Global Warming Hits Sea Creatures Hardest

Marine life more sensitive to warming, less able to escape from heat, study finds

Global warming

The greater vulnerability of sea creatures may significantly impact human communities that rely on fish and shellfish for food and economic activity, according to the study published in the journal Nature. 

The study is the first to compare cold-blooded marine and land species’ sensitivity to warming and their ability to find refuge from the heat while staying in their normal habitats. The authors, including a McGill University biologist, combed through worldwide research on nearly 400 species from lizards and fish to spiders. They calculated safe conditions for 88 marine and 294 land species as well as the coolest temperatures available to each species during the hottest parts of the year. 

“We find that, globally, marine species are being eliminated from their habitats by warming temperatures twice as often as land species,” said lead author Malin Pinsky, an associate professor in the Department of Ecology, Evolution, and Natural Resources at Rutgers University–New Brunswick. “The findings suggest that new conservation efforts will be needed if the ocean is going to continue supporting human well-being, nutrition and economic activity.” 

The researchers found that marine species are, on average, more likely to live on the edge of dangerously high temperatures. Additionally, many land animals can hide from the heat in forests, shaded areas or underground, a luxury not open to many sea animals. 

“It’s relatively easy for a lizard to move on land and find warmer or colder temperatures, but most ocean animals just can’t escape from the heat to the same degree,” said Jennifer Sunday, a co-author and assistant professor in McGill’s Department of Biology. 

The loss of a population can deplete the species’ genetic diversity, have cascading impacts on their predators and prey and alter ecosystems that benefit human society. 

The study notes that ancient extinctions have often been concentrated at specific latitudes and in specific ecosystems when the climate changed rapidly. Future warming is likely to trigger the loss of more marine species from local habitats and more species turnover in the ocean. 

“Understanding which species and ecosystems will be most severely affected by warming as climate change advances is important for guiding conservation and management,” the study says. 

Scientists from Rutgers, McGill, University of California Santa Barbara, Stanford University and University of Oslo contributed to the study. 

Funding for the research was provided in part by the Natural Sciences and Engineering Research Council of Canada and by the Biodiversity Research Centre at the University of British Columbia. 

“Greater vulnerability to warming of marine versus terrestrial ectotherms”, Malin L. Pinsky et al, Nature, published April 24, 2019. DOI: 10.1038/s41586-019-1132-4