Weart 4

The next question was whether human-caused clouds and dust might cause cooling
in the 1960s some scientists saw evidence of global cooling (in the northern hemisphere due to volcanos)

what does Weart mean by "The view of scientists and public evolved together"? p. 66

scientists took the possibility of global warming seriously enough to argue the government should fund more research, but it wasn't clear enough to recommend action to reduce CO2 emissions

studies of ice and sea bottom cores began to yield better dates

• this gave clear patterns for ice ages, matching the variations in the earth's orbit
• but those had very small effects on sunlight so they must have been amplified by positive feedbacks
• climate was so unstable it could shift dramatically in a century

The effect of pollution and dust began to be studied more carefully

• some haze and smog might trap heat rather than reflect it
• this was demonstrated with data from Mars
  

Mikhail Budyko

• simple model showed the climate to be very unstable
• William Sellers came to similar results using different equations
• Carl Sagan as a young scientist showed that the greenhouse effect made Venus very hot
• it turned out later that the atmosphere of Venus is mostly CO2
• Mars showed how unstable climate can be