Do we have to do this again? We do.
Due to high demand from journalists and others as to the “Sure, the climate is changing but how much is due to humans?” – talking point rolled out in back to back interviews from Donald Trump and Senator Marco Rubio – experts Stefan Rahmstorf and Andrew Dessler have offered some tweeted primers.
How do we know global warming is human-caused? Because we know where the extra energy that heats our planet is coming from. Through changes in the energy budget of Earth – that’s how much radiation comes in, how much goes out. The change in this is called “radiative forcing”.
Possible causes of radiative forcing: changes in solar activity, in volcanic activity or greenhouse gases. The latest US Climate Assessment shows how much each of these contributed. See https://science2017.globalchange.gov/ The human contribution is about 100%…
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