The Chesapeake Bay watershed is one of most vulnerable regions in the United States to climate change and is already experiencing effects like rising seas and warming temperatures. Many areas throughout the watershed experienced their wettest year on record in 2018, and reports like the National Climate Assessment warn that climate change will increase the risks of floods and fires, rising waters and higher temperatures. But how do the issues associated with a changing climate factor into the restoration and protection work the Chesapeake Bay Program has guided for over 35 years?
In 2010, the Environmental Protection Agency (EPA) established the Chesapeake Bay Total Maximum Daily Load (Bay TMDL) to advance the restoration of the Chesapeake Bay. The Bay TMDL sets limits on the amount of nitrogen, phosphorus and sediment that can enter the Bay, while still meeting water quality standards. Chesapeake Bay watershed jurisdictions (Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia) committed to have all pollutant control practices in place by 2025 to meet these targets.
To determine how they will meet their pollutant reduction goals, the jurisdictions develop Watershed Implementation Plans (WIPs). The first and second phases of the WIPs were developed in 2010 and 2012, respectively. In April 2019, the jurisdictions completed their draft Phase III WIPs, which provide information on the actions and commitments they plan to implement between 2019 and 2025 to meet their local and Bay restoration goals. For the first time, jurisdictions were expected to include a written strategy in their Phase III WIPs, detailing how they currently, and will account for a changing climate while putting plans in place to reduce pollutant loads.
Under the Chesapeake Bay Watershed Agreement, Bay Program partners committed to continually monitor and assess the trends and likely impacts of changing climatic and sea-level conditions. For the first time, the 2017-18 Bay Barometer tracked changes in air temperature, stream temperature and sea level rise across the watershed.
- Air temperature: Over the past century, air temperature has increased over the Chesapeake Bay watershed by 0.4 degrees Fahrenheit in southern West Virginia to more than 2.5 degrees Fahrenheit in Delaware. Regions closer to the Bay have warmed more than regions further upstream.
- Stream temperature: Over the past 60 years, stream temperature has increased by an average of 1.1 degrees Fahrenheit. Like air temperature, stream temperature has increased in regions closer to the Bay more than in regions further upstream.
- Sea level rise: Since 1960, waters levels in the Bay have risen between one-eighth and approximately one-sixth of an inch each year.
These indicators play a role in how the jurisdictions factor climate change into their Phase III WIPs. Using these trends, jurisdictions can estimate what the climate will look like in 2025 and build these considerations into their Phase III WIPs. Any additional pollutant loads that would arise from climate change are added to the loads the jurisdictions have already committed to reducing.
There is still uncertainty about the long-term impacts of climate change on the Chesapeake Bay watershed, and the jurisdictions agreed that they need more information to consider how much more pollutant loads they would need to reduce. Under the Bay TMDL, each jurisdiction submits milestones to the EPA every two years so that they may check on their progress to reduce pollutants. While the Phase III WIPs are expected to include a written strategy for addressing climate impacts, each jurisdiction must begin accounting for climate impacts in their 2022-23 milestones.
To help inform these decisions, the jurisdictions agreed to identify research gaps and needs, as well as develop an estimate of how they anticipate pollutant loads will change based on climate change. This will help them better understand how conservation practices address climate change conditions.