I ought to argue the point. I will do so by RAA. Assume that energy users do not learn to cope with just renewables. In that case CO₂ emissions go as at presen

I ought to argue the point. I will do so by RAA. Assume that energy users do not learn to cope with just renewables. In that case CO₂ emissions go as at present, ie. the CO₂ content in the atmosphere increases by about 2.25ppm/year. In 2050 that works out to about 500ppm and in 2100 to 600ppm (these are conservativish numbers, since they assume that the 2.25ppm/year stays flat while in reality it has been increasing steadily). ITER is not thought to lead all the way to fusion power; at least one more round of experiments is required afterwards. The Wikipedia page mentions 2035, so assuming that the next round also takes 20 years and only one more round is necessary, the first actual fusion reactors could start construction around 2055, and large amounts of fusion power could perhaps be available around 2075 or 2095, when CO₂ content is 550-600ppm. This is absurdly high, therefore the assumption is untenable. Learn or die.