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Climate Change

Climate Change- As sea levels rise and weather events become more extreme, coastal flooding and erosion will increase across the Chesapeake Bay.
Tangier Island, Va. - Shoreline erodes near a seawall on Tangier Island, Va., on Dec. 7, 2012. (Photo by Steve Droter/Chesapeake Bay Program) Eroding marsh, Kent Narrows - An eroding marsh in the Kent Narrows in Maryland Flooding in Annapolis, Md. - Storm surge floods Dock Street in downtown Annapolis, Maryland Flooding in Annapolis, Md. - Storm surge floods Dock Street in downtown Annapolis, Maryland Flooding in Annapolis, Md. - A man observes a stretch of Dock Street in Annapolis, Md., that flooded after the area received over three quarters of an inch of rain in 24 hours on January 25, 2010. (Photo by Matt Rath/Chesapeake Bay Program) Flooding in Annapolis, Md. - A car drives through flood waters on Main Street in Annapolis, Maryland. Flooding in Annapolis, Md. - Storm surge floods downtown Annapolis, Maryland Mahogany tide - An algae bloom called a "mahogany tide" in a tributary of the Chesapeake Bay.
As sea levels rise and weather events become more extreme, coastal flooding and erosion will increase across the Chesapeake Bay.


A changing climate will affect the Chesapeake Bay. Some effects—like rising seas, warming water temperatures and prolonged periods of extreme weather—have already been observed in the region. Other impacts include a rise in coastal flooding and shoreline erosion and changes in wildlife abundance and migration patterns. Chesapeake Bay Program partners are working to increase the climate resilience of resources and communities across the watershed.

How will climate change affect the Chesapeake Bay? 

The Chesapeake Bay is one of the most vulnerable regions in the nation to the effects of climate change. According to a report from the Chesapeake Bay Program’s Scientific and Technical Advisory Committee, some of these effects—including rising water temperatures and sea levels—have already been observed in the watershed, and the region is expected to experience further shifts in environmental conditions.

Rising Seas

According to the U.S. Geological Survey (USGS), two factors have contributed to sea level rise around the world: thermal expansion caused by the warming of the oceans, and the melting of glaciers and ice sheets. Over the past century, Bay waters have risen about one foot, and are predicted to rise another 1.3 to 5.2 feet over the next 100 years. This is faster than the global average because the land around the Bay is sinking through a process called subsidence.

As water levels rise, so will coastal flooding and erosion. Marshes and wetlands will be inundated with saltwater and will disappear faster than wetland plants can populate higher ground. A loss of marshes and wetlands will mean a loss of the habitat that traps pollution and provides food and shelter to fish, shellfish and birds.

Warming Temperatures

According to the U.S. Environmental Protection Agency (EPA), average temperatures across the northeastern United States rose almost 2 degrees Fahrenheit between 1895 and 2011. Projections indicate warming of 4.5 to 10 degrees in the region by the 2080s.

Warmer air means warmer water, and warmer water means a change in aquatic habitats. Eelgrass, for instance, becomes stressed when waters are warmer than 86 degrees Fahrenheit for long periods of time; a loss of eelgrass would affect the fish, crabs and waterfowl that use grass beds for food and shelter. According to a study by the University of Maryland Center for Environmental Science (UMCES), warming water temperatures have been recorded in more than 92 percent of the Bay's waters. And a study by the U.S. Geological Survey found an overall increase of 1.98 degrees Fahrenheit in air temperatures and 2.52 degrees in stream temperatures in the Chesapeake Bay region from 1960 to 2010.

Warmer waters are also less able to hold oxygen. A drop in dissolved oxygen means a rise in the dead zones that suffocate marine life. 

Extreme Weather

According to the EPA, between 1958 and 2012, the northeastern United States saw a more than 70 percent increase in the amount of rainfall measured during heavy precipitation events—more than any other region in the nation. Strong rain and snow storms can damage crops, erode soil and increase flooding. Floods can damage ports, marinas and historical monuments and threaten buildings, sewer systems, roads and tunnels.

Ocean Acidification

As the amount of carbon dioxide in the air rises, so does the amount of carbon dioxide in our oceans. When oceans absorb carbon dioxide, the chemical compound reacts with seawater to produce carbonic acid. This raises acidity levels and lowers carbonate ion levels, making it harder for oysters and other shellfish to produce the calcium carbonate needed to form their shells. A loss of oysters and their reefs would affect water quality and habitat.

Changes in Wildlife

Climactic changes can alter the abundance and migration patterns of wildlife. The timing of leaf growth and flower blooms, for instance, has changed across the United States. North American birds—including the ducks, geese and other waterfowl that spend cold months in the Bay’s marshes and wetlands—have shifted their wintering grounds northward and farther from the coast. And data from the National Oceanic and Atmospheric Administration (NOAA) show 60 percent of the northeast’s major fish stocks have shifted toward colder northern waters since the mid-twentieth century. Warming air and water temperatures could also favor the introduction of new, potentially invasive species.

What is climate resilience?

In June 2013, the White House issued an Executive Order to prepare the nation for the impacts of climate change. The Climate Action Plan urges communities to increase their climate resilience, or to take steps to protect themselves from climate impacts by updating building codes, adjusting natural resources management, investing in resilient infrastructure and planning for weather-related damages that might occur.

Current climate resiliency goals

Under the 2014 Chesapeake Bay Watershed Agreement, Chesapeake Bay Program partners committed to the goal of increasing the resiliency of the Chesapeake Bay watershed, including its living resources, habitats, public infrastructure and communities, to withstand adverse impacts from changing environmental and climate conditions. Learn more about the Bay Program's climate resiliency work and stay updated on our current climate-related efforts on the Climate Resiliency Workgroup page.

Take Action

For Chesapeake Bay restoration to be a success, we all must do our part. Our everyday actions can have a big impact on the Bay. By making simple changes in our lives, each one of us can take part in restoring the Bay and its rivers for future generations to enjoy.

To combat climate change in the Bay watershed, consider lowering air pollution by learning how to drive the Bay-friendly way; walking, biking or taking public transportation when possible; or using electric or manual lawn mowers and yard tools instead of gas-powered machines.



Chesapeake Bay News

In The Headlines


Climate Change and the Chesapeake Bay: State-of-the-Science Review and Recommendations

Publication date: December 01, 2008 | Type of document: Report | Download: Electronic Version

The U.S. EPA’s Chesapeake Bay Program charged the Scientific and Technical Advisory Committee (STAC) with reviewing the current understanding of climate change impacts on the tidal Chesapeake Bay and identifying critical knowledge gaps and…

From Around the Web

Bay FAQs

  • How rapid is sea level rising in the Chesapeake Bay?
  • What is ocean acidification?
  • How will climate change affect the Chesapeake Bay?


Bay Terms

  • Dead zone
  • Dissolved oxygen (DO)
  • Erosion
  • Migration
  • Precipitation
  • Wetland


Bay-Friendly Tips

  • Drive Less
  • When possible, walk, bike or take public transportation to reduce vehicle emissions that can pollute our air and water.


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