© Zuma PressCold Oceans: Some skeptics say breaks in a warming trend of the 21st century cast doubt on findings by the U.N. panel of climate scientists that climate change is man-made.
Many experts had previously explained a slight global cooling around 1970 as a side-effect of a slow build-up of sun-dimming air pollution from factories, power plants and cars that cleared up in later years with stricter air pollution laws.
But scientists in the United States and Britain said an examination of temperature records revealed "a rapid drop in Northern Hemisphere sea surface temperatures of about 0.3 degree Celsius (0.5 F) between about 1968 and 1972."
The cooling was most in the North Atlantic. Reasons for the chill were unclear but it coincided with a sudden inflow of cold water from the Arctic.
