An ambitious new study publishing October 15 in the open access journal PLOS Biology describes the full chain of events by which the ocean biogeochemical changes that are predicted to be triggered by manmade greenhouse gas emissions over the next 100 years may cascade through marine habitats and organisms, penetrating to the deep ocean and eventually influencing humans.
Previous analyses have focused mainly on ocean warming and acidification, potentially considerably underestimating the biological and social consequences of climate change. Factoring in predictable synergistic changes such as the depletion of dissolved oxygen in seawater and a decline in productivity of ocean ecosystems, the new study shows that no corner of the world ocean will be untouched by climate change by 2100. "When you look at the world ocean, there are few places that will be free of changes; most will suffer the simultaneous effects of warming, acidification, and reductions in oxygen and productivity," said lead author Camilo Mora, assistant professor at the Department of Geography in the College of Social Sciences at the University of Hawai'i at Mānoa.
The authors show that the human ramifications of these changes are likely to be massive and disruptive. Food chains, fishing, and tourism could all be impacted. Some 470 to 870 million of the world's poorest people who rely on the ocean for food, jobs, and revenues live in countries where ocean goods and services could be compromised by multiple ocean biogeochemical changes.
The researchers used models of projected climate change developed for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) to inform their analysis. They discovered that most of the world's ocean surface will be simultaneously impacted by varying intensities of ocean warming, acidification, oxygen depletion, or shortfalls in productivity. Only a very small fraction of the oceans, mostly in polar regions, will face the opposing effects of increased oxygen or productivity, and nowhere will there be cooling or pH increase.
The researchers then assembled global distribution maps of 32 marine habitats and biodiversity hotspots to assess their vulnerability to the biogeochemical changes. As a final step, they used available data on human dependency on ocean goods and services and measures of social adaptability to estimate the vulnerability of coastal populations to the projected ocean biogeochemical changes. Co-author Lisa Levin, a professor at Scripps Institution of Oceanography at the University of California, San Diego, notes: "Because many deep-sea ecosystems are so stable, even small changes in temperature, oxygen, and pH may lower the resilience of deep-sea communities. This is a growing concern as humans extract more resources and create more disturbances in the deep ocean."
"The impacts of climate change will be felt from the ocean surface to the seafloor. It is truly scary to consider how vast these impacts will be," said co-author Andrew K. Sweetman of the International Research Institute of Stavanger, Norway. "This is one legacy that we as humans should not be allowed to ignore."
Funding: This study was funded by the University of Hawaii Sea Grant. We thank the Norwegian Research Councilfor funding a workshop on Climate Change Stress on Deep-Sea Benthic Ecosystems (CLIDEEP) and the Sloan Foundation through the Census of Marine Life Program for funding several meetings as part of the International Network for Scientific Investigations of Deep-Sea Ecosystems (INDEEP) that led to the idea of this paper.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Citation: Mora C, Wei C-L, Rollo A, Amaro T, Baco AR, et al. (2013) Biotic and Human Vulnerability to Projected Changes in Ocean Biogeochemistry over the 21st Century. PLoS Biol 11(10): e1001682. doi:10.1371/journal.pbio.1001682
Department of Geography
College of Social Sciences
University of Hawai'i at Mānoa
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University of Hawai'i at Mānoa
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