article_snippet.sent: I've heard the 2-degree threshold referred to as the "north star" for climate negotiations.
article_snippet.sent: William Nordhaus, an economist at Yale.
article_snippet.sent: Nordhaus, 73, proposed the 2-degree threshold in a 1977 (1977!) paper titled "Economic Growth and Climate:
article_snippet.sent: If there were global temperatures
article_snippet.sent: more than 2 or 3 degrees above the current average temperature, this would take the climate outside of the range of observations which have been made over the last several hundred thousand years," he wrote in "The Climate Casino.
article_snippet.sent: You need a judgment call for these things," said Carlo Jaeger, chair of the Global Climate Forum, who has written on the history of 2 degrees Celsius.
article_snippet.sent: And this 2-degree thing was a judgment call that happened at the interface of science and policy.
article_snippet.sent: Germany was first to push 2 degrees as an policy goal, Jaeger told me.
article_snippet.sent: Later came the European Commission, the G8, the U.S. National Academy of Sciences and, most significantly, the Copenhagen Accord, which was signed by more than 100 nations who agreed 2 degrees would be too much.
article_snippet.sent: The United States was among the signatories.
article_snippet.sent: I'm from New Mexico," said Nordhaus, the economist who proposed the 2-degree threshold.
article_snippet.sent: Targeting 1 degree of warming is "ridiculous because you can't do it," said Nordhaus, the economist.