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EmailThreats
Climate change, perhaps the
greatest threat to the Pacific Ocean's health, jeopardizes all aspects
of the Pacific Ocean and its communities' sustainability. Increasing
sea surface temperature, sea level rise, and ocean acidification all
result from increased CO2
levels. Pacific countries have already identified strong effects of
ocean warming, changes in ocean circulation, and abrupt shifts in
precipitation patterns. The bleaching and subsequent deaths of
reef-building corals caused by warm water pulses have destroyed reef
ecosystems. Shifts in ocean and atmospheric currents have created
massive dead zones or changed migration patterns of whales and
seabirds. In addition, decreasing pH levels due to CO2
acidosis are shifting the ecological balance of marine plankton and
bottom dwelling species that form calcium skeletons. Some ocean areas
have already acidified to levels known in laboratory studies to cause
harm to ocean life. The rates of current environmental change caused by
climate change far outpace anything seen in human history—and will
likely accelerate in the near future.
Environmental & Socioeconomic Impacts
All aspects of climate change have potentially grave consequences for
Pacific ecosystems and societies. Sea surface temperature increases,
for example, can alter biochemical dynamics and ocean chemistry, which,
in turn, directly affect the physiology, behavior, growth, development,
reproductive capacity, mortality, and distribution of primary and
secondary producers. During the last decade, melting sea ice in the
southeastern Bering Sea produced sea ice-associated phytoplankton
blooms that critically affected the entire food web structure. Small
increases (+1-3 °C) in water temperature can also cause devastating
coral bleaching events throughout the Pacific. The link between
increased greenhouse gases, climate change, and regional bleaching
events is widely accepted.
Sea level rise is also a growing threat. As temperatures increase with global climate change, oceans absorb more heat from the atmosphere, causing them to expand and rise. Globally, sea level increased 10 to 20 centimeters during the 20th century. Sea level rise could create the potential for more frequent and intense storms and typhoons that devastate atolls and low-lying coastal regions with wetlands, seagrass beds, mangroves, and shallow reefs, thereby impairing many ecosystems. High latitude coasts are especially vulnerable to these impacts. Ocean acidification, which alters seawater chemistry, compounds the impacts of sea warming and sea level rise. It compromises carbonate accretion, and particularly affects reef-building corals by limiting their growth. Acidification thus affects food web dynamics and other ecosystem processes.
Climate change poses very serious threats for coastal communities as well. Because sea warming alters food web relationships, it threatens fisheries and livelihoods. Acidification also puts further pressure on fisheries and coral reefs that supply food, tourism, and other economic and aesthetic benefits. Sea level rise can threaten entire island states, particularly low-lying ones, with total submersion. Associated impacts include changes in aquifer volume and water quality, with increased saline intrusion that renders water undrinkable; and loss of agriculture and vegetation, artisanal fishing, food security, and income resulting from reduced tourism. All of these impacts curtail the long-term ability of people to inhabit many low-lying island states. Sea level rise, may, in the end, produce major population upheavals, inter-island migrations (accompanied by social instability), and greater pressure on those countries that will need to accommodate these refugees.
Click here for key readings about climate change's threat to and impact on the Pacific Ocean.
