Living with Earth

An Introduction to Environmental Geology

Travis Hudson

• Éditeur: Routledge
• Année: 2016
• ISBN:
  9781315506593
• Édition: 1
• Sujet: Physical Sciences
• Sous-sujet: Geography

For many students with no science background, environmental geology may be one of the only science courses they ever take. Living With Earth: An Introduction to Environmental Geology is ideal for those students, fostering a better understanding of how they interact with Earth and how their actions can affect Earth's environmental health. The informal, reader-friendly presentation is organized around a few unifying perspectives: how the various Earth systems interact with one another; how Earth affects people (creating hazards but also providing essential resources); and how people affect Earth. Greater emphasis is placed on environment and sustainability than on geology, unlike other texts on the subject. Essential scientific foundations are presented - but the ultimate goal is to connect students proactively to their role as stakeholders in Earth's future.

FIGURE 1-1 Earth as Seen from Space

This photograph of Earth, known as “the blue marble,” was taken from Apollo 17 on December 7, 1972. What can you tell about our home from 55,000 kilometers away?

CHAPTER
1
WHAT DOES “LIVING WITH EARTH” MEAN?

In the early morning hours of December 7, 1972, the three-man crew of Apollo 17—Eugene Cernan, Ron Evans, and Harrison “Jack” Schmidt—blasted off to land a human on the Moon. At first they zoomed around Earth at 29,000 kilometers per hour (18,000 mph) in 90-minute orbits and the scenes below passed by very quickly. Then they left Earth’s orbit and headed for the Moon. About five hours after initial liftoff, and 55,000 kilometers (34,000 mi) into space, they took what is now the most widely distributed photograph in the world—it is shown in Figure 1-1.

NASA credits the entire Apollo 17 crew for this photograph, but Jack Schmidt probably snapped the picture. Schmidt, a geologist, was especially focused on observing Earth as they departed. He even gave weather descriptions as the crew sped away. But it was fellow astronaut Eugene Cernan who memorably radioed back to mission control, “… we’d like to confirm, from the crew of Apollo 17, that the world is round.”

At a distance of 55,000 kilometers, Earth is clearly a sphere. What else could you observe about Earth from that distance? If you were like Jack Schmidt, you could readily identify the continents, oceans, and regional features like the Red Sea. But what if you were a traveler from another galaxy, and the Apollo 17 vantage point of 55,000 kilometers away were as close as you would ever come to Earth? What would you observe then?

Look closely at the photo of Earth. You can probably distinguish the oceans from the continents. If you were completely unfamiliar with Earth, your first observations might identify:

1. Areas with swirling white patterns,

2. Large deep-blue and smooth expanses,

3. Brown or reddish-brown rough-looking areas, and

4. Green-tinted areas.

These very first observations identify the four basic components of Earth—(1) its atmosphere, with constantly moving and changing white clouds, (2) blue areas where waters of the hydrosphere cover the surface, (3) brownish landmasses of the geosphere, and (4) green areas where the living organisms that comprise the biosphere are abundant. Atmosphere, hydrosphere, geosphere, and biosphere are Earth’s four most basic components, or what we call Earth systems in this book, and they are readily apparent even from 55,000 kilometers away.

Perhaps more important, the “blue marble” in the photo shows that Earth is an isolated place. With a few exceptions, such as journeys like that of Apollo 17, people are stuck on the space-capsule Earth, and we are all doing a lot more than just going along for the ride.

IN THIS CHAPTER YOU WILL LEARN:

➧ How environmental geology is a part of your life

➧ How human population, resource consumption, and technology are factors that influence people’s impact on the environment

➧ The costs of Earth’s impacts, such as earthquakes and floods, on people

➧ How Earth systems are defined and how they interact

➧ How science works and how it will play a part in your future

➧ The meaning of sustainability and why it is important for people to achieve

1.1 Environmental Geology and You

Look again at the photo of Earth. What factors do you think significantly influence global environmental conditions, things like climate, air quality, and the availability of fresh water? Perhaps surprisingly, one of the most important turns out to be the part of the biosphere that includes you—people! People are so numerous and cause so many changes in Earth’s systems that they now influence environmental conditions on a global scale. And in turn, Earth systems affect people. Thousands of people die each year in earthquakes, floods, and other natural disasters. Environmental studies relate to you because Earth and people interact, and those interactions have consequences.

Environmental geology is the part of Earth Science that studies the interactions between people and Earth. It is rooted in understanding the natural processes that shape and change Earth, processes that cause earthquakes, landslides, or floods, for example (Figure 1-2a). Environmental geology also investigates how people affect Earth, especially through their use of natural resources (such as soil, fuel, minerals, air, and water) and by the manner in which they dispose of their wastes. By studying environmental geology, we learn to become better stewards of our planet and its life-sustaining natural resources.

The “environment” in environmental geology is broadly defined. It includes all the physical and biological components that people commonly associate with the word environment, such as rivers, mountains, and forests. It also includes the changes people make to Earth, such as damming rivers to control floods, clearing forests to create farms, or constructing buildings, roads, bridges, and the rest of the infrastructure that supports our communities (Figure 1-2b). As we consider the parts of the environment that people create or change, we will also consider the personal, social, economic, cultural, and political factors that shape human actions. Thus, “environment” in the context of environmental geology encompasses all of the natural and human factors that have come to shape the world.

The goal of Living with Earth is to help you understand and, more important, use the information it contains. Studying environmental geology is not merely an academic exercise. People enter this field specifically to help other people and the planet. The lessons people have learned, sometimes in difficult ways, are valuable guidelines for you.

This book emphasizes four central themes to help you understand and apply what people have learned about living with Earth:

1.How people and Earth interact.

2.How Earth systems interact with each other.

3.How science helps people to understand and deal with issues related to Earth, and

4.How people can take steps to achieve a sustainable future.

The idea of sustainability is a critical concept in environmental studies and is one that we will use as a measure throughout Living with Earth. To say that something is sustainable means that it is capable of being continued with minimal long-term effect on the environment (Figure 1-3). In the context of people, it means that the needs of the present generation are met without compromising the ability of future generations to meet their needs. Thus, making good choices about how we live on and interact with Earth will help to determine the future of our planet.

FIGURE 1-2 Earth Affects People; People Change Earth

(a) Earth systems processes shape and change Earth, creating natural hazards such as severe floods, (b) But people also influence Earth—for example, by damming rivers to control floods, provide irrigation, and generate electric power.

FIGURE 1-3 Many Natural Resources Can Be Sustained

On farms like this experimental agricultural station in Peru, crops, fertilizers, irrigation methods, and tilling practices are carefully chosen to help maintain the soil’s quality. |Sustainable agriculture research and education

1.2 How People and Earth Interact

Virtually everything people do has environmental consequences. How people provide food for themselves, how they construct buildings, how they move about, and where they choose to live all affect the environment in some way. Everyone on Earth is a player in this interaction, and the number of players is unfathomably large and growing.

HUMAN POPULATION

Do you know how many people you are going to have to share Earth with? Although predictions of future population require several assumptions, especially about the rates at which people are born and die, we can study general trends. As you can see in Figure 1-4, the human population grew faster than ever before during the last few hundred years. The highest average growth rate (birth rate minus death rate) of 2.1% was in the 1960s, and the greatest number of people added in a year, 86 million, was in the 1980s. At the end of 2008, the world population totaled 6.7 billion, and it was increasing by about 80 million people per year—a rate of 1.2%.

Concerns about the impact of an increasing number of people are having an effect on the number of births around the world. For example, many developed countries, such as Japan and most European countries, have essentially stable populations. Population growth has also been stemmed in Latin America, where more than 60% of the women of childbearing age (15–49) use some sort of modern contraception. National policies and economic changes in China have lowered that country’s population growth rate from 2.6% in 1969 to 0.6% in 2004. The U.S. Census B...