Coastal Issues | Climate Change
Climate Change
This portion of Angel Glacier in Jasper National Park, Alberta, Canada, shows how the glacier is in retreat because of melting.
Climate change—the variation in the Earth’s climate over time—is a very important issue for ocean and coastal managers. Climate change, which is causing global warming and sea level rise is beginning to have—and will likely continue to have—a significant impact on coastal populations, economies, and natural resources. Here are some ways climate change is affecting our ocean and coastal environment and the people and species that inhabit, work in and visit our coastal areas:
- Increasing temperature
- Changing species distribution
- Changing ocean chemistry
- Rising sea levels
- Shifting weather patterns
- Spreading exotic species
- Ocean and coastal managers respond
- Resources
The Intergovernmental Panel on Climate Change (IPCC) reports that the average global temperature has increased 1.3 degrees Fahrenheit during the last century and is expected to increase an additional two to 11.5 degrees over the next 100 years. Ocean water temperatures are expected to increase as well (IPCC 2007).
Many marine and coastal species are adapted to specific temperature ranges. An increase in temperatures will likely change the distribution of many important species, including those that are commercially valuable. For example, the commercial harvest of soft-shell clams, which exist at their southern temperature limits in the Chesapeake Bay, could be lost as the Bay warms. Species not able to migrate to a more tolerable temperature zone will die out. (CCSP 2008)
Bleaching can occur when coral is exposed to higher than normal water temperatures and can lead to coral death. Credit: Dave Burdick
Coral reefs are especially vulnerable to temperature increases. Coral exposed to ocean temperatures of just 1.8 degrees Fahrenheit above the average monthly temperature frequently “bleach," or turn white at the tips by ejecting symbiotic algae that give the coral its color and help supply it with nutrients. Although coral can recover from brief bleaching events, they can die from prolonged stress and bleaching (NOAA 2006).
This graphic illustrates the basic chemistry of ocean acidification. Carbon dioxide from the atmosphere dissolves in ocean water to form carbonic acid. Some of the acid then combines with carbonate ion, to form bicarbonate ion. The result is a reduction of the availability of the carbonate ion that corals, marine plankton, coralline algae, and other shellfish need to build shells and skeletons. Credit: NOAA Coral Reef Watch
The oceans have absorbed about 50 percent of the carbon dioxide released from the burning of fossil fuels, resulting in chemical reactions that have increased acidity in ocean waters about 30 percent since the start of the Industrial Age. The process is known as “ocean acidification.” While much remains unknown about the full impacts of ocean acidification, there is a growing concern in the scientific community that it will significantly affect biological systems in the ocean. Recent studies show that under increased carbon dioxide levels, many reef-building corals slow or cease production of their shell material, potentially compromising the ability of coral reefs to withstand erosion, disease, bleaching, and rising sea-level. A growing number of studies also show adverse impacts on other marine organisms. Ocean acidification decreases the ability of marine algae and free-swimming zooplankton to maintain protective shells and reduces the survival of larval marine species, including commercial fish and shellfish. These studies also suggest that ocean acidifaction may cause other future changes in the food web, structure, and viability of ocean ecosystems.
Many coastal areas are at risk from sea level rise.
As Earth’s climate warms, so do the oceans. Ice caps melt, ocean water expands, and, as a result, sea level rises. Even when glacier melt is not considered, the average global sea level is predicted to increase as much as seven to 23 inches over the next century (IPCC 2007). Sea level rise increases the risks coastal communities face from coastal hazards such as floods, storm surge, and chronic erosion. In the Gulf of Mexico region, a recent multi-agency report noted that within the next 50 to 100 years, 27 percent of the region’s major roads and other critical transportation infrastructure will be below projected sea levels for the region (CCSP 2008). The effects of storms would be even greater; more than half of the region’s major highways, almost half of its rail miles, 29 airports, and all ports are projected to be more vulnerable to damage from storm surge.
Sea level rise may also lead to the loss of important coastal habitats and public access areas. Due to existing shoreline development and protective structures (such as sea walls and bulkheads), wetlands, beaches, and other intertidal areas may not be able to migrate inland as sea level rises. These important areas would drown under the rising sea. Sea level rise can also lead to saltwater intrusion—salt water moving further up rivers and seeping into groundwater—making the water unfit for drinking or irrigating crops.
Scientists also predict shifts in weather patterns as a result of climate change. Hurricane intensity may increase, and some regions will receive more rainfall while others will experience drought conditions (IPCC 2007). More rain, combined with increased coastal development, would lead to increased storm water runoff, which could pick up and transport pollutants to coastal waters, impairing water quality and increasing flooding. The IPCC projects that storm water runoff could increase by as much as 10-40 percent in higher latitudes by 2050.
Phragmites, or common reed, is a highly aggressive species that can crowd out other native plants in wetlands, waterways, and brackish areas.
Climate change is predicted to increase the spread of harmful exotic species—non-native species that outcompete native varieties. Temperature and precipitation changes can enhance non-native species’ transportation pathways while decreasing ecosystem resilience, making habitats more vulnerable to invasion (EPA 2008). Invasive species already cause a tremendous amount of economic and environmental damage to coastal ecosystems and communities. Climate change will likely lead to greater struggles to combat invasive species and keep our coastal ecosystems intact.
Ocean and Coastal Managers Respond
Climate change is and will continue to be a pressing issue in our coastal areas. Ocean and coastal managers have an important role in planning for, adapting to, and reducing the impacts of climate change. Their challenges could involve planning for sea level rise, encouraging “smart growth” to reduce greenhouse gas emissions from vehicles, and monitoring changes in coastal and marine ecosystems caused by climate change.
Intergovernmental Panel on Climate Change – The Intergovernmental Panel on Climate Change (IPCC) was established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to provide decision-makers and others interested in climate change with an objective source of information about climate change.
NOAA’s Climate Program Office – The Climate Program Office focuses on developing a broader user community for climate products and services, provides NOAA a focal point for climate activities within NOAA, leads NOAA climate education and outreach activities, and coordinates international climate activities.
U.S. Climate Change Science Program – The Climate Change Science Program (CCSP) integrates federal research on climate and global change, as sponsored by 13 federal agencies, including NOAA, and overseen by the Office of Science and Technology Policy, the Council on Environmental Quality, the National Economic Council and the Office of Management and Budget.
Sea Levels Online - This NOAA interactive site shows regional trends in sea level, including direction and magnitude of change figures for specific locations.
Climate Change, Wildlife and Wildlands Toolkit for Formal and Informal Educators - NOAA and six other federal agencies worked together to update this popular, award-winning kit originally developed by the EPA. Includes case study of the Caribbean highlighting Corals.
For more information, contact Maggie Ernst.
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