North Sea Climate Change

Affects on Marine Life


In the North Sea, global warming is affecting plankton and the marine food chain, compounding the pressures of overfishing. Future warming is also expected to exert a significant impact on the marine ecosystem, creating further uncertainty for the fishing industry.

  • Warming of the North Sea has affected the distribution and abundance of plankton—the foundation of the marine food chain4—and shifted their seasonal cycles.
  • Changes in the plankton ecosystem linked to warmer surface temperatures have already harmed other species that rely on plankton for food, such as cod.
  • Further climate change is expected to intensify these effects on North Sea plankton, cod, and marine ecosystems7—with implications for the fishing industry and the communities that depend on it.
Big image

More Info

Bridlington, Whitby, and other English coastal towns have long depended on the North Sea fishery for food and income. But global warming is affecting plankton and changing the marine food chain, compounding the pressures of overfishing. The resulting disruption of the ecosystem could damage the fishing industry and hurt North Sea coastal communities from the United Kingdom to Scandinavia.

Plankton anchor the marine food chain. Phytoplankton, which live close enough to the water's surface to perform photosynthesis—critical to maintaining oxygen in Earth's atmosphere—form the base of the marine food web. Although phytoplankton are microscopic, they can be seen from satellites when they grow in a concentrated area (bloom) on the ocean's surface. Zooplankton, which feed on phytoplankton, and bacterioplankton, which recycle nutrients in the water, make up the next levels of the web.

Plankton are particularly sensitive to climate change. Since 1950, global mean sea surface temperatures have risen roughly 1° F (0.6° C). Scientists estimate that regional sea surface temperatures in the North Sea increased by 1.6° F (0.9° C) from 1958 to 2002.

The result is changes in the distribution and abundance of plankton species, as well as shifts in their seasonal cycles. For example, in the northeast Atlantic, both warmer-water and colder-water plankton moved 10° latitude farther north over a four-decade period at the end of the twentieth century.

The changes have not been uniform, however. While some types of plankton bloomed 30 days earlier at the beginning of this century than in the middle of the twentieth century, other types maintained their seasonal cycles throughout that period. Mismatches in marine communities and disruption of the food chain are the result.