Thermal Balance

How This Affects Climate

The dominant effect that triggered the ice ages was orbital conditions that favored reduced sunlight during summer seasons in the northern hemisphere. This resulted in accumulation over time of increased reflective layers of ice that promoted further cooling. The Milkanovich cycles provide a good explanation of the historical 100,000-year cycle in ice ages. The combined effect of these natural cycles is a variation in the sun's energy that reaches the earth at different times and in different...

Solar Electricity Photovoltaics

Global Thermal Balance

Enough energy from the sun strikes the earth in 1 hour to provide all the energy consumed by the earth's entire population in 1 year. In most places, sufficient sunlight strikes the earth's surface to power an (energy-efficient) home and support a plug-in hybrid car. Solar energy stands out as an opportunity that overshadows all the other renewable energy sources and fossil fuels combined. Today, only a small fraction of this vast potential has been exploited. Solar cells were developed (by...

Review Questions

On average, how often is a new large coal-fired electricity power plant currently coming online in China 2. Which of the following is an example of carbon sequestration (a) Turning coal to more efficient syngas (b) Replacing coal-fired plants with alternative sources of energy (c) Capturing and storing the carbon dioxide from a coal-fired plant and sending it to an abandoned coal mine (d) Using natural gas instead of coal 3. Which of the following does not produce greenhouse gases 4. Which of...

Burning Coal More Efficiently

Standard coal-fired electricity-generating plants burn the coal in air, which consists of nearly 80 percent nitrogen gas. The heat generated produces steam, which turns a turbine, which turns a generator. Removal of the carbon dioxide from the gas stream is difficult because of the large amount of nitrogen gas that is also coming out of the smokestack. A more advanced approach to burning coal is called integrated gasification combined cycle (IGCC). In this approach, the coal is first treated...

Sunspot Cycles

In order to identify how much human activities are influencing the temperature of the earth, it is important to isolate changes that would be taking place without the presence of humans. Accurate measurements of solar output date back only as far as 1978, when satellites began measuring solar intensity outside the interfering influence of the earth's atmosphere. Details about how these satellites monitor the various aspects of the earth's climate can be found in Appendix C. Satellite...

Burning Fossil Fuels

The fossil fuels are coal, oil, and natural gas. The name fossil fuels derives from the origin of these fuels from the remains of organic matter preserved from prehistoric times. Most of our energy used for electricity and transportation today comes from the burning of fossil fuels, which generates carbon dioxide as a by-product. As a result of fossil fuel combustion, carbon dioxide in the atmosphere is now 35 percent higher than it was a century and a half ago. Whenever anything containing...

Plugin Hybrids Producing Much Less Carbon Dioxide

How about taking a hybrid car and putting in an even higher-performance battery that can be charged when the vehicle is not in operation A supersized battery would reduce the need for the gasoline engine substantially. Basically, this would be an electric car with a small gasoline motor to supplement the power of the electric motor the small percentage of the time that greater acceleration is needed. The gasoline motor also would extend the range of the vehicle so that it could continue back...

Causes For Thermal Balance

Salinity, ocean, 36-37, 63, 102-103, 172 SAM (southern annular mode), 99-100 detecting infrared radiation with, 78 determining global temperature with, 25-27 monitoring weather climate with, 253-255 sea levels with gauges, 37-38 with satellites, 39-40 movements of earth oceans, 40 rising increasing liquid volume, 63 populations most at risk from, 163-164 rate of, 161-162 thermal expansion, 40-41, 63 sea surface temperatures, 34-35, 63, 99 seasonal layers, 16-18 semiconductor lighting, 192...

Lingering Doubts and Concerns

Concern How can we be sure the average global temperatures are really increasing Response Temperature measurements collected from around the world show that the atmosphere and sea surface temperatures are increasing. These data were presented in Chapter 2 and show a statistically significant pattern of increasing temperature. Concern If the Earth is warming, how come some places are getting colder Response Heat is constantly redistributed across the Earth after it is received from the sun. The...

Basic Uncertaintieswhere The Jury Is Still

In science, it is usually valuable to know what you do not know. Defining the limitations of knowledge clarifies areas for follow-up effort and separates logical Table 7-4 Likelihood of Various Trends Table 7-4 Likelihood of Various Trends Likelihood that Trend Occurred in the Late Twentieth Century Likelihood of a Human Contribution to Observed Trend Likelihood of Future Trends in the Twenty-First Century Warmer and fewer cold days and nights (over land areas) Warmer and more frequent hot days...

Ethanol Corn Sugar Cellulose

Ethanol, or grain alcohol, can be produced from corn, sugar beets, sugar cane, or other crops primarily by fermentation. Ethanol came onto the scene largely as a means of moving toward energy independence. Brazil currently uses ethanol to meet an estimated 40 percent of its transportation requirements. Presently, roughly 20 percent of the corn grown in the United States is converted to ethanol. Current farming methods use a high percentage of petrochemicals, which to some extent defeats the...

Absorption of Light by Gases in the Atmosphere

Fossil fuels are a concern because they increase the absorption of incoming solar radiation above the amount absorbed naturally. This is referred to as the enhanced greenhouse effect. When a gas molecule absorbs energy, it has no place to store that energy other than in some form of movement of the molecule itself. According to the kinetic theory of matter, molecules are constantly in motion. The molecules move faster when their temperature goes up. Gas molecules in the atmosphere can absorb...

Origin and Impact of Greenhouse Gases

The climate of the earth has gone through a recurring pattern of temperature changes which has brought the earth in and out of a series of historic ice ages. Gases in the atmosphere also have ebbed and flowed with the temperature cycles. However, the levels of greenhouse gases building up in the atmosphere today have never been this high throughout Earth's history. This chapter will explore where these greenhouse gases are coming from and how they are driving climate changes. There are several...

Overall Impactradiative Forcing

Scientists have developed a way to compare the various factors affecting the earth's temperature based on the idea of radiative forcing. We know that the sun delivers solar power at a rate of 1370 W for every square meter of surface. The total impact of human activities adds 1.6 W m2 to this value. A positive forcing tends to make the earth warmer. A negative forcing offsets the positive factors and contributes a cooling effect. According to the Intergovernmental Panel on Climate Change (IPCC),...