic parameters of penguin populations. They have investigating how the different populations would react to various scenarios of climate change (RCP 8.5, Paris Agreement of 2°C, and Paris Agreement of 1.5°C), and what would be the consequences at the scale of the whole metapopulation.
Their results indicate that the fate of the whole species is highly dependent on our ability to limit carbon emissions. Under the worst scenario RCP 8.5, 80% of the populations are projected to be quasi-extinct in 2100. This massive decline is observed with either high or low dispersal rate, or even when considering optimal information for individual in their dispersal decision. The respect of the Paris Agreement however would limit the negative consequences: only 31 to 19% of populations would be driven to quasi extinction.
As a predator, emperor penguins are indicators of the whole biota, and their decline only points at more massive changes in the Antarctic ecosystems. “The adaptive capacity of emperor penguins is unknown, but is likely limited because they have a long life spans, delayed maturity, and low reproductive rates, coupled with low genetic diversity” say the scientists.
Near-term response to allow mitigation of climate change is mandatory if we hope to conserve biodiversity and associated services in the polar regions. And recent news imply that such a goal will indeed be very hard to reach.
A summary in French here.
The detailed article here :
The Paris Agreement objectives will likely halt future declines of emperor penguins. Jenouvrier, S., Iles, D., Labrousse, S., Landrum, L., Garnier, J., Caswell, H., Barbraud, C., Weimerskirch, H., LaRue, M., Ji, R. & Holland, M. Global Change Biology 07 November 2019. https://doi.org/10.1111/gcb.14864