Climate change is already causing significant impacts to the world ocean, according to a new report by IUCN that is the most comprehensive review so far on the subject. Compiled by 80 scientists from 12 countries, the report finds ocean warming is already:

  • Driving entire groups of species such as plankton, jellyfish, turtles, and seabirds up to 10 degrees of latitude toward the poles;
  • Causing the bleaching and death of many coral reefs and other fish habitats;
  • Causing the loss of breeding grounds for turtles and seabirds;
  • Affecting the breeding success of marine mammals;
  • Increasing disease in plant and animal populations, and impacting human health as pathogens spread more easily in warmer waters, including cholera-bearing bacteria and harmful algal blooms.

In addition to examining global trends, the report looks at regional impacts. In Southeast Asia, for example, fisheries catches could fall 10%-30% by 2050 compared to the period 1970-2000, due to warming-related shifts in the distribution of fish species.

“We were astounded by the scale and extent of ocean warming effects on entire ecosystems made clear by this report,” says Dan Laffoley, Marine Vice Chair of the World Commission on Protected Areas at IUCN, and one of the lead authors.

Recommendation: larger MPAs and MPA networks

To combat these impacts, the most important step will be to cut greenhouse gas emissions rapidly and substantially, state the authors. The ocean’s ability to absorb large amounts of CO2 is likely to decline as the ocean warms, which will only speed up climate change unless severe emissions cuts are made.

Along with emission reductions, larger MPAs and MPA networks are needed to increase ecosystem resilience to warming, according to the report. Implementing these may increase the likelihood of conserving species following climate change-induced range shifts, namely by ensuring that future habitats for wildlife are protected. MPAs can also help reduce the total number of stressors on ecosystems.

This is consistent with arguments made by the administration of US President Barack Obama in August, when he expanded the Papahānaumokuākea Marine National Monument in the northwestern Hawaiian Islands and referred to it as a “climate reserve”. In an essay in support of the expansion, John Holdren, co-chair of the President’s Council of Advisors on Science and Technology, wrote, “In short, marine reserves support climate resilience.”