1. Because our planet's climate is always changing, the key question becomes, howmuch of global warming is caused by human activities versus natural climatevariability? On this issue, most scientists agree that the causes aremainly
2. The greenhouse effect is a natural phenomenon that keeps the earth's surfacewarm. Without greenhouse gases—water vapor, carbon dioxide, methane, nitrousoxide, halocarbons, and ozone—life as we know it wouldn't exist. The currentproblem is that
B. the atmospheric concentration ofgreenhouse gases has reached its highest level in 400,000 years, and this risehas upset the balance of radiative forcings working to warm and cool the earth
3. Because of global climate change, arctic landscapes and ecosystems are changingrapidly and perceptibly, as the residents of Newtok, Alaska, can attest. Withthe land upon which they have built their homes slowly melting and sinking, theyhave appealed to the state and federal governments for assistance in helpingthem cover the costs of moving their town to a different location.Ironically,
D. decades ago, the U.S. governmentmandated that they and other Alaskan natives abandon a nomadic life based onhunting and fishing for sedentism.
4. Which is the single greatest obstacle to slowing climate change?
D. meeting energy needs, particularly inenergy-hungry countries such as the United States, China, and India
5. Anthropology has always been concerned with how environmental forces influencehumans, and how human activities affect the biosphere and the earth itself. The1950s through the 1970s witnessed the emergence of an area of study known ascultural ecology or ecological anthropology. This field
A. focused on how cultural beliefs andpractices help human populations adapt to their environment.
6. Today's ecological anthropology, also known as environmental anthropology,attempts not only to understand but also to
A. find solutions toenvironmental problems, acknowledging that ecosystems management involvesmultiple levels.