Without action, climate scientists have warned that temperatures could rise by nearly 5° C above pre-industrial levels by 2100. World leaders meeting in Paris hope to keep average global surface temperature rises below 2° C – but their pledges to cut emissions could still see up to 3° C according to analyses. While it is very hard to make firm predictions, here are some of the potential impacts. All are for possible temperature rises occurring by 2100. Jump to “Summary of Impacts”

Introduction
Although urban and rural regions in the Northeast have profoundly different built and natural environments, both include populations that have been shown to be highly vulnerable to climate hazards and other stresses. Both also depend on aging infrastructure that has already been stressed by climate hazards including heat waves, as well as coastal and riverine flooding due to a combination of sea level rise, storm surge, and extreme precipitation events.

Sixty-four million people are concentrated in the Northeast. The high-density urban coastal corridor from Washington, D.C., north to Boston is one of the most developed environments in the world. It contains a massive, complex, and long-standing network of supporting infrastructure. The region is home to one of the world’s leading financial centers, the nation's capital, and many defining cultural and historical landmarks.

The region has a vital rural component as well. The Northeast includes large expanses of sparsely populated but ecologically and agriculturally important areas. Much of the Northeast landscape is dominated by forest, but the region also has grasslands, coastal zones, beaches and dunes, and wetlands, and it is known for its rich marine and freshwater fisheries. These natural areas are essential to recreation and tourism sectors and support jobs through the sale of timber, maple syrup, and seafood. They also contribute important ecosystem services to broader populations – protecting water supplies, buffering shorelines, and sequestering carbon in soils and vegetation. The twelve Northeastern states have more than 180,000 farms, with $17 billion in annual sales. The region’s ecosystems and agricultural systems are tightly interwoven, and both are vulnerable to a changing climate.

Although urban and rural regions in the Northeast have profoundly different built and natural environments, both include populations that have been shown to be highly vulnerable to climate hazards and other stresses. Both also depend on aging infrastructure that has already been stressed by climate hazards including heat waves, as well as coastal and riverine flooding due to a combination of sea level rise, storm surge, and extreme precipitation events.

The Northeast is characterized by a diverse climate. Average temperatures in the Northeast generally decrease to the north, with distance from the coast, and at higher elevations. Average annual precipitation varies by about 20 inches throughout the Northeast with the highest amounts observed in coastal and select mountainous regions. During winter, frequent storms bring bitter cold and frozen precipitation, especially to the north. Summers are warm and humid, especially to the south. The Northeast is often affected by extreme events such as ice storms, floods, droughts, heat waves, hurricanes, and major storms in the Atlantic Ocean off the northeast coast, referred to as nor’easters. However, variability is large in both space and time. For example, parts of southern New England that experienced heavy snows in the cold season of 2010-2011 experienced little snow during the cold season of 2011-2012. Of course, even a season with low totals can feature costly extreme events; snowfall during a 2011 pre-Halloween storm that hit most of the Northeast, when many trees were still in leaf, knocked out power for up to 10 days for thousands of households.

Source: http://nca2014.globalchange.gov/report/regions/northeast

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Observed Climate Change
Between 1895 and 2011, temperatures in the Northeast increased by almost 2˚F (0.16˚F per decade), and precipitation increased by approximately five inches, or more than 10% (0.4 inches per decade). Coastal flooding has increased due to a rise in sea level of approximately 1 foot since 1900. This rate of sea level rise exceeds the global average of approximately 8 inches, due primarily to land subsidence, although recent research suggests that changes in ocean circulation in the North Atlantic – specifically, a weakening of the Gulf Stream – may also play a role.

The Northeast has experienced a greater recent increase in extreme precipitation than any other region in the United States; between 1958 and 2010, the Northeast saw more than a 70% increase in the amount of precipitation falling in very heavy events (defined as the heaviest 1% of all daily events).

Source: http://nca2014.globalchange.gov/report/regions/northeast

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Projected Climate Change
Heat waves, heavy downpours, and sea level rise pose growing challenges to many aspects of life in the Northeast. Infrastructure, agriculture, fisheries, and ecosystems will be increasingly compromised. Many states and cities are beginning to incorporate climate change into their planning.

As in other areas, the amount of warming in the Northeast will be highly dependent on global emissions of heat-trapping gases. If emissions continue to increase (as in the A2 scenario), warming of 4.5ºF to 10ºF is projected by the 2080s; if global emissions were reduced substantially (as in the B1 scenario), projected warming ranges from about 3ºF to 6ºF by the 2080s.

Figure 1: (Map) Local sea level trends in the Northeast region. Length of time series for each arrow varies by tide gauge location. (Figure source: NOAA1). (Graph) Observed sea level rise in Philadelphia, PA, has significantly exceeded the global average of 8 inches over the past century, increasing the risk of impacts to critical urban infrastructure in low-lying areas. Over 100 years (1901-2012), sea level increased 1.2 feet (Data from Permanent Service for Mean Sea Level).

Under both emissions scenarios, the frequency, intensity, and duration of heat waves is expected to increase, with larger increases under higher emissions. Much of the southern portion of the region, including the majority of Maryland and Delaware, and southwestern West Virginia and New Jersey, are projected by mid-century to experience many more days per year above 90°F compared to the end of last century under continued increases in emissions. This will affect the region’s vulnerable populations, infrastructure, agriculture, and ecosystems.


Figure 2: Projected number of days per year with a maximum temperature greater than 90°F averaged between 2041 and 2070, compared to 1971-2000, assuming continued increases in global emissions (A2) and substantial reductions in future emissions (B1). (Figure source: NOAA NCDC / CICS-NC).

The frequency, intensity, and duration of cold air outbreaks is expected to decrease as the century progresses, although some research suggests that loss of Arctic sea ice could indirectly reduce this trend by modifying the jet stream and mid-latitude weather patterns.

Projections of precipitation changes are less certain than projections of temperature increases. Winter and spring precipitation is projected to increase, especially but not exclusively in the northern part of the region. A range of model projections for the end of this century under a higher emissions scenario (A2), averaged over the region, suggests about 5% to 20% (25th to 75th percentile of model projections) increases in winter precipitation. Projected changes in summer and fall, and for the entire year, are generally small at the end of the century compared to natural variations. The frequency of heavy downpours is projected to continue to increase as the century progresses. Seasonal drought risk is also projected to increase in summer and fall as higher temperatures lead to greater evaporation and earlier winter and spring snowmelt.

Global sea levels are projected to rise 1 to 4 feet by 2100, depending in large part on the extent to which the Greenland and West Antarctic Ice Sheets experience significant melting. Sea level rise along most of the coastal Northeast is expected to exceed the global average rise due to local land subsidence, with the possibility of even greater regional sea level rise if the Gulf Stream weakens as some models suggest. Sea level rise of two feet, without any changes in storms, would more than triple the frequency of dangerous coastal flooding throughout most of the Northeast.

Although individual hurricanes cannot be directly attributed to climate change, Hurricanes Irene and Sandy nevertheless provided “teachable moments” by demonstrating the region’s vulnerability to extreme weather events and the potential for adaptation to reduce impacts.

http://nca2014.globalchange.gov/report/regions/northeast

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Climate Risks to People
Heat waves, coastal flooding, and river flooding will pose a growing challenge to the region’s environmental, social, and economic systems. This will increase the vulnerability of the region’s residents, especially its most disadvantaged populations.

Urban residents have unique and multifaceted vulnerabilities to heat extremes. Northeastern cities, with their abundance of concrete and asphalt and relative lack of vegetation, tend to have higher temperatures than surrounding regions (the “urban heat island” effect). During extreme heat events, nighttime temperatures in the region’s big cities are generally several degrees higher than surrounding regions, leading to increased heat-related death among those less able to recover from the heat of the day.Since the hottest days in the Northeast are often associated with high concentrations of ground-level ozone and other pollutants, the combination of heat stress and poor air quality can pose a major health risk to vulnerable groups: young children, the elderly, and those with pre-existing health conditions including asthma. Vulnerability is further increased as key infrastructure, including electricity for potentially life-saving air conditioning, is more likely to fail precisely when it is most needed – when demand exceeds available supply. Significant investments may be required to ensure that power generation keeps up with rising demand associated with rising temperatures.

Finally, vulnerability to heat waves is not evenly distributed throughout urban areas; outdoor versus indoor air temperatures, air quality, baseline health, and access to air conditioning are all dependent on socioeconomic factors. Socioeconomic factors that tend to increase vulnerability to such hazards include race and ethnicity (being a minority), age (the elderly and children), gender (female), socioeconomic status (low income, status, or poverty), and education (low educational attainment). The condition of human settlements (type of housing and construction, infrastructure, and access to lifelines) and the built environment are also important determinants of socioeconomic vulnerability, especially given the fact that these characteristics influence potential economic losses, injuries, and mortality.

Increased health-related impacts and costs, such as premature death and hospitalization due to even modest increases in heat, are predicted in the Northeast’s urban centers. One recent study projected that temperature changes alone would lead to a 50% to 91% increase in heat-related deaths in Manhattan by the 2080s (relative to a 1980s baseline). Increased ground-level ozone due to warming is projected to increase emergency department visits for ozone-related asthma in children (0 to 17 years of age) by 7.3% by the 2020s (given the A2 scenario) relative to a 1990 baseline of approximately 650 visits in the New York metropolitan area.

Heat wave research has tended to focus on urban areas, but vulnerability to heat may also become a major issue in rural areas and small towns because air conditioning is currently not prevalent in parts of the rural Northeast where heat waves have historically been rare. Some areas of northern New England, near the Canadian border, are projected to shift from having less than five to more than 15 days per year over 90°F by the 2050s under the higher emissions scenario (A2) of heat-trapping gases. It should be noted that winter heating needs, a significant expense for many Northeastern residents, are likely to decrease as the century progresses.

The impacts of climate change on public health will extend beyond the direct effects of temperature on human physiology. Changing distributions of temperature, precipitation, and carbon dioxide could affect the potency of plant allergens, and there has been an observed increase of 13 to 27 days in the ragweed pollen season at latitudes above 44°N.

Vector-borne diseases are an additional concern. Most occurrences of Lyme disease in United States are in the Northeast, especially Connecticut. While it is unclear how climate change will impact Lyme disease, several studies in the Northeast have linked tick activity and Lyme disease incidence to climate, specifically abundant late spring and early summer moisture. West Nile Virus (WNV) is another vector-borne disease that may be influenced by changes in climate. Suitable habitat for the Asian Tiger Mosquito, which can transmit West Nile and other vector-borne diseases, is expected to increase in the Northeast from the current 5% to 16% in the next two decades and from 43% to 49% by the end of the century, exposing more than 30 million people to the threat of dense infestations by this species.

Many Northeast cities, including New York, Boston, and Philadelphia, are served by combined sewer systems that collect and treat both stormwater and municipal wastewater. During heavy rain events, combined systems can be overwhelmed and untreated water may be released into local water bodies. In Connecticut, the risk for contracting a stomach illness while swimming significantly increased after a one inch precipitation event, and studies have found associations between diarrheal illness among children and sewage discharge in Milwaukee. More frequent heavy rain events could therefore increase the incidence of waterborne disease.

Historical settlement patterns and ongoing investment in coastal areas and along major rivers combine to increase the vulnerabilities of people in the Northeast to sea level rise and coastal storms. Of the Northeast’s population of 64 million, approximately 1.6 million people live within the Federal Emergency Management Agency’s (FEMA) 100-year coastal flood zone, with the majority – 63% of those at risk – residing in New York and New Jersey. As sea levels rise, populations in the current 1-in-100-year coastal flood zone (defined as the area with at least a 1% chance of experiencing a coastal flood in a given year) will experience more frequent flooding, and populations that have historically fallen outside the 1-in-100-year flood zone will find themselves in that zone. People living in coastal flood zones are vulnerable to direct loss of life and injury associated with tropical storms and nor’easters. Flood damage to personal property, businesses, and public infrastructure can also result.

This risk is not limited to the 1-in-100-year flood zone; in the Mid-Atlantic part of the region alone, estimates suggest that between 450,000 and 2.3 million people are at risk from a three foot sea level rise, which is in the range of projections for this century.

Throughout the Northeast, populations are also concentrated along rivers and their flood plains. In mountainous regions, including much of West Virginia and large parts of Pennsylvania, New York, Vermont, and New Hampshire, more intense precipitation events will mean greater flood risk, particularly in valleys, where people, infrastructure, and agriculture tend to be concentrated.

http://nca2014.globalchange.gov/report/regions/northeast

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Stressed Infrastructure
Infrastructure will be increasingly compromised by climate-related hazards, including sea level rise, coastal flooding, and intense precipitation events.

Disruptions to services provided by public and private infrastructure in the Northeast both interrupt commerce and threaten public health and safety. In New York State, two feet of sea level rise is estimated (absent adaptation investment) to flood or render unusable 212 miles of roads, 77 miles of rail, 3,647 acres of airport facilities, and 539 acres of runways. Port facilities, such as in Maryland (primarily Baltimore), also have flooding impact estimates: 298 acres, or 32% of the overall port facilities in the state. These impacts have potentially significant economic ramifications. For example, in 2006 alone the Port of Baltimore generated more than 50,200 jobs, $3.6 billion in personal income, $1.9 billion in business revenues, and $388 million in state, county, and municipal tax. The New York City Panel on Climate Change highlighted a broader range of climate impacts on infrastructure sectors. Although this study focused specifically on New York City, these impacts are applicable throughout the region. Predicted impacts of coastal flooding on infrastructure were largely borne out by Hurricane Sandy; sea level rise will only increase these vulnerabilities.

The more southern states within the region, including Delaware and Maryland, have a highly vulnerable land area because of a higher rate of sea level rise and relatively flat coastlines compared to the northern tier. The northern states, including Massachusetts, Rhode Island, and Connecticut, have less land area exposed to a high inundation risk because of a lower relative sea level rise and because of their relatively steep coastal terrain. Still, low-lying coastal metropolitan areas in New England have considerable infrastructure at risk. In Boston alone, cumulative damage to buildings and building contents, as well as the associated emergency costs, could potentially be as high as $94 billion between 2000 and 2100, depending on the sea level rise scenario and which adaptive actions are taken.

In the transportation sector, many of the region’s key highways (including I-95) and rail systems (including Amtrak and commuter rail networks) span areas that are prone to coastal flooding. In addition to temporary service disruptions, storm surge flooding can severely undermine or disable critical infrastructure along coasts, including subway systems, wastewater treatment plants, and electrical substations. Saltwater corrosion can damage sensitive and critical electrical equipment, such as electrical substations for energy distribution and signal equipment for rail systems; corrosion also accelerates rust damage on rail lines. Saltwater also threatens groundwater supplies and damages wastewater treatment plants.

http://nca2014.globalchange.gov/report/regions/northeast

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Agricultural and Ecosystem Impacts
Agriculture, fisheries, and ecosystems will be increasingly compromised over the next century by climate change impacts. Farmers can explore new crop options, but these adaptations are not cost- or risk-free. Moreover, adaptive capacity, which varies throughout the region, could be overwhelmed by a changing climate.

Farmers in the Northeast are already experiencing consequences of climate change. In addition to direct crop damage from increasingly intense precipitation events, wet springs can delay planting for grain and vegetables in New York, for example, and subsequently delay harvest dates and reduce yields. This is an issue for agriculture nationally, but is particularly acute for the Northeast, where heavy rainfall events have increased more than in any other region of the country. In the future, farmers may also face too little water in summer to meet increased crop water demand as summers become hotter and growing seasons lengthen., Increased frequency of summer heat stress is also projected, which can negatively affect crop yields and milk production.

Despite a trend toward warmer winters, the risk of frost and freeze damage continues, and has paradoxically increased over the past decade. These risks are exacerbated for perennial crops in years with variable winter temperatures. For example, midwinter-freeze damage cost wine grape growers in the Finger Lakes region of New York millions of dollars in losses in the winters of 2003 and 2004. This was likely due to de-hardening of the vines during an unusually warm December, which increased susceptibility to cold damage just prior to a subsequent hard freeze. Another avenue for cold damage, even in a relatively warm winter, is when there is an extended warm period in late winter or early spring causing premature leaf-out or bloom, followed by a damaging frost event, as occurred throughout the Northeast in 2007 and again in 2012 when apple, grape, cherry, and other fruit crops were hard hit.

Increased weed and pest pressure associated with longer growing seasons and warmer winters will be an increasingly important challenge; there are already examples of earlier arrival and increased populations of some insect pests such as corn earworm. Furthermore, many of the most aggressive weeds, such as kudzu, benefit more than crop plants from higher atmospheric carbon dioxide, and become more resistant to herbicide control. Many weeds respond better than most cash crops to increasing carbon dioxide concentrations, particularly “invasive” weeds with the so-called C3 photosynthetic pathway, and with rapid and expansive growth patterns, including large allocations of below-ground biomass, such as roots. Research also suggests that glyphosate (for example, Roundup), the most widely-used herbicide in the United States, loses its efficacy on weeds grown at the increased carbon dioxide levels likely to occur in the coming decades. To date, all weed/crop competition studies where the photosynthetic pathway is the same for both species favor weed growth over crop growth as carbon dioxide is increased.

Effects of rising temperatures on the Northeast’s ecosystems have already been clearly observed. Further, changes in species distribution by elevation are occurring; a Vermont study found an upslope shift of 299 to 390 feet in the boundary between northern hardwoods and boreal forest on the western slopes of the Green Mountains between 1964 and 2004. Wildflowers and woody perennials are blooming earlier , and migratory birds are arriving sooner. Because species differ in their ability to adjust, asynchronies (like a mismatch between key food source availability and migration patterns) can develop, increasing species and ecosystem vulnerability. Several bird species have expanded their ranges northward as have some invasive insect species, such as the hemlock woolly adelgid, which has devastated hemlock trees. Warmer winters and less snow cover in recent years have contributed to increased deer populations that degrade forest understory vegetation.

As ocean temperatures continue to rise, the range of suitable habitat for many commercially important fish and shellfish species is projected to shift northward. For example, cod and lobster fisheries south of Cape Cod are projected to have significant declines., Although suitable habitats will be shrinking for some species (such as coldwater fish like brook trout) and expanding for others (such as warmwater fish like bass), it is difficult to predict what proportion of species will be able to move or adapt as their optimum climate zones shift. As each species responds uniquely to climate change, disruptions of important species interactions (plants and pollinators; predators and prey) can be expected. For example, it is uncertain what forms of vegetation will move into the Adirondack Mountains when the suitable habitat for spruce-fir forests disappears. Increased productivity of some northern hardwood trees in the Northeast is projected (due to longer growing seasons and assuming a significant benefit from higher atmospheric carbon dioxide), but summer drought and other extreme events may offset potential productivity increases. Range shifts in traditional foods gathered from the forests by Native American communities, such as Wabanaki berries in the Northeast, can have negative health and cultural impacts.

In contrast, many insect pests, pathogens, and invasive plants like kudzu appear to be highly and positively responsive to recent and projected climate change. Their expansion will lead to an overall loss of biodiversity, function, and resilience of some ecosystems.

The Northeast’s coastal ecosystems and the species that inhabit them are highly vulnerable to rising seas. Beach and dune erosion, both a cause and effect of coastal flooding, is also a major issue in the Northeast., Since the early 1800s, there has been an estimated 39% decrease in marsh coverage in coastal New England; in the metropolitan Boston area, marsh coverage is estimated to be less than 20% of its late 1700s value. Impervious urban surfaces and coastal barriers such as seawalls limit the ability of marshes to expand inland as sea levels rise.

Source: http://nca2014.globalchange.gov/report/regions/northeast

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Planning and Adaptation
While a majority of states and a rapidly growing number of municipalities have begun to incorporate the risk of climate change into their planning activities, implementation of adaptation measures is still at early stages.

Local and state governments in the Northeast have been leaders and incubators in utilizing legal and regulatory opportunities to foster climate change policies. The Regional Greenhouse Gas Initiative (RGGI) was the first market-based regulatory program in the U.S. aimed at reducing greenhouse gas emissions; it is a cooperative effort among nine northeastern states. Massachusetts became the first state to officially incorporate climate change impacts into its environmental review procedures by adopting legislation that directs agencies to “consider reasonably foreseeable climate change impacts, including additional greenhouse gas emissions, and effects, such as predicted sea level rise.” In addition, Maine, Massachusetts, and Rhode Island have each adopted some form of “rolling easement” to ensure that wetlands or dunes migrate inland as sea level rises and reduce the risk of loss of life and property.

Northeast cities have employed a variety of mechanisms to respond to climate change, including land-use planning, provisions to protect infrastructure, regulations related to the design and construction of buildings, and emergency preparation, response, and recovery. While significant progress has been made, local governments still face limitations of legal authority, geographic jurisdiction, and resource constraints that could be addressed through effective engagement and support from higher levels of government.

Keene, New Hampshire, has been a pilot community for ICLEI’s Climate Resilient Communities program for adaptation planning – a process implemented through innovative community engagement methods. The Cape Cod Commission is another example in New England; the Commission has drafted model ordinances to help communities incorporate climate into zoning decision-making. Farther south, New York City has taken numerous steps to implement PlaNYC, a far-reaching sustainability plan for the city, including amending the construction code and the zoning laws and the implementation of measures focused on developing adaptation strategies to protect the City’s public and private infrastructure from the effects of climate change; some major investments in protection have even been conceptualized.

One widely used adaptation-planning template is the eight-step iterative approach developed by the New York City Panel on Climate Change; it was highlighted in the contribution of the National Academy of Science’s Adaptation Panel to America’s Climate Choices and adopted by the Committee on America’s Climate Choices. It describes a procedure that decision-makers at all levels can use to design a flexible adaptation pathway to address infrastructure and other response issues through inventory and assessment of risk. The key, with respect to infrastructure, is to link adaptation strategies with capital improvement cycles and adjustment of plans to incorporate emerging climate projections, – but the insights are far more general than that (see the Adaptation Panel Report).

In most cases, adaptation requires information and tools coupled to a decision-support process steered by strong leadership, and there are a growing number of examples in the Northeast. At the smaller, municipal scale, coastal pilot projects in Maryland,, Delaware, New York, and Connecticut are underway.

Research and outreach efforts are underway in the region to help farmers find ways to cope with a rapidly changing climate, take advantage of a longer growing season, and reduce greenhouse gas emissions,, but unequal access to capital and information for strategic adaptation and mitigation remain a challenge. Financial barriers can constrain farmer adaptation., Even relatively straightforward adaptations such as changing varieties are not always a low-cost option. Seed for new stress-tolerant varieties is sometimes expensive or regionally unavailable, and new varieties often require investments in new planting equipment or require adjustment in a wide range of farming practices. Investment in irrigation and drainage systems are relatively expensive options, and a challenge for farmers will be determining when the frequency of yield losses due to summer water deficits or flooding has or will become frequent enough to warrant such capital investments.

Regional activities in the Northeast are also being linked to federal efforts. For example, NASA’s Agency-wide Climate Adaptation Science Investigator Workgroup (CASI) brings together NASA facilities managers with NASA climate scientists in local Climate Resilience Workshops. This approach was in evidence at the Goddard Space Flight Center in Maryland, where scientists helped institutional managers address energy and stormwater management vulnerabilities.


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