Most scientists agree that we are in a warming period. The argument is about the influence of CO2 emissions from coal-fired power plants and the automobiles we drive.
Recent recorded history has documented these warming-cooling periods: 600 to 200 B.C., cold period; 200 B.C. to A.D. 600, Roman Warming period; 600 to 900, the Dark Ages-cold; 900 to 1300, Medievel warming period; 1300 to 1850, Little Ice Age; 1850 to present, warming period.
One theory is that variations in the energy released by our sun is the culprit in the Earth's temperature change debate. These and other theories need more careful evaluation and research before we believe Al Gore's doomsday predictions and jump off the cliff in despair.