The earth’s climate is predicted to change because human activities are altering the chemical composition of the atmosphere through the buildup of greenhouse gases — primarily carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. The heat-trapping property of these greenhouse gases is undisputed. Although there is uncertainty about exactly how and when the earth’s climate will respond to enhanced concentrations of greenhouse gases, observations indicate that detectable changes are under way. There most likely will be increases in temperature and changes in precipitation, soil moisture, and sea level, which could have adverse effects on many ecological systems, as well as on human health and the economy.

The Climate System
Energy from the sun drives the earth's weather and climate. Atmospheric greenhouse gases (water vapor, carbon dioxide, and other gases) trap some of the energy from the sun, creating a natural greenhouse effect. Without this effect, temperatures would be much lower than they are now, and life as known today would not be possible. Instead, thanks to greenhouse gases, the earth's average temperature is a more hospitable 60°F. However, problems arise when the greenhouse effect is enhanced by human-generated emissions of greenhouse gases. Global warming would do more than add a few degrees to today's average temperatures. Cold spells still would occur in winter, but heat waves would be more common. Some places would be drier, others wetter. Perhaps more important, more precipitation may come in short, intense bursts (e.g., more than 2 inches of rain in a day), which could lead to more flooding. Sea levels would be higher than they would have been without global warming, although the actual changes may vary from place to place because coastal lands are themselves sinking or rising.

Over the last century, the average temperature in Amherst, MA has increased 2˚F, and precipitation has increased by up to 20% in many parts of the state (EPA, 1997). Over the next century, further change is predicted. The Intergovernmental Panel on Climate Change has used the climate model HadCM2 to project a temperature increase for Massachusetts of 4˚F  in the winter and spring of 2100 and 5˚F in the summer and fall. Climate change poses global risks to human and ecosystem health, as well as to sources of economic revenue such as agriculture, forestry, and fisheries. Below is an exploration of some of the potential impacts of climate change specific to Massachusetts.

Public Health

Temperature-related Illness
Over the past fifty years, heat stress days and nights have increased in Boston (PfSR, 2001). Hotter temperatures mean more cases of heat exhaustion, heat cramps, and heat stroke, as well as a higher death rate from other medical conditions. The sick, elderly, and young would be the most vulnerable. One study estimates for Boston that by 2050 heat-related deaths during a typical summer could increase 50%, bringing the total heat-related deaths per summer to over 150 (this does account fully account for increased air-conditioning however) (EPA, 1997).

Although overall winter temperatures in Massachusetts may rise, the frequency and intensity of storms may also increase, thus causing more winter days with extreme low temperatures. Extreme cold leads to increased cases of hypothermia and frostbite, while temperature fluctuations exacerbate pre-existing respiratory and heart problems.

Extreme Weather
Because greenhouse gases increase moisture in the atmosphere as well as heat, instability is created. This leads to more frequent and possibly more severe storms. Precipitation in Massachusetts is projected to increase by 10% in spring and summer, 15% in the fall, and 20-60% in the winter (PfSR, 2001). This could lead to more flooding. Flooding increases the risk of water contamination, gastrointestinal illnesses, and property damage. It can also result in cases of bacterial disease and respiratory problems, as well as fungal growth in homes (PfSR, 2001). Atmospheric instability could lead to more thunderstorms, tornadoes, hailstorms, and lightning strikes. The strong winds from storms could cause property damage, injuries and fatalities (PfSR, 2001).   

Air travel would also be affected by increased stormy weather. On February 25, 1999, Logan International Airport cancelled half of their 700 scheduled flights because of a storm that delivered 6.5 inches of snow (PfSR, 2001). Heavier snowfalls, flooding, and sea-level rise may require relocating runways and constructing barriers. Severe storm increase could necessitate relocating the entire airport, which is built on a landfill in Boston Harbor and only 17 ft above sea level (PfSR, 2001). 

Air Pollution
Volatile organic compounds (VOCs) are generated by power plants, waste combustors, motor vehicles, solvent use, and chemical and food industries; they are involved in the formation of ground-level ozone. Higher temperatures cause VOCs to evaporate and disperse more rapidly into the atmosphere, causing increased ozone formation. Some VOCs are also directly toxic; they are associated with cancer and adverse neurological, reproductive, and developmental effects (PfSR, 2001). Ground-level ozone contributes to asthma and other respiratory illnesses as well as eye irritation. It can also reduce crop yields and impair ecosystem health. Ozone concentrations in Massachusetts already exceed the national ozone health standards throughout the state.  

Warmer temperatures are cause for increased use of air-conditioning, which leads to increased power plant operations and emissions, including ozone precursors and other harmful pollutants. The extreme cold in winter caused by climate variability will prompt more oil and gas heating, which could increase atmospheric greenhouse gas concentrations in a vicious cycle. 

In 2001, a report by the U.S. Department of Agriculture concluded that an increase of carbon dioxide (CO₂) in the atmosphere results in increased pollen production of ragweed, a common allergen. They found that at carbon dioxide levels of 280 ppm (the atmospheric concentration in 1990) pollen production was 5.5 grams per plant. In today’s atmosphere of 370 ppm, pollen nearly doubled, reaching 10 grams. Pollen production doubled again when CO₂ concentrations were upped to 660 ppm (the amount in the atmosphere projected for 2050). Findings also showed that CO₂ could cause ragweed pollen production to begin earlier in the year. Earlier springs and warmer winters could also increase pollen count (PfSR, 2001).

Some scientists believe that rising temperatures will create favorable conditions for a wider variety of pollen producing plants, leading to increases of airborne pollen and spores that aggravate respiratory disease, asthma, and allergies. Humidity and floods also aggravate respiratory allergies (PfSR, 2001). 

Food and Water Diseases
Climate change may alter current water cycles, greatly affecting water supplies. Lower water tables may necessitate dredging, which could release toxins in the sediment. Disruptions in water supplies may have an impact on the spread of gastrointestinal diseases such as giardiasis and cryptosporidiosis, which annually affect many Massachusetts residents (PfSR, 2001). Warmer, moister weather encourages the growth of food contaminants such as E. coli, salmonella, Hepatitis A, listeria, shigella, cyclospora, and campylobacter (PfSR, 2001). These diseases contaminate water and also affect Massachusetts residents each year.

Warmer oceans may increase the occurrence and intensity of harmful algal blooms, also known as “red tides”. These blooms damage fish and shellfish nurseries, can carry cholera causing bacteria, and can be toxic to humans who consume shellfish. 

Insect-borne Disease
Global warming and other climate changes could expand the habitat and infectivity of disease carrying insects and rodents, such as mosquitoes and ticks. Incidents of Lyme disease, which is carried by ticks, have increased in the Northeast (EPA, 1997). Mosquitoes carry malaria, Eastern equine encephalitis and West Nile Virus, which has recently spread to Massachusetts (PfSR, 2001). If conditions in the state become warmer and wetter, mosquito and tick populations could increase, thereby increasing the residents’ risk of disease. 

Water Resources
Water supplies will be affected by changes in precipitation associated with climate change. Some areas may get more rain, while others receive less. Decreased precipitation may impair the ability of a local water supply to recharge. In one scenario for the Boston Metropolitan water supply, an annual precipitation decrease of 2% is estimated to reduce stream flows by 15% and the reliable water supply by 20% (EPA, 1995). Water management planning must assess the options available for replacing such great water loss. The capital cost of these options is estimated at $700 million (EPA, 1995). Warmer weather may also increase the rate of evapotranspiration and melt snow packs earlier, reducing available water supplies and reserves. 

Coastal Areas – Sea Level Rise
Global warming is causing Antarctic glaciers and ice shelves to melt and raise the height of the ocean. Sea level rise could lead to flooding of low-lying property, loss of coastal wetlands, erosion of beaches, saltwater contamination of drinking water, and decreased longevity of low-lying roads, causeways, and bridges (EPA, 1997). In addition, sea level rise could increase the vulnerability of coastal areas to storms and flooding.

The coast of Massachusetts is an important resource with over 1,500 miles of shoreline including stretches of rocky shore, barrier beaches, productive estuaries, fragile salt marshes, tidal flats, and dozens of islands (EPA, 1997). In Boston, sea level is already rising 11 inches per century, and it is likely to rise another 22 inches by 2100 (PfSR, 2001). Each year, an average of 65 acres of Massachusetts coastal upland is submerged by a combination of rising seas and subsiding land. This does not include land that has been lost because of erosion by storm waves or wetland erosion. Much of this loss occurs along the outer shore of Cape Cod and the islands of Nantucket and Martha’s Vineyard (EPA, 1997).

Possible responses to sea level rise include building walls to hold back the ocean water, allowing the sea to advance and adapting to it, and raising the land by replenishing beach sand or elevating houses and infrastructure. Each of these responses will be costly, both monetarily and in lost land and structures. It is estimated that the cumulative cost of sand replenishment to protect the coast of Massachusetts from a 20-inch sea level rise by 2100 is between $490 million and $2.6 billion (EPA, 1997).

Wildlife and Ecosystems
The coastal beaches and tidal marshes of Massachusetts are especially sensitive to the effects of sea level rise and changes in river flows. Sea level rise could inundate coastal wetlands, destroying the habitat of commercial and game species as well as migratory birds and other wildlife (EPA, 1997). Barrier beach island refuges such as the Monomoy National Wildlife Refuge south of Cape Cod and the Parker River National Wildlife Refuge in northeastern Massachusetts could be threatened or lost (EPA, 1997). These refuges provide important habitat for migratory birds, including the threatened piping plover and the endangered roseate tern. Harbor and gray seals, which use the beaches as refuge in the winter, could also lose habitat if sea levels rise (EPA, 1997).

Forests and woodlands support much of the wildlife in the state. Climate change could result in changes to these ecosystems, affecting the species diversity. Changes in rainfall and runoff could change sediment levels in streams and wetlands, thus affecting fish and aquatic habitats (EPA, 1997).

Agriculture
The type of crop and livestock production in a state is influenced by the climate and water availability. As the weather warms, production patterns could shift northward. Warmer climates and less soil moisture due to increased evaporation may increase the need for irrigation. Very little of the crop acreage in Massachusetts is currently irrigated, and warmer temperatures could stress the water supplies available, which are also needed by other sectors, such as natural ecosystems, urban populations, and industry (EPA, 1997).

Adaptation of farmers to climate variability must be a factor when analyzing the impact of climate change on agriculture. Most studies, however, have not accounted for this. Analyses that assume effective adaptation by farmers, suggest that regional changes in agriculture may be significant, but that overall U.S. food production would not be harmed (EPA, 1997).

In Massachusetts, agriculture is a $500 million annual industry, three-fourths of which comes from crops (EPA, 1997). The major crops in the state are silage, hay, and potatoes. It is uncertain how climate change will affect crop yields, but it could cause them to fall by as much as 45% (EPA, 1997). Decreased yields may lead to an increase in farmed acreage in order to raise production.

Forestry
Trees and forests are adapted to specific climate conditions. As climate warms, forests will change. These changes could include changes in species, forest extent and location, and health and productivity; significant change could happen in less than a century (EPA, 1997). If conditions become drier, forests could be reduced and replaced by grasslands and pasture. In a warmer and wetter climate, trees that are more tolerant of higher temperatures, such as oaks and pines, could infringe upon the currently Maple-dominated hard-wood forests, potentially creating a denser forest. This change would diminish the brilliant autumn foliage as the number of maple trees declines, as well as the economically viable production of maple syrup. Across the state, as much as 30-60% of the hardwood forests could be replaced by warmer climate forests with a mix of pines and hardwoods (EPA, 1997).

Fisheries
Massachusetts fisheries are the most valuable fisheries in New England, mainly due to lobster catch (PfSR, 2001). In 1996, lobsters accounted for 25% of all Northeast fishing revenue and were valued at 242 million dollars, supporting 50,000 jobs (PfSR, 2001).

Global warming could have a devastating impact on lobsters, fish, and other aquatic organisms. The water may become too warm and the chemical composition of the water may be changed, causing the dissolved oxygen levels to decrease while pollution and salt levels increase. Declining shrimp populations, as well as the deaths of sea urchins; sea cucumbers; crabs; worms; and sponges off the coast of Maine, show evidence that these conditions may be prevailing in New England (PfSR, 2001). This is a concern because of the economic and psychological stress on the fishing industry, as well as the increased risk of disease from human consumption of contaminated seafood.

References

City of Medford. Climate Action Plan. October 2001.

City of Portland & Multnomah County. Local Action Plan on Global Warming. April 2001.

Environmental Protection Agency, U.S. “Climate Change and the Massachusetts”.  

September 1997. Available at http://yosemite.epa.gov/oar/globalwarming.nsf/ UniqueKeyLookup/SHSU5BUSRR/$File/ma_impct.pd

Environmental Protection Agency, U.S. “Climate Change and the Boston Area Water Supply”. May 1995. Available at http://yosemite.epa.gov/oar/globalwarming.nsf/content/Resource

CenterPublicationsBoston_h2o.html

International Council for Local Environmental Initiatives (ICLEI): U.S. Cities for Climate Protection Campaign. http://www.iclei.org/us/ccp/ Accessed 2003.

Physicians for Social Responsibility. Death by degrees: the health threats of climate change in Massachusetts. Washington, D.C. 2001.

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