It is not Malthusian to point out that hanging the hopes of future generations on the possibility of new discoveries is plainly unwise. You seem to be attacking Nathans prudent warning that the advances that renewables fans hang everything upon, may not happen, or may happen way too late to sway the GW tripping point.
" Well no. There is still no existence proofs that solar and wind can be used affordably on 90%, 80%, or even 60% non-fossil grids (I'm referring to average whole-grid penetration, not the momentary peaks that generate so many headlines, nor the localized offsetting of fossil fuel imports with variable renewable exports).
There is still no energy storage cheap enough to allow use of solar energy at night or wind on a calm day. Essentially all grid deployments of advanced batteries have been sub-hour endurance systems designed allow slow-throttling coal plants to co-exist with renewables."
We are spending billions locking our future in on renewables tech, in the hopes that storage will one day get cheaper, when we don't have to put all our eggs in that one basket at all.