- Distinguish between renewable and nonrenewable resources.
- Describe threats to soil and water resources.
- Identify the causes and effects of air pollution.
- Explain global climate change.
low-pH precipitation that forms with air pollution combines with water
chemical substances and particles released into the air mainly by human actions such as burning fossil fuels
excessive growth of algae in bodies of water because of high levels of nutrients, usually from fertilizer in runoff
area in the ocean or other body of water where low oxygen levels from excessive growth of algae have killed all aquatic organisms
recent rise in Earth’s average surface temperature generally attributed to an increased greenhouse effect
natural feature of Earth’s atmosphere that occurs when gases in the atmosphere radiate the sun’s heat back down to Earth’s surface, making Earth’s temperature far warmer than it otherwise would be
something supplied by nature that helps support life
natural resource that exists in a fixed amount and can be used up
hole in the ozone layer high in the atmosphere over Antarctica caused by air pollution destroying ozone
natural resource that can be replenished by natural processes as quickly as humans use it
mixture of eroded rock, minerals, organic matter, and other materials that is essential for plant growth and forms the foundation of terrestrial ecosystems
use of resources in a way that meets the needs of the present and also preserves the resources for the use of future generations
A natural resource is something supplied by nature that helps support life. When you think of natural resources, you may think of minerals and fossil fuels. However, ecosystems and the services they provide are also natural resources. Biodiversity is a natural resource as well.
Renewable and Nonrenewable Resources
From the human point of view, natural resources can be classified as renewable or nonrenewable.
Renewable resources can be replenished by natural processes as quickly as humans use them. Examples include sunlight and wind. They are in no danger of being used up (see Figure below). Metals and other minerals are renewable too. They are not destroyed when they are used and can be recycled.
Wind is a renewable resource. Wind turbines like this one harness just a tiny fraction of wind energy.
Living things are considered to be renewable. This is because they can reproduce to replace themselves. However, they can be over-used or misused to the point of extinction. To be truly renewable, they must be used sustainably. Sustainable use is the use of resources in a way that meets the needs of the present and also preserves the resources for future generations.
Nonrenewable resources are natural resources that exist in fixed amounts and can be used up. Examples include fossil fuels such as petroleum, coal, and natural gas. These fuels formed from the remains of plants over hundreds of millions of years. We are using them up far faster than they could ever be replaced. At current rates of use, petroleum will be used up in just a few decades and coal in less than 300 years. Nuclear power is also considered to be a nonrenewable resource because it uses up uranium, which will sooner or later run out. It also produces harmful wastes that are difficult to dispose of safely.
Soil and Water Resources
Theoretically, soil and water are renewable resources. However, they may be ruined by careless human actions.
Soil is a mixture of eroded rock, minerals, partly decomposed organic matter, and other materials. It is essential for plant growth, so it is the foundation of terrestrial ecosystems. Soil is important for other reasons as well. For example, it removes toxins from water and breaks down wastes.
Although renewable, soil takes a very long to form—up to hundreds of millions of years. So, for human purposes, soil is a nonrenewable resource. It is also constantly depleted of nutrients through careless use and eroded by wind and water. For example, misuse of soil caused a huge amount of it to simply blow away in the 1930s during the Dust Bowl (see Figure below). Soil must be used wisely to preserve it for the future. Conservation practices include contour plowing and terracing. Both reduce soil erosion. Soil also must be protected from toxic wastes.
The Dust Bowl occurred between 1933 and 1939 in Oklahoma and other southwestern U.S. states. Plowing had exposed prairie soil. Drought turned the soil to dust. Intense dust storms blew away vast quantities of the soil. Much of the soil blew all the way to the Atlantic Ocean.
Water is essential for all life on Earth. For human use, water must be fresh. Of all the water on Earth, only 1 percent is fresh, liquid water. Most of the rest is either salt water in the ocean or ice in glaciers and ice caps.
Although water is constantly recycled through the water cycle, it is in danger. Over-use and pollution of freshwater threaten the limited supply that people depend on. Already, more than 1 billion people worldwide do not have adequate freshwater. With the rapidly growing human population, the water shortage is likely to get worse.
KQED: Are We in Danger of Running Out of Water?
California's population is growing by 600,000 people a year, but much of the state receives as much annual rainfall as Morocco. With fish populations crashing, global warming, and the demands of the country's largest agricultural industry, the pressures on our water supply are increasing. Are we in danger of running out of water? See http://www.kqed.org/quest/television/state-of-thirst-californias-water-future for additional information.
Too Much of a Good Thing
Water pollution comes from many sources. One of the biggest sources is runoff. Runoff picks up chemicals such as fertilizer from agricultural fields, lawns, and golf courses. It carries the chemicals to bodies of water. The added nutrients from fertilizer often cause excessive growth of algae, creating algal blooms (see Figure below). The algae use up oxygen in the water so that other aquatic organisms cannot survive. This has occurred over large areas of the ocean, creating dead zones, where low oxygen levels have killed all ocean life. A very large dead zone exists in the Gulf of Mexico. Measures that can help prevent these problems include cutting down on fertilizer use. Preserving wetlands also helps because wetlands filter runoff.
Algal Bloom. Nutrients from fertilizer in runoff caused this algal bloom.
The atmosphere plays an important part in maintaining Earth’s freshwater supply. It is part of the water cycle. It refills lakes and rivers with precipitation. The atmosphere also provides organisms with gases needed for life. It contains oxygen for cellular respiration and carbon dioxide for photosynthesis.
Earth’s atmosphere is vast. However, it has been seriously polluted by human activities. Air pollution consists of chemical substances and particles released into the atmosphere, mainly by human actions. The major cause of outdoor air pollution is the burning of fossil fuels. Power plants, motor vehicles, and home furnaces all burn fossil fuels and contribute to the problem (see Table below). Ranching and using chemicals such as fertilizers also cause air pollution. Erosion of soil in farm fields and construction sites adds dust particles to the air as well. Fumes from building materials, furniture, carpets, and paint add toxic chemicals to indoor air.
Sulfur oxides (SOx)
Coal-fired power plants
Nitrogen oxides (NOx)
Motor vehicle exhaust
Carbon monoxide (CO)
Motor vehicle exhaust
Carbon dioxide (CO2)
All fossil fuel burning
Particulate matter (smoke, dust)
Wood and coal burning
Respiratory disease, Global Dimming
Coal-fired power plants, medical waste
Respiratory problems; eye irritation
Motor vehicle exhaust
Respiratory problems; eye irritation
In humans, air pollution causes respiratory and cardiovascular problems. In fact, more people die each year from air pollution than automobile accidents. Air pollution also affects ecosystems worldwide by causing acid rain, ozone depletion, and global warming. Ways to reduce air pollution from fossil fuels include switching to nonpolluting energy sources (such as solar energy) and using less energy. What are some ways you could use less energy?
All life relies on a relatively narrow range of pH, or acidity. That’s because protein structure and function is very sensitive to pH. Air pollution can cause precipitation to become acidic. Nitrogen and sulfur oxides—mainly from motor vehicle exhaust and coal burning—create acids when they combine with water in the air. The acids lower the pH of precipitation, forming acid rain. If acid rain falls on the ground, it may damage soil and soil organisms. If it falls on plants, it may kill them (see Figure below). If it falls into lakes, it lowers the pH of the water and kills aquatic organisms.
Effects of Acid Rain. These trees in a European forest were killed by acid rain.
There are two types of ozone. You can think of them as bad ozone and good ozone. Both are affected by air pollution.
- Bad ozone forms near the ground when sunlight reacts with pollutants in the air. Ground-level ozone is harmful to the respiratory systems of humans and other animals.
- Good ozone forms in a thin layer high up in the atmosphere, between 15 and 35 kilometers above Earth’s surface. This ozone layer shields Earth from most of the sun’s harmful UV radiation. It plays an important role in preventing mutations in the DNA of organisms.
Unfortunately, the layer of good ozone is being destroyed by air pollution. The chief culprits are chlorine and bromine gases. They are released in aerosol sprays, coolants, and other products. Loss of ozone has created an ozone hole over Antarctica. Ozone depletion results in higher levels of UV radiation reaching Earth. In humans, this increases skin cancers and eye cataracts. It also disturbs the nitrogen cycle, kills plankton, and disrupts ocean food webs. The total loss of the ozone layer would be devastating to most life. It’s rate of loss has slowed with restrictions on pollutants, but it is still at risk.
Global Climate Change
Another major problem caused by air pollution is global climate change. Gases such as carbon dioxide from the burning of fossil fuels increase the natural greenhouse effect. This raises the temperature of Earth’s surface.
What Is the Greenhouse Effect?
The greenhouse effect is a natural feature of Earth’s atmosphere. It occurs when gases in the atmosphere radiate the sun’s heat back down to Earth’s surface (see Figure below). Otherwise, the heat would escape into space. Without the greenhouse effect, Earth’s surface temperature would be far cooler than it is. In fact, it would be too cold to support life as we know it.
The Greenhouse Effect. Without greenhouse gases, most of the sun’s energy would be radiated from Earth’s surface back out to space.
Global warming refers to a recent increase in Earth’s average surface temperature (see Figure below). During the past century, the temperature has risen by almost 1°C (about 1.3°F). That may not seem like much. But consider that just 10°C is the difference between an ice-free and an ice-covered Earth.
The average annual temperature on Earth has been rising for the past 100 years.
Most scientists agree that global warming is caused by more carbon dioxide in the atmosphere (see Figure below). This increases the greenhouse effect. There is more carbon dioxide mainly because of the burning of fossil fuels. Destroying forests is another cause. With fewer forests, less carbon dioxide is removed from the atmosphere by photosynthesis.
This graph shows the recent trend in carbon dioxide in the atmosphere.
Effects of Climate Change
How has global warming affected Earth and its life? Some of its effects include:
- Decline in cold-adapted species such as polar bears.
- Melting of glaciers and rising sea levels.
- Coastal flooding and shoreline erosion.
- Heat-related human health problems.
- More droughts and water shortages.
- Changing patterns of precipitation.
- Increasing severity of storms.
- Major crop losses.
These two videos discuss some of the consequences from changes in ecosystems: http://www.youtube.com/watch?v=jHWgWxDWhsA (7:47) and http://www.youtube.com/watch?v=5qblwORXwrg (2:26).
KQED: Climate Watch: California at the Tipping Point
The world's climate is changing and California is now being affected in both dramatic and subtle ways. In 2008, scientists determined that California’s temperatures increased by more than 2.1°F during the last century. What’s more, the data showed that human activity has played a significant role in that climate change. "What's just 2 degrees?" you may wonder. But, as the science shows, just 2 degrees is extremely significant.
What does all this temperature change mean? For starters, declining mountain snowpack and prolonged drought conditions could pose a threat to limited water supplies. Heat waves are projected to be longer, bringing increased danger from wildfires and heat-related deaths. Rising sea levels due to temperature shifts jeopardize life in coastal areas, both for human communities and the plants and animals that rely on intertidal and rich wetland ecosystems. Also, more precipitation is expected to fall as rain rather than snow, thereby increasing the risk of floods. And, as heat increases the formation of smog, poor air quality could get even worse.
Climate change may also profoundly affect the economy in California and elsewhere. Shorter ski seasons and damage to the marine ecosystem mean a reduction in tourism. Water shortages mean issues with the commercial and recreational fishing industry, and higher temperatures will affect crop growth and quality, weakening the agricultural industry, to name just a few of the economic issues associated with climate change.
Get an in-depth look at the science behind climate change at http://www.kqed.org/quest/television/climate-watch-california-at-the-tipping-point-part-one.
KQED: Giant Redwoods and Global Warming
Forest ecologist Steve Sillett is leading a team of scientists as they climb and measure every branch of some of the last and tallest old growth redwoods in California. Their goal is to learn how these ancient giants have historically responded to climatic shifts and to monitor how they are being impacted today by global warming. See http://www.kqed.org/quest/television/science-on-the-spot-measuring-redwood-giants for additional information.
KQED: Acidic Seas
Melting glaciers, rising temperatures and droughts are all impacts of global warming. But how does global warming actually affect the oceans? The sea, it turns out, absorbs carbon dioxide emissions. The ocean acts like a giant sponge, absorbing carbon dioxide emissions from the air. And as we add more and more carbon dioxide to air by burning fossil fuels, the ocean is absorbing it. On one level, it's done us a big favor. Scientists say that we would be experiencing much more extreme climate change were it not for the ocean's ability to remove the heat-trapping gas. However, these emissions are causing the oceans to become more acidic. Changing pH levels threaten entire marine food webs, from coral reefs to salmon. See http://www.kqed.org/quest/radio/acidic-seas for additional information.
What Can Be Done?
Efforts to reduce future global warming mainly involve energy use. We need to use less energy, for example, by driving more fuel-efficient cars. We also need to switch to energy sources that produce less carbon dioxide, such as solar and wind energy. At the same time, we can increase the amount of carbon dioxide that is removed from air. We can stop destroying forests and plant new ones.
KQED: Earth Day
Earth Day Network's mission is to broaden, diversify and activate the environmental movement worldwide, driving action year-round through a combination of education, public policy, and consumer campaigns. See http://www.earthday.org/ for additional information.
Each year, April 22 marks the anniversary of what many consider the birth of the modern environmental movement in 1970. The idea came to Earth Day founder Gaylord Nelson, then a U.S. Senator from Wisconsin, after witnessing the ravages of the 1969 massive oil spill in Santa Barbara, California. On the 22nd of April, 20 million Americans took to the streets, parks, and auditoriums to demonstrate for a healthy, sustainable environment in massive coast-to-coast rallies. Thousands of colleges and universities organized protests against the deterioration of the environment. Groups that had been fighting against oil spills, polluting factories and power plants, raw sewage, toxic dumps, pesticides, freeways, the loss of wilderness, and the extinction of wildlife suddenly realized they shared common values.
As 1990 approached, a group of environmental leaders organized another big campaign. This time, Earth Day went global, mobilizing 200 million people in 141 countries and lifting environmental issues onto the world stage. Earth Day 1990 gave a huge boost to recycling efforts worldwide and helped pave the way for the 1992 United Nations Earth Summit in Rio de Janeiro.
As the year 2000 approached, 5,000 environmental groups in a record 184 countries reached out to hundreds of millions of people. Earth Day 2000 used the Internet to organize activists, but also featured a talking drum chain that traveled from village to village in Gabon, Africa, and hundreds of thousands of people gathered on the National Mall in Washington, DC. Earth Day 2000 sent world leaders the loud and clear message that citizens around the world wanted quick and decisive action on clean energy.
In 2010, the Earth Day Network reestablished Earth Day as a powerful focal point around which people could demonstrate their commitment. The Earth Day Network brought 225,000 people to the National Mall for a Climate Rally, amassed 40 million environmental service actions toward its 2012 goal of A Billion Acts of Green, launched an international, 1-million tree planting initiative with Avatar director James Cameron, and tripled its online base to over 900,000 members. The fight for a clean environment continues in a climate of increasing urgency, as the ravages of climate change become more manifest every day.
See http://www.kqed.org/quest/television/earth-day-tv-special-where-weve-been-where-were-headed for more information on California's environmental movement.
- Renewable resources can be replaced by natural processes as quickly as humans use them. Examples include sunlight and wind. Nonrenewable resources exist in fixed amounts. They can be used up. Examples include fossil fuels such as coal.
- Soil and water are renewable resources but may be ruined by careless human actions. Soil can be depleted of nutrients. It can also be eroded by wind or water. Over-use and pollution of freshwater threaten the limited supply that people depend on.
- Air pollution consists of chemical substances and particles released into the air, mainly by human actions. The major cause of outdoor air pollution is the burning of fossil fuels. Indoor air can also be polluted. Air pollution, in turn, causes acid rain, ozone depletion, and global warming.
- Gases such as carbon dioxide from the burning of fossil fuels increase the natural greenhouse effect. This is raising the temperature of Earth’s surface, and is called global warming.
Lesson Review Questions
1. Define natural resource.
2. Distinguish between renewable and nonrenewable resources and give examples.
3. Summarize the environmental effects of burning fossil fuels.
4. How does air pollution contribute to global warming?
5. How could you create a three-dimensional model of the greenhouse effect? What processes would you demonstrate with your model? What materials would you use?
6. Apply lesson concepts to explain the relationship between the graphs in Figure above and Figure above
7. Infer factors that determine whether a natural resource is renewable or nonrenewable.
8. Why would you expect a dead zone to start near the mouth of a river, where the river flows into a body of water?
9. Explain how air pollution is related to acid rain and ozone depletion.
Points to Consider
Microorganisms such as bacteria are important living resources in all ecosystems. They recycle nutrients and other matter.
- What do you know about microorganisms? Besides bacteria, are there other types of microorganisms?
- Are viruses microorganisms? Are they living things?
Opening image courtesy of Metatron (http://en.wikipedia.org/wiki/File:Ocellaris_clownfish.JPG) and under the Creative Commons license CC-BY-SA 3.0.