The State of Global Climate Change in Maine 2004

Brendan J. Carroll


Global Climate Change: The Issue in Context


Global climate change, popularly known as “global warming,” has the potential to greatly impact the natural environment and human society in many significant ways. In the last two hundred years, both global temperatures and atmospheric concentrations of greenhouse gases have accelerated, compared to rates observed on a geologic timeframe10-12. While a growing body of scientific consensus has determined that changes in the climate system are unmistakably human in origin, a great deal of uncertainty still exists as to the extent of future changes and impacts. The high profile of the science and its dire implications have caught the attention of policymakers the world over. An international strategy to address the issue has been in the works for over ten years, although the perceived high costs of policy changes have stalled these efforts. Still, governments at all levels, businesses, and other organizations around the world have enacted substantive climate policies.

            The basic science behind global climate change involves many complex interactions among the chemicals and energy of the sun, the earth, and its atmosphere10-14. Solar radiation travels towards the earth, some is reflected immediately upon reaching the atmosphere, and the remainder passes through. This energy is then absorbed into the climate system – by the oceans, land, and biota, which re-emit the energy. Some of this passes through the atmosphere but some is absorbed by the atmosphere. Since more energy penetrates the atmosphere than passes out of the atmosphere, a natural “greenhouse effect” heats the earth. The gases in the earth’s atmosphere that trap this energy are known as greenhouse gases, and include water vapor, carbon dioxide, methane, nitrous oxides, and several chemically complex gases. Without this natural greenhouse effect, the earth would be at least 33˚C cooler.

While this natural greenhouse effect is necessary for life on earth as we know it today, a growing consensus among scientists has shown that human activities since the industrial revolution have resulted in an increased greenhouse effect10-14. An international body of climate experts, the Intergovernmental Panel on Climate Change (IPCC), has synthesized this consensus into three scientific assessment reports, each with more detailed and certain conclusions and predictions10-12. According to the IPCC, human activities emit greenhouse gases that have raised atmospheric concentrations of carbon dioxide by 31 percent over the 20th century. While concentrations of other greenhouse gases have changed as well, carbon dioxide stays in the atmosphere for tens to hundreds of years, thus impacting the climate system long after its associated human activity has emitted the gas. This increased greenhouse effect has led to a rise of 0.6ْC in the global mean temperature in the 20th century. The increase has not been evenly distributed around the world. The latest scientific assessment report has indicated that this relatively rapid change in the climate system is caused by greenhouse gases released from human activities, and all major scientific studies and reviews have validated this point11,13,14.

            Predicting the future is no easy task for any scientific assessment. The large amount of uncertainty regarding feedback effects, nonlinearity, complex interactions, and human societal changes make predicting future scenarios for human-induced climate change particularly problematic11,13,14. The IPCC predicts a further rise in mean temperature between 1.4 and 5.8˚C. While the estimates and predictions of the IPCC are accepted by the vast majority of climate scientists, a small but vocal minority of climate skeptics present different models for the future, based on different scenarios for growth in emissions and the notion of a robust rather than fragile world15,16.

            The impacts from this changing climate are likely to be very severe and widespread, impacting virtually all human and natural systems, according to the IPCC and other scientific reviews13,14,17,18. Higher average temperatures that expand the volume of the world’s oceans along with melting polar ice will accelerate natural sea level rise. The IPCC predicts a sea level rise of between 0.09 and 0.88 meters by the end of the next century. Low-lying islands and coastal countries, as well as coastal communities, are particularly at risk from higher sea levels. Millions of people likely will be displaced by the end of the next century18. Other significant impacts of a changing global climate are likely to include droughts, increased frequency and severity of weather events, and extinction or migration for many vulnerable species18-21. Fears of abrupt climate change, resulting from such possible events as a breakdown in the North Atlantic Oscillation, a sea temperature and salinity dependent system that determines weather in the North Atlantic, have aroused the attention of scientists outside of the IPCC14,22.

            Growth in human activities such as transportation and consumption, as well as growth in human population will determine how much climate will change11,13,14. The IPCC estimates that three quarters of anthropogenic emissions of greenhouse gases stem from fossil fuel combustion. The burning of fossil fuels to create energy to power our cars, appliances, machines, and virtually everything that runs on electricity has become a necessary part of the modern life. This is particularly true for the United States, the single largest emitter of greenhouse gases, whose carbon dioxide emissions account for twenty-five percent of the world’s total23. If fossil fuel consumption continues to rise, climate change will continue to accelerate. Consequently, any policy designed to seriously limit future impacts on the global climate system will involve changes in the way society generates energy24,25. Such policies will require shifts toward renewable energy sources in addition to reductions in energy use.

            The transportation sector is one of the largest and fastest growing sources of greenhouse gas emissions worldwide. The sector accounts for 20 percent of the world’s carbon dioxide emissions, and a large share of its emissions of nitrous oxides and other greenhouse gases26. Light truck and automobile transportation accounts for 50 percent of all transportation emissions26. Since the oil crisis of the 1970s, considerable fuel efficiency gains have led to reductions in emissions of carbon dioxide per vehicle, but these improvements have not kept up with rapid growth in vehicle transport. In only fifty years, the global fleet increased from 46 million vehicles at the end of World War II to 641 million in 199626. US total and per capita fuel consumption from transportation exceeds that of any other nation, as total travel activity in the US is larger than other nations, and US vehicles are much more fuel intensive27. Consequently, many local, national, and international policies aimed at reducing greenhouse gas emissions focus on the transportation sector.

Historical Context

            Scientists associate rising carbon dioxide and other greenhouse gas emissions with changes in human activities over the past two-hundred years11. Since the industrial revolution of the late 18th century, humans have generated millions of tons of carbon dioxide through combustion of fossil fuels. Since then, technology has allowed greater productivity and higher living standards for the countries that industrialized rapidly. This revolution required coal, oil, and other carbon-intensive inputs to fuel production. As a result, atmospheric concentrations of greenhouse gases have increased18.


Recent Issues

The increasing awareness by scientists and policymakers of climate change as a serious issue has generated an international dialogue aimed at mitigating this threat to our climatic system26,28-30. In 1992, heads of state and environmental ministers from around the world gathered at an environmental summit in Rio de Janeiro, Brazil, drafting the first international treaty aimed at addressing the threat of global climate change31. The United Nations Framework Convention on Climate Change (UNFCCC), ratified by virtually all nations, became the framework through which further policy dialogues would take place. A major component of this framework treaty required that all parties to the convention submit national inventories of emissions. The framework set a goal of reducing emissions to a level that would not be harmful for future generations, but did not set a timetable and so this goal has neither been met nor even credibly attempted by policy measures in most countries28,29.

            Five years later the parties to the Convention met in Kyoto, Japan to draft a Protocol to the convention that would set emissions targets and timetables32. They set a goal to reduce world greenhouse gas emissions by 8 percent from 1990 levels, by the first commitment period of 2008 to 2012, to be shared among all countries that ratified the treaty. For some countries, particularly the former communist states of Eastern Europe, this meant an increase in emissions, as emissions there have decreased significantly since 1990. For others, such as the United States, this meant a substantial decrease in emissions. Legislators and policymakers in the US deemed this too costly for the US economy, and so the US has refused to ratify the treaty33. Some contend a new approach to international climate agreements is necessary to lead to a stabilization of atmospheric greenhouse gas concentrations through inclusion of the US34-36.

With ratification by Russia, the Kyoto Protocol will go into effect in February of 2005, binding countries representing only 62 percent of the world’s total emissions to emissions reductions in the next ten years37. Developing countries were exempt from reductions in this round of negotiations in order to promote economic development, despite their growing share of the world’s emissions. As a result, rising emissions in both the US and developing countries will undermine the success of the Kyoto Protocol in achieving its goal of lowering atmospheric concentrations of greenhouse gases.

            The US has remained a part of the Kyoto process only as an observer since 2002. The predicted costs to the US economy were judged by the federal government as too high to offset the benefits38. Other analysts argue that these benefits (i.e., the future costs of inaction) were underestimated, and the costs were not easily understood, and hence overestimated33. Since then, climate change policy has taken a more voluntary form in the US39,40. Businesses have engaged in voluntary emissions trading schemes to reduce their emissions, with tax credits and other incentives provided by the federal government39.

At the regional, state, and local levels, innovative voluntary initiatives have set targets and policies for reducing emissions41,42. Twenty-eight states and Puerto Rico have created policies to reduce emissions in sectors over which these states have significant authority, including taxation, land-use, utilities, and transportation40. Some of these efforts comprehensively address climate change, as exemplified by the Climate Action Plans of Maine and Connecticut. Other initiatives, such as the California auto emissions standards, are more narrowly focused. Many initiatives will have additional benefits, including cleaner air and lower energy costs40. Although still in their infancy, if these initiatives are carried out to their targets, many greenhouse gas producing activities in the US will be under emissions limitations.


Global Climate Change: The Issue in Maine


Global climate change will leave no area unchanged. In Maine, where so much identity and so many livelihoods are strongly tied to the natural world, this global issue has already impacted human and natural systems. Recent estimates of future climate change predict even more visible and devastating effects on the state43. Early recognition of the need to address this problem has generated a noteworthy local policy response to a problem of global origins. While Maine cannot single handedly prevent further degradation of its environment by climate change, lessons from its groundbreaking approach can inform policymakers everywhere.

Maine’s traditional ties to its coasts, weather, and wildlife make its people vulnerable to stresses in the natural world. Current computer simulation models used to predict future climatic changes cannot easily predict impacts at such small scale as Maine itself or even New England. However, from what broad changes scientists can estimate from larger scale models, many predicted changes will have spillover effects on Maine’s economy and identity44. Many of these changes will be both costly and irreversible.

            Maine’s most noteworthy geographic feature, its coastline of 3,000 miles, traces a line through many of the state’s communities, is responsible for millions of dollars of Maine’s economy, and provides immeasurable symbolic value to the state. Thermal expansion of the world’s oceans, resulting from rising sea temperatures, coupled with melting polar ice caps, are predicted to raise sea levels significantly by the end of this century18. People who live along Maine’s coastline will witness the encroachment of the sea on their communities. Although scientists have been unable to predict the exact extent of this sea level rise, the EPA estimates that a 14-inch rise in Rockland and a 19-inch rise in Portland are both likely by the end of this century43,45. The increased frequency and severity of storm events will magnify the effects of a rising sea, as flooding and storm surges will be more frequent and devastating. Although seaside communities will have a limited ability to adapt to these conditions, vulnerable coastal wetlands will face even greater difficulty in surviving. In the Casco and Saco Bay areas, 10 to 20 percent of local wetlands are likely to be lost under widely accepted scenarios46.

            The cost of sea level rise to these coastal communities is significant. A 20-inch rise, well within scientists’ estimates for the next century, would flood 80 acres of land in Old Orchard Beach, where out-of-state tourists and Maine resident vacationers inject money into the local economy every summer46. In some areas, where expensive beachfront property already clings precipitously to the land, coastal erosion and storm surges may plunge hundreds of homes into the rising sea in the next hundred years. The cost of insuring coastal property has doubled since the 1970s; one study estimates that 286 million dollars of Maine’s insurance costs in the 1990s were weather-related47. In addition to residential areas, public infrastructure such as sewage treatment plants and underground storage tanks are also at risk from flooding.

            Further inland, changes in the nature and timing of Maine’s weather will impact natural systems throughout the state. Although scientists have been unable to predict with certainty future changes in the amount of precipitation the state receives, a recent study by the US Geological Survey (USGS) has shown evidence that over the past century, Maine’s precipitation has turned increasingly from snow to rain43,44,48. Throughout the past century, the ice-out dates for many rivers and lakes throughout the state have occurred earlier and earlier in the season, and river ice thickness has been decreasing49,50. Additional, unpredicted changes are also likely to occur.


Historical Context

Fossil fuel combustion, and hence carbon dioxide emissions, became a part of Maine’s economy more slowly than in the rest of New England. Traditionally, and still to a greater extent than anywhere else in New England, water has provided Maine’s power. When steam power generated from oil or coal reached the industrial cities of southern New England in the 1820s, the high cost of transporting the fuel to Maine and Maine’s abundant water power kept fossil fuel power from Maine for decades51. These sources of power became more widely used when electricity came to Maine in 188051.

            On the other hand, fossil fuel use in the transportation sector has played a major role in Maine since the first steam-powered railroads laid their tracks in the 1830s52. By 1912, over 2,000 miles of track crisscrossed the state, carrying passengers and cargo from York to Aroostook52. The railroad gave way to the automobile in the early 20th century. The opening of the Maine Turnpike, from Kittery to Portland in 1947 and then to Augusta in 1955 spurred rapid growth in automobile use in Maine53. Highway accessibility led to a huge expansion of Maine’s tourism industry, solidifying the “Vacationland” image for vacationers from southern New England and New York.

Recent Issues

Policymakers in the New England and in Maine in particular have responded quickly to the rising evidence of climatic changes to their natural systems. Soon after countries created the United Nations Framework Convention on Climate Change of 1992, policymakers in the state and region were considering how the policy tools within their jurisdiction could be used to address the problem. In 1993, Dean Marriott, then Maine Department of Environmental Protection Commissioner, commented on the need for Maine to form its own climate change policies, given the impacts likely to be felt by Maine’s environment and people54.

From the beginning of the 1990s, scientific and policy collaboration among the six New England states (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont), and the five eastern Canadian provinces (New Brunswick, Newfoundland and Labrador, Nova Scotia, Prince Edward Island, and Quebec) generated a uniquely regional yet international approach to addressing a global problem55. The Conference of New England Governors and Eastern Canadian Premiers (NEG/ECP), recognized their similar vulnerabilities to climate change and their interdependence through trade, transport, energy, and electricity generation. These provinces and states committed themselves in 2001 to a plan to reduce greenhouse gas emissions by specified targets with short, medium and long-run timetables56.

In order to fulfill its commitments under the NEG/ECP Plan, Maine passed a landmark bill, the Act to Provide Leadership in Addressing the Threat of Climate Change, which required the state to draft a climate change action plan by July of 2004 that will reduce greenhouse gas emissions to 1990 levels by 2010, with further reduction targets for 2020 and the long-term57. The bill is the first of its kind in the nation. Drafting the plan required the Maine Department of Environmental Protection (DEP) to work with other state agencies, industry, non-governmental organizations, and individuals. This stakeholder process occurred throughout 2004, and the governor released the plan in December of that year.

The plan has been intensely debated among state agencies, businesses, and citizen organizations. Lack of consensus in several of the five working groups – buildings, facilities and manufacturing; agriculture and forestry; transportation and land use; energy and solid waste; and education/public awareness – has slowed the process. Environmental organizations have resisted industry efforts to compromise the ability of the plan to generate sound policies that will actually reduce greenhouse gas emissions.

The possible policy outcomes from the transportation and land-use working group are the most debated, and noteworthy possibilities from the entire Maine climate process. Emissions from mobile sources (transportation emissions) comprised the largest share of the state’s carbon dioxide emissions, representing 40 to 50 percent of emissions of this largest greenhouse gas emitted by the state, and are also one of the fastest growing sources4. The policy under consideration in 2004 was to adopt the same standards that the California Air Resources Board, the state agency responsible for air quality standards in that state, will adopt58. These “Pavley” standards require significant reductions in greenhouse gas emissions, including carbon dioxide, from passenger vehicles and light trucks. The Plan included these standards, but the legislature makes the final decision as to whether they become law59.

Strong opposition by the automobile industry has slowed California’s adoption of its standards, and strong opposition by the industry and by auto sellers in Maine has heightened the debate in the Maine climate action stakeholder process. If California, Maine, and other states are able to follow through with this bold attempt at transportation regulation, significant reductions in greenhouse gas emissions in these areas will be possible60,61. Although these standards are only one of the many policy responses that came from the stakeholder process, they will likely have the greatest spillover effects throughout the nation, as automakers are likely to adopt this single standard to reduce costs associated with facing multiple standards, as has previously occurred with auto emissions standards in Europe.

            By itself, Maine’s policy responses will be unable to reverse the trends in climatic change throughout Maine’s environment. But, some of these policy responses will have positive benefits for Maine citizens, through cleaner air and lower utility bills, regardless of their impact on reducing climate change. Maine will also be setting a precedent for other states and the federal government, which have not addressed climate change with a comprehensive target-setting response. The success Maine has in addressing greenhouse gas emissions and other causes of climate change will provide lessons for policymakers throughout the world on the ability of local responses to a changing climate.


Indicators, Policy, and Analysis


Many activities occurring in Maine, including transportation, building heating, electricity generation, and forestry practices, contribute to climate change by releasing greenhouse gases62. Trends in the transportation sector are one of the most relevant and noteworthy for policymakers. These emissions account for a large and still growing portion of the state’s total. The following indicators describe the state of greenhouse gas emissions from the transportation sector in Maine. Consumption of motor gasoline in the transportation sector comprises the majority of Maine’s transportation emissions. Thus, this is a useful indicator of Maine’s total greenhouse gas emissions.

            I used four indicators to evaluate the transportation emissions in Maine. One indicator measures the outcome - increased fuel consumption as a proxy for greenhouse gas emissions. Three indicators – vehicle miles traveled, number of registered vehicles, and the percent of the workforce that drives to work alone - measure potential drivers influencing the problem. The indicators express states and trends as per capita consumption or percentages to facilitate comparison between Maine and the national average.

            Policymakers have historically focused largely on the composition of vehicles registered. Different vehicles require different amounts of fuel to travel a given distance; hence they vary in the amount of carbon dioxide they emit per mile. A major within the transportation sector is whether or not to require vehicles to meet emissions standards, and if so, what these standards should be. In general, vehicles classified as trucks emit more greenhouse gases per mile traveled than do regular automobiles63. Because these indicators examine factors in addition to the composition of vehicles registered, they will illuminate potential shortfalls of focusing primarily on this policy device.


Transportation Carbon Dioxide Emissions in Maine

            In Maine, the greatest contributor to climate change is carbon dioxide emissions from the combustion of fossil fuels in the transportation sector. In 1999, the most recent year for which emissions data has been published, carbon dioxide accounts for 93 percent of Maine’s total greenhouse gas emissions (in terms of carbon dioxide equivalents – a way of standardizing these gases by their greenhouse effect potential) 11. Methane and nitrous oxide comprised the remaining 7 percent. Fossil fuel combustion in the transportation, commercial, residential, industrial, and utility sectors are primarily responsible for these carbon dioxide emissions (Figure 1). According to the US Environmental Protection Agency (EPA), the transportation sector accounts for 45 percent of Maine’s fossil-fuel combustion-related carbon dioxide emissions. Other major sources include residential and industrial emissions.

From 1990 to 1999, transportation emissions exceeded industrial and residential emissions, the second and third largest sources during this period (Figure 2). Industrial emissions approached transportation emissions in the mid-1990s but decreased in importance by 1999. Meanwhile, residential emissions (produced from the burning of oil and natural gas to heat homes) increased by 54 percent. Although these sectors are important, the transportation sector is still the largest source of emissions, and changes in driving habits and vehicle choices can have major impacts on Maine’s total greenhouse gas emissions.


The following indicators do not address all emissions from the transportation sector. Instead, I considered only emissions generated through the combustion of motor gasoline (non-diesel fuel used to power automobiles and light trucks) the largest portion of transportation emissions. Other sources of CO2 from transportation include combustion of jet fuel, residual fuel, and distillate fuel (which includes all diesel from the transportation sector, including military, marine, and railroad)64. Emissions from the motor gasoline subcomponent of the transportation sector exceed total emissions from any other sector (Figure 1). The indicators also focus on this subcomponent because it is relevant to a greater portion of Maine’s population, as motor gasoline consumption is more directly related to personal travel.


Indicator 1: Motor Gasoline Consumption in Maine

Maine: 15.7 barrels per person per year               US: 13.9 barrels per person per year


Figure 3 shows changes in annual motor gasoline consumption per person in Maine, from 1970 to 2000. I developed this indicator by dividing a portion of the population in 2000 by the motor gasoline consumption in Maine during that year. Motor gasoline consumption data, measured in thousands of barrels per year, was obtained from the Energy Information Administration (EIA) of the US Department of Energy (USDOE)1. Population data came from the US Census Bureau’s annual estimate of state populations. I used only the portion of the population over the age of fifteen to represent the population of Maine that drives7-9. The population over 16 would be a closer approximation because citizens can obtain driver’s licenses at that age, but the US Census Bureau only publishes annual population estimates in five-year age categories.

Average per capita motor gasoline consumption in Maine is 13 percent higher than the nationwide value. There are several explanations for this difference. First, because Maine is a rural state, its citizens face, on average, longer driving distances, including distances to work and other leisure activities. Second, Maine’s small population and small urban population (relative to urban populations in other states and the US as a whole) make large-scale public transportation less cost-effective. Also, Maine’s weather, marked by more snow and ice than most of the US, induces a greater share of the population to choose light trucks or sturdier, less fuel efficient cars, as their primary vehicles. Each of these explanations will be explored further in the indicators that follow.

Consumption of motor gasoline by volume from the transportation sector is used as a proxy for emissions of carbon dioxide from this source, since no long-term comprehensive inventory of greenhouse gas emissions at the state level yet exists. Fuel consumption data obtained from EIA, on the other hand, stretches back as early as 1960. Fuel consumption is a good approximation of carbon dioxide emissions from this sector because any fuel consumed by vehicles will release carbon dioxide emissions related to the carbon content of that fuel. Although the carbon content of motor gasoline varies from year to year, this variation is small enough to make little difference in the amount of carbon dioxide emitted for each barrel of fuel consumed65.

From 1960 to 2000, total motor gasoline consumption in Maine nearly doubled (Figure 4). Consumption did not increase uniformly, however, as consumption in from 1979 to 1980 witnessed a sudden drop, while nearly ten years later consumption rose to a short-lived peak. This non-uniformity results from national and world events that affected the price of oil (motor gasoline is a derivative of oil). One major oil shock occurred in 1973, as OPEC nations cut supplies to the US and other Western nations. Fuel consumption in Maine did not immediately respond to this shock, however. In the short run, people are less likely to change their driving habits or switch to more fuel efficient vehicles. Consequently, people paid a higher price to maintain their transportation activities, but as time passed, and more fuel efficient vehicles emerged, fuel consumption decreased dramatically.

Motor gasoline consumption per capita increased by only three percent between 1970 and 2000 (Figure 3). In the 1980s and 1990s, however, motor gasoline consumption per capita was as low as 17 percent below that of 2000 in the 1980s, and 9 percent below motor gasoline consumption per capita of 2000 in the 1990s. Two explanations for the similarity of the early value of the indicator and the current value of the indicator are changes in fuel efficiency and changes in total travel. Since the 1970s, fuel efficiency in the US has improved dramatically for all vehicles; fuel efficiency in Maine, has almost certainly followed that trend27. Although fuel efficiency is much higher now than in 1970, miles traveled (which will be examined later) have increased considerably.


Indicator 2: Vehicles in Maine

Maine: 1.69 vehicles per household                     US: 1.72 vehicles per household


            The second indicator measures vehicles registered in Maine as a function of the number of households. The US Census Bureau’s Census Transportation Planning Package (CTTP) calculates this value based on the number of households in the state, obtained from the 2000 Census, and the number of registered vehicles, obtained from the Maine Department of Transportation (MEDOT)6. In contrast to the previous indicator, the basic unit of comparison is the household, rather than total population. Generally, households own vehicles, so changes in the number of households will change the total number of vehicles registered.

Households in Maine on average own only two percent fewer vehicles than households nationally. One explanation for the slightly smaller value for Maine relates to income. Income (measured in Gross State Product per capita) is smaller in Maine than in the US by 23 percent66. A lower average income for Maine likely means that citizens in Maine cannot buy as many vehicles as the average US citizen. On the other hand, one might expect a higher value for Maine as less public transportation options are available than in the US as a whole.

Between 1960 and 1973 (the year in which the oil shock occurred), motor gasoline consumption correlated closely with the number of registered vehicles (Figure 5). The vehicles people drove mostly had similar fuel efficiencies. As people owned more vehicles, fuel consumption increased at a constant rate. After 1973, a weaker correlation exists. People switched to more fuel efficient vehicles, but the switch was not uniform. Since then, the range of fuel efficiency for vehicles in the US is broader 63 . Consequently, vehicle registration data alone cannot explain the relationship between vehicles and motor gasoline consumption in Maine between 1974 and 2000. The increasing popularity of less fuel efficient pickup trucks and SUVs in the 1990s and 2000s throughout the US further complicates this relationship.

In Maine, truck registrations increased relative to automobile registrations from 1985 to 2000, reflecting the nationwide popularity of sport utility vehicles (SUVs) and pickup trucks (Figure 6). Before 1985, personal passenger vans, mini-vans, and utility-type vehicles were classified as automobiles. From 1985 onwards, these vehicles classified as trucks. Vehicles currently classified as trucks (particularly SUVs and mini-vans) used by individuals in a non-commercial or non-industrial fashion did not become widely used until after 1985. Although vehicles registered in Maine continue to be predominately automobiles, trucks have increased as a proportion of total vehicles since 1985, while automobiles registrations have slightly decreased. In 1985, trucks represented 30 percent of vehicle registrations; by 2000 this had increased to 40 percent.

            The increasing popularity of trucks relative to automobiles has received considerable attention from policymakers in Maine and elsewhere. Policies proposed in Maine and elsewhere to cut greenhouse gas emissions mandate more fuel efficient vehicles. Less fuel efficient vehicles are now more popular relative to vehicles with greater fuel efficiency than they were in 1985. Consequently, fuel use is greater than it would have been had trucks maintained their smaller relative popularity. On the other hand, policymakers should not overstate the importance of this trend. The next indicator shows that fuel efficiency is not the only major driver of increasing motor gasoline consumption in Maine.


Indicator 3: Travel in Maine

Maine: 13,736 miles per person per year              US: 12,433 miles per person per year


            The third indicator measures total travel in Maine, in annual vehicle miles traveled (VMT) per capita. Vehicle miles traveled are the total miles traveled by every vehicle in the state for a given period of time. I obtained these data from the Federal Highway Administration (FHWA) of the US Department of Transportation (USDOT)2. As in Indicator 1, the portion of the population I used includes only individuals over the age of fifteen.

The rise in VMT in the 1980s (Figure 7) partly explains the rise in fuel consumption during this period. Total vehicle miles traveled increased throughout the period for which data are available (1970-2000), but witnessed its fastest increase between 1983 and 1989, when total miles traveled increased by 54 percent in just six years2. This period coincided with the same years that total fuel consumption witnessed a significant increase.

As with overall fuel consumption, VMT per capita in Maine is higher than that of the US. As noted above, the rural character of Maine requires people to drive further on average. Large scale public transportation does not exist in Maine, so most citizens have no other option but to drive to work. Maine’s higher VMT per over-fifteen capita might also relate to the importance of tourism in the state. Thousands of tourists drive long distances in Maine to reach out of the way places such as Acadia National Park, Baxter State Park, or Sugarloaf USA. Vehicle miles traveled data do not differentiate between residents and visitors, so part of the increase in travel reflects increases in the number of visitors.

            Total travel is quickly becoming a significant driver for fuel consumption in Maine. While fuel consumption per capita increased very little from 1970 to 2000, VMT per capita increased by 81 percent in this period (Figure 7). This indicator is still increasing, so over time it will likely have a greater effect on overall fuel consumption.

            Significant variations in vehicle miles traveled within the state have still greater implications for overall fuel consumption (and hence contribution to climate change from this sector). I obtained countywide vehicle miles traveled data from the Maine Department of Transportation and annual population estimates for each county from the US Census Bureau. The age category for countywide includes people over sixteen (rather than over fifteen) years of age population (

). As a result, VMT per capita indicators for each county are lower than the corresponding indicator presented at the state and national level above.


            Table 1 and Figure 8 show that Maine’s larger counties tend to have high vehicle miles traveled per capita. As with Maine itself, larger, more rural areas such as Aroostook, Washington, or Somerset counties require longer distances to get from place to place. For their size, other counties also have large values as well. Cumberland, Sagadahoc, and York have high values relative to their size. This is even more important than the larger values for Maine’s larger, rural counties, as Maine’s population shifts out of these areas into the southern counties.

            Policymakers in Maine and throughout the nation have generally avoided regulating vehicle miles traveled. The freedom to travel is regarded by many as a freedom not to be meddled with. Evidence in Maine shows, however, that closer attention should be paid to vehicle miles traveled, as it has increased dramatically in recent years, and continues to increase. Similarly, if places such as Cumberland or York County have high levels of VMT per capita, and large populations, then incentives for public transportation or carpooling should be provided.

Indicator 4: “Drive Alone” Rates

Maine: 80.0% drive alone            US: 76.31% drive alone


            The percentage of the workforce that drives to work alone (the “drive alone rate”) reflects culture and attitudes as well as incentives and disincentives present or not present for carpooling. I obtained these values from the National Household Travel Survey of the USDOT’s Bureau of Transportation Statistics (BTS), and it provides some insight into vehicle miles traveled in Maine examined in Indicator 33.

“Drive alone” rates increased everywhere in the US between 1990 and 2000, including in Maine. During the same period, the state witnessed an increase in vehicle miles traveled as well, although not as large as in the previous decade. Since more people are driving alone in Maine than in the US as whole, total miles traveled per person are consequently larger in Maine. In 2000, New York had the lowest percentage of commuters driving alone (after the District of Columbia), and Alabama had the highest. Of the fifty states, Maine had the nineteenth highest “drive alone” rate.

Incentives can influence driving rates. The Capitol building in Augusta is an excellent example of such a policy device – better parking spots are offered to government workers that carpool. In New York, public transportation has likely kept New York’s drive alone rates low, but incentives for carpooling and disincentives for driving have also probably played a role. While public transportation on a scale equivalent to New York’s is impossible in Maine, incentives for carpooling should be explored as a policy option. Disincentives, such as traffic jams or low availability of parking are not appropriate policy measures. Where disincentives already exist, however, the state should consider how removal of these disincentives might lead to more vehicle miles traveled and hence more fuel consumption in the state. For example, the widening of I-95 in southern Maine will reduce congestion on that primary artery of the state, therefore making the costs of driving to work alone lower.


Policy Recommendations

            In order for Maine to effectively address its contribution to global climate change, serious policy measures are needed to address Maine’s rising emissions of carbon dioxide from the transportation sector, particularly the motor gasoline portion of that sector, which is mainly related to personal and business transportation. These emissions make up the largest portion of Maine’s carbon dioxide emissions from fossil fuel combustion. From an examination of motor gasoline consumed in the state, it is clear that these emissions are rising, both in total and per capita. Consequently, policymakers should address all drivers of these emissions.

            Emissions standards for vehicles, currently the most strongly advocated policy response to Maine’s rising carbon emissions, should not be the only type of policy used to address these emissions. While evidence shows that purchases of trucks are on the rise in Maine, fuel efficiency data on such a scale is unavailable. If anything the data above only understates the potential for emissions reductions possible in Maine through fuel efficiency gains. Although emissions reductions may be significant from these proposed policies, they can only carry the state to a certain point, as factors other than the types of vehicles driven in Maine also play an important role in determining Maine’s emissions from this sector. From a broader perspective, however, if enough states act as Maine might in requiring the same progressive emissions standards that California will soon require, the necessary response by automakers might have positive implications that will stretch across the nation.

            Any gains Maine makes through requiring vehicles to emit less greenhouse gases may be offset by the continued increase in total and per capita vehicle miles traveled within the state. Although miles traveled per capita in Maine will likely remain larger than other states, as Maine is a rural state, the increasing trend in per capita miles traveled should be reversed. A large percent of Maine workers drive to work alone. In response, policymakers should stress incentives for carpooling or public transportation. Preferential parking for ridesharing at state government buildings is an excellent start, but if businesses have no incentives for following the government’s lead, this incentive will have a smaller impact. Park and ride programs near Maine’s urban centers, particularly Portland, if made significantly more affordable than driving alone to work any day, could encourage fewer workers to drive alone in all businesses. Regardless of the method, Maine must consider growth in total travel within the state if its contribution to climate change is to be reduced. Emissions reductions in the transportation sector should be coupled with reductions in the other major sectors as well.




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