u.s. Population, Energy & Climate Change

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1 / U.S. Population and Climate Change, www.cepnet.org

Center for

Environment &

Population

U.S. POPULATION,

ENERGY &CLIMATE CHANGE


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U.S. PoPUlation,

EnErgy& ClimatE ChangE

Center for

Environment &

Population

By Victoria D. Markham


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About This Report

This report is the rst in a series opublications on U.S. Population, Energy andClimate Changeby the Center or Environ-ment and Population (CEP). The seriescontains brie, easy-to-read reports, act

sheets, and brieng materials on populationand climate change trends in the U.S. andglobally. Activities are also being conductedto integrate the inormation into U.S. policyand public action at the local, national andinternational levels.

For more inormation contact:

Victoria D. Markham, DirectorCenter or Environment and Population (CEP)161 Cherry Street, New Canaan, CT 06840

Phone: 203-966-3425Fax: 203-966-5443Email: [email protected]: www.cepnet.org

Acknowledgements

Special thanks to Kara DiFrancesco and MercedesBravo who contributed to the research and writing o thisreport, and to Martha Farnsworth Riche, Brian ONeill andNadia Steinzor or their expertise and insights. The Centeror Environment and Population (CEP) is grateul to theCompton Foundation, Richard and Rhoda Goldman Fund,

New-Land Foundation, Wallace Global Fund, WinslowFoundation, and an anonymous donor or their invaluablesupport o this project.

Center or Environment and Population(CEP)

The Center or Environment and Population (CEP)is a non-prot research, policy, and public advocacyorganization that addresses the relationship betweenhuman population and its environmental impacts. TheCenter works to strengthen the scientic basis o policiesand public outreach to achieve a long-term sustainable

balance between people and the natural environment inthe U.S. and globally.CEP links science to policy, public education, and

advocacy to better understand and address the issues.To do this, the Center: compiles and assesses the bestavailable current knowledge and emerging trends on theissues; produces easy to understand science-based ma-terials or policymakers and the public, and; undertakesactivities to integrate the inormation directly into policiesand public outreach. The Centers work ocuses on theU.S. populations environmental impact in the nation, andwithin the global context.

The Center has two major program areas: Emerging

Issues in Environment and Population and BuildingNew Population-Environment Leadership. CEPproduces unique, cutting-edge reports and briengmaterials including the U.S. National Report on Populationand the Environment, U.S. State Reports, the Issueson Population & the Environmentseries, and theAAAS

Atlas o Population and Environment(all available onlineatwww.cepnet.org). Activities are also undertaken toincorporate the inormation into policy and publicoutreach. The Center engages leading organizations,scientists, and other experts as partners in its eorts.CEP is a project o the Tides Center, and works in theU.S. (rom the local community to national level) and

internationally.

2008 Center or Environment and Population (CEP).

All rights reserved.


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Acknowledgements...................................................................................................... 2

Introduction................................................................................................................... 4

U.S. Population and Climate Change Prole

The Issues

l U.S. Population Factors, Energy Use, and Climate Change...................................... 6

The Eects

lAltered Weather, Rising Sea Levels, Freshwater, Biodiversity, Human Health......... 8

In More Detail

lMetropolitanization, Land Use, Households.............................................................. 9lPopulation and the Coasts.......................................................................................... 12lClimate Change and Population: Eects and Impacts.............................................. 14

In Your Region: U.S. Population and Climate Change

lNortheast, Midwest, South and West......................................................................... 19

Conclusion..................................................................................................................... 21

Endnotes........................................................................................................................ 24

Contents

U.S. Population, Energy & Climate Change


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W

There is growing evidence that population, linked to energy use and greenhouse gas

emissions, is a key actor in global climatic change.1 In the climate change equation,

population is the big multiplier particularly when linked with resource consumption

because it intensies the rate, scale, and scope o both the root causes and eects o

climate change in the United States (U.S.), and worldwide.

ithin the global context, the U.S. standsout or two reasons: it has by ar thelargest population amongst other industrial-

ized nations, the onlysizable one withsignicantpopulation growth, and; it uses more energythan anyother country and is the largest carbon dioxide(CO

2)

greenhouse gas emitteramongst industrialized nationsworldwide.2

This unique combination Americas high popula-

tion numbers and growth, together with its high rates oper capita energy consumption and pollution makesthe U.S. pivotal in the national and global population-climate change debate.

In simple terms, the U.S. is the worlds largestdeveloped nation, consumes energy and resources atvery high rates, and is growing rapidly. This has majorimplications or global climate change because theAmerican populations energy consuming habits are sodisproportionate to that o other nations. While the U.S.represents about5% o the global population, it consumesabout 25% o the worlds energy, and generates 5 times

the world average o CO2

emissions. Because Americans

are high resource consumers in a country with alarge, rapidly growing population base, the U.S.

has a much bigger per-person impact on global

climate change than any other nation. With about8,000 people added daily in the U.S., and 3 millionpeople added each year, theres real potential to reach1 billion high-energy-consuming Americans by 2100.Meeting the energy demands o this large and rapidlygrowing population that consumes elevated levels oresources and energy while at the same time reducingthe greenhouse gas emissions contributing to climatechange will prove daunting in the coming decades.Even now we are seeing its eects.

The relationship between U.S. population trendsand global climate changeis characterized byseveralkey elements. These include U.S. demographicactors relatively high population numbers and rapidgrowth; high and increasing density in coastal andmetropolitan areas; an increase in energy-consuminghouseholds, and; a large Baby Boomer population coupled with high per-capita energy use, ossil uelburning, land and vehicle use. These are all linked, and

their unique combination makes the U.S. one o the

worlds most important players in population and climate

change.

While the U.S. population and climate changeconnection is complex, it maniests itsel in two primaryways:

l rst, population is related to the causes oclimate change, mainly through high per capitaenergy use and greenhouse gas emissions (the

carbon ootprint) and;l second, population actors can exacerbate

climate changes eects by placing more pressureson the natural resource base at specic sites, orexample, when there is high population density andcontinued rapid growth in coastal, urban, suburban,or ecologically vulnerable areas o the U.S.

In addition, gains made in addressing climate changecan be made much more dicult in some cases evenoset altogether by these population actors, whencombined with high per capita natural resourceconsumption.

IntroduCtIon

U.S.-WORLD POPULATION & CLIMATE CHANGE

United States World Europe DevelopingCountries

Source: US Census Bureau, US Energy Information Administration,

World Resources Institute, 2008

Population

Energy Consumption

COEmissions

Energy consumption in total kilograms of oil equivalent (Kgoe),

and CO2

emissions in metric tons, per person.


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IntroduCtIon

The most recent scientic data reveals the answer,showing that thelinks between population and climatechange are particularly acute when you look at the U.S.

case within the global arena. In short, while America hasabout 1/20th o the worlds population, it consumes about

1/4th o the worlds energy.11 And, Americansproducealmost 20 tons o CO

2per person per year aboutve

times the world average o 4 tons o CO2per person a

year, and also substantially larger than 8 tons o CO2per

person per year or Europeans, and 2 tons or develop-ing countries.12

These trends in U.S. population, energy consump-tion, and CO

2emissions are expected to continue, and

even rise, in the oreseeable uture. The U.S. populationis expected to double in one generation, by 2076, andeven reach 1 billion in some o our lietimes.13 On the

energy side, while U.S. greenhouse gas emissions roseabout 15% rom 1990 to 2006,14 by 2020 they are pre-dicted to increase by nearly 30% under a business asusual scenario.15

Taking into account how climate change works as

a global commons, where the planets air and emissions

over a specic location, like the U.S., typically move hal-

way around the world a week later Americas unique

population and energy prole place it ront and center

in relation to the worlds climatic changes.16

We oten see population growth and climate

change as being separate, rather than making the

connection between the two and this is particularly true

in the U.S. The issues are, however, inextricably linkedand must be understood and addressed at the same time,

as they relate to one another, as two sides o the same

coin. This science-based report helps to make thatconnection, providing the basic inormation needed tobetter understand these issues, and to take rst steps toeectively address them, as they are associated. It can beused as a tool to demonstrate how U.S. population andresource consumption trends are linked to climaticchange, in the U.S. and globally.

Americas Role in Global Climate Change

The worlds leading scientists agree that unprec-edented changes to the climate o the U.S. and the planetare underway, due in large part to human-inducedactors.3 Over the past ve decades humans have playedthedominant role in the worlds changing climate, mainlythrough the generation o greenhouse gases like carbondioxide (CO

2), with metropolitanization (metro area and

suburban growth) and land use changes also playing animportant part.4

The eectso climate change are elt both worldwideand here in the nation. Globally, the 11 warmest years onrecord have all occurred in the past 13 years,5 and 2006was the U.S. warmest year on record.6 Average annual

U.S. temperatures are over two degrees Fahrenheit higherthan a century ago.7 There is increased requency osevere weather events (such as rainstorms, heat wavesand hurricanes), and major shits in U.S. growing seasonsand in the ranges o plant and animal species. Climaticchange is causing the spread o vector-borne diseasesrarely seen in the U.S., such as malaria and dengueever.8 The nations reshwater resources are more proneto drought and the consequences o less mountain snowpack. Glaciers are retreating, sea ice is melting, and sealevel is rising.9

Yet, how is the U.S. population its growth, density,movement, composition and per-person natural resource

consumption connected to climate change in thecountry, and globally?Today 98% o the worlds popula-tion growth is in developing countries, a growth trendthat is expected to continue well into this century.10 Withmost population growth occurring in other parts o theworld, why ocus on the U.S.? And why is America inthe hot seat o population-climate change impacts

worldwide?

Population

CO2

Emissions

1950 1970 1990 2010 2030

Energy Consumption

Source: US Census Bureau, US EIA, WRI, 2008

Projections based on mid-range data estimates.

CO2

emissions in metric tons, and energy consumption

in Btus, per person.

............................

.............................

U.S. POPULATION,

CO2

EMISSIONS, & ENERGY CONSUMPTION

PER CAPITA


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summary

U.S. contributions to climate change are associated with human population through a

combination o actors, including: the number o people and rate o population growth;

where and how they live and consume natural resources, and; energy consumption

patterns and type o energy used to meet the demand.

These actors when taken individually may havesmall impacts, however, when combined as theyare in the U.S., contribute signicantly to theworlds climate change causes and eects. To understandhow population aects climate change, it is critical tograsp whichkey U.S. population and energy/resource-use actors are involved:

U.S. Population Factors Linked to

Climate ChangeThe our population actors in the U.S. most

closely associated with climate change include:

lPopulation size and growth rate

lPopulation density:where the U.S. populationlives (Metropolitan areas, Coast, South and West

regions)

lPer capita resource use: how the U.S. population

lives(Land use, Vehicles, Households)lPopulationcomposition(Age, Baby Boomers,

Income)

Population size and growth rate: the U.S. has byar the largest population amongst industrialized nationsin the world17 it is the third most populous country inthe world ater China (1.3 billion) and India (1.1 billion) and is the only large developed nation experiencing

signicant population growth.18 The U.S. population hasmore than doubled since 1950, and will double again in70 years.19 Today the U.S. is home to over 304 millionpeople; this number is expected to reach 400 million by2043, with potential to reach the billion mark this cen-tury.20 This is important because it shows the U.S. has arelatively high number o people, with rapid growth thatis expected to continue throughout this century, and high

levels o per capita energy, land and orest consumption all o which are closely linked to climate change.

Population density(where the population is

distributed and growing) and per capita resource use

(how the U.S. population lives) on a day-to-day basis arelinked to climate change because, these actors:a) intensiy land use changes that directly aect climatechange; b) increase per-capita energy use (i.e. house-holds and transportation) or each persons carbon oot-print; c) transorm carbon sinks into carbon sources,and; d) create heat islands. Key issues include:

n Metropolitanization, or, the growth in cit-ies and surrounding suburban areas, characterizesthe nations population growth trends consistentlyover the past century. By 2000, hal o all Americanslived in suburban areas, and 4 out o 5 lived in

broader metropolitan areas.21 Most important withregard to the population and climate change linkis that growth outside cities in the suburban andsurrounding exurban areas ar outpaces growth

within cities. As a result o this trend, land in theU.S. is converted or development at about twicethe rate o population growth22, and each Americaneectively occupies 20% more developed land (orhousing, schools, shopping, roads, and other uses)than he/she did 20 years ago.23 This is importantin this context because the wayland is most otendeveloped today in the U.S. to accommodate mucho the growth is through sprawl development.This is characterized by spread-out rather than clus-tered residential and commercial land development,and is the nations most predominant orm o landuse change today. It results in a marked increase in

vehicle use and road systems, and in a rise in thenumber and energy-consumption level o households all associated with high levels o energy use and

ossil uel burning. It also leads to rapid loss oorest and agricultural land which would otherwiseact as carbon sinks (see page 9).

n Households(and what is used within them)is a key demographic actor in the rise o U.S. per

capita energy use and climate change. In recentdecades there has been a major increase in: thenumbero households(with ewer people per houseand the number o second homes on the rise);

house size(square ootage), and; amount o landaround each. Each o these actors translate intomore energy use and CO

2emissions per person.

Also, wherethe households are placed (in sprawl-ing rather than clustered communities) and amounto energy used in each residenceare key.24The U.S.residential sector is the largest such energy use

sector worldwide, and household appliances(rerigerators, microwaves, dishwashers, air condi-tioning and heating units) are the astest grow-ing energy consumers nationwide, ater cars.25


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summary

In developed nations like the U.S., home appliancesnow consume 30% o all electricity used, emitting12% o global greenhouse gases.26 By 2015 house-

hold energy use is expected to rise by 15%.27

n Densely populated U.S. coasts is a key actorin relation to climatic change because more peopleare susceptible to the eectso climate change there.Over hal (53%) o all U.S. residents now live within

50 miles o the coast on just 17% o the nationstotal land area where they are most vulnerable to

sea level rise and the severe weather events (such as

hurricanes and fooding) associated with climate

change.28 Population density on U.S. coasts is vetimes that o other parts o the country.29 An addi-tional 27 million people, accounting or about hal

o the projected overall U.S. population increase, areexpected to move to the coastal areas in the next 15years alone.30 And, over 80 million people annuallyvisit the coast or recreation, temporarily yet signi-cantly swelling coastal populations and pressures onthe areas natural resources.31

n The South and West are the nations most heav-ily populated and astest growing regions they nowcontain over hal (59%) o the entire U.S. population and these trends are expected to continue in com-ing decades. The South and West are among the na-tions population-climate change hotspotsbecause

o their combination o population numbers andgrowth, andecological vulnerabilities (as associatedwith the coastal areas o the South and reshwaterresources in the West). For example, o the nationstop ten astest growing states, hal are in the coastalSouth, and our are in the arid West both areas oexceptional ecological sensitivity to climate changeimpacts o sea level rise and altered temperaturesthat aect reshwater sources.32 (See In YourRegion, pages 19-20).

Population composition: The make-up o a

population (i.e., its age or income) oten determineswhere and how people live, move, vacation and con-sume resources and energy and these are all linked toclimate change. For example:

nThe nations Baby Boomers, the largest evero this particular U.S. demographic (26% o the totalU.S. population) are wealthier, spend more money,drive more vehicles and miles, have more homes per-capita including second homes, and use more energy

per capita than any generation beore them.33

nThe youth o Americas population is criticalbecause they represent a large demographic whom in a departure rom generations beore them aremaking key personal choices regarding resourceand energy consumption andamily size, taking intoconsideration climate change impacts and overallenvironmental sustainability.

nIncome is closely associated with energyconsumption and pollution in the U.S. Statisticsshow that generally the more afuent a person is,the more resource and energy consumption andpollution they are responsible or. For example, inAmerica, rising income generally results in a greaternumber o larger houses, more vehicle use and avia-tion travel, and, the associated increase in ossil uelburning and CO

2emissions. U.S. per capita income

is nearly $40,000 in contrast to $26,000 or other

developed nations, and $4,000 or less developednations. On the fip side, afuence can acilitatepositive trends in that it makes the typically moreexpensive energy-ecient technologies (i.e. hybridvehicles and appliances) more accessible, but onlyto those who can aord them.

For more details on this Summary, see page 9.

AMERICAS GROWING CARBON FOOTPRINT

Acarbon footprint is a measure of

the impact that human activities

have on the environment in terms of

greenhouse gases produced, measured in

units of carbon dioxide (CO). It is used to

conceptualize impact in contributing to

climate change. Experts say Americas carbon

footprint is expanding, and that with a

growing population and expanding economy,

Americas settlement area is widening.

As it does, Americans are driving more,

building more, consuming more energy,

and emitting more carbon.

Sources:Weidmann & Minx, 2008; Brookings Institution,2008.


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summary

U.S. Energy Use, Population, andClimate Change

There are two main actors that link U.S.

energy issues to population and climate change:

lThe nations energy use, relative to its

population size

lThe greenhouse gas carbon dioxide (CO2)

emissions, per capita

These energy issues are important in this contextbecause the U.S. is the single largest carbon dioxide(CO

2) emitter o the industrialized nations in the

world, accounting or nearly a quarter o all globalemissions.34 These are predicted to increase by 30% by2020.35 With about 5% o the global population, the

U.S. consumes approximately 25% o the worldsenergy.36The nation has the highest oil consumptionworldwide, and is projected to use 43% more oil thancurrent levels by 2025.The U.S. residential sectoris thelargest single consumer o that particulartype o energy use worldwide, with American homesgenerating 25% o global home-related greenhouse gas

emissions.37 The commercial and transportationsectors are projected to be the astest growing U.S.

energy use sectors rom 2005 to 2030, with 1.4% and

0.7% annual growth, respectively.

38

This has majorimplications or uture increases in ossil uel burningand CO

2emissions.

The Eects: Climate Change andPopulation

An important link between population and

climate change is rom climate changes effects,

i.e., through increased severity and requency o

major storms, sea level rise, or increased droughts

which are all occurring in some of the most

heavily populated and fastest growing areas in

the U.S. (such as the coasts, and the South and

West regions). The main eects include:

l altered weather and seasonal patternsl rising sea levels

l less available reshwater

l habitat and biodiversity loss

l human health threats

These are all occurring at present to varying degrees,and are predicted to continue or the oreseeable utureunder a business as usual scenario. For example, theaveragetemperature increase in the U.S. over thenext 100 years is predicted to be 5-9oF.39 Temperature

increases by 2100 are predicted to vary by region andseason, with a 4-5oF average increase across the North-east and Midwest, a slightly lower 3-4oF average increasein much o the South and West, and the greatest warm-ing, 10oF in winter, predicted or Alaska.40Sea level riseand more severe weather events that will impact theheavily populated coastal areas are predicted, particularlyin the U.S. Mid-Atlantic and Gul Coasts. Freshwaterresources in the U.S., especially throughout the West,are being severely aected by climate change-drivendrought and reduction o mountain ice pack. Ecologicaland biodiversitychanges triggered by climate changecould render 15-37% o all sampled plant and animal

species extinct by 2050, both worldwide and in the U.S.41

For more details on this Summary, see page 14.

U.S. ENERGY USEBY SECTOR, 2006

Other Transportation

5%

Residential

15%

Commercial

11%

Industrial

34%

Highway

Transportation

31%

Air Transportation

4%

Source: US EIA, 2008.


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In more detaIl

Population and Energy-Use FactorsLinked to Climate Change

Metropolitanization and Land Use

Americas current population growth, movement anddistribution, andthe manner in which people consumeland, have created undamental changes in how landhas been used in the nation today. This is particularlytrue in recent decades, and as such has contributed toclimate change uniquely occurring in our lietimes. Thetype oland use change that is central here is directlylinked to growth trends in the nations metropolitanareas (a result o the nations century-long movementrom being primarily rural to urban and suburban), and,the subsequent development that has taken place orresidential, commercial, and related inrastructure. Thismetropolitanizationo the nation is characterized

by the expansion o cities and suburbs outwards, and the

subsequent loss o armland, orests, prairies, wetlands,

natural coastal areas, and the remaining open spaces.42

Americas land-use changes rom population

growth and associated development result in three

main trends that have signicant consequences, allof which are closely associated with climate change:

l Sprawl development

l Increase in vehicle use and road systems

l Increase in number and energy consumption

o households

Sprawl Development

Much o the nations land conversion or develop-

ment in the past ew decades (or residential and related

services) has triggered an entire set o unique land use

patterns, called sprawl. This expansive developmentgenerally occurs around city and town centers, and intosurrounding neighborhoods and rural areas. The amounto land utilized or these sprawling metropolitan areashas increased aster than their populations are growing.Nationwide, during the 1980s and 1990s population grewby 17%, yet the amount o developed land grew 47%.43By 2030, hal o the buildings in which we live, work,and shop will have been built ater 2000.44

Sprawl is characterized by high amounts o land

development per unit o human activity. It is refected inlow-density residential subdivisions, commercial strips,

large retail complexes surrounded by acres o parking,oce parks ar rom homes and shops, and a growingnetwork o roads linking them together. This type o

development oten spurs everyday activities that arelinked to global warming, including:

increasesinpercapitavehicleuseandmilestraveled, because o the large area that sprawlingcommunities cover

relativelyhighenergyuseandfossilfuelburning rom increased use o vehicles and rommore, larger, homes to maintain, heat and cool

openland/spacedevelopmentforresidentialand

other inrastructurehighlevelsoftrafccongestion45

Sprawl development involves the conversion o

all types o land, including terrestrial and aquatic eco-systems (such as orests and wetlands), and armland.Many o these land uses prior to the development areconsidered carbon sinks because theynaturally soakup more carbon than they emit. Such carbon sinks helpregulate CO

2, the main greenhouse gas contributing to

climate change. However, when these lands are devel-oped, not only are the areas that ormerlystoredcarbon (such as the orests) eliminated, but they alsotend to be replaced with land uses (such as roads,parking lots, suburban residential areas) that contribute

In this section, the main U.S. population, energy use and climate change actors

are described in more detail.

U.S. POPULATION & URBANIZATION

60

50

40

30

20

10

0

Northeast Midwest South West

Source: Fulton, W., et al, Who Sprawls Most? How Growth Patterns

Differ Across the US, 1982-97. Brookings Institution, 2001

Population Growth

Land Urbanized


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to or become carbon sources, or net emitters ogreenhouse gases into the atmosphere. This is a goodexample o how the U.S. populations demand or land

to support growth scenario plays out across the nation,and is a key part o the climate change equation.

Another key actor is how densely populated andast growing U.S. metropolitan areas contribute to climatechange by increasing their heat island eect wheretemperatures in urban and suburban areas are 2 to 10oFhotter than nearby rural areas.46 The heat island eectresults rom several actors, including: displacing treesand vegetation whose shade and evaporation rates havenatural cooling abilities; the trapping o heat betweentall buildings and narrow streets that reduce air fow, and;the addition o waste heat rom vehicles, actories andair conditioners into the surrounding air. The elevated

temperatures oten increase peak energy demand or airconditioning, which in turn causes more burning o ossiluels that contribute to climate change, and exacerbatesheat-related illnesses and mortality.47

Increase in Vehicle Use and Road Systems

The U.S. populations shit into suburban and exur-

ban areas has created modern land use changes that by

nature require more vehicle use and increased amounts

o construction and land transormed to build new

highways, roads, and parking lots. Over 81,000 miles ohighway have been built rom 1995-2004, bringing thetotal to more than 4 million miles.48

In more detaIl

More vehicles are on the road, and the amount oAmericans driving time has increased at a rapid rate. Thenumber o vehicle miles traveled rose by nearly 2.5%

annually during the 1990s (with a marked increase in thenal years o the decade), reaching nearly 3 trillion milesannually or the nation as a whole by 2000.49And, theaverage miles traveled (and ossil uels burned) is grow-

ing aster than the population: rom 1995-2004 when the

U.S. population grew by less than 10%, the transportation

miles traveled by Americans increased by 23%.50

With more people taking more and longer trips aspart o daily lie, and, a growing number o cars on theroad, congestion has also increased. The average U.S.traveler now spends 47 hours each year stuck in tracdelays during rush hour, compared to just 16 hours twodecades ago. There are also now ten times more urbanareas (51) with more than 20 hours o annual rush hourdelays.51

Looking at the environmental impacts, these trends

have contributed to increased ossil uel combustion, andhigher greenhouse gas emissions. The transportationsectoruses 15% more energy today primarily rom

petroleum than it did a decade ago.52 It now accounts

or one-third o all U.S. carbon dioxide (CO2) emissions.53

This refects an annual increase o over 2% during the1990s.54 Most (41%) o the CO

2emissions created by the

transportation sector are emitted rom the miles Ameri-cans travel on highways.55 In addition, an estimated 2.3billion gallons o uel are wasted every year rom idlingin trac, nearly 80% more than in the early 1990s.56

U.S. VEHICLE USE

3,000,000,000

2,500,000,000

2,000,000,000

1,500,000,000

1,000,000,000

500,000,000

0

25,000,000

20,000,000

15,000,000

10,000,000

5,000,000

0

Source: APTA & FHWA, 2008

Vehicle Miles Traveled

Transit Boardings

Miles(inthousands)

Boardings

Temperature

URBAN HEAT ISLAND EFFECT

Rural

Suburban

Residential

Commercial

Downtown

Source: US Environmental Protection Agency, 2008


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In more detaIl

Gasoline price rises are due in part to increaseddemand or oil and a reduction in stocks, as well asdisruptions in supply, such as the damages caused by

storms such as Hurricane Katrina and Rita in the year2005. Although high gas and oil prices may lead to adecrease in miles driven and a shit towards moreecient orms o transportation, they can also pose athreat to passing climate change legislation whichwould urther increase gas prices.

Even the U.S. populations increasing use o air travelis related to climate change. In the last decade, the totalmiles traveled by U.S. aircrats has increased 40%, and by2025 U.S. air trac is expected to rise by 60%. In addi-tion to producing signicant greenhouse gases, scientistssay that the impact o carbon emissions rom airplanes inthe upper atmosphere is amplied and at least twice as

harmul to the environment as those on sea level. 57

VEHICLE OWNERSHIPBY COUNTRY

140 million

120 million

100 million

80 million

60 million

40 million

20 million

1 million

Source: International Road Federation, 2008

U.S. (2005) Japan (2006) China (2005) India (2003)

Increase in Number andEnergy Consumption o Households

Households, and the resources and energyAmericans consume to support them, is an important

demographic variable in calculating populations

climate change linkages.

Every household has a minimum number opossessions, occupies a certain amount o space, andemits certain waste and/or pollutants. However, theextent o environmental stress, including climate change,that is linked to households depends on three mainactors: household size (the number o people withina given household)/number o households;size ohomes (square ootage o a house), and; the amounto land surrounding and used to build homes.

In recent decades, while the average U.S. house-hold size has decreased, the number o households hasincreased signicantly, and the amount o living space

in and around homes has risen. The number o peopleper household was 2.6 people in 2000, down rom 3.1 in1970 (or one ewer person or every two households),58and as a result, the number o households has increasedmarkedly. In 2000, there were nearly 14 million morehousing units nationwide than a decade earlier.59 Be-tween 1970 and 2000, average household size declinedrom 3.1 to 2.6 persons (one ewer person or every twohouseholds), resulting in demand or new housing unitsin addition to that already needed to keep pace withpopulation growth.60Smaller household size in the aceo population growth is one reason behind a nationwide

building boom: between 2000 and 2006, 10 million

new housing units were built.61 In addition, the numbero second homes is at an all time high: second homeownership increased rom 5,537,000 units to 6,489,000units, a 17% increase or 2.7% annual increase rom1999 to 2005.62

The averagesize o new, single-amily homes hasexpanded steadily, reaching more than 2,300 square eetby 2004. Nearly 40% o new single-amily homes areover 2,400 square eet, double the proportion in 1987.63

With more people living in super-sized houses thatoccupy more land, the amount o resources (rom lumberto plastic) used or new construction is rapidly on the rise,

and more energy is consumed or heating and cooling

(thus more ossil uels burned). With many houses builtin new sprawling communities rather than clustered orcity-based development that oten uses existing oot-prints to build new homes development begins romscratch, and there is higher resource use, and ragmen-tation o open space. Data shows that increases in theaverage lot sizes, on which new houses are built, are


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In more detaIl

prevalent in many suburban areas.64 About 55% oarmland developed since 1994 has gone to housesbuilt on lots ten acres or larger.65 More than 3,000

square miles o land is converted annually to residentialdevelopment over one acre in size.66Energy use within each household is also a key

population-climate change link.The U.S. residen-

tial sector is the largest o that energy use sector

worldwide, and household appliances are the

astest growing energy consumers nationwide.67

GROWTHIN U.S. HOUSEHOLDS

Source: US Census Bureau, 2008

U.S. Energy Consumption by Income Level

and Square Feet of Household

Household income level Square feet of home Energy consumption ofhousehold (million Btus)

$15,000 - $19,999 1,500 81

$30,000 - $39,999 1,700 87

$75,000 - $99,999 2,700 113

$100,000 or more 3,400 136

Source: US Energy Information Administration, 2008

Population and the U.S. Coasts

One key link between population and climate change

in the U.S. is the high concentration o Americans who

live and recreate in coastal areas, because it meansmore people are then vulnerable to theeffects o climate

change (such as sea level rise and strong weather events

like storms).68 Over hal (53%) o all Americans now livewithin 50 miles o the U.S. coasts. An additional 27 mil-lion people (accounting or about hal o the projectedU.S. population increase) are expected to move therein the next 15 years alone, and, there are higher growthrates on the coasts than the inland areas o the U.S.69 Asa result,the U.S. coastal zone represents a hot spotor population and climate change vulnerability.70

The coastal vulnerabilities associated with climate

change include sea level rise, shoreline erosion, food-

ing, coastal storms, and degradation o coral rees and

marine ecosystem health.71 These all, in turn, aect the

dense and ast growing coastal populations in the orm

o health, accessibility and availability, and property. Iglobal warming continues as it is, major coastal urban/metropolitan areas built near sea level (including NewYork, Boston, Washington DC and Miami) will be at riskrom the expected sea level rise o 18-20 inches abovecurrent levels by 2100 (see box, page 13). Low lyinginrastructure in these areas such as buildings, roads,power lines, airports, trains and subway systems aresubject to fooding. Where land is already sinking (such

as along the Gul Coast including New Orleans, LA andGalveston, TX) sea level rise will likely be aster. Recre-ational areas enjoyed by millions, including New Jerseyand Caliornia beaches, Long Island and the Hamptons,Cape Cod, Nantucket, North Carolina and Floridas GoldCoast will be subject to beach erosion.72


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Experts now say that even i storm intensity andrequency associated with climate change does notincrease, the expected growth and density in the U.S.

coastal population, in combination with its associatedland development and the anticipated increase in

fooding rom sea level rise, will undoubtedly cause

property losses to increase.73

Population Composition: Age and Income

The composition o a population its age, income,

educational level, culture/race, and other characteris-

tics can determine where and how people live, move,

vacation, and develop land. Many o these demographicactors can be linked to climate change.

Age is a prime example o how demographic actors

can have major implications or climate change in the

U.S., and it applies to both the younger and older seg-

ments o the population.

Youth are key in the population and climate

change equation. The young demographic in thenation today aged 0-24 is about 35%, and those aged24-44 are an additional 30%.74 This large segment o theAmerican population is critical because they are uniquely

In more detaIl

positioned to make key choices that will aect thenations uture with regard to climate change, and variouspopulation actors. Their choices with regard to ertility

(how many children they decide to have) and resourceand energy consumption (including energy, vehicle,transportation and land use, recycling, etc) are key.The decisions they make both individually, collectively asconsumers, in academia, research, business and industry,and, as voters at the local to national levels, will all deter-mine trends in population and climate change through-out this century.

Baby Boomers are a key demographic or

resource and energy consumption. The trend towardsaging o the U.S. population as the proportion o olderpeople increases is also signicant in relation to climate

change. Todays older population is larger than it hasever been in the nations history, and the overall medianage in 2000 (35.3 years) was also higher than it has everbeen.75

This segment o the population, the nations BabyBoomers(born between 1946 and 1964), represent over78 million or 26% o the total U.S. population.76 They arewealthier, spend more money, consume more resources

including energy, have more homes per capita, and move

more oten than any generation beore them.77Thisis important because they represent both a large

percent o the total American population andhigh

energy consumption, the combination o which is

signicant in terms o climate and environmentalimpact.

In addition, a substantial share o Americas popula-tion age 65 and older moves to and settles in retirementmagnet states such as Arizona, Florida, and Nevada,where pressure on natural resources (especially water),and high energy demand, is already evident. Over thenext quarter century, the proportion o elderly Americansis projected to double in at least 14 states in the coastalSouth and arid West.78

Incomeis critical to resource and energy use

becauseresource and energy consumption is oten associ-ated with level o income, or afuence.Evidence showsthat as a whole, those more afuent in the populationconsume more energy resources and generate morewaste and pollution than do lower-income populations.

The median household income in the U.S. was about$44,000 in 2004.79 In international dollars America has aper capita income o nearly $40,000, compared to about$26,000 or more developed countries, $4,000 or devel-oping countries, and $9,000 globally.80

U.S. COASTAL METRO AREAS

MOST AFFECTEDBY SEA LEVEL RISE

Moderately Eroding

Severely Eroding

New York

Boston

Washington DC

Miami

New Orleans

Source: US Global Change Research Program, 2008

The US coastal areas most vulnerable to future sea level

rise are those with low relief which are already experiencing

rapid erosion rates, from the Northeast to the Gulf Coast.


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In more detaIl

In America, rising income generally brings aboutgreater motor vehicle use, resulting in more road-building, air pollution, and the CO

2emissions that cause

climate change. And, relative to their share o worldpopulation, Americans consume disproportionatelyhigh amounts o meat and dairy products, whichrequire more land, water, and energy (and producemore wastes) compared to diets based on grains andvegetables.81

On the fip side, however, afuence can acilitate

positive trends by encouraging the consumption o goods

that are environmentally sound. People with higherlevels o disposable income are oten more inclinedto purchase more expensive, energy ecient hybridvehicles, appliances, and lighting, and to purchasehigher priced yet more energy-ecient solar powered

panels, recycled paper, organic oods, and otherenvironmentally-riendly products as they are generallynot yet priced or mass consumption at all incomelevels.

Climate Change and Population:Eects and Impacts

The relationship between population and climatechange is very complex, however, in simple terms: theU.S. population contributes both to thecauses o climate

change(through, or example, accumulated land usechanges, high per capita energy use and greenhouse

gas emissions), and its effects (where, or example,there are large and/or rapidly growing populationconcentrations in areas that are particularly vulnerableto the eects o climate change such as the coastalor arid areas o the U.S.).

This section describes the major environmen-

tal and health related eects relating to climate

change with regard to its population linkages.

They include:

laltered weather and seasonal patternslhabitat and biodiversity loss

lrising sea levels

l

less available reshwaterlhuman health threats

Climate Changein alaska

The state o Alaska is experiencing some

o the most proound climate change impacts

now occurring in the nation. Permarost thawing

is causing the ground to subside 16-33 eet

in parts o interior Alaska, and the permarost

surace has warmed by about 3.5 oF since

the 1960s. Summer days without snow have

increased rom ewer than 80 in the 1950s to

more than 100 in the 1990s. Sea-ice extent has

shrunk by about 5% over the past 40 years, and

the area covered by sea ice declined by about

6% rom 1978 to 1995. A study o 67 glaciers

shows that between the mid-1950s and mid-

1990s the glaciers thinned by an average oabout 1.6 eet per year, and the rate o thinning

had increased to nearly 6 eet more recently.

The states annual average temperatures have

warmed up to 1.8 oF per decade over the last

three decades, and winter warming has been

as high as 3 oF per decade.

The consequences o global warming or

wildlie species will be severe. An example

is the polar bear, which has been placed on

the U.S. Endangered Species List. It has been

designated by the U.S. Interior Department as

threatened with extinction because o shrinking

sea ice,making it the frst creature added tothe endangered species list primarily because

o global warming.Experts say that two-thirds

o the polar bears habitat may disappear by

2050. Polar bears are dependent on hunting

ringed seals and other prey rom sea ice. They

are so unsuccessul on land that they spend

their summers asting, losing more than 2

pounds a day. This orced ast is now about

three weeks longer than it was 30 years ago.

This gives the bears less time to hunt and build

up the at reserves they need to survive until

ice re-orms in the all and they can resume

hunting. As bears have become thinner, thereproductive rates o emales and survival rates

o cubs have declined. As Arctic ice breaks

up earlier and earlier, bears now come ashore

roughly 22 lbs. lighter and in poorer condition.

The bears reduced body condition can lead to

lower reproduction rates, which in the long run

could lead to local extinction.102


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Altered Weather and Seasonal Patterns

A main impact o climate change is seen in altered

weather and seasonal patterns throughout the U.S.Some o these changes are with us today, and othersare predicted by experts to occur in the uture, depend-ing on population actors linked to peoples energy andresource consumption, and whether or not greenhousegases continue to be generated in a business as usualscenario.

One o the weather-related changes now occurring

and expected to continue is an altered water cycle result-

ing rom higher atmospheric temperatures.82 With highertemperatures, more precipitation will all as rain, andless as snow. Both reduced snow pack and earlier snow-melt could reduce river and stream fow in the spring

and summer, times when supplies are needed most,particularly or irrigation.83 In some parts o the country,such as in the West and parts o New England, snowalready remains on the ground or a shorter time thanin past decades.84 (See page 17).

Greater fuctuation in precipitation also contributesto a wider disparity between wet and dry seasons, mak-ing planning or water supplies and use more dicult.Although overall precipitation is predicted to increase inarid states, decreases in summer months are also likely.85Similarly, extreme weather events would be morecommon. Higher temperatures and more rain alling onsnow would result in rapid thawing, which in turn could

spur fash foods as water rushes into rivers and streamsor across dry land.86

Nationwide, more rain can increase pollutant runorom agricultural elds and pavement in urban areasinto water systems, a signicant problem today. Highertemperatures could be exacerbated as pavement orroads, parking lots, and residential and commercial areas(which retain and radiate heat more than natural areas)spreads along with development and population growth.Reduced ice cover will mean that more heat will beabsorbed rather than refected by land and water. Warm,wet conditions also oster carriers or vectors (such as

mosquitoes) that spread diseases like West Nile virus,

malaria, and dengue ever.87 (See box, page 18).Rises in ood prices are partly brought about by

climate change because it hampers agriculturalproduction through altered weather patterns and recorddroughts around the world, including the U.S. South andSouthwest. In addition, increased ood demand rom agrowing population, increased gas prices, and increasedspeculative demand or biouels whose crops are beingplanting in place o staples such as rice, wheat, and cornhave all driven up the price o ood.

Habitat and Biodiversity Loss

The main cause o biodiversity loss in the U.S. ishabitat loss rom land use changes or rapidly occur-ring, widespread development across the country,extraction o energy resources, and other means. Theseare all linked to increases in population numbers and

peoples consumption o land and other resources. Most(85%) o the species known to be at risk or extinctionin the U.S. are rom habitat loss and alteration.88

Climate change is already having many impacts on

the biological diversity o plant and animal species in the

U.S.Among them is its eect on the composition andrange o the nations orests.An increase o 2oF over aperiod o 100 years, well within the range o currentpredictions, can orce some tree species ideal rangeto shit about 200 miles northwards.89 As temperaturesand moisture levels increase, some orests will expand,in particular southern types (such as oak, hickory, andcypress).90 The tree line in alpine regions could alsomove higher, and New Englands sugar maples aremoving northward. Drier soil conditions would decreasethe range and density o some orests, which could be

hurriCane katrina: PoPulationandClimate

ChangeConvergeontheCoast

Hurricane Katrinas eect on the U.S. Gul

Coast in 2005 demonstrated the hazards o

severe weather events on heavily populated and

developed coastal areas. For example, climate

change appears to be associated with the

increasedintensity o hurricanes. The number

o severe (Category 4 and 5) hurricanes, like

Katrina, has nearly doubled worldwide, rom 10

annually in the 1970s to 18 annually in 1990.

Such storms made up 35% o all hurricanes

in the past decade, compared to 20% in the

1970s.108 One cause o this change is thought

to be rising ocean temperatures. Since 1970,the temperature o the worlds oceans has risen

one degree Fahrenheit, while the tracking o

temperatures in the Atlantic Ocean shows a

steady increase in the last several decades.109

Because warm surace waters are a source o

energy or hurricanes, this trend has probably

contributed to the shit toward stronger

hurricanes.110

In more detaIl


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replaced with more extensive grasslands and pasture.91Increased precipitation could spur the growth o treesand vegetation, but heat could spur the loss o nutri-

ents.92

Spring is arriving sooner now than in the past, and

many indicators show spring is occurring 1-3 weeks

earlier than usual.93 In New England, or example, this isshown by data on river fow and runo, last-rost dates,air temperature, snow melt, and leang and foweringpatterns.94

Changes in reshwater temperature are also a actor.An increase o 4-5oF over the next 70 years could reducehabitat o coldwater sh by one-ourth to one-thirdnationwide.95 Higher water temperatures are also linkedwith the bleaching and die-o o coral rees, and algalblooms which deprive aquatic lie o oxygen and light.

Whether and how species adapt to climate changewill depend on the pace and geography o the climaticshits, how the composition and location o habitats arealtered, and the availability o habitat.Many species arealready adjusting their migration, breeding, and eed-

ing habits in order to survive. But because all parts oan ecosystem do not adjust to climate shits in the sameway, many species could ace a lack o ood-base,or inadequate habitat. For example, some butterfyspecies are moving northwards in response to tempera-ture increases in their home ranges, while egg layingamong certain birds and the budding o some trees nowoccur earlier than in previous decades. 96

This is also particularly evident in the Arctic(including Alaska), where retreating sea ice is makingit harder or seals and polar bears now on the U.S.Endangered Species list or threat o extinction to ndood.97 (see box, page 14).

The species most vulnerable to climate change will be

those with habitat needs aorded only by certain ecosys-

tem types. It will be especially hard or wildlie to adjustin the ace o human population and development, sinceragmented, built environments prevent migration tonew habitats. Another key population actor here is that,given current patterns o land use, there will likely beless habitat available, even i birds and animals canreach it.98

Another key population actor here is that sprawl

development ragments or breaks up wildlie habitat.This can have detrimental eects on wildlie as well asdiminish the services perormed by ecosystems, such asthe ability o wetlands to lter waste and control food-ing. As this development paves over land, it compactssoils, increases fooding and polluting chemical runo,and reduces groundwater reserves.99And, orecasts show

In more detaIl

sPeCies threatenedby Climate Change

Plant and animal species in the U.S.and globally are being aected by what

researchers call the double hit o habitat

loss and climate change. The polar bear

is the rst species ever to be placed on

the U.S. Endangered Species List due to

climate change (see box, page 14). Yet many

other species are also at risk. For example,

climate change is pushing one in eight bird

species globally to extinction because o

the combination o widespread habitat loss

and the severe droughts, orest res, and

extreme weather events brought about by

global warming.In addition, one third o the planets

ree-building corals, including those o the

U.S. coasts, are threatened with extinction.

Built over millions o years, coral rees are

home to more than 25% o marine species,

making them the most biologically diverse

o marine ecosystems. Corals produce rees

in shallow tropical and sub-tropical seas

and are highly sensitive to changes in their

environment. Researchers have identied the

main threats to corals as climate change and

localized stresses rom destructive shing,

declining water quality rom pollution, and

the degradation o coastal habitats. Climate

change causes rising water temperatures

and more intense solar radiation, which lead

to coral bleaching and disease oten resulting

in mass coral mortality.

Source: IUCN, 2008

considerable expansion o sprawling development in the

uture, with signicant implications or ecosystems. Forexample, orest and prime armland made up most (60%)o the acreage developed nationwide during the 1980sand 1990s.100 At current population growth and rates osprawling development the U.S. could lose 23 millionacres o orest land to development by 2050, primarilydue to increases in residential areas.101


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In more detaIl

Populations linkages to water resources and climatechange play out dierently in each U.S. region, and eachregion has tremendous, unique, water-related pressures

related both to water quality and quantity (see U.S.National Report on Population and the Environ-ment,www.cepnet.org). Yet these issues are particu-larly widespread and pervasive in the American West.There the nationsdriest states have become some o our

astest-growing, exacerbating issues resulting rom limit-

ed water availability.112Water, not land, is the limitingresource in the West, and rapid growth continues

in those areas where experts say there is already a

lack o water to sustain the current and expected

uture population infux.

For example, a major, prolonged drought combinedwith rapid population growth in urban areas like Las

Vegas has stressed nearby Lake Mead, and the rest o theColorado Basin, which provides water to armers andcities located rom Colorado to Southern Caliornia.Now, there are ears that global warming could drastical-ly reduce the Colorado Rivers fow, even as the South-west continues to expand in population.

Also in another part o the West, the steady decreasein the Sierra Nevada mountain ice pack that providesmost o Northern Caliornias water was recently at itslowest level in 20 years, and current models suggest30-70% o the snow pack will disappear by the secondhal o this century. A new National Academies report onthe Colorado River Basin says the combination o limited

Colorado River basin water supplies, increasing popula-tion demands, warmer temperatures, and the prospecto climatic change-induced droughts point to a uture inwhich the potential or people-water conficts will be-come ever-present. Over the past ew decades, the driest

states in the U.S. have become some o the astest growing,

while ongoing drought has brought the fow o the

Colorado River to its lowest since measurements began

85 years ago. We have to nd a new way o meetingthe needs o all this population thats turning up, andstill satisy all our recreational and environmentaldemands, says one Colorado ocial a sentimentheld by many Western states water managers.113

Rising Sea Levels

With over hal o the U.S. population already living

in coastal areas and millions more moving there each

year, predictions o sea level rise resulting rom climatechange is a major concern. The sea level rise due toglobal warming is the result o higher water temperatures(which expands water volume), and the additiono reshwater rom melting glaciers and ice.

The greatest sea level changes are expected along

the heavily populated U.S. Mid-Atlantic and Gul Coasts

because o sea level rise and the simultaneous occur-rence o land subsidence rom natural geological change.In these regions, studies predict that a one oot rise in sealevel is likely by 2050, and as much as a our oot rise is

possible in the coming century.103 Rates o sea level riseare also expected to be considerably higher in the uture

than they have been in the past. (See box, page 13).In the next 60 years, 25% o buildings within 500

eet o the U.S. coastline could be lost because o coastal

erosion. Hal o these structures are on the U.S. Atlan-tic Coast, and the remainder along the Gul and PacicCoasts and the Great Lakes.104Flood damages couldincrease by 36-58% with a one-oot rise, and by 100-

200% with a three-oot rise.105Sea level rise would also increase salt intrusion into

rivers, streams, and aquiersand the salinization o watersupplies. This is already a problem because o ground-water pumping and the alteration o natural water fowsto satisy growing demand.106

It is also estimated that a two-oot rise in sea level

could eliminate an estimated 17-43% o U.S. wetlands.107Somewhat paradoxically, the structures erected to protectpopulated coastal areas rom shoreline erosion (such asseawalls, dikes, and bulkheads) oten prevent wetlandsand marshes (which serve as natural buers rom thesea and storms) rom migrating and re-orming urtherinland as sea levels rise.

Freshwater Resources, Population andClimate Change

Although people may more commonly link

climate changes eect on water with rising sea

levels, the aect o climate change on reshwater

resources is also a serious concern.111 Across the

U.S., in all regions, climate change is aecting

reshwater resources, mainly through:

l Increased temperatures and evaporation rates

l Decreases in the volume o snow pack and

glaciers (a critical supply o reshwater during

spring melting)

l Decreased rainall and increased drought

conditions


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In more detaIl

Human Health Threats

One o the most acute aects o climate change thatis associated with the U.S. population relate to peoples

health. Major health issues associated with climate changeinclude increased requency o heat waves (which are o

special concern or the elderly and the poor) and extreme

weather events, posing dangers o drought and fooding;

increasing risk o ood-borne and waterborne inectious

diseases; more severe air pollution due to higher tem-

peratures, and; migration o vector-borne and zoonotic

diseases (e.g., Lyme disease, West Nile virus, malaria and

dengue ever) with changing seasonal patterns.114

There are direct and indirect health impacts associat-ed with climate change: direct and indirect eects.Directeectsoccur when weather associated with a changingclimate produce health eects (e.g., heat-related mortal-ity and morbidity resulting rom elevated temperatures).

Indirect eectsare health impacts caused by climatechange through an intermediary pathway, or example,when elevated average temperatures alter the distributiono habitat suitable or a disease vector, expanding therange o the disease vector and the population poten-tially at risk.

For example, direct health eects include extremetemperatures, particularly in urban areas oten suer-ing rom the heat island eect, which can dramaticallyimpact human health. Chicago may see a 25% increase inthe requency o heat waves and Los Angeles a our-to-

eight-old increase in heat wave days by the end o thecentury. Extreme temperatures pose a greater risk tocertain populations such as the elderly, young children,the poor, and people with health conditions such asheart problems or asthma.

Indirect health eects include higher averagetemperatures, and rain patterns that could prolongdisease transmissions seasons in locations where diseas-es already exist, and, introduce diseases into previouslyuntouched areas. West Nile virus, never seen in NorthAmerica beore 1999, had inected more than 21,000people in the U.S. and Canada by 2006. Lyme disease,the most common vector-borne disease now in the U.S.,

is predicted to signicantly expand its range north intoCanada due to the infuence o climate change. Asthmat-ics and other sensitive and susceptible sub-populationsmay suer rom air quality problems exacerbated byclimate change. For example, warmer temperatures couldincrease the reaction o chemicals that produces ground-level ozone (O

3), the main component in smog, which

is harmul to human health. Similarly, elevated averagetemperatures could prolong the pollen season or resultin greater pollen production, exacerbating symptoms oallergy suerers.

Climate Change s toP 10

health effeCts

A wide variety o potential environmental

changes associated with climate change

could have negative health impacts. The

ten most serious health eects related to

climate change ollows. They are mortality and

morbidity associated with:

l Extreme temperatures (e.g., heat waves)

l Exacerbated air quality problems

due to higher temperatures (e.g., ozone/

photochemical smog)

l Prolonged and/or increase severity o

allergy season due to elevated averagetemperatures, resulting in higher

aeroallergen levels

l Altered transmission o inectious disease

through expansion o suitable habitat

range or conditions or vector survival

l Eects on ood production via climatic

infuences on plant pests and diseases

l Intensied drought events and resulting

amine

l Population displacement due to crop

ailure, water shortages, natural disasters

l Destruction o health, transportation, and

communication inrastructure due tonatural disasters

l Human conficts over increasingly scarce

and valuable natural resources

l Increase in level and ambient temperature

o oceans, which can aect human health

by increasing vulnerability to waterborne

pathogens115


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In your regIon: u.s. PoPulatIon & ClImate Change

northeast

TheNortheastisthemost densely

populated region in the nation

(337 persons per square mile).116

Ithasthelowest energy consumption

(268 million Btus) 117, CO2

emissions

(15.0 metric tons)118, and vehicle miles

traveled (8,263)119per capita in the nation.

Temperatureincreasesspurredbyclimate

change in the Northeast may render areas

such as Boston, MA and Portsmouth, NH tohave temperatures similar to Richmond, VA

or Atlanta, GA, by 2100.120

Currently,changesintheNortheasts

seasonal weather patterns are aecting the

all oliage and winter recreation industries,

garden zones, species' habitats, and lake

"ice-outs". Spring in the Northeast now

occurs 1-3 weeks earlier on average than

30 years ago.121

Thepredictedtemperatureriseof4F

could contribute to the loss o 50-70% o

sugar maples and 40-50% o spruce in some

parts o the region.122

Highertemperaturesandprecipitationare

associated with the spread o Lyme disease

and equine encephalitis, and increases in

health-damaging smog.123

Risingwatertemperaturescouldreducethe

productivity o Atlantic lobster sheries in

the southern part o their range, and reduce

the populations o trout and other species in

the Northeasts brooks and streams.124

south

TheSouthhasthelargest numerical

population o all U.S. regions,125 and is the

second-astest growing.126 (Two Southern

states had the nations rst and third largest

numerical increases: Texas (3 million) and

Florida (2.2 million) rom 2000-2007.127)

Italsohasthehighest number and percent

increase o new housing units, with nearly

70% single-amily homes.128

TheSouthhasthehighest energyconsumption (401 million Btus)129, second

highest CO2

emissions (23.2 metric tons),130

and highest vehicle miles traveled

(11,590)131per capita in the nation.

Inthelast20years,morethanhalfofthe

nations costliest weather-related disasters

(in particular hurricanes and foods) occurred

in the South.132

Inthepast100years,annualrainfallhas

increased 20-30% across several southern

states, including Alabama, Arkansas,

Louisiana, Mississippi, South Carolina, and

Tennessee.133 IntheChesapeakeBay,sealevelcouldbe

27 inches higher in 2100 than it was in 1990,

refecting double the rate o the rise recorded

during the 20th century.134

Risingseascouldmakewatersystemsinthe

Everglades saltier high levels o salinity

have already been linked to the die-o o

100,000 acres o sea grass beds and the

decline o coral rees in Florida.135

This section describes each U.S. region and its distinctive characteristics in relation

to population and climate change.


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In your regIon: u.s. PoPulatIon & ClImate Change

midwest

TheMidwestisthenationssecondleast

densely populated region (87 persons

per square mile).136 It is the second slowestgrowing U.S. region.137 Still, metropolitan

areas around cities are growing rapidly, at

the national rate.138

Ithasthesecondhighestenergy

consumption (357 million Btus), 139 highest

CO2

emissions (23.6 metric tons),140

and second highest vehicle miles traveled

(10,292)141 per capita in the nation.

Despitethepredictionofmorerainfallin

the Midwest, higher temperatures and

evaporation could combine to result in a net

decline in water levels in the Great Lakes

by the end o the 21st century, possibly by

as much as 1.58 eet.142

Ave-footdropintheGreatLakeswould

result in 2040% less fow into the

St. Lawrence Seaway, increasing the costs

and diculty o navigation and commerce.143

A2-4Ftemperatureincreaseinthe

Midwest could increase concentrations o

ozone and smog by 8% and pose

considerable health threats.144

Morethanhalfofallprairiepondsinthe

Midwest could permanently dry up by 2060,

reducing the number o breeding ducks byhal.145

Althoughoveralltheproductivityofthe

nations agricultural center could improve

due to more rain and higher levels o carbon

dioxide, the mix o crops in particular areas

could also shit and yields o some (such

as corn) could decline.146 Growth might

also be oset by the expansion o weeds,

the reduced nutritional value o rangeland

grasses, and drier soil conditions rom

higher temperatures.147

west

TheWestisthecountrysastest growing

region, increasing by one and a hal times

the national rate.148 Caliornia is the largeststate in numerical terms (36.6 million

residents), accounting or over 50% o

theWests,and12%ofthenationstotal

population.149 Nevada is the nations astest

growing state, with population increases o

over 3.5% per year, rom 2000-2007.150

Seven o the top ten astest growing U.S.

cities (in Arizona, Nevada, and Caliornia)151

and fve o the top six astest growing

metro areas (St. George, UT; Greeley, CO.;

Bend,OR; Las Vegas-Paradise, NV; and

Provo-Orem,UT) are in the West.152

TheWesthasthesecondlowestenergyconsumption (280 million Btus),153 CO

2

emissions (15.7 metric tons),154 and vehicle

miles traveled (8,868)155 per capita in the U.S.

Someofthewesternstatesrelativelylow

per capita energy use compared with other

U.S. region is uniquely achieved through a

combination o aggressive energy-reduction

policies, hydropower, and mild weather.156

Thegreatestwarmingobservedinthenation

is in Alaska, where temperatures have

increased4-7Finthelastcentury,andthe

growing season has increased more than14 days since the 1950s.157

InSeptember2007,theextentofArcticsea

ice in the summer reached a record low,

shattering all previous lows since satellite

record-keeping began nearly 30 years ago.

(By the early 2000s the Arctic sea ice had

already melted back12-15% beyond its

normal minimum summer ice extent).

Experts now say we may be about to reach

a threshold beyond which the sea ice may

not be able to recover.158

InCaliforniaandNevada,thesnowseason

decreased 16 days between the 1950s andthe 1990s.159

By2050,thesnowlineinmountainsofthe

Pacic Northwest could be more than 1,000

eet above where it is today, orcing the dying

o o much spruce, r, and pine.160

AlongtheWestcoast,butteriesareleaving

the southern ends o their natural range and

moving north and to higher altitudes in search

o tolerable climate conditions.161


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ConClusIon

his science-based report provides arst stepto understanding the linkages between

population and climate change in the U.S.While the scientic evidence shows that America is amajor contributor to global climate change, so, too, isit poised to be a world leader in terms o solutions.Thenext step is to determine which policy, research and

public-outreach options are the best viable responses to

this new age o U.S. population and climate changes.Here are some important considerations:

nEnvironmental sustainability the ability tocreate indenitely a healthy natural resource base onwhich all our lives depend is central in addressingclimate change. As part o this,Americans at all levels,

rom individuals to national leaders, must thinkin-

clusively, placing climate change, environmentalsustainability, and population in the same frame.Science demonstrates that the issues maniest themselvesin this way, and the approach and solutions shouldrefect that in order to be eective.

In response, Americans must make strategicchoices both in their individual lives, and collectively asa nation rom the local community to national levels in order to balance the increasing pressures o humanactivity and their climate change impacts in our nationand the world.

Now Americans are showing keen, widespread inter-est in these issues as ood and gas prices rise, water be-

comes more scarce, and the eects o climate change areall around us. But we have to think dierently and makethe connections, rather than seeing them as individualoccurances, which is now the norm.

This requires a multi-aceted approach:Americansmust seriously choose to reduce energy use and

greenhouse gas emissions, andtake steps to put

population and demography on the table as a way

to address climate change. Right now, this inclusiveapproach is not being taken and this is curtailing eortsto curb climate change, stabilize population growth, andensure environmental sustainability.162 This muti-acetedapproach is the only way to eectively address the

global and national climate change challenge, rom bothsides o the same population and climate change coin.

This involves making policy shit making

environmental sustainability a U.S. national

priority. On the energy and resource consumptionside, this includes everyday individual consumer choicesto be energy ecient, as well as local, state and ederalgovernments commitment, concrete plans, and nan-cial incentives or energy eciency and greenhouse gasreduction. There should be local-national plans and tax/

T nancial incentives or energy ecient mass transport,household appliances, heating and cooling, and buildingcodes. Federalresearch or new energy ecient technologies shouldbe a priority, and such products should be madeavailable to all Americans at every price point.

On the population side, this includes acknowledg-ing that population actors, including per capita resourceconsumption and the population growth trends as men-tioned in this report, are part and parcel o the U.S. andglobal climate change challenges, and solutions. Inter-national and national policies on climate change mustinclude population and demographic actors as a corepart not just a sideline or introduction in theirconsiderations. And, the approach must include attentionto population, in the U.S. and globally, as an essential

part o halting and even adapting to climate change.There are many ways to do this, and they need to beaddressed.

In addition, the numbers o young people in orentering their childbearing years in the U.S. alreadyguarantee a certain amount o growth. At the same time,a large unmet demand or reproductive healthcare andamily planning, in the U.S. and worldwide, by thosewho would like to limit their amily size, is anothersource o growth. Providing good quality reproductivehealthcare and amily planning, easily accessible andaordable, to those who voluntarily wish to choose thenumber o children they have, would contribute to

sustainability.As part o all these eorts to achieve environmental

sustainability, peoples choices and ocusing on audi-ences such as youth as the nations uture decisionmakers can be a powerul combined strategy to helpcurb climate change and turn things around or theshort and long term.

nChoices are a central part o the climate

change solution. A population can have impacts onthe environment or climate change through the sheernumbers o individuals consuming a natural resource(like energy sources, water, orests, land, marine lie).

Yet, it is not always a straight-orward cause and eectrelationship.For example, 20,000 people in one town can have a

very dierent environmental impact than that samenumber in another town. This is based on decisionsmade about, say, the way land is developed (with clusterdevelopment vs. sprawl); type o transport or energyused (mass transit vs. single person vehicle road travel,energy ecient cars and appliances, Smart Growthwalking riendly town development), or; industry used(polluting or not, i.e. emitting small vs. large amounts


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ConClusIon

o CO2). So, while large numbers o people are critically

important in the climate change equation, the same

numbers o people do not always have equally detrimental

climate impacts. A shit in individual and collectivechoicesabout the type o and scale o energy andresource consumption can make a big dierence as towhether the outcome is environmentally sustainable ornot.

nYouth in the U.S. play a key part in the popula-

tion and climate change debate, both in terms o

the challenges, and the solutions. In 2007, 34% o theU.S. population was aged 0-24 and 20% were aged 25-39.This important demographic o young people is currentlyover hal o the U.S. population, and predicted to grow0.5% annually, and 7% by 2020.163Youth are critical

becausethey are in the position of making impor-tant choices both about population (the numbero children to have) and climate change(as energyconsumers, whether to recycle, which vehicles to drive,whether to use mass transportation, where to live, etc.,and, as potential pollution emitters).

Unlike any generation beore them, they are begin-ning to take climate changeand other environmental

sustainability issues into account when making signi-

cant lie choices about natural resource and energyconsumption, recycling, where to live, what to drive, and

how many children to have. These are small, everyday,as well as major, lie transorming choices that all make a

dierence in maintaining a balance between people andthe natural resource base on which all lie depends.

Youth also represent the segment o the populationwhose votes and decisions in the social, reproductivehealthcare, business, industry, policy and local to nationalpolitical arenas, will have a bigger impact than everbeore on the uture trends in both climate change andpopulation trends.

Their decisions represent both sides o the popula-tion and climate change coin in terms o choices andpossible outcomes. It is their generation that will likelymake the most dierence in the uture o our planet andnation, because the issues they are aced with are unlike

any generations beore them.In addition, local to international government

policies, business and corporate practices, and economicand social actors also have signicant roles in popula-tions environmental impacts. These, and individualchoices, are oten mitigating actors, and all must bepart o the solutions. Yet, while all these activities canchange the uture course o business as usual with

regard to global warming, we must also adapt to

the inevitabilities of climate change and to the

population momentum already in place.

n Adaptation is a key actor because somedegree o uture climate change will occur regardless outure greenhouse gas emissions. Adapting to or copingwith climate change will thereore become necessary incertain U.S. regions, socioeconomic and environmentalsystems.

Here, population is also key, because the need

or adaptation will most likely be increased by growing

populations in areas vulnerable to extreme events, and

the nations per capita resouce use.164 Thus, populationactors must be a core part o the U.S. adaptive strategyto climate change.

Human-induced climate change represents a new

challenge, and may require adaptation approaches to

changes that are potentially larger and aster than past

experiences with recorded natural climatic variability.

All climate-sensitive systems o society and the natu-ral environment (including agriculture, orestry, waterresources, human health, coastal settlements, and naturalecosystems) will need to adapt to a changing climate orpossibly ace diminished productivity, unctioning andhealth. In unmanaged natural systems, adaptation is notplanned but occurs when orced to do so. For example,as the climate warms, tree and animal species may mi-grate northward to remain in suitable climatic conditionsand habitat (to the extent that human barriers, such asroads and cities, allow such migration).165

In human society, however, much o adaptation maybe planned and undertaken by private decision mak-

ers and by public agencies or governments. Yet, thereare individuals and groups within all societies that haveinsucient capacity to adapt to climate change, andhigh adaptive capacity does not necessarily translate intoactions that reduce vulnerability. For example, despite ahigh capacity to adapt to heat stress through relativelyinexpensive adaptations, residents in urban areas in someparts o the world continue to experience high levels omortality.166

Regarding ecosystems, and on species diversity inparticular, eects are expected to be negative overall.Although biological systems have an inherent capacity toadapt to changes in environmental conditions, given the

rapid rate o projected climate change that is largelyhuman-induced, adaptive capacity is likely to beexceeded or many species. The ability o ecosystemsto adapt to climate change is severely limited by theeects o highly populated urban/suburban areas,barriers to wildlies migration paths, and ragmenta-tion o ecosystems, all o which have already criticallystressed ecosystems independent o climate changeitsel.167


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ConClusIon

There is still much to understand about how popula-tion and climate change trends relate to adaptive strate-gies.This report will be a tool or better understandingthe dynamics o that relationship. Looking orward, somescientists are predicting how U.S. populations will haveto adapt to climatic changes, including, or example, ashit in the New England communities centered on winterrecreation-based activities, to accommodate less snowdays and more mild weather recreation and activities.And, more and more people are re-thinking moving toU.S. coastal areas, where they are more vulnerable toextreme weather events and less able to receive realestate and house insurance.

n a broader scale, a new and emergingeld o science which combinespopulation and climate change is

beginning to take hold in the U.S. and internationally.Scientists are looking at how the ormerly disparateelds o population and demography overlap with theenvironmental and climate change sciences. Thiswork will help to inorm policymakers, business, industry,and the public on a new, combined, approach to theseissues. This is especially important because it refects andresponds to the changes now occuring in the U.S. andglobally. The merging o these two elds is an importantrst step or all o us to better understand and eectivelyaddress population and climate change as two compo-

nents that are inextricably linked.Finally, as we consider what to do, allocationissues emerge as we try to keep pace with more andmore people, their increasing energy needs, and, alldepending on a limited natural resource base. Asenergy demands increase in the U.S. and globally, howdo we choose between the increasingly competing needso humans, the environment, and species? How will wedecide how natural resources are allocated so we canall have the energy, ood, and shelter we need and, sothere is sucient space let or healthy ecosystem andspecies unctioning, particularly because our own healthis dependent on a sustainable environment.

The climatic changes are happening all around us.So what are we willing to change, or give upis it theworlds climate, as we know it? plentiul water supplies?land? species? or, do we have to make dierent policy,liestyle, business, or industry choices in order torespond to these changes?

As we look to the uture, we must remember thatpast decisions about resource allocation are not necessar-ily suitable to todays U.S. and global population, climatic,and broader ecological changes. For example, most othe energy sources we have today grew out o the needso people years ago, when the countrys and worlds population numbers and energy use were much less thanthey are now.

As or next steps, there are many. We need to beaware o the population and climate change challengeswe ace, and apply sound, science-based planning to ourapproaches

Documents

u.s. Population, Energy & Climate Change