An international team of researchers has found evidence suggesting that if global warming continues, the recovery of southern right whales may be stifled. In their paper published in the journal Science Advances, the group describes their study of the whales and what they learned about them.
Southern right whales are a type of baleen whale that live in the Southern Hemisphere and are currently listed as endangered. Prior to modern whaling, their population is believed to have been approximately 35,000. Their numbers dwindled significantly until the 1930’s when protection laws were put in place. In this new effort, the researchers have found evidence suggesting the recovery of the whales may run into trouble if global warming continues.
The work by the team focused on the Southern Right Whale Program, a project involving the study and preservation of the whales that includes 50+ years of data. Included in the data are population numbers of whales that calf near the Valdes peninsula each year, which is a measure of population growth in general. The researchers noted population dips following El Niño years—both in 1997–1998 and 2015–2016. They suggest the dips were the result of warmer waters melting more glacial ice in Antarctica resulting in reductions in krill, which is the main food source for southern right whales. Noting that prior studies have suggested that as the planet continues to grow warmer, El Niño events are likely to occur more often, they built a model to find out how global warming may impact southern right whale population growth.
The model showed that if the frequency and intensity of El Niño events remain as they are now, the population of the whales will continue to grow—reaching approximately 85% of their pre-whaling days numbers over the next century. But if the frequency and intensity of El Niño events increase due to global warming, the situation grows dire. The worst-case scenario (a 4.4°C global rise in temperatures over the next century) showed the increase in population slowing to the point that the whales would never reach their former numbers.
Macarena Agrelo et al, Ocean warming threatens southern right whale population recovery, Science Advances (2021). DOI: 10.1126/sciadv.abh2823
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Study suggests climate change could prevent recovery of southern right whales (2021, October 18)
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