In a paper in the journal Science Advances, [an international team of researchers] said the actual range could be between 4.78C to 7.36C by 2100, based on one set of calculations.
Professor Michael Mann, of Penn State University in the US, who led research that produced the famous “hockey stick” graph showing how humans were dramatically increasing the Earth’s temperature, told The Independent the new paper appeared "sound and the conclusions quite defensible".
“And it does indeed provide support for the notion that a Donald Trump presidency could be game over for the climate,” he wrote in an email.
“If there is science backing that up, that there’s a higher sensitivity of the climate to greenhouse gases, that puts at risk the prospect of keeping the globe at the Paris target of well below 2C.
“Anybody who understands the situation we find ourselves in would have already have realised we are in an emergency situation.”
Just don't tell that to the Trudeau government or to any of the western provincial governments. There response to the existing "emergency situation" is to flood world markets with the highest carbon ersatz petroleum on the planet, bitumen.
What the researchers have discovered is that climate sensitivity to greenhouse gas emissions isn't linear. The sensitivity itself, the rate at which warming occurs, actually accelerates as the atmosphere heats up. In other words, a few gigatonnes of greenhouse gases in a cold atmosphere may result in X degrees of warming. However the same few gigatonnes of greenhouse gases emitted into a warmer atmosphere will result in much more warming than had previously been expected. Our targets have been based on the old, linear concept that has now gone by the boards.
That has led scientists to conclude that we're on the path to upwards of 7C of warming by 2100.