The Paris Agreement objectives will likely halt future declines of emperor penguins

Abstract

The Paris Agreement is a multinational initiative to combat climate change by keeping a global temperature increase in this century to 2°C above preindustrial levels while pursuing efforts to limit the increase to 1.5°C. Until recently, ensembles of coupled climate simulations producing temporal dynamics of climate en route to stable global mean temperature at 1.5 and 2°C above preindustrial levels were not available. Hence, the few studies that have assessed the ecological impact of the Paris Agreement used ad‐hoc approaches. The development of new specific mitigation climate simulations now provides an unprecedented opportunity to inform ecological impact assessments. Here we project the dynamics of all known emperor penguin (Aptenodytes forsteri) colonies under new climate change scenarios meeting the Paris Agreement objectives using a climate‐dependent‐metapopulation model. Our model includes various dispersal behaviors so that penguins could modulate climate effects through movement and habitat selection. Under business‐as‐usual greenhouse gas emissions, we show that 80% of the colonies are projected to be quasiextinct by 2100, thus the total abundance of emperor penguins is projected to decline by at least 81% relative to its initial size, regardless of dispersal abilities. In contrast, if the Paris Agreement objectives are met, viable emperor penguin refuges will exist in Antarctica, and only 19% and 31% colonies are projected to be quasiextinct by 2100 under the Paris 1.5 and 2 climate scenarios respectively. As a result, the global population is projected to decline by at least by 31% under Paris 1.5 and 44% under Paris 2. However, population growth rates stabilize in 2060 such that the global population will be only declining at 0.07% under Paris 1.5 and 0.34% under Paris 2, thereby halting the global population decline. Hence, global climate policy has a larger capacity to safeguard the future of emperor penguins than their intrinsic dispersal abilities.

Discovery of new colonies by Sentinel2 reveals good and bad news for emperor penguins

“…However, as these areas away from the coast are more northerly, they will be in warmer areas and therefore will be more likely to be susceptible to early sea ice loss (Ainley et al 2010). Jenouvrier et al (2019) identified colonies that are projected to be either quasi-extinct, endangered, vulnerable or stable by the end of this century assuming a businessas-usual GHG emissions scenario and a climate-dependent-meta-population model. The revised map of emperor penguin distribution (Fig.…”

“…2019). The 12 colonies are all in areas where colonies are expected to become extinct or quasi-extinct by the end of the century (Jenouvrier et al 2019).…”

Accounting for sources of uncertainty when forecasting population responses to climate change

“…Gamelon et al., 2017; Hansen et al., 2019; Nater et al., 2018). When demographic data are available, forecasts can, and should account for uncertainty about population structure, initial population size, and in a metapopulation context, dispersal among local populations (Iles & Jenouvrier, 2019; Jenouvrier et al., 2020). For other species, like the blue mussels Mytilus trossulus described in Jaatinen et al.…”

“…Reliable forecasts of wildlife populations rely on methods that can account for these varied sources of uncertainty (bottom right; with blue-and green-shaded areas representing the proportion of total uncertainty associated with population model-and climaterelated sources respectively). Failing to account for uncertainties in population forecasts can result in biased inferences and overly confident predictions about how populations are likely to respond to future changes in climate metapopulation context, dispersal among local populations (Iles & Jenouvrier, 2019;Jenouvrier et al, 2020). For other species, like the blue mussels Mytilus trossulus described in Jaatinen et al (2021), it is impossible to track individuals and estimate demographic rates.…”

Juvenile emperor penguin range calls for extended conservation measures in the Southern Ocean

“…270 000 breeding pairs in known colonies around the continent 25 , the species is severely threatened by global warming and expanding fishing activities in the Southern Ocean 15,26 , facing the risk to be nearly extinct within this century 27 . The most effective actions to protect the Emperor penguin from anthropogenic impacts would be a reduction in greenhouse gas emissions 26,27 as well as the establishment of MPAs throughout its habitat range 26 . However, little is known about the early life at sea of emperor penguins, even though their survival is crucial for the viability of the global population 28 .…”