1. Which of the following is NOT indication of global warming?
a. melting of icebergs b. rising of sea level c. shift in ocean currents d. increasing humidity
2. It is thought that the Earth's climate is being changed rapidly by ____
a. human caused releases of impurities b. increased oxygen content c. dust from volcanoes d. decreases in carbon dioxide
3. When does greenhouse effect happen?
a. Greenhouse gases on the surface absorb heat from the atmosphere. b. Greenhouse gases on the surface absorb heat from the Earth's interior. c. Greenhouse gases in the upper atmosphere absorb heat from outer space. d. Greenhouse gases in the lower atmosphere absorb heat from the Earth's surface.
