Climate change threatens the future of marine ecosystems

provided by The Pew Center


omprising nearly 70 percent of the Earth's surface, the world's oceans not only play a crucial role in influencing the global climate, but also harbor some of the most diverse and important ecosystems on the globe, both ecologically and economically. According to a new study by the Pew Center on Global Climate Change, US coastal and marine ecosystems will become increasingly challenged in the next century by the potential impacts of climate change.

    “Climate change could likely be the 'sleeper issue' that pushes our already stressed and fragile coastal and marine ecosystems over the edge,” said Eileen Claussen, President of the Pew Center on Global Climate Change. “Particularly vulnerable are coastal and shallow water areas already stressed by human activity, such as estuaries and coral reefs. The situation is analogous to that faced by a human whose immune system is compromised and who may succumb to a disease that would not threaten a healthy person.”

    Based on current projections for climate change in the next century, The Pew Center report, Coastal and Marine Ecosystems and Global Climate Change: Potential Effects on U.S. Resources, explores the hazards climate change will pose to delicate marine life. The key conclusions of the report include:

  • Temperature changes in coastal and marine ecosystems will influence organism metabolism and alter ecological processes such as productivity and species interactions. Species are adapted to specific ranges of environmental temperature. As temperatures change, species' geographic distributions will expand or contract, creating new combinations of species that will interact in unpredictable ways. Species that are unable to migrate or compete with other species for resources may face local or global extinction.
  • Changes in precipitation and sea-level rise will have far-reaching consequences for the water balance of coastal ecosystems. Increases or decreases in precipitation and runoff will respectively increase the risk of coastal flooding or drought. Meanwhile, sea-level rise will gradually inundate coastal lands. Coastal wetlands may migrate inland with rising sea levels, but only if they are not obstructed by human development.
  • Climate change is likely to alter patterns of wind and water circulation in the ocean environment. Such changes may influence the vertical movement of ocean waters (i.e., upwelling and downwelling), increasing or decreasing the availability of essential nutrients and oxygen to marine organisms. Changes in ocean circulation patterns can also cause substantial changes in regional ocean and land temperatures and the geographic distributions of marine species.
  • Critical coastal ecosystems such as wetlands, estuaries, and coral reefs are particularly vulnerable to climate change. Such ecosystems are among the most biologically productive environments in the world. Their existence at the interface between the terrestrial and marine environment exposes them to a wide variety of human and natural stressors. The added burden of climate change may further degrade these valuable ecosystems, threatening their ecological sustainability and the flow of goods and services they provide to human populations.

    “It is increasingly apparent that the United States needs a strategy to address the very real threat of climate change. The longer we wait, the graver the risks – and the cost of averting them,” said the Pew Center's Eileen Claussen.

Part of “Impacts” Series

    Coastal and Marine Ecosystems and Global Climate Change: Potential Effects on U.S. Resources, was prepared for the Pew Center by Victor S. Kennedy (University of Maryland), Robert R. Twilley (University of Louisiana at Lafayette), Joan A. Kleypas (National Center for Atmospheric Research), James H. Cowan, Jr. (Louisiana State University), and Steven R. Hare (International Pacific Halibut Commission). It is the eighth in a series of Pew Center reports examining the potential impacts of climate change on the US environment. Other Pew Center reports focus on domestic and international policy issues, climate change solutions, and the economics of climate change.

    A complete copy of this report and other Pew Center reports can be accessed from the Pew Center's web site,

    The Pew Center was established in May 1998 by The Pew Charitable Trusts, one of the United States' largest philanthropies and an influential voice in efforts to improve the quality of the environment. The Pew Center is an independent, nonprofit, and nonpartisan organization dedicated to providing credible information, straight answers, and innovative solutions in the effort to address global climate change. The Pew Center is led by Eileen Claussen, the former US Assistant Secretary of State for Oceans and International Environmental and Scientific Affairs.