RE: The Extinction
Yes, but it is not one and the same whether this will happen in 50 years ... or in 50 mln. There is a huge difference.
We are really faced to extinction, and the name of the extinction is not an exotic event from the outer space, but is called CO2. There is a limit within which we can pump CO2 in the air, beyond which the things will start to become interesting.
The problem is that CO2 is directly related to our metabolism & to the metabolism of the flora and fauna on the planet ... and also to the industrial energy sources, which means that if we cannot pump more CO2 in the air, we will be faced to biological catastrophy and energy crises - a jam of 7th star magnitude.
The dilemma is: either to resolve the energy crisis as fast as possible and to switch-over to clean fuels and energy (Hydrogen, Helium 3, solar, wind, geothermal, etc.) ... or we continue to make business as usual and fall deeper and deeper into the abyss of the CO2 trap.
As we cannot disconnect our metabolism from the CO2, if we don't succeed to diconnect the industrial energy from the CO2 ... we are dead on arrival as species ... literally.