chapter 19Review
In this chapter, we learned the distinctions among global change, global climate change, and global warming. Global warming is an inherently natural process whereby a tiny percentage of gases in the atmosphere, known as greenhouse gases, absorb infrared radition from Earth and emit some of this energy back to Earth. This warms the planet. Environmental scientists are concerned that human activities have caused a higher concentration of greenhouse gases in the atmosphere that is responsible for a gradual warming of the planet above that observed a century ago. The average amount of warming around the world has been relatively small at 0.8°C but some regions such as high northern latitudes have experienced increases of up to 4°C. This warming has caused a decline in polar ice, a decline in glaciers, an increased thawing of permafrost, and an increase in sea level. It has also affected the timing of plant flowering, bird migration, insect emergence, and the length of growing seasons. While these effects have already been observed, other climate changes are also predicted to occur including more extreme temperatures, more instense storms, changing patterns of precipitation, and altered ocean current. The Kyoto Protocol was designed to reduce the global emissions of greenhosue gases, but the goal set by nations around the world has not yet been achieved.
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Module 62 Global Climate Change and the Greenhouse Effect
Distinguish among global change, global climate change, and global warming.
Global change refers to changes in the chemical, biological, and physical properties of the planet. One aspect of this is global climate change, which refers more specifically to the average weather that occurs in an area over a period of years or decades. One aspect of global climate change is global warming, which refers to the warming of the oceans, land masses, and atmosphere.
Explain the process underlying the greenhouse effect.
The greenhouse effect occurs when high-
Identify the natural and anthropogenic sources of greenhouse gases.
The natural and anthropogenic sources of greenhouse gases include water vapor, carbon dioxide, methane, and nitrous oxide. Chlorofluorocarbons are a type of greenhouse gas that only has an anthropogenic source.
Module 63 The Evidence for Global Warming
Explain how CO2 concentrations have changed over the past 6 decades and how emissions compare among the nations of the world.
CO2 concentrations have continually increased since atmospheric measurements first began in 1958. These concentrations have increased from 310 ppm in 1958 to nearly 400 ppm in 2013. The major producers of CO2 include large developed countries, such as the United States and Russia, and rapidly growing developing countries, such as China and India. When we consider the per capita production of CO2, we see that some of the largest producers of CO2 have relatively low per capita production of CO2.
Explain how temperatures have increased since records began in 1880.
Direct measurements of land and sea temperatures have taken place since 1880. Averaged across the globe, mean annual temperatures have increased by 0.8°C. However, some regions have become a bit cooler while other regions have become much warmer with increases up to 4°C.
Discuss how we estimate temperatures and greenhouse gases over the past 500,000 years and into the future.
To estimate changes in global temperatures over 500,000 years, we can use changes in the species composition of foraminifera that are found in ocean sediments. We can also examine the ratio of 16O and 18O atoms in the air bubbles that are preserved in ancient ice. These air bubbles can also be used to determine the concentrations of various greenhouse gases from different time periods in the past. We can predict future climate changes using climate models designed to understand processes that affect climate, such as air and ocean temperatures, CO2 concentration, extent of vegetation, and sea ice coverage at the poles. The models use estimates about how changes in these factors will change in the future to predict how climates will change.
Explain the role of feedbacks on the impacts of climate change.
Feedbacks in the environment can be either positive or negative. Positive feedbacks, such as global warming that causes higher rates of soil decomposition, can amplify the effects of global warming. Negative feedbacks, such as plants responding to increased CO2 concentrations, can reduce the effects of global warming.
Module 64 The Consequences of Global Climate Change
Discuss how global climate change has affected the environment.
Global warming has already caused a decline in the ice mass of the Arctic polar ice cap and in Antarctica and Greenland. It has also caused a decline in glaciers around the world, an increase in the thawing of permafrost, and an increase in sea level.
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Explain how global climate change has affected organisms.
Warmer global temperatures have caused longer growing seasons. Warmer temperatures have also caused many species of plants to flower earlier, and they have changed the times when animals breed and insects emerge.
Identify the future changes predicted to occur with global climate change.
Future global changes include longer periods of cold and warm temperatures, more intense storms, changes in global precipitation patterns, and the alteration of ocean currents. These changes may not only affect wild plants and animals but also may influence where humans can live and how humans are affected by diseases.
Explain the global climate change goals of the Kyoto Protocol.
The Kyoto Protocol is an international agreement to reduce the concentrations of greenhouse gases by 5.2 percent below 1990 levels by 2012. Different developed countries agreed to different emission limits and the protocol did not impose emission limits for developing countries. Today, some developed countries have accomplished substantial reductions in the emissions whereas others have not. Collectively, the global goal has not been met.