Moving image of a nor'easter, or major storm sytem

Source: NOAA

New England has already started to feel the effects of global climate change. Snow cover is decreasing and spring arrives earlier. Scientists predict that we may be headed for a Boston climate much like that of Charlotte, North Carolina, or Atlanta, Georgia. Find out what is in store for Massachusetts and the other New England states—and what could happen to Boston. How could coastal flooding affect us? And what is the likelihood of extreme weather such as nor’easters and ice storms. Learn how our geography—with our vulnerable wetlands and coastal habitats—may determine our destiny.

Much of the information in this section is sourced from “Confronting Climate Change in the U.S. Northeast: Science, Impacts and Solutions,” a report of the Northeast Climate Impacts Assessment © 2007 Union of Concerned Scientists.

Full length presentations are available for download from the Changing Climates, Changing Coasts Symposium, co-hosted by the Aquarium and the Woods Hole Oceanographic Institution.

 

How is New England being impacted by climate change?

Satellite zoom out from Boston

Source: NASA/Goddard Space Flight

Center Scientific Visualization Studio

Part of New England’s charm is the distinct four seasons—a climate that includes crisp falls, snow-filled winters and temperate springs and summers. The climate has started to change, however. Snow cover is decreasing and spring arrives earlier. And the number of extremely hot summer days has been increasing. According to a report from the Northeast Climate Impacts Assessment (NECIA) team, since 1970, the Northeast has been warming at a rate of nearly .5 degrees F per decade, with winter temperatures rising faster, at a rate of 1.3 degrees F per decade from 1970 to 2000, all changes consistent with those expected to be caused by global warming. 2010 was the warmest year on record.

New England has clearly warmed since the end of the 19th century, with winter temperatures increasing more than summer temperatures, and with the greatest warming taking place in New Hampshire, Vermont and Rhode Island. Annual precipitation has increased. While more rain has fallen in intense storms, snowfall in northern New England has decreased since 1953.

According to the New England Climate Coalition, temperature increases could affect New England’s brilliant fall colors as trees migrate north or die out, and maple syrup production may be jeopardized because sap flow depends on freezing nights and warm days. And the ski industry will face the threat of less natural snowfall and the inability to produce artificial snow, which requires temperatures of 28 degrees or less. Under a high emissions scenario, for example, only western Maine is projected to retain a reliable ski season.

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How is climate change likely to affect Massachusetts and the other New England states?

According to the New England Climate Coalition, these are some of the impacts of climate change in Massachusetts: Over the last century, the average temperature in Amherst, Massachusetts, has increased 2 degrees F. Precipitation has increased by up to 20 percent in many parts of the state. By 2100, temperatures could increase by about 4 degrees in winter and spring and about 5 degrees in summer and fall.


Precipitation by 2100 is estimated to increase by about 10 percent in spring and summer, 15 percent in fall, and 20 to 60 percent in winter. The amount of precipitation on extremely wet or snowy days in winter is likely to increase while the frequency of extremely hot days in summer would also increase. Heat-related deaths in Boston during a typical summer could increase 50 percent by 2050.


The potential for transmission of diseases such as malaria, Dengue fever, West Nile virus and Lyme disease is expanded with warming as the habitats of disease-carrying insects expand. Warmer seas could contribute to the increased intensity, duration and extent of harmful algal blooms, which damage habitat and shellfish nurseries and can be toxic to humans. Massachusetts loses an average of 65 acres to rising sea levels each year. Much of this loss occurs along the south-facing coast between Rhode Island and the outer shore of Cape Cod, including Nantucket and Martha’s Vineyard.


In Boston, the sea level has risen by 11 inches over the last 100 years (both because of climate change and land subsidence) and could rise another 2 to 6 feet by 2100. The cost of sand replenishment to protect the coast of Massachusetts from a 20-inch sea level rise by 2100 is estimated at $490 million to $2.6 billion. The New England Climate Coalition also provides information about potential impacts to Connecticut, Maine, New Hampshire, Rhode Island and Vermont.

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Projections for Boston

from the Climate Choices report

Confronting Climate Change in

the U.S. Northeast (pdf 7.5 MB)

(Click images to enlarge)

What is the likely impact of global warming on the Northeast and on Boston?

More than half the country’s population now lives along the nation’s coasts, and one third lives in the highly populated coastal areas of the Northeast. The area between Boston and Philadelphia is one of the most populous areas of the country, with extensive infrastructure, buildings and businesses.

Global climate change affects the coastal areas with rising air temperature, increasing rainfall, rising ocean temperatures and rising sea levels, which lead to increased coastal flooding. In addition to sea level rises, much of the Northeast shoreline is gradually sinking, increasing the effects of rising ocean waters.

In Boston, if the number of 100-year storms increases, more buildings and infrastructure will be at risk of being inundated by rising waters during intense weather such as hurricanes and nor’easters. While many of Boston’s neighborhoods are protected from wave action and flooding by seawalls, they have not been fully tested by extreme weather conditions and rising sea levels.

Many of Boston’s neighborhoods and landmarks—including the New England Aquarium—are built in areas that are highly susceptible to flooding and the effects of extreme weather. For example, under projected 100-year storms (based on a high emissions scenario), many of Boston's best-known landmarks are threatened, including Faneuil Hall, Quincy Market, North Station, Fan Pier, Copley Church, John Hancock Tower and the Public Garden.

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How could coastal flooding affect Boston and the Northeast?

Sea levels are rising inexorably, with significant impacts to the Northeast. Our highly developed coastline, barrier beaches and coastal ecology are all vulnerable to rising sea levels. Sea level rise would swamp low-lying coastal areas and increase erosion of our shoreline and loss of wetlands. The areas most vulnerable to shoreline erosion and beach loss include parts of south Cape Cod, most of Nantucket Island and the eastern portions of Martha’s Vineyard. The impact of storm waves intensify the effects of rising sea levels, eating away at sand beaches and low-lying wetlands. In addition, the bluffs and cliffs of the New England shoreline will be eroded at their base, causing the cliffs to crumble.

Scientists use a benchmark, the 100-year flood, to describe how frequently a major flood could occur in the future as sea levels rise. They look at the historical record to determine the frequency with which major storms have occurred in the past and then estimate the likelihood that such a storm, or a more severe storm, will occur in the future. In any one year, for example, there is a 1 percent likelihood that a 100-year flood will occur. According to current estimates, Boston can expect a coastal flood equivalent to today’s 100-year flood every two to four years on average by mid-century and almost annually by the end of the century. (This is a more extreme estimate than New York City’s for example, where a 100-year flood can be expected every 46 to 50 years.)

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Satellite image of New England

snow cover after a blizzard

Source: NASA/Goddard Space Flight

Center Scientific Visualization Studio

 

What is the likelihood of extreme weather events such as heat waves, nor’easters and ice storms in New England?

Global warming is predicted to increase the frequency of severe storms in New England at the same time that sea level rise magnifies their impact on low-lying coastlines and islands.

Climate change is expected to dramatically increase the number of extremely hot days. The average number of days each year with temperatures exceeding 90 degrees has doubled over the past 45 years. By late-century, many northeastern cities can expect 60 or more days per year over 90 degrees under a higher emissions scenario and 30 or more such days under a lower emissions scenario.

The Northeast is projected to see a steady increase in precipitation, with total increase of around 10 percent, about four inches per year, by the end of the century. It is winter precipitation that is rising fastest, with more precipitation expected to fall as rain rather than snow. Rainfall is expected to become more intense and periods of heavy rainfall are expected to become more frequent.

Our coast is susceptible to a variety of storms from hurricanes to nor’easters, which are lower-energy storms that occur more frequently, last longer and cover more area, causing significant damage. Nor’easters are named for the strong winds that generally hit the coasts from the northeast between October and April. Since the 1970s, nor’easters have struck New England more frequently and with greater intensity.

As intense storms reach shallow coastal waters, they frequently generate storm surges, wind-driven swells that increase sea levels further. When these occur at the same time as high tides, the damage can be substantial. Storm surges wash over barrier beaches and cut inlets through them. In 2007, for example, a nor’easter cut an opening through the Nauset Beach peninsula on Cape Cod. These openings then expose the shoreline behind the barrier beach to additional wave damage and erosion.

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How will climate change affect our wetlands?

Wetlands are a buffer for coastal areas, protecting them from waves and erosion, filtering out pollutants before they reach the oceans, serving as a breeding ground for fish and shellfish and providing habitats for birds and other animals. In particular, a large portion of the fish and shellfish eventually caught off the Northeast coast were hatched in estuaries and wetlands. These include lobsters, clams, scallops, menhaden, herring and some sharks. Similarly, bluefish and striped bass depend on wetlands for the smaller fish they eat.

Marshes can maintain their elevations if the sea level rise is gradual enough. If however the rise is too rapid, the marshes could be inundated, leaving formerly protected coastal areas vulnerable to flooding and erosion.

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