World's coastal oceans warming faster than predicted

The findings of a recent global assessment show the Large Marine Ecosystems (LMEs) of our planet are warming much more rapidly than expected and are over-fished and over-fertilized.

The findings, launched at the Fifth Global Environment Facility Biennial International Waters Conference in Cairns, Australia, found that 61 of the world’s 64 large marine ecosystems — large areas of coastal waters adjacent to continents — show a significant increase in sea surface temperatures in the last 25 years, contributing to decreasing fisheries catches in some areas and increasing catches in others.

Fisheries harvests in several northern LMEs are increasing due to the increase in zooplankton, a vital fish food, brought about by the warming waters. However, climate warming is contributing to decreasing fisheries harvests in several European LMEs, according to The UNEP/GEF Large Marine Ecosystem Report: a Perspective on Changing Conditions in LMEs of the World’s Regional Seas.

The report documents the most rapid warming in the Northeast Atlantic and Mediterranean Region, the Northwest Pacific in East Asia, and in the Northwest Atlantic. Sea-surface temperatures from satellite monitoring over the last 25 years show some of the LMEs warming 2-3 times over estimates provided by the Intergovernmental Panel on Climate Change.

“We hope that the release of this global assessment will call attention to the degraded state of our planet’s coastal and marine ecosystems that are so important as “blue forests” to absorb excessive carbon from the atmosphere and provide livelihoods and food security for coastal communities,“noted GEF CEO Monique Barbut. “A number of LME projects funded by the GEF are showing success in reducing coastal pollution, restoring damaged habitats such as mangroves and sea-grass beds, and recovering depleted fisheries.”

She further noted that the satellite-based time series of warming included in the assessment presents a stark picture as do the trends of overfishing that depletes marine life and the excessive nitrogen pollution from agricultural fertilizers, livestock, and human sewage.

“The large majority of these LMEs are shared by two or more countries, underscoring the need for regional cooperation to advance sustainable management,” further noted Dr. Kenneth Sherman, expert on Large Marine Ecosystems and editor of the assessment. “The added stress of climate warming makes it that much more important that nations cooperate to sustainably manage Large Marine Ecosystems, the areas where most marine fisheries are produced and caught.”

According to the exhaustive report, 70 percent of global fish stocks within LMEs are overexploited, reducing the availability of fish for food, which is especially critical in LMEs off the coasts of Africa, Asia and Latin America, where fish is a major protein source.

The assessment also underscored that an unprecedented volume of nitrogen pollution to coastal waters is causing a greater frequency and extent of harmful algal blooms, oxygen depletion events and dead zones. During the algal blooms, small plankton consume excessive amounts of available dissolved oxygen, sink to the bottom and deprive fish and shellfish of the oxygen they need to survive.

“The effort to reverse the degraded status of LMEs will take time, well-focused and creative policies, and funding,” said Achim Steiner, UN Under-Secretary General and Executive Director of UNEP, the agency that released the report.