Global Warming and the Free State - Highlights


On August 27, 2008, the Commission released its Plan of Action that assesses likely climate change impacts in Maryland and presents strategies to reduce greenhouse gas emissions and reduce the state’s vulnerability to climate change. Global Warming and the Free State is the comprehensive climate change impact assessment included as Chapter 2 of the Plan of Action. It was prepared by a Scientific and Technical Working Group, consisting of leading Marylanders with expertise in climate and its impacts.


  • Average air temperatures are projected to increase by about 3˚F by mid-century. Average summer temperatures could increase by as much as 9˚F with extended heat waves later in the century under the higher emissions scenario.
  • The number of days with air temperatures exceeding 90˚F is projected to double (and could even triple) by the end of the century. Under the higher emissions scenario, each year could average more than 24 days of air temperatures exceeding 100˚F.
  • Precipitation is projected to increase during the spring and winter months, but become more episodic. During the summer months, extended droughts are projected to be more likely.
  • More intense rainfall events are likely to increase peak flooding events in urban areas and will likely result in larger amounts of pollution reaching the Chesapeake Bay and its tributaries.
  • There is a greater likelihood that more powerful rain and wind storms will strike Maryland as ocean waters warm, accompanied by higher storm surges and rainfall.


  • Sea level rise could rise of 2-3 feet by late century, inundating hundreds of square miles of wetlands and low-lying areas.
  • Native species such as the Baltimore oriole may be forced out of the area because of changes to their preferred habitat.
  • The Chesapeake Bay has already warmed by 3˚F since the 1930s and could warm by another 5-9˚F by 2100.
  • Increases in winter-spring runoff will send more nutrients to the Chesapeake and Coastal Bays, and with higher water temperatures will further degrade water quality and impede restoration efforts.
  • Dead zones in the Bay are likely to increase with higher water temperatures and nutrient input, stressing native aquatic species. Warming could also favor the establishment of invasive populations of non-native species.


  • Warming air temperatures are projected to decrease the number of frost days and increase the length of the growing season. However, later in the century, crop production is likely to be reduced due to heat stress and summer droughts. Milk and poultry production would also be impacted by heat stress.
  • While Maryland forests are likely to experience a modest increase in productivity in the first half of the century; this could change later in the century due to increased drought and vulnerability to insect pests and forest fires.

Human Health

  • Heat-related illness and death are projected to increase, especially for the poor, the elderly and urban populations.
  • Respiratory illnesses will likely increase unless air pollution is greatly reduced.
  • Increased risks of pathogenic diseases will be less likely.

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