Climate change will have a significant impact on the extent, distribution, and biological diversity of Massachusetts' plants, animals, and their habitats. Since climate is a major determinant of ecosystem function and the distribution, abundance, and behavior of organisms, climatic change is likely to trigger fundamental alterations to Massachusetts' coastal and freshwater ecosystems
(References and select text taken from Climate Change Adaptation Strategies, Executive Office of Energy and Environmental Affairs, 2009, draft document in preparation)

Coastal Ecosystems

One of the main climate change-related threats to Massachusetts coastal wetlands is sea level rise. Current projections for global sea level rise by the year 2100 range from three to six feet, depending on the assumptions made about polar regional ice melt.

The vulnerability of intertidal habitats in Massachusetts to climate change is being evaluated by many researchers and government agencies. As sea level rises, some habitats that are currently intertidal will become subtidal, while salt marsh will migrate further inland (if conditions permit) in response to changes in tide levels and salinity.

Vulnerabilities
• Important coastal habitats will be lost due to increased wave action and inundation
• Reduction of sediment supply to coastal habitats due to dams, tide gates, and under-sized culverts inhibits the ability of these areas to maintain accretion rates to keep pace with sea level rise

Adaptation Strategies
• Remove impediments to tidal flow and sediment supply, such as dams on coastal rivers, tide gates, and culverts to restore natural tidal range, sediment supply, and habitat migration potential
• Remove obstructions and protect coastal lands upgradient of tidal wetlands to facilitate inland migration of salt marsh and other coastal habitats
• Adopt flexible regulations, planning policies, and landuse laws to promote coastal wetland restoration and increase protective buffers

Freshwater Ecosystems
Predicted changes in climate include increased temperature, drought and the number of extreme heat days, and a decrease in summer precipitation. Higher temperatures and changes in flow discharge will degrade water quality and habitat integrity.

A decrease in summer precipitation and an increase in drought will result in impaired stream flow.

Hydrologic changes can amplify erosion and scour in streams and initiate channel incision. Problems associated with channel incision include undermining of structures, downstream sedimentation, severe bank erosion, and widening and degradation of aquatic and riparian habitats.

Vulnerabilities
• Changes in timing, frequency, and duration of precipitation events
• Increases in temperature trends and extreme high temperature events. Disconnection between flowing waters and their flood plains risks conversion of flood plains to other habitat types
• The potential for increased incidence of invasive species

Adaptation Strategies
• Remove in-stream barriers (dams and undersized culverts) and re-establish in-stream flows to restore aquatic habitats
• Protect and conserve land including remaining critical coldwater fish habitat areas, reconnect high quality habitats, protect belt-width-based river corridors, and restore floodplains