Global warming of the past century, and especially in the past decade, is at least partly a consequence of human activities that have increased ____ in the atmosphere.
A)smog
B)PCBs
C)ozone
D)"greenhouse gases"

Question

Quizplus · Accepted Answer

The phrase "greenhouse gases" specifically refers to gases like carbon dioxide, methane, and water vapor that trap heat in the Earth's atmosphere and contribute to global warming. Human activities such as burning fossil fuels, deforestation, and industrial processes have increased the levels of these gases in the atmosphere, leading to the warming observed in recent decades.

Global Warming of the Past Century, and Especially in the Past