Scientists have actually addressed directly how much of the current warming trend is caused by humans. And their assessment is stronger and more definitive than Trump’s statement above.
Here’s what they said in the United Nations’ Intergovernmental Panel on Climate Change’s fifth assessment report, in 2013: ” It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”
Moreover, scientists are very confident in this conclusion. The claim that the conclusion is “extremely likely” means it has a “95–100%” probability of being correct, according to the IPCC.
Why are scientists so sure? Because the evidence is sort of everywhere, they say: “Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes.”
Still, Trump’s admission of “some connectivity” is stronger not only than many of his Tweets — here are three where he implies or directly says climate change is a “hoax” — but perhaps even than what he said to the Washington Post editorial board back in March, where when asked about human-caused climate change he responded:
I think there’s a change in weather. I am not a great believer in man-made climate change. I’m not a great believer. There is certainly a change in weather that goes – if you look, they had global cooling in the 1920s and now they have global warming, although now they don’t know if they have global warming. They call it all sorts of different things; now they’re using “extreme weather” I guess more than any other phrase. I am not – I know it hurts me with this room, and I know it’s probably a killer with this room – but I am not a believer. Perhaps there’s a minor effect, but I’m not a big believer in man-made climate change.
Whatever view Trump expresses on the matter, the most telling fact may be this: He has appointed Myron Ebell, a think tanker from the Competitive Enterprise Institute who has long questioned various aspects of climate change science, to lead his transition team for the Environmental Protection Agency.
Brady Dennis contributed to this report.
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