Weart 8

the recording of Wednesday's class is available on the class zoom page (choose cloud recordings) or here

Dr Weart said in class that in his opinion we should start planning to take action (not just more research) when the scientific community is 85% certain of a danger

• Did we meet that standard with COVID-19?
• A moving recent story about one of the leaders of the IPCC

In the 1990s proposals were made for "economically sound ways to get a start on reducing the risk" (p. 157)

• promote fuel efficiency of vehicles
• reduce subsidies on fossil fuel
• a 1991 report listed 58 possibilities

Fossil fuel industry lobbying and public relations campaigns stopped action
The press took the "scientists disagree" approach even when the scientists publishing in the top journals no longer did

natural experiment from a volcano

• better understanding of aerosols and dust
• they reduced warming in the 20th century to half what it would have been from CO2 alone

In the 1990s the science is becoming much stronger--getting past 85% certainty

In the international process, what would be fair to developing countries became an increasing issue--should they have the same limits or be allowed to catch up first?
But the US Senate rejected any treaty exempting developing countries

Scientists were still refining their models
rise in global temperature was becoming very clear, regional effects less so
new research showed rapid changes (over decades) were possible

Global warming began to be indisputably visible in small ways