Recent Progress: Increase

Recent progress toward the Climate Monitoring and Assessment outcome has increased. The partnership developed a list of prioritized climate change indicators to assist in how we focus our resources and efforts. The updates for the air temperature change and precipitation change indicators, the two that remain current, are set to be updated within the coming months for the first time since 2017.

Collaboration has been key in this outcome’s recent progress, notably in the Scientific and Technical Advisory Committee (STAC) Rising Water Temperatures Workshop. This full-day special meeting brought multiple workgroups together to discuss the effects of rising water temperatures on living resources and habitats and assess the utility of a Bay water temperature change indicator. Another collaboration was with the Water Quality Goal Implementation Team, Urban Stormwater Workgroup and Virginia Tech to assess Best Management Practice (BMP) climate resilience uncertainties. This included a joint meeting on stormwater BMP vulnerabilities to climate change and next steps for more resilient designs.

Outlook: On Course

The outlook of this outcome is on course as progress continues on assessing climate change trends related to physical change (e.g., temperature, precipitation, sea level rise). We have developed trend-based recommendations related to restoration and protection policies, programs and projects (e.g., STAC Rising Water Temperature Workshop, BMP climate uncertainty report). To stay on course, these recommendations need to be reviewed and implemented by their respective partner programs (e.g., natural resource agencies, federal agencies, local governments).

Air Temperature Change

According to data from the National Oceanic and Atmospheric Administration (NOAA), air temperature across the Chesapeake Bay watershed has increased over the last 100 years. Of the 33 climate divisions located within the watershed, 32 have experienced statistically significant long-term increases in air temperature. Average increases in air temperature have ranged from 0.4 degrees Fahrenheit per century in southern West Virginia to more than 2.5 degrees Fahrenheit per century in Delaware. Regions closer to the mainstem of the Bay have warmed more than regions farther upstream. In some parts of the country, climate change is causing more frequent “high temperature extremes.”

Annual Precipitation Change

According to data from NOAA, annual precipitation totals in some parts of the Chesapeake Bay watershed have increased over the last 100 years. Of the 33 climate divisions located within our watershed, 32 experienced an increase in total annual precipitation between 1901 and 2017. Seven of these divisions—four of which are located in New York—experienced increases that can be considered statistically significant.

As climate change alters air circulation patterns across the region and around the world, annual precipitation rates will rise in some areas and fall in others. In our watershed, annual precipitation rates have increased most notably in New York and slightly in Maryland, Pennsylvania, West Virginia and Washington, D.C. In contrast, annual precipitation rates have experienced very little change in western Virginia.

Indicators Under Refinement or Development

Refinement of these indicators is currently being assessed with partner Chesapeake Bay Program workgroups to better align with ecological and community impacts and will be updated when new methodologies are developed.

High Air Temperature Extremes

While there is more than one way to define a high temperature extreme, the Chesapeake Bay Program considers an unusually hot day to be one on which the maximum temperature observed at a particular weather station is among the top five percent of daily highs observed at that weather station across all years of measurement. In our watershed, only one weather station has experienced a statistically significant increase in high temperature extremes since 1948.

In contrast, a “tropical nights” analysis—which examines trends in nighttime lows rather than daytime highs—does show a clear warming trend in the region. High nighttime temperatures are often linked to a heat wave’s more serious impacts on human health.

Sea Level Rise

According to data from NOAA, relative sea level has risen at each of the seven long-term tide gauge stations on the Chesapeake Bay and its tributaries. Between 1960 and 2017, sea level has increased between one-eighth of an inch and approximately one-sixth of an inch each year.

Total increases in sea level at these seven tide gauge stations range from seven inches in Baltimore to more than 10 inches in Norfolk, Virginia. (This is taller than the height of the average pencil.) Regionally, relative sea level rise is compounded by the natural sinking of the land’s surface. Locally, it can be exacerbated by the human extraction of groundwater.

Stream Temperature

According to data from the U.S. Geological Survey (USGS), average annual stream temperature in the Chesapeake Bay watershed has increased by 1.1 degrees Fahrenheit over the past six decades.

Seventy-nine percent of the 72 stream sites monitored between 1960 and 2014 experienced an increase in water temperature. Of these increases, more than half are considered statistically significant trends. At these sites, stream temperature has increased by an average of 2.1 degrees Fahrenheit.

In general, the largest increases in stream temperature have occurred in the southern part of the watershed.

The refinement strategy of this indicator could include connecting it with stream health and identifying resilient brook trout habitat.

River Flood Frequency and Magnitude

According to data from USGS, river flooding in the Chesapeake Bay watershed has grown larger and more frequent over the past 50 years. Between 1965 and 2015, 72 percent of 47 stream sites in Delaware, Maryland, Pennsylvania, Virginia and West Virginia experienced an increase in the size of river floods. Seventy-one percent of stream sites experienced an increase in the frequency of river floods. Because most of these stream sites experienced variation in flood size and frequency from year to year, experts do not consider these trends to be statistically significant.

While flood size and frequency can be impacted by site-specific and regional factors, climate change has been linked to more extreme precipitation events. Experts anticipate more frequent and more extreme precipitation events to generate larger and more frequent upstream floods.

The Climate Resiliency Workgroup is currently looking for data providers for a flooding indicator that draws connections to community resilience.

Bay Water Temperature Change

The Climate Resiliency Workgroup is exploring development of an indicator that connects tidal water temperature change with water quality thresholds to assess habitat suitability for fish and submerged aquatic vegetation (SAV) to inform adaptive management decisions. Recent efforts towards development of this indicator include discussions of utility, methodology, and implementation at the 2-day STAC workshop titled, “Rising Watershed and Bay Water Temperatures – Ecological Implications and Management Responses,” that took place in January and March 2022. Additional efforts include collaborating with the Integrated Trends Analysis Team (ITAT) at the Chesapeake Bay Program. The ITAT’s efforts include tracking surface water temperature trends throughout the Bay in both the short- and long-term timeframes.

Potential Indicators

In 2018, Eastern Research Group, Inc., (ERG) worked with the Chesapeake Bay Program to develop an implementation strategy that defines and describes the steps and resources needed to create various climate change-related indicators. As partnership priorities evolve and new sources and methods of analyzing data emerge, the Chesapeake Bay Program may choose to change its course or implement certain indicators from this suite. Further development of these indicators will depend on the quality of supporting data, the added value of the indicators in question and the priorities and resources of the Climate Resiliency Workgroup.

Additional indicators of climate change related to physical stressors may include

  • changes in the acidity of the Bay and its tidal tributaries,
  • extreme precipitation events, and
  • shoreline condition.

Additional indicators of climate change related to ecological impacts may include

  • the change in abundance of harmful algal blooms,
  • the spatial extent and ability of wetlands to act as a physical buffer,
  • the spatial distribution of select climate-sensitive bird species,
  • the spatial distribution of select climate-sensitive fish species, and
  • the change in community composition of underwater grasses in the Chesapeake Bay.

Additional indicators of the social conditions affected by climate conditions may include

  • the frequency of tidal flooding in four coastal cities and
  • the extent of developed land located within a floodplain or storm surge risk zone and the estimated property damage caused by flooding and storm events.

Learn About Factors Influencing Progress

Management Strategy

To achieve this outcome, Chesapeake Bay Program partners have committed to

  • defining goals and establishing baselines for the monitoring, modeling and assessment of different aspects of climate change;
  • identifying and prioritizing gaps in available assessment tools, scientific understanding and baseline monitoring;
  • developing a conceptual climate monitoring, modeling and assessment model;
  • designing climate monitoring and modeling plans;
  • assessing climatic trends, documenting observed changes and conducting climate vulnerability assessments of the Chesapeake Bay ecosystem;
  • developing a research agenda; and
  • reassessing priorities and revising goals.

As part of the Chesapeake Bay Program’s partnership-wide implementation of adaptive management, progress toward this outcome was reviewed and discussed by the Management Board in November of 2022. It will be reviewed and discussed by the Management Board again in November 2024.

Download Management Strategy (.pdf)

Logic & Action Plan

Chesapeake Bay Program partners have committed to taking a series of specific actions that will support the management approaches listed above.

Learn About Logic & Action Plan

Participating Partners

The Climate Resiliency Workgroup leads the effort to achieve this outcome. It works in partnership with the Sustainable Fisheries, Habitat, Water Quality and Healthy Watersheds goal implementation teams.

Participating partners include the following:

  • Alliance for the Chesapeake Bay
  • Chesapeake Research Consortium
  • College of William and Mary (Commonwealth of Virginia)
  • District of Columbia
  • Ecosystem Planning and Restoration
  • Hampton Roads Planning District Commission (Commonwealth of Virginia)
  • Howard County Environmental Sustainability Board Resiliency Subcommittee
  • Maryland Sea Grant
  • Maryland Department of Planning
  • Maryland Department of Natural Resources
  • Maryland Department of Transportation
  • Maryland Department of the Environment
  • Metropolitan Washington Council of Governments
  • Morgan State University (State of Maryland)
  • National Oceanic and Atmospheric Administration
  • National Wildlife Federation
  • New York State Department of Environmental Conservation
  • NOAA Mid-Atlantic Regional Integrated Sciences and Assessments
  • Northern Virginia Regional Commission
  • Old Dominion University (Commonwealth of Virginia)
  • Polytechnic Institute and State University (Commonwealth of Virginia)
  • Rand Corporation
  • Sierra Club
  • State of Delaware
  • State of West Virginia
  • Tetra Tech
  • The Chesapeake Bay Commission
  • The Conservation Fund
  • The Nature Conservancy
  • University of Delaware Cooperative Extension (State of Delaware)
  • University of Maryland (State of Maryland)
  • U.S. Army Corps of Engineers
  • U.S. Department of the Navy
  • U.S. Environmental Protection Agency
  • U.S. Fish and Wildlife Service
  • U.S. Forest Service
  • U.S. Geological Survey
  • Virginia Agribusiness Council
  • Virginia Institute of Marine Science (Commonwealth of Virginia)
  • Virginia Sea Grant Land Trust Alliance
  • Wetlands Watch