Juliana Barrett, Ph.D. Connecticut Sea Grant, UConn Extension
Climate change in the northeastern United States Annual average temperature has increased by 2 F with winter temperatures rising twice this much in the northeast over the last century. More frequent days with temperatures above 90 F A longer growing season Increased heavy precipita?on National Weather Service
Extreme heat in our ci6es
Increased heavy precipita6on events http://precip.eas.cornell.edu/
Less winter precipitation falling as snow and more as rain Reduced snowpack and earlier breakup of winter ice on lakes and rivers Earlier spring snowmelt leading to earlier peak river flows
Rising sea surface temperatures and sea level Temperature of Long Island Sound has increased 1 C (1.8 F) since 1900. Impacts to flora and fauna, water quality, sea level rise (thermal expansion) Sea level rise in Long Island Sound will increase approximately 10 to 20 inches in the next 50 100 years.
The Union of Concerned Scientists 2007 synthesis report of Northeast Climate Impacts Assessment (NECIA), suggests that we may see an increase in the number of winter storms received in coastal Connecticut, especially late in the winter.
By 2100: Most locations are projected to experience increases over the current 100- year- flood elevation of roughly 1.5 feet under the higher- emissions scenario and roughly 1.0 feet under the lower emissions scenario. Today s 100- year floods will recur even more often. In the case of New London, CT one might expect the effects of a 100 year storm by today s standards (2010) to recur every 17 to 32 years based on the higher or lower emissions scenarios, respectively.
Wetlands and Climate Change We know that greenhouse gases such as carbon dioxide and methane are accumulating in the atmosphere at a rate that exceeds the ability for that carbon to be sequestered (such as by carbohydrates in plants). Wetlands play a significant role in global carbon budgets both as sources and sinks for greenhouse gases. Their role in climate change is an area of active research.
Climate Change and Disturbance to Wetlands Wind damage to wetland forests in the Pearl River Basin caused by Hurricane Katrina changed carbon sinks to carbon sources Louisiana State University
Of all aquatic systems, wetlands will likely be the most susceptible to climate change. Shallow wetlands that are dependent on precipitation will be the most vulnerable to drying, warming and changes in water quality. Intermittent and perennial streams, vernal pools, and coastal wetlands and marshes will also be particularly vulnerable to projected changes in temperature, precipitation and sea level rise. Lawler, J.J., et al. 2008
Climate change impacts that will affect wetlands Increased mean annual air temperatures Changes in precipitation patterns (amount, timing, intensity) Increases in average water temperatures Sea level rise Intense storm events (hurricanes, nor easters) Increased carbon dioxide
Increased mean annual air and water temperatures Will impact hydrologic regimes Changes to plant and animal ranges, migrations (USDA hardiness zones) on land and water systems
In the US, spring now arrives 10 to 14 days earlier than it did 20 years ago. Obvious changes related to the timing of the seasons: when plants bud in spring; when birds and other animals migrate Shifts in tree species on mountains in New England (largely in the transition zones) Large declines in trout populations
Changes in precipita?on Will change hydrologic regimes based on amount of precipitation, forms of precipitation, intensity and timing Leading to changes in hydrologic regimes: ground water levels, earlier spring snowmelt leading to earlier peak river flows (Connecticut River), runoff, soil moisture
Sea Level Rise Sea level has been rising; the rate of SLR is increasing due to climate change leading to: Loss of tidal wetlands where sedimentation rates not keeping up with SLR or no room for marsh migration Even a 2 ft rise in relative sea level over a century would result in the loss of a large amount of the US coastal wetlands as many are not able to build new soil at a fast enough rate.
Coastal Wetlands Kirwan et al. (2010) ran 5 different numerical models and concluded that coastal marshes are likely to survive conservative SLR projections but are vulnerable under scenarios of rapid SLR that include ice sheet melting.
Long Island Sound Marshes Hoover, Whelchel, and Civco have developed a salt marsh migration tool and have applied it to the tidal wetlands of LIS. Changes in high marsh to low marsh Marsh migration scenarios/management scenarios (constraints on landward side) Surface Elevation Tables (SET s) numerous locations along CT s coast
The Surface Elevation Table (SET) is a portable mechanical leveling device for measuring the relative elevation change of wetland sediments.
Changes at Barn Island Stonington, CT
Connec?cut River Salt wedge may move further upriver with sea level rise. Some of the freshwater tidal wetlands may transition to brackish, and brackish wetlands to salt marshes. Changes in the timing of the spring freshet will also impact wetlands.
Climate Change Impacts to Inland Wetlands Increased precipitation, intensity of storm events, increased air temperatures Where precipitation increases, size and number of inland freshwater wetlands could increase. Where precipitation decreases or air temperatures increase without increases in precipitation, some wetland could become smaller and/or dry out.
Changes in ground water or surface water can impact wetlands Many plants and animals in Connecticut are on the edge of the ranges and may be sensitive to changes in water regimes and water temperatures.
Vernal pools may decrease in size or dry up Wetland types may change such as from marsh to forest Associated flora and fauna may change as wetlands change
Poten?al human threats to wetlands associated with climate change Coastal wetlands: coastal hardening to protect infrastructure from SLR Dams to prevent flooding, provide water to drought stricken areas Drainage of wetlands to reduce risk of disease
What can we do? Identification of at risk wetlands statewide (eg tidal marshes, vernal pools, shallow to groundwater wetlands, poor fens)
Vegetated buffers and setbacks
Tidal marshes protec6on of surrounding land to allow for marsh migra6on (depending on eleva6ons)
Wetlands restora6on
Wetlands protec6on
Control of Invasive Species
Water Control Structures Drop pipe Flap gate structure Flash boards or stoplogs
Wetlands and Global Scale Changes Wetlands are significant sources and sinks of greenhouse gases and play an important role in global climate change Wetlands are very vulnerable to the effects of global climate change Sea level rise driven by climate change is the greatest threat to coastal wetlands Increases in temperature pose the greatest threat to inland wetlands