tl,dr: The direct effect of burning most of the fossil fuels (6 to 10°C temperature rise) may be survivable for some. But that does not take into account secondary effects triggered by the warming, like heat waves, ocean deoxygenation, flooding, melting of ice caps, etc.
The study below is already a bit dated, latest research has shown that earlier ...
Although conventional oil, gas and
coal reserves total between 829 and 1,501 GtC, estimates of the global recoverable fossil fuel resource including oil shales range upwards from about 4,000
GtC. If exotic resources, especially methane hydrates, are included the total
may be 15,000-25,000.
Millenial timescale carbon cycle and climate change in an ...