1. According to the text, volcanoes such as Mount Pinatubo may affect global temperatures

    a. because they produce so much heat during eruption.
    b. by increasing the amount of insolation received at the surface of the Earth.
    c. by increasing atmospheric albedo and absorbing insolation, thus causing cooling at the surface by reducing insolation input.
    d. by clearing the atmosphere of aerosols.
    e. by eliminating the vegetation in large areas via lava flows and explosions, thereby decreasing the Earth's albedo.

2. Based on principles discussed earlier in the course, you know that if the Earth's axial tilt were to decrease from 23.5 degrees to 21.5 degrees

    a. winters would become colder.
    b. summers would become hotter.
    c. seasonal temperatures would become less extreme.
    d. temperatures would not change at all from season to season.
    e. cities in higher elevations would receive more sunlight.

3. Over the past 100 years, the average global temperature has

    a. remained constant.
    b. risen about 0.7 C degrees.
    c. decreased about 0.7 C degrees.
    d. been so variable as to show no trend of increase or decrease.
    e. increased during and immediately after years with significant volcanic activity.

4. Presently the perihelion of the Earth's orbit occurs during January, while the perihelion 9000 years ago was during July. How does this orbital variation affect climate in the northern hemisphere?

    a. Winters are warmer and summers are cooler now than 9000 years ago.
    b. Winters are cooler and summers are warmer now than 9000 years ago.
    c. There is greater seasonality now than 9000 years ago.
    d. This orbital variation has no influence on climate in the northern hemisphere.
    e. Both winters and summers are cooler now than 9000 years ago.

5. The shape of the Earth's orbit around the sun varies from circular to elliptical. The changing eccentricity causes long-term climate variability by

    a. directly altering the oceanic current patterns.
    b. directly altering the amount of greenhouse gases in the atmosphere.
    c. directly altering the tilt of the Earth's axis of rotation.
    d. directly altering the seasonal variation of insolation on the globe as a whole.
    e. directly altering volcanic activity, thus influencing the dust and aerosol content of the atmosphere.

6. Precession ("wobble") of the Earth on its axis has a cycle of ________ years, and influences climate by _______.

    a. 26,000; determining which hemisphere contains the subsolar point, and thus the highest energy input, during which month.
    b. 40,000; determining the angle that the Earth's axis describes relative to the ecliptic, and thus the degree of seasonality.
    c. 100,000; determining the shape of the Earth's orbit, and thus the distance from the Earth to the sun which in turn determines the amount of energy input.
    d. 7; altering the energy output from the sun.
    e. between 2 and 11; determining the temperature of the equatorial eastern Pacific ocean and thus some aspects of global atmospheric circulation.

7. Eccentricity of the Earth's orbit has a cycle of __________ years, and influences climate by ______.

    a. 26,000; determining which hemisphere contains the subsolar point, and thus the highest energy input, during which month.
    b. 40,000; determining the angle that the Earth's axis describes relative to the ecliptic, and thus the degree of seasonality.
    c. 100,000; determining the shape of the Earth's orbit, and thus the distance from the Earth to the sun which in turn determines the amount of energy input.
    d. 7; altering the energy output from the sun.
    e. etween 2 and 11; determining the temperature of the equatorial eastern Pacific ocean and thus some aspects of global atmospheric circulation.

8. Obliquity of the Earth's axis varies with a cycle of _________ years, and influences climate by _______.

    a. 26,000; determining which hemisphere contains the subsolar point, and thus the highest energy input, during which month.
    b. 40,000; determining the angle that the Earth's axis describes relative to the ecliptic, and thus the degree of seasonality.
    c. 100,000; determining the shape of the Earth's orbit, and thus the distance from the Earth to the sun which in turn determines the amount of energy input.
    d. 7; altering the energy output from the sun.
    e. between 2 and 11; determining the temperature of the equatorial eastern Pacific ocean and thus some aspects of global atmospheric circulation.

9. The dominant feature of global climate over the past 2 million years is

    a. its stability.
    b. its long-term cooling trend.
    c. the slow rate at which it changes.
    d. its extreme variability and rapidity of change.
    e. that it is insensitive to changes in forcing factors such as Milankovitch cycles.

10. A glacial period takes about ________ years to develop, whereas an interglacial period usually lasts about _______ years.

    a. 1,000; 100
    b. 1,000,000; 100,000
    c. 10,000; 90,000
    d. 90,000; 10,000
    e. 10,500; 50

11. According to the text, a study called the CLIMAP project estimates that average sea-surface temperatures 18,000 years ago were

    a. 15 C degrees (27 F) lower than they are today.
    b. 1.4 C deg. (2.5 F) lower in february and 1.7 C deg. (3 deg F) lower in August.
    c. similar to today's temperatures.
    d. 1.7 C deg. (3 F) warmer in February and 1.4 C deg. (2.5 F) cooler in August.
    e. warmer than today's air temperature.

11. Which of the following is not true?

    a. A typical ice age includes periods of warming above those of the severest cold periods.
    b. During most of Earth's history, the planet has been much cooler than it has been during the last two million years.
    c. Modern humans and our immediate ancestors (Homo erectus and Homo sapiens) lived during a climate anomaly.
    d. Our current era is an interglacial of an ice age.
    e. No matter what we do in terms of carbon management (e.g. decreasing the burning of fossil fuels), global climate will change.

12. A very important seasonal process that determines the extent of glacial coverage worldwide is

    a. how warm the summer is - more ice melts in hot summers melt while ice always accumulates in the winter.
    b. how cold the winter is - more ice accumulates in colder winters while the same amount of ice melts no matter how hot the summer is.
    c. how warm the winter is - less ice accumulates in warmer winters while the same amount of ice melts no matter how hot the summer is.
    d. only the winter temperature - the same amount of ice melts in both warm and cool summers while ice always accumulates in the winter.
    e. there is no seasonal process that determines the extent of global glaciers because the overall annual temperature average determines whether ice accumlates or melts.

13. The best explanation for the dominant cause of the glacial-interglacial pattern over the past 2 million years, if not the magnitude of temperature change, is

    a. changes in the radiation output from the Sun.
    b. variations in Earth-Sun orbital relationships.
    c. blocking of insolation by volcanic eruptions.
    d. blocking of sunlight by galactic dust.
    e. human activities such as agriculture and burning fuels.     

14. How do we know the temperatures of the Earth more than 160 years ago?

    a. Very long-term records of daily measurements were made beginning with Classical Greek civilization.
    b. People in Iceland have recorded the day of the year that the ice breaks up in Reykjavik harbor since AD 1000, and we can infer the global temperature from knowing this.
    c. The Milankovitch cycles can be modeled to the point that we can estimate temperatures to within about a tenth of a degree anywhere on the Earth's surface.
    d. Global climate models are so accurate that we can run them back in time and simulate global temperatures very well.
    e. There are many different indicators of paleo-temperature that can be studied from long cores of ocean and lake sediments and ice that that have accumulated over long periods of time. 

15. According to the text, the El Niño/La Niña cycle occurs over a period of ________ years, and influences climate by ________.

    a. 26,000; determining which hemisphere contains the subsolar point, and thus the highest energy input, during which month.
    b. 40,000; determining the angle that the Earth's axis describes relative to the ecliptic, and thus the degree of seasonality.
    c. 100,000; determining the shape of the Earth's orbit, and thus the distance from the Earth to the sun which in turn determines the amount of
energy input.
    d. 7; altering the energy output from the sun.
    e. between 2 and 12; determining the temperature of the equatorial eastern Pacific ocean and thus some aspects of global atmospheric
circulation.

16.  According to the text, in El Niño years, the trade winds in the Pacific Ocean blow ________, and the result is:

    a. east to west; dominance of the cold current originating in the Antarctic along the west coast of Peru.
    b. east to west; continued upwelling of the deep, nutrient-rich waters off the west coast of Peru.
    c. west to east; dominance of warm water originating in the equatorial regions of the Pacific along the west coast of Peru.
    d. west to east, continued upwelling of the deep, nutrient-rich water off the west coast of Peru.
    e. west to east; higher sea levels near Australia than near Peru.