Weart 6

"The temporary northern cooling from the 1940s to the 1960s had been bad luck for climate science." (p. 116)

• due to pollution and volcanoes
• it wasn't until about 2000 that global warming would be clear despite the large annual fluctuations
  
• could more of that variation be explained?
  

 Jack Eddy brought attention back to changes in the energy from the sun
(As a college student I worked with him and another professor on a little of this work:
Foukal, P. V., Mack, P. E. and Vernazza, J. E. (1977): ‘The Effect of Sunspots and Faculae on the Solar Constant,’ Astrophys. J.,215,952–959.)

Mario Molina and Sherwood Rowland looked at the role of CFCs (Chlorofluorocarbons like freon)

• found they could damage the ozone layer in the upper atmosphere, letting in more ultraviolet resulting in an increase in skin cancer
• satellite data showed the ozone layer was already damaged; after CFCs were banned it has recovered
• that is unrelated to global warming but CFCs are greenhouse gasses as well as damaging the ozone layer

While CFCs were successfully regulated, that drew attention to other greenhouse gasses such as methane

new research on cores obtained by deep sea and ice drilling showed that CO2 was much lower during ice ages
small increases in sunlight must cause increases in CO2, but by what mechanism?

• many weird candidates
• sulfur dioxide released by volcanoes?
• the transmission of heat by the ocean, which turned out more to be by eddies than by currents like the Gulf Stream
• the oceans might cause rapid changes in climate if the circulation of heat northward in the Atlantic (the conveyor) shut down