Editing Chesapeake Bay (section)

=== Climate change ===
[[File:Urban-Rural Population and Land Area Estimates, v2, 2010 Washington D.C., U.S. (13873799193).jpg|thumb|Population density and elevation above sea level around the Chesapeake Bay. The Chesapeake Bay is especially vulnerable to [[sea level rise]].]]
The Chesapeake Bay is already experiencing the effects of [[climate change]]. Key among these is sea level rise: water levels in the bay have already risen one foot, with a predicted increase of 1.3 to 5.2 feet in the next 100 years. This has related environmental effects, causing changes in marine ecosystems, destruction of coastal marshes and wetlands, and intrusion of saltwater into otherwise brackish parts of the bay. Sea level rise also compounds the effects of [[extreme weather]] on the bay, making [[coastal flooding]] as part of the events more extreme and increasing runoff from upstream in the watershed.<ref name="Climate-CBP"/><ref name="UMCES-Climate">{{Cite web |date=2017-04-04 |title=Climate change already affecting Chesapeake Bay region |url=https://www.umces.edu/research-highlights/climate-change-already-affecting-chesapeake-bay-region |access-date=2020-12-16 |publisher=University of Maryland Center for Environmental Science |location=Cambridge, MD}}</ref>

With increases in flooding events and sea level rise, the 11,600 miles of coastline, which include significant historic buildings and modern infrastructure, will be at risk of erosion. Islands such as [[Holland Island]] have disappeared due to the rising sea levels.<ref>{{Cite web |title=Climate Change and the Chesapeake Bay |url=https://www.conservationfund.org/projects/climate-change-and-the-chesapeake-bay |access-date=2020-12-16 |publisher=The Conservation Fund |location=Arlington, VA |archive-date=2020-11-29 |archive-url=https://web.archive.org/web/20201129044439/https://www.conservationfund.org/projects/climate-change-and-the-chesapeake-bay |url-status=dead }}</ref><ref name="CBP-Island">{{cite web |title=Portrait of an Island Part I: What used to be home |date=20 June 2018 |url=https://www.chesapeakebay.net/news/blog/portrait-of-an-island-part-i |access-date=2022-12-25 |publisher=Chesapeake Bay Program}}</ref>

Beyond sea level rise, other changes in the marine ecosystem due to climate change, such as [[ocean acidification]] and temperature increases, will put increasing pressure on marine life. Projected effects include decreasing dissolved oxygen, more acidic waters making it harder for shellfish to maintain shells and changing the seasonal cycles important for breeding and other lifecycle activities.<ref name="Climate-CBP"/> Seasonal shifts and warmer temperatures also mean that there is a greater likelihood of pathogens to stay active in the ecosystem.<ref name="UMCES-Climate"/>

Climate change may worsen [[Hypoxia (environmental)|hypoxia]]. However, compared to the current effects of [[nutrient pollution]] and [[algal bloom]]s, climate change's effect to increase hypoxia is relatively small. Warmer waters can hold less dissolved oxygen. Therefore, as the bay warms, there may be a longer duration of hypoxia each summer season in the deep central channel of the bay. However, comparing the effects of climate change and nutrient pollution, reduced nutrient pollution would increase oxygen concentrations more dramatically than if climate change were to level out.<ref name="Irby">{{cite journal | last1=Irby | first1=Isaac D. | last2=Friedrichs | first2=Marjorie A. M. | last3=Da | first3=Fei | last4=Hinson | first4=Kyle E. | title=The competing impacts of climate change and nutrient reductions on dissolved oxygen in Chesapeake Bay | journal=Biogeosciences | publisher=Copernicus GmbH | volume=15 | issue=9 | date=4 May 2018 | issn=1726-4189 | doi=10.5194/bg-15-2649-2018 | pages=2649–2668| bibcode=2018BGeo...15.2649I | doi-access=free }}</ref>

[[Climate change adaptation]] and mitigation programs in [[Climate change in Maryland|Maryland]] and [[Climate change in Virginia|Virginia]] often include significant programs to address the communities in the Chesapeake Bay.<ref name=":3">{{Cite news |title=After decades of waterfront living, climate change is forcing communities to plan their retreat from the coasts |url=https://www.washingtonpost.com/magazine/2020/04/13/after-decades-waterfront-living-climate-change-is-forcing-communities-plan-their-retreat-coasts/ |newspaper=The Washington Post}}</ref> Key infrastructure in Virginia, such as the port of [[Norfolk, Virginia|Norfolk]],<ref name=":3" /> and major agriculture and fishing industries of the [[Eastern Shore of Maryland]] will be directly impacted by the changes in the bay.<ref name="EPA">{{cite web |date=August 2016 |title=What Climate Change Means for Maryland |url=https://19january2017snapshot.epa.gov/sites/production/files/2016-09/documents/climate-change-md.pdf |publisher=EPA}}</ref>