- New research finds that marine animals have disappeared from their habitat due to global warming at twice the rate of wildlife on land.
- According to the study, published late last month in Nature, the loss of whole populations of ocean-dwelling species not only depletes the genetic diversity of those species, but can also trigger a cascade of impacts on predators and prey, thereby altering entire marine ecosystems.
- The heightened vulnerability of marine life to global warming could have significant implications for the food supply and economies of seafood-reliant human communities.
New research finds that marine animals have disappeared from their habitat due to global warming at twice the rate of wildlife on land.
According to the study, published late last month in Nature, the loss of whole populations of ocean-dwelling species not only depletes the genetic diversity of those species, but can also trigger a cascade of impacts on predators and prey, thereby altering entire marine ecosystems. The heightened vulnerability of marine life to global warming could thus have significant implications for the food supply and economies of seafood-reliant human communities.
A team of researchers led by Malin Pinsky, an associate professor in the Department of Ecology, Evolution, and Natural Resources at Rutgers University-New Brunswick in the United States, looked at how sensitive cold-blooded marine and land species’ are to warming. The researchers examined research from around the globe covering 88 marine and 294 land species, from lizards and spiders to fish, in order to calculate the “safe” conditions for each species and determine the coolest temperatures the species are subjected to during the hottest times of year.
Pinsky and co-authors also analyzed each species’ ability to beat the heat by seeking refuge within their typical habitat. They found that marine species are more likely to be subject to temperatures approaching their upper thermal limits, while, at the same time, many land animals can escape the heat by retreating underground or seeking the shelter of forest canopies and other shaded areas, options that are not available to most ocean life.
The researchers write that their study shows “that marine ectotherms experience hourly body temperatures that are closer to their upper thermal limits than do terrestrial ectotherms across all latitudes — but that this is the case only if terrestrial species can access thermal refugia. Although not a direct prediction of population decline, this thermal safety margin provides an index of the physiological stress caused by warming.” The researchers also determined that local extirpations related to rising temperatures have been “twice as common in the ocean as on land, which is consistent with the smaller thermal safety margins at sea.”
The smallest thermal safety margins for land-based species were found at mid-latitudes, where hourly body temperatures were the hottest. The smallest thermal safety margins for marine species were found near the equator.
“We find that, globally, marine species are being eliminated from their habitats by warming temperatures twice as often as land species,” Pinsky said in a statement. “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.”
Past extinction events driven by rapid climatic changes were usually concentrated at specific latitudes and in specific ecosystems, the researchers note in the study. Understanding which species and ecosystems will be most severely affected by the current global climate crisis is therefore crucial to designing conservation and management plans to mitigate impacts to Earth’s biodiversity.
“Our results suggest that different processes will exacerbate thermal vulnerability across these two realms,” the authors write. “Higher sensitivities to warming and faster rates of colonization in the marine realm suggest that extirpations will be more frequent and species turnover faster in the ocean. By contrast, terrestrial species appear to be more vulnerable to loss of access to thermal refugia, which would make habitat fragmentation and changes in land use critical drivers of species loss on land.”
• Pinsky, M. L., Eikeset, A. M., McCauley, D. J., Payne, J. L., & Sunday, J. M. (2019). Greater vulnerability to warming of marine versus terrestrial ectotherms. Nature, 1. doi:10.1038/s41586-019-1132-4
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