1  Sustainability in the Built Environment

This chapter introduces the need for infrastructure, the problem of sustainability, and the concept of sustainable infrastructure.

1.1 Infrastructure

Let’s consider the leading causes of death in the United States in 1900 and 2010 shown in Figure 1.1. First, note that the life expectancy is longer, meaning that fewer people per capita die each year of any cause. Consider ailments like diphtheria, gastro-intestinal infections (like cholera), and pneumonia. These diseases which were formerly leading causes of death have almost disappeared as threats in modern life. Medical science has played a major role, especially through antibiotics and vaccines. But think of all of the engineering improvements that have played a major role in this lifesaving trend:

• Water systems bring clean water into homes, and remove dirty water through sewage and treatment systems. Cholera and diphtheria outbreaks are virtually impossible in modern cities.
• Electricity grids power domestic refrigeration units, keeping food at safe temperatures.
• Transportation systems bring fresh produce to supermarkets in any climate during all seasons, promoting nutrition and economic growth.
• Structures are considerably less vulnerable to fires, earthquakes, and any other number of catastrophes, reducing loss of life in accidents

Figure 1.1: Leading causes of death in the United States in 1900 and 2010. Data from the Centers for Disease Control and Prevention via Jones, Podolsky, and Greene (2012)

These facilities designed by engineers for civil society — roads, buildings, dams, sewers, aqueducts, tunnels, ports, power plants, bridges, etc. — are collectively referred to as infrastructure. Without adequate infrastructure, a prosperous and healthy society is unlikely. Infrastructure enables people to work, travel, and live in today’s world.

The American Society of Civil Engineers (ASCE) defines critical infrastructure as

Systems, facilities, and assets so vital that their destruction or incapacitation would have a debilitating impact on national security, the economy or public health, safety, and welfare. —ASCE (2021)

According to ASCE(ASCE 2021), infrastructure can be:

• Built (structural, electric, water, transportation systems)
• Natural (surface or ground water resources)
• Virtual (information systems)(ASCE 2021)

What is a system?

A system is a group of interacting components that work together to achieve some common purpose. —Vanek et al. (2014)

A system has the following attributes:

• purpose
• components and subsystems
• part of a larger system

For example, an airport is an infrastructure system. Let’s discuss the attributes of an airport system.

Figure 1.2: An Airport is a system, Image from ConstructionReviewOnline (2024)

• What is the purpose of an airport?
  • Transport passengers safely and efficiently.
• What are the components and subsystems of the airport?
  • Runways, the terminal, the control tower, the baggage handling system, the security checkpoints, the parking lots, the rental car facilities, the roads leading to and from the airport, and the public transit system(Copilot 2023).
• What larger systems is the airport part of?
  • An airport is part of a larger system of airports and air routes across the world. It is also part of other infrastructure systems such as electric grids, road networks, gas and water pipe networks.

The definition of infrastructure that we will use in this class is provided by the The Center for Infrastructure Transformation and Education (CIT-E) (Fields, Hart, and McBurnett 2024):

A system of systems or a “metasystem” that supports the daily needs of people, communities, and nations. Infrastructure includes the people, physical structures and information networks that help society function safely and efficiently.

We can review the same questions about the attributes of a system for infrastructure.

• What is the purpose of infrastructure?
  • support the daily needs of people, communities, and nations
• What are the components and subsystems of infrastructure?
  • built environment (structural, electric, water, transportation systems)
  • natural resources (surface or ground water resources)
  • information networks
  • people who operate, build, and maintain infrastructure ¹

• What larger systems is infrastructure part of?
  • Infrastructure is part of a larger systems including the lives of people who use infrastructure, economies, nations, and the natural environment.

The Center for Infrastructure Transformation and Education (CIT-E)(Fields, Hart, and McBurnett 2024) also provides attributes of good infrastructure.

• Capable of supporting the demands placed on it (Capacity > Demand)
• Resilient (able to recover from disruptions)
• Sustainable

We will discuss the attributes of good infrastructure, particularly sustainability, in more detail in the next sections.

1.1.1 Quality of US Infrastructure

One of the central struggles with infrastructure in society is that it costs money to build it, and once something is built it costs money and effort to maintain. The American Society of Civil Engineers (ASCE) publishes an an Infrastructure Report Card every four years. The most recent report card is shown in Figure 1.3, and you can see that on these metrics, the United States could be doing better. Now, it’s important to point out that the purpose of this report card is to lobby government to spend money on infrastructure projects, thereby benefiting civil engineers. But the fact remains that many of the facilities collectively comprising America’s infrastructure are not getting any younger, and will need repair or replacement in the near term.

(a) Findings

(b) Grades

Figure 1.3: ASCE 2021 Infrastructure Report Card (infrastructurereportcard.org)

1.1.2 Infrastructure in the United States and the World

For an international and non-lobbyist perspective, the 2019 World Economic Forum Global Competitiveness Index tries to measure and compare countries by how well-equipped they are to foster economic development. This includes political structures, legal systems, and — unsurprisingly — infrastructure. Figure 1.4 shows how the United States scores on these metrics, as well as identifying the countries that are ranked first in each metric. Overall, the U.S. comes in second behind Singapore. The U.S. scores highly in the openness of its markets, the consistency of its legal system, and its ability to innovate. In the infrastructure category, however, the U.S. is only 13^th of the 141 countries included (Singapore leads in this category as well).

Figure 1.4: US 2019 Global Competitiveness Summary (weforum.org)’

One disadvantage the United States faces relative to other countries is that it made a series of massive infrastructure investments in the middle of the 20^th Century, from the New Deal-era hydroelectric projects along the Tennessee and Colorado Rivers to the Interstate Highway System. During the same time period, the infrastructure of other developed nations in Europe and Asia was effectively destroyed in World War II, and their economies were crippled as a result. But in the intervening decades, these other countries have improved their infrastructure with more modern techniques and practices, setting the United States comparatively behind some of its peers.

But why is this this the case? Why can’t a nation simply build great infrastructure and then continue maintaining and expanding that infrastructure so that it remains performant, relevant, and in good repair? Why didn’t we as a nation sustain this advantage? It’s a good question without a simple answer.

Think

Based off of the information in Figure 1.3 and Figure 1.4, how well do you think the United States is poised to maintain and improve its infrastructure in the coming century? What would need to change to make this happen?

1.2 Sustainability

When was the last time you spun a top? For how long did it spin? Eventually, even the most well-calibrated tops spinning on the smoothest possible surfaces will topple as the combined forces of gravity, air resistance, and friction overwhelm the angular momentum of the top. Because the top cannot spin forever, this system is unsustainable.²

Figure 1.5: Spinning top. Image copyright Warner Brothers / Legendary Pictures.

A top is not a very consequential system. But other systems, including the economy and the various systems that compose public infrastructure, have a lot riding on them. It is not hyperbole to say that when these systems fall apart, large numbers of people suffer poverty and death. Keeping these systems going indefinitely needs to be the goal. The science of designing human and physical systems so that they will operate indefinitely is called sustainability. Sustainability is a technical problem rooted in an ethical question: how can we use the earth’s resources in such a way that they are available to future generations?

1.2.1 Triple Bottom Line

There are three main dimensions of sustainability, sometimes called the triple bottom line, showin in Figure 1.6. These dimensions are:

• Economic Does the system cost more to operate than its operation justifies?
• Environmental Does the system extract resources from the environment more quickly than they can be replenished?
• Social: Does the system balance costs and benefits equitably among different groups?

All three dimensions of sustainability must be handled, or the system will eventually collapse: If a system is economically sustainable but exerts an unacceptable social or environmental toll, then the system is unsustainable. Because of this, the ordering of the three dimensions is immaterial.

Figure 1.6: Triple Bottom Line

1.2.1.1 Economic

Many of us have looked at an old car in need of repairs, and tried to determine if we would spend more money making the car work again than we would obtaining and maintaining a newer, or different car. Or even if we would spend more money keeping the old car on the road than we could earn by driving it to a job. If the cost of keeping a system running exceeds the benefit derived from that system, it is unsustainable.

In terms of infrastructure, this question can come in many different ways. It is cheaper to repair a pavement than replace it. But a pavement repair needs to occur regularly, or the pavement will deteriorate to the point that it must be replaced. But many cities do not have sufficient funds to repair the pavement frequently, meaning that they prioritize the roads in the worst condition for more expensive replacement. This is unsustainable: eventually more roads will need to be replaced than the city can budget for, and the quality of the entire road system begins to degrade.

Good questions to ask about economic sustainability of an infrastructure project are:

• Is the project affordable?
• Will it put a financial burden on future generations?
• Does the project return more value than it costs?

Think

What would need to change to make this pavement maintenance system economically sustainable?

1.2.1.2 Environmental

The US Environmental Protection Agency discusses sustainability in terms of the natural environment.

Everything that we need for our survival and well-being depends, either directly or indirectly, on our natural environment. To pursue sustainability is to create and maintain the conditions under which humans and nature can exist in productive harmony to support present and future generations.- US EPA

Good questions to ask regarding environmental sustainability of infrastructure projects include:

• Is the project clean?
• Does it pollute or degrade our natural environment?
• Does the project use resources in a way that can be sustained indefinitely?
• Does the project harm the environment in a way that cannot be mitigated? (Copilot (2023))

Environmentalism and conservation are some of the words many people associate with sustainability. These are important concepts, but sustainability means something different. Environmentalism and conservation concern protecting natural habitats from degradation or destruction. Environmental sustainability is more concerned with the manner of resource use and extraction, and whether the environment can perpetually bear the cost of human activity.

To see the difference, consider a timber forest. A conservation approach might try to prohibit logging in that forest in an effort to preserve habitat for wildlife or for other reasons. A sustainability approach would instead identify ways to extract timber from the forest that can be sustained indefinitely. This might include limits on how much timber can be extracted so that the forest can regenerate itself, seasons when logging is permissible, and techniques for harvesting and transporting timber that minimize impact on the forest environment. There may be cases where a sustainable logging practice cannot be developed; in this case, sustainability and conservation reach the same conclusion.

Think

Given the distinction between environmental sustainability and environmental conservation, could an economy based on fossil fuel extraction and consumption ever be considered sustainable?

1.2.1.3 Social

Humans build and operate systems of all different kinds in an effort to make their lives better. Civil infrastructure systems are carefully engineered to fill their role. Economic systems by contrast arise as a consequence of people trying to improve their individual situations. Both systems exist to improve quality of life. But what happens when a system improves the quality of life for some people, but degrades the quality of life for others? If the inequality is too great, it is considered unsustainable.

A stark example of a socially unsustainable system is the system of African slavery that existed in the United States and other American colonies for hundreds of years before it was abolished in the middle 19^th century. Agricultural plantations seized Native American land and enslaved Black people as labor to generate immense wealth for plantation owners, their descendants, and for many others who participated in the economic system fueled by this wealth. But the human costs born by the individuals and families who lived and died as enslaved people were too great to be ignored, and the system was forcibly dismantled through military and political action. Slavery was socially unsustainable because enough people were willing to fight and die rather than see it continue for another generation. However, later forms of racial oppression such as Jim Crow laws, convict leasing, racial segregation, mass incarceration, mortgage redlining, and disproportionate killings of unarmed Black civilians have persisted after the American Civil War and give us new urgency to design civil and economic systems with social sustainability as a top priority.

Good questions to ask regarding social sustainability of infrastructure projects include:

• Is the project fair?
• Does it value all people equally?
• Does it positively impact some groups more than others?
• Does it negatively impact some groups more than others?
• Can the negative impacts on people be reduced and/or compensated?

1.2.1.3.1 Environmental Justice

Some infrastructure projects come with negative externalities — discussed in Section 3.4 — or unpleasant side-effects: train tracks and highways have lots of noise and pollution, and wastewater treatment plants often have unpleasant odors. Historically, engineers have located these facilities in low-value locations to save financial resources and spare the noses of wealthier citizens. But this often results in low-income and minority communities bearing the majority of these negative costs. As shown in Figure 1.7, Black, Hispanic, and Asian Americans on average are exposed to higher concentrations of \(NO_2\) than White Americans. \(NO_2\) is a pollutant predominately emitted from motor vehicles. While average air quality, as measured with \(NO_2\) concentrations, has improved for all racial and ethnic groups between 1990 and 2010, the disparities in air quality still persist.

Figure 1.7: Discrepancy in ambient \(NO_2\) concentrations by ethnic/racial groups (NH = Non-Hispanic) in the US from Liu (2021)

Environmental justice is a principle and a goal to address inequalities in environmental protection. Environmental Justice in encompasses both social and environmental sustainability. The US Environmental Protection Agency defines environmental justice as

Environmental justice is the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income, with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. This goal will be achieved when everyone enjoys: The same degree of protection from environmental and health hazards, and Equal access to the decision-making process to have a healthy environment in which to live, learn, and work. - US EPA (US EPA 2023)

1.3 Sustainable Development Goals

In 2015, the United Nations member states agreed to a set of 17 Sustainable Development Goals (SDG’s). From the UN SDG website,

The 2030 Agenda for Sustainable Development, adopted by all United Nations Member States in 2015, provides a shared blueprint for peace and prosperity for people and the planet, now and into the future. At its heart are the 17 Sustainable Development Goals (SDGs), which are an urgent call for action by all countries - developed and developing - in a global partnership. They recognize that ending poverty and other deprivations must go hand-in-hand with strategies that improve health and education, reduce inequality, and spur economic growth – all while tackling climate change and working to preserve our oceans and forests.

The 17 goals are shown in a graphic in Figure 1.8. These goals are ambitious, and are based in a comprehensive understanding of the triple bottom line of sustainability.

Figure 1.8: UN Sustainable Development Goals

A major element of the SDG’s is not necessarily in achieving the goal, but in helping nations and other organizations build capacity to track their progress and achieve them in the future. To this end, the goals are associated with targets and paired indicators that can be measured. For example, SDG 11 is “Make cities and human settlements inclusive, safe, resilient and sustainable”, a rather amorphous goal. But this is broken into more manageable targets, such as 11.1: “By 2030, ensure access for all to adequate, safe and affordable housing and basic services and upgrade slums.” Progress towards this target is measured as the proportion of the urban (non-rural) population living in slums. Slums are then defined as housing situations with overcrowding, lacking water or sanitation, or without contract tenure. An interactive graphic of data from this program is given in Figure 1.9. In general, most countries have made progress on the proportion of their population living in slums, but many countries — especially in South Asia and Africa — still see an increase in the number of people living in slums.

Figure 1.9: Global slum population, via Our World in Data

The hope is by tracking the indicator, cities and countries can begin to make plans to address the indicator and thereby start to meet the UN SDG’s. The data at the midway point of the 2015-2030 period is sobering: The UN estimates that we are on track to achieve only 15% percent of the measurable indicators by 2030, as illustrated in Figure 1.10.

Figure 1.10: Progress towards the UN SDGs, from the 2023 Progress Chart.

1.4 Environmental Policy and Stewardship

1.4.1 NEPA

In the National Environmental Policy Act (NEPA) , the United States Congress “declared that it is the continual policy of the Federal Government … to create and maintain conditions under which humans and nature can exist in productive harmony, that permit fulfilling the social, economic and other requirements of present and future generations”(U.S. Code 2023).

In other words, NEPA is a law to puruse sustainability in the US government actions. In practice, NEPA is a federal law that requires all federal agencies to evaluate the environmental consequences of their proposals, document their analysis, and make the information available to the public prior to making decisions. This applies to direct actions by federal agencies, as well as indirect actions including all projects that use federal money or required a federal permit or regulatory decision — which includes most large civil infrastructure projects (Environmental Excellence | AASHTO (2024)).

NEPA does not say that federal projects can have no environmental impact. It does say that the potential impacts must be known, they must be told to the public, and that an equivalent alternative with fewer environmental impacts could not be found. The process for ensuring that a project complies with NEPA is illustrated in Figure 1.11 and is as follows:

1. The agency determines if the project falls under a Categorical Exclusion (CATEX). This happens when common projects have been previously determined to have no significant impact. For example, the Federal Highway Administration (FHWA), lists bike paths, resurfacing projects, and adding an additional lane in the existing right-of-way as projects with a CATEX (US DOT 2025). If a CATEX does not apply, then
2. The agency conducts an Environmental Assessment (EA) to identify if there are any likely environmental impacts. If the EA determined that the impacts were minimal or negligible, then the agency issues a Finding of No Significant Impact (FONSI), and the project can proceed. If there is a potential for significant impact, then
3. The agency prepares an Environmental Impact Statement (EIS). An EIS is a detailed analysis of all the alternatives considered across multiple dimensions that occurs in several stages.
   1. The agency publishes a “Notice of Intent” to inform the public that an EIS is about to occur, including its scope and purpose.
   2. The agency completes and publishes a draft EIS, which must be open for public comment for at least 45 days
   3. The agency completes the final EIS, which must respond to substantive public comment.
   4. The Environmental Protection Agency (EPA) reviews the EIS and issues a Record of Decision (ROD)

Figure 1.11: NEPA process (note: you can right-click to open this image in a new tab or download it to view it better).

Large infrastructure projects are frequently targets of legal action under NEPA. For instance, if a community feels its needs were not adequately considered when a FONSI was issued in response to an EA, then the community may sue the funding agency; a court can then overrule the FONSI and require the agency to conduct a complete EIS. A court could also invalidate a ROD if it determined the EIS was conducted improperly, for instance if the EIS and subsequent ROD ignored the agency’s responsibilities under the Endangered Species Act or other federal legislation.

NEPA applies only to project receiving federal funding or requiring federal permit or a regulatory decision. But, that does not mean that non-federal projects are exempt from environmental regulations. There are other national environmental laws and regulations that apply to infrastructure projects, regarding air pollution, water pollution, waste removal, especially for toxic materials including lead and asbestos. A summary of these laws are located in US EPA (2024).

For many of these laws, the EPA delegates the authority to the States. For example, the State of Utah issues permits for Storm Water Pollution Protection Plans (SWPPP) (Utah DEQ 2025) as required by the Clean Water Act (US EPA 2025). In addition, States or local governments may have passed additional environmental regulations (US EPA 2003).

Figure 1.12: Silt fencing used as part of a Storm Water Pollution Protection Plan, image and best practices discussed at Utah State University (2025).

1.4.2 Stewardship

Doctrine and Covenants 104:14-17 roots the principles of triple-bottom line sustainability firmly in the doctrines of the Gospel.

I, the Lord, stretched out the heavens, and built the earth, my very handiwork; and all things therein are mine.

And it is my purpose to provide for my saints, for all things are mine.

But it must needs be done in mine own way; and behold this is the way that I, the Lord, have decreed to provide for my saints, that the poor shall be exalted, in that the rich are made low. For the earth is full, and there is enough and to spare; yea, I prepared all things, and have given unto the children of men to be agents unto themselves.

The Lord promises that there will be enough resources on earth for all of His children only if we use the resources in ways that are economically, environmentally, and socially sustainable.

Think

Consider this exercise from the Gospel Topics essay on Environmental Stewardship and Conservation

Learn, ponder, and pray about what you can do to be a better steward. Use the resources of the earth sparingly and reverently. Adopt lifestyles and personal habits that respect the Creation. As you can, fix up and keep clean the places where you live, work, recreate, and worship. Make your own living space more beautiful and inspirational. Contemplate the ways that nature bears testimony of God and the harmony between the laws and patterns of nature and the gospel of Jesus Christ.

Many of these same ideas are reflected in the Hannover Principles, which were developed for the 2000 World’s Fair as a foundation for Ecological Design and relate to our discussion on sustainability. The principles are:

• Insist on the rights of humanity and nature to coexist
• Recognize interdependence
• Respect relationships between spirit and matter
• Accept responsibility for the consequences of design
• Create safe objects of long-term value
• Eliminate the concept of waste
• Rely on natural energy flows
• Understand the limitations of design
• Seek constant improvements by the sharing of knowledge

1.5 Urbanization and Sprawl

In some ways, fully agrarian societies are highly sustainable. Pre-industrial agriculture has low environmental impact, a modest return on investment (in typical years), and and generates relatively little variation between rich and poor. They can continue for thousands of years without depleting natural resources. But there are many ways that pre-industrial agrarian societies were not sustainable.

Think

What are ways that pre-industrial agrarian societies were not sustainable?

For one, there is low variation in incomes because almost everyone is poor, and living standards in such societies are low: life expectancy is short, infant mortality is high, and there are relatively few opportunities for cultural expression, education, and thought.

Also, these societies could be more susceptible to disease, famines, and natural disasters. The Black Death, for example, killed between 30% and 60% of the population of Europe in the 14^th century (Dewitte 2010). The Great Famine of Ireland in the 19^th century killed over a million people and caused another million to emigrate (Editors 2022). The Dust Bowl of the 1930s in the United States caused hundreds of thousands of people to leave their homes and farms in search of work [California Capitol Museum (2025)](Copilot 2023). Modern society and infrastructure has helped alleviate these impacts as previously discussed in Section 1.1.

Figure 1.13: The Dust Bowl. “thousands left their homes in Oklahoma, Texas, Arkansas, and Missouri. Over 300,000 of them came to California. From the California Capitol Museum (2025).

We will discuss more about comparative advantage later, but for now we can simply assert that by living close to other people, it is possible for individuals to specialize. When everyone is a farmer, everyone has to make their own tools and those tools might not be well made. But if one person is a blacksmith and sells better tools to lots of farmers, everyone is better off. But that blacksmith needs to invest time and money in a forge and tools and training that will leave little extra time for successful farming, so the blacksmith will need to locate in a place where he or she can access many other farmers. When you repeat this for blacksmiths, bankers, coopers, doctors, merchants, and many other professions that require training or special equipment, you begin to have a town, and then a city. This process of people moving from an agrarian society to a community — and usually learning a trade instead of practicing subsistence agriculture — is called urbanization.

Urbanization has happened throughout human history³, but it has accelerated since the industrial revolution in the 19^th century. Figure 1.14 shows the growth of urban populations over the last sixty years in a selection of countries. Western developed nations tend to have urbanization rates over 80%, while the world average passed 50% for the first time in 2010. This average is still rising, driven largely by rapidly increasing urbanization in India, China, and sub-Saharan Africa.

Figure 1.14: Urbanized population for selected countries and world population-weighted average. Data from the World Bank / United Nations.

There is obviously an upper limit of 100% urbanization that has has already been reached in places like Singapore and Hong Kong, but even these areas experience immigration and native population growth. Is perpetually increasing urban population growth sustainable? This is an important question, but for the most part we (civil engineers, city planners, etc.) need to take perpetual urban growth as a fact, and build infrastructure that makes this growth sustainable in each dimension of the triple-bottom line. This is not easy, as the following examples will illustrate.

1.5.1 Suburban Sprawl

Many regions — especially in the United States — have experienced a form of quasi-urbanization — literally, sub-urban — where urban population growth agglomerates on the edges of metropolitan areas where land is cheap. Households build large homes on larger tracts of land, aided by tax and zoning policies that incentivize or even require this kind of development, and supported by high private vehicle ownership rates. Distinguishing features of sprawl include (Hamidi et al. 2015):

• Low development density in terms of population and jobs per square mile
• Low diversity of land use: residential areas are strongly separated from office and retail areas.
• Low activity centering: heavily sprawled communities often lack a defining central area
• Poor street connectivity (lots of cul-de-sacs), making walking and biking trips artificially long and difficult.

This type of land use can create many sustainability challenges:

• Social:
  • Automobiles are the only viable form of transport, excluding the poor and some with disabilities from participating productively in society.
  • Automobiles are a major contributor to air pollution, exacerbating respiratory illness.
  • People are separated from each other and have few opportunities to interact
• Environmental:
  • Homes, retail, offices, and all the parking necessary to make this system work consume large amounts of land, destroying wildlife habitat or agricultural land in an unsustainable way.
  • Water consumption — often for lawns — increases faster than it can be seasonably replenished, leading to aquifer drawdown and reservoir depletion.
  • Water runoff patterns are changed by urban development (see Figure 1.15).
  • High energy use from air conditioning and transportation is a major factor in climate change.
  • Pavement radiates heat, raising the temperature of the surrounding area and causing people to use even more resources to cool their living spaces.
• Economic:
  • Demand for road infrastructure increases faster than tax revenues, leading to underfunded maintenance needs and traffic congestion.

Figure 1.15: Water runoff in urban versus natural land use.

1.6 Climate Change

We questioned earlier whether an economy built on fossil fuels could be sustainable. There are reasonable uncertainties regarding how long the current system could be sustained in terms of unknown and unexplored reserves. What is considerably more certain however, is that were we to consume a large portion of those fuel resources, the earth’s climate could be dramatically altered.

Climate change describes the long-term fluctuations in temperature, precipitation, wind, and all other aspects of Earth’s climate. Kibert (2016) suggests

The main cause of climate change is the dramatically increasing emissions of carbon gasses, mainly carbon dioxide (CO2), into the atmosphere from fossil fuel combustion by power plants, transportation, building energy systems, cement production, and agriculture. At the same time, Earth is losing its ability to stabilize CO2 concentrations because biomass, such as forests, which absorb CO2 are being lost to land development, deforestation, and mining. The combination of rapidly increasing emissions and decreasing absorption capacity is accelerating the atmospheric concentrations of CO2. Climate change gasses like CO2 trap solar energy, and as their atmospheric concentrations rise, average global atmospheric temperatures also increase. The likely results will be rapidly rising sea levels, substantially reduced crop yields, drought, and more energetic hurricanes and cyclones.

1.6.1 Climate Change Science

The world is getting warmer, and is doing so at an accellerating rate. This is shown in multiple datasets collected by different agencies using different methods. The data shown in Figure 1.16 comes from a scientific estimate of the average temperature at the Earth’s surface over the last 140 years. This is true in almost every season, and the rate of temperature growth has been increasing.

Figure 1.16: Global monthly average surface temperature, 1880-2024. Video by NASA Scientific Visualization Studio

Since the Industrial Revolution in the early 19th Century, humans have made great use of the energy contained in fossil fuels such as coal and oil. This energy has helped us build modern economies and enjoy great wealth. But there is a challenge with using fossil fuels. One of the many hydrocarbon molecules in gasoline is octane, \(C_8 H_18\). When octane combusts in your engine, the carbon atoms combines with oxygen, and the molecules are rearranged into carbon dioxide and water vapor, releasing substantially more energy than was used to initiate the reaction, as shown below: \[C_8H_{18} + 12.5 O_2 \rightarrow 8 CO_2 + 9 H_2O\] Because the carbon in the octane combines with oxygen, one U.S. gallon (3.8 L) of gasoline produces 19.3 lb (8.74 kilograms) of carbon dioxide (or 2.3 kg/L) when it burns. So, the mass of carbon dioxide gas ends up being greater than the mass of the fuel entering the engine. Continued use of carbon-based fuels has led to a substantial increase in the concentration of carbon dioxide in Earth’s atmosphere, as shown in Figure 1.17. In this chart, the red line represents monthly average observations and the black line is a moving average trend line.

Figure 1.17: Historical atmospheric carbon concentrations measured at the Mauna Loa observatory.

Figure 1.18 shows the correlation between atmospheric carbon dioxide and global mean surface temperatures for the last 120 years. Of course, correlation and causation are not the same thing. But there is a strong explanatory relationship that lends causal support for the idea that the Earth is getting warmer because of the increased carbon.

Figure 1.18: Global mean temperature and atmospheric carbon dioxide. From Melillo et al. (2014).

Planck’s law describes the spectral wavelengths of radiation emitting from an object as an inverse function of the object’s temperature T (in Kelvin), with the highest density of waves at a particular wavelength \[\lambda_{max} = \frac{2.897\times 10^6}{T}\] where \(\lambda\) is in nanometers and \(2.897\times 10^6\) is derived from the Planck constant and the speed of light. As the temperature of the sun is very high (6000 K), the highest density of waves is low (482 nm, or about 0.5 micrometers). Figure 1.19 illustrates the spectrum of light emitted from the sun, and the maximum is right at 0.5 micrometers, well within the range of visible light. The earth is much cooler however, so it’s primary wavelength is emitted at just around 10 micrometers. It turns out that this is just about the exact wavelength of infrared light that is absorbed by carbon dioxide and other greenhouse gasses, like methane, ozone, and water vapor.

Figure 1.19: Wavelength of solar and radiated light. Image from Seinfeld and Pandis (2016)

This greenhouse effect is an essential element in keeping our planet habitable. As shown in Figure 1.20, greenhouse gasses in the atmosphere absorb some incoming solar radiation, and also reflect the earth’s radiation back to the surface. This keeps the overall system in balance. Without this layer of greenhouse gasses, Earth would be cold (like Mars). But if you increase the concentration of greenhouse gasses even modestly, the balance is thrown off and the Earth gets warmer.

Figure 1.20: Atmospheric energy budget. From UCAR.

The overall increase in temperature has serious potential impacts on human life and infrastructure. Precipitation patterns will change as tropical storms and hurricanes draw more energy from warmer oceans. Some areas will be wetter than usual, and others will be drier. The number of days of extreme heat in many places will increase. Pests may increase their reproductive rate with shorter winters, damaging crops and natural habitats. Perhaps most concerning, there are feedback cycles that are expected to accelerate climate change. As the arctic ice cap melts, the exposed ocean water absorbs more solar heat than the ice previously reflected, accelerating warming. There are also frozen bogs and swamps in Canada and Siberia that begin emitting carbon dioxide and other greenhouse gasses as they thaw. And water vapor itself is a potent greenhouse gas; warmer air can hold more vapor.

The overall impact of climate change is that we might not always be able to rely on historical patterns to anticipate future stresses on structures, dams, power systems, and the like.

Think

Dallin H. Oaks said in a General Conference address

There are many political issues, and no party, platform, or individual candidate can satisfy all personal preferences. Each citizen must therefore decide which issues are most important to him or her at any particular time. Then members should seek inspiration on how to exercise their influence according to their individual priorities. This process will not be easy. It may require changing party support or candidate choices, even from election to election.

Climate change policy is a contentious issue in United States politics. The costs of action are high, and the evidence for it can be hidden in the natural variability of the climate. You need to decide for yourself where climate change ranks among the various policy priorities you might have. It might be your most important issue, or it might be an issue that isn’t in your top ten. It is important that members of the Church respect each other’s priorities and political choices.

In this class, you don’t have to consider climate change as your primary political issue. But you do need to understand the science behind it, and the likely impacts of climate change on infrastructure. And, how we can use infrastructure to adapt to climate change or even mitigate it.

1.6.2 Climate Change Adaptation and Mitigation

Climate change is interrelated with the sustainability of infrastructure systems in two distinct ways: mitigation and adaptation.

1.6.2.1 Mitigation

The goal of climate change mitigation is to change human behaviors and systems so that the climate will change less than currently forecast. There are a few basic strategies to do this:

• Reduce the amount of carbon dioxide and other greenhouse gases emitted by human activities.
• Increase the earth’s capacity to absorb carbon dioxide, such as increasing the total volume of vegetation.
• Reduce the amount of solar energy absorbed by earth’s surface to offset the greenhouse effect.

Figure 1.21 shows greenhouse gas emissions by sector over the last thirty years. The three largest sectors are transportation, electricity generation, and industry. But it is worth digging more into what some of these sources are. Fossil fuels are a large and obvious culprit. Less obvious, however is concrete; refining portland cement emits large amounts of carbon dioxide through running the refinery ovens, and the actual chemical process of creating the cement.

Figure 1.21: U.S. greenhouse gas emisisons by source.

One of the most important techniques is to conduct a life cycle cost (LCC) analysis of a project, in terms of both money and energy. This must consider not just the cost and energy of constructing a project, but also the the energy cost of the materials used, as well as the cost of repurposing, rebuilding, or demolishing and recycling a project (See Figure 1.22 ). This will ensure that the project remains useful even if its intended purpose fades away. A LCC analysis might also discover that construction materials that are renewable or energy-saving could deliver long-term economic savings

Figure 1.22: Life cycle for buildings

When choosing building materials, it is important to consider the embodied energy of products and materials. This holistic evaluation of embodied energy is a key factor used to assess the sustainability of a construction material or product. Sustainable materials and products have low levels of embodied energy. A material that is locally sourced and is relatively un-processed will have a low level of embodied energy. Materials that have high levels of embodied energy are generally not sustainable and should be avoided where possible. However, it is often the case that embodied energy of a material may be insignificant in comparison to its potential to save energy over the operational lifetime of the building. Raw and engineered timber that has been sustainably harvested and processed actually removes carbon from the atmosphere and stores it until and unless the timber is incinerated. Some concrete also can absorb carbon from the atmosphere. Also, materials like aluminum have very high embodied energy if refined from bauxite, but are easily recycled. For these reasons material selection for a building is complex and requires careful consideration to find and use materials which deliver on all aspects of sustainability.

Other ideas abound. Buildings can be designed in ways that limit heat absorption in the summer and maximize it in the winters, lowering energy expenditures. Neighborhoods and cities can be laid out in ways that maximize the usefulness of walking and public transit, or that minimize water consumption while remaining pleasant and green.

1.6.2.2 Adaptation

The goal of climate change adaptation is to engineer systems so that human activity can continue in an altered global climate. The consequences of climate change are both dire and highly unpredictable. Warmer oceans will generate more frequent and energy-intensive hurricanes. Melting antarctic and Greenlandic ice sheets will raise sea levels, inundating some coastal regions. Some areas will experience desiccation and drought, while others will see more frequent deluges. Glaciers and snowpack might be reduced or eliminated, threatening municipal water supplies.

At this point it is unlikely that all deleterious effects of climate change can be avoided. Engineers need to understand how climate change might affect their current practices, and how these practices might need to adapt. For example, a coastal structure might need to withstand elevated or more powerful tides resulting from rising sea levels. What used to be a 100-year storm could become 50- or 20-year storm, meaning that culverts and drainage systems need to be engineered for a considerably larger storm surge. Existing culverts and drainage systems might need to be prioritized for replacement.

1.6.2.3 Unintended Consequences

Sometimes attempts to improve the sustainability of a system can backfire, or can lead to unintended unsustainable consequences elsewhere in the system. This underlines the importance of considering entire systems when trying to improve sustainability.

Many have recognized that operating a transportation system primarily on fossil fuels is environmentally unsustainable, primarily as a result of air pollution and climate change caused by carbon dioxide emissions. So there is a major push to develop electric vehicles fueled partially or entirely by batteries that can be charged through the power grid.⁴ If all vehicles were electrified, it would go a long way to making the transportation system more environmentally sustainable. But this effort may backfire in other ways.

Batteries used in electric vehicles are made from rare earth metals including cobalt, lithium, and others. Over 50% of the earth’s reserves of cobalt are located in the Democratic Republic of the Congo, where rudimentary mining techniques have caused contaminated mine tailings to infiltrate the water supply, leading to birth defects and high rates of childhood cancer. As demand for these metals grows — largely driven by demand for high-capacity vehicle batteries — this system becomes unsustainable in its social dimension. And if more socially and environmentally sustainable mining practices were implemented, would the system become economically unsustainable, with costs for building electric vehicles exceeding what most people will pay? Or should engineers instead be looking for battery materials that are more sustainably sourced? There are not clear answers for this problem.

It is worth noting also that carbon emissions are only one area of many in which transportation by automobiles is unsustainable. Perhaps building cities in a way that makes transit or bicycling more feasible would be more sustainable on all of these dimensions, while also solving the transportation energy problem.

ASCE. 2021. “Policy Statement 518 - Unified Definitions for Critical Infrastructure Resilience.” https://www.asce.org/advocacy/policy-statements/ps518---unified-definitions-for-critical-infrastructure-resilience.

California Capitol Museum, State of. 2025. “The Dust Bowl, California, and the Politics of Hard Times.” https://capitolmuseum.ca.gov/exhibits/the-dust-bowl-california-and-the-politics-of-hard-times/.

ConstructionReviewOnline. 2024. “An in-Depth Look at Airport Operations and Construction Options.” https://constructionreviewonline.com/features/an-in-depth-look-at-airport-operations-and-construction-options/.

Copilot, GitHub. 2023. “GitHub Copilot: Your AI Pair Programmer.” https://copilot.github.com/.

Dewitte, Sharon N. 2010. “Age Patterns of Mortality During the Black Death in London, a.d. 1349-1350.” J Archaeol Sci 37 (12): 3394–3400. https://doi.org/10.1016/j.jas.2010.08.006.

Editors, HISTORY.COM. 2022. “Irish Potato Famine: Date, Cause & Great Hunger.” https://www.history.com/topics.

Environmental Excellence | AASHTO, Center for. 2024. “Environmental Process Overview.” https://environment.transportation.org/focus-areas/environmental-process/environmental-process-overview/.

Fields, Kristina, Steven Hart, and Lauren McBurnett. 2024. “The Center for Infrastructure Transformation and Education (CIT-e): Lesson 1 What Is Infrastructure and Why Do We Care?” https://www.cit-e.org/.

Hamidi, Shima, Reid Ewing, Ilana Preuss, and Alex Dodds. 2015. “Measuring Sprawl and Its Impacts: An Update.” Journal of Planning Education and Research 35 (1): 35–50.

Jones, David S., Scott H. Podolsky, and Jeremy A. Greene. 2012. “The Burden of Disease and the Changing Task of Medicine.” New England Journal of Medicine 366 (25): 2333–38. https://doi.org/10.1056/NEJMp1113569.

Kibert, Charles J. 2016. Sustainable construction: Green building design and delivery. John Wiley & Sons.

Liu, L. P.; Bechle, J.; Clark. 2021. “Disparities in Air Pollution Exposure in the United States by Race/Ethnicity and Income, 1990–2010.” Environmental Health Perspectives 129 (12): 127005. https://doi.org/10.1289/EHP8584.

Melillo, Jerry M, TT Richmond, G Yohe, et al. 2014. “Climate Change Impacts in the United States.” Third National Climate Assessment 52.

Seinfeld, John H, and Spyros N Pandis. 2016. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change. John Wiley & Sons.

U.S. Code. 2023. “Title 42, the Public Health and Welfare, Chapter 55, National Environmental Policy, Subchapter i, Policies and Goals.” https://www.govinfo.gov/content/pkg/USCODE-2023-title42/html/USCODE-2023-title42-chap55-subchapI.htm.

US DOT. 2025. “23 CFR 771.117 - Categorical Exclusions. Federal Highway Administration.” https://www.ecfr.gov/current/title-23/chapter-I/subchapter-H/part-771/section-771.117.

US EPA. 2003. “Federal Environmental Requirements for Construction.” https://nepis.epa.gov/Exe/ZyPDF.cgi/600004MA.PDF?Dockey=600004MA.PDF.

———. 2023. “Environmental Justice.” https://www.epa.gov/environmentaljustice.

———. 2024. “Construction Sector (NAICS 23).” https://www.epa.gov/regulatory-information-sector/construction-sector-naics-23.

———. 2025. “About NPDES. National Pollutant Discharge Elimination System (NPDES).” https://www.epa.gov/npdes/about-npdes.

Utah DEQ. 2025. “General Construction (Storm Water): UPDES Permits.” https://deq.utah.gov/water-quality/general-construction-storm-water-updes-permits.

Utah State University. 2025. “Construction Stormwater Best Management Practices.” https://extension.usu.edu/stormwater/construction/construction-stormwater-bmps.

Vanek, F. M., L. T. Angenent, J. H. Banks, R. A. Daziano, and M. A. Turnquist. 2014. Sustainable Transportation Systems Engineering. USA: McGraw-Hill Education.

---

1. Note that the CIT-E definition is consistent with the ASCE definition, but adds people to one of the components of infrastructure.

2. In some ways, no system on Earth can be considered infinitely sustainable, because in a few billion years the Sun will expand and incinerate our planet. And even if we should avoid that, the universe will eventually either lose all of its latent heat and tear itself apart in a great freeze, or collapse on itself in a excruciatingly and incomprehensibly dense inferno. So when we say “indefinitely,” we mean “for conceivable human generations to come.”

3. because historians didn’t exist before urbanization started

4. It’s easier to build a large solar power plant that can power up a battery than to make cars run on their own solar cells.