Stephen Hawking has gained a less than stellar reputation for predicting doomsday catastrophes multiple times. Seems his non-scientific predictions are classic clickbait catnip for mainstream media publications and net tabloids.
And then there is his latest doomsday scenario of human CO2 emission causing global warming so hot that humanity on Earth is wiped out by a Venus-like climate of 250 degrees. Unfortunately for Hawking, the empirical evidence clearly indicates that Earth becoming Venus is such an absurdity that even the fear-mongers at the IPCC won't support this vaporfear.
Why is Hawking's Venus prediction so way out there in the twilight zone of black holes? Just look at the adjacent chart.
Plotted are the absolute temperatures for the tropical oceans and the atmosphere above the tropical oceans, as of April 2016 (purple columns). If the oceans are going to be boiled-off by Venus atmospheric temperature levels, then we are a very long way from that happening.
But what about Earth's temperatures a 100 years from now, due to that "runaway" warming Hawking insinuates that we suffer from?
Well, based on the linear trend of temperatures since the satellite measurement age began in 1979, the expected tropical temperatures for April 2116 (yellow columns on chart) will barely budge up - ahem, 250 degrees is not in the cards. Earth's actual experience with Hawking's modern "runaway" warming clearly indicates that we can't get there (250 degrees) from here (25.3°, -4.2°, -24.2°).
And by the time the next 100 years passes, humanity will no longer be using fossil fuels as the primary source of energy. Technology will advance far enough during that time to make the issue of runaway warming or climate change tipping points from human greenhouse gas emissions moot historical footnotes.
Note: Calculated rolling absolute temps using 12-month averages of anomalies and then adding an average absolute temp to the anomalies. Absolute average temp used for HadSST, 24.4C; absolute average temp for UAH lower troposphere -5.0C; absolute average temp for mid-troposphere, -25.0C. Excel used to calculate averages and plot column chart. Venus surface, lower and mid-troposphere temperatures are vastly hotter than 250 degrees that Hawking alluded to.