It is these interim targets that should now be addressed by all countries during the coming weeks. If we are to reach the goal of reducing emissions to 20 gigatonnes by 2050, we must be at about 35 gigatonnes by the halfway point of 2030.
That means global emissions have to peak within the next five years and be steadily falling by 2020. And while the commitments by the largest emitters already on the table for 2020 offer significant cuts relative to today\’s emissions, they collectively fall 4 or 5 gigatonnes short of what is necessary if we are to be on a realistic trajectory to reach the 2030 and 2050 targets.
I\’m afraid that what you present here as inescapable logic is not in fact inescapable.
Assume, arguendo, that you are correct about the 2050 target. Hitting that target does not require getting halfway by halfway. You\’re missing the impact of changing technology.
I do not say that this is certain, of course not, just that it is possible: a new technology, or further refinements of an extant one, become economic. Economic in the sense that, say power generation by solar PV rather than coal, the new method is cheaper than the old. This will lead to quite a rapid switch over as in such an economic environment new installations will all be of the new technology and over a period of 30-40 years as depreciation takes its toll and the capital replacement cycle turns we\’ll end up with no coal and all solar.
It\’s also true that we rather expect this particular economic change to happen pretty soon: there are those who claim it now for electricity consumed by households and just about everyone thinks that it will indeed happen in the next 10 years.
Certainly, there are things that would help: a decent Pigou tax on CO2 emissions for example. Maybe even cap and trade if the politicians can keep their hands off it.
But your argument that to get to point x in 2050, from point y where we are now, requires that we travel a straight line from x to y simply is not true.
And thus, sadly, your argument fails.