The diffusion of general-purpose artificial intelligence (AI) systems is collapsing the marginal cost of cognition, coordination, and
capital formation. This abundance of intelligence is simultaneously re-pricing the three residual scarcities that still constrain human
welfare: atmospheric carbon space, human labor hours, and irreversible time. Using a unified production–climate–welfare model, we
show that (i) AI accelerates decarbonization by driving the cost curve of clean technologies below that of fossil fuels; (ii) labor
markets bifurcate into a vanishing low-skill wage sector and an expanding high-skill rent sector, generating a transfer problem that
can only be solved by AI dividends; and (iii) the option value of future consumption rises as AI compresses the calendar time needed
to unlock large-scale decarbonization, longevity, and existential-risk mitigation. The conjunction of these effects drives the Ramsey
rule for optimal climate policy to its mathematical limit: the social discount rate (SDR) must converge to zero. We provide empirical
calibration using the latest IPCC scenarios, large-language-model energy-intensity data, and labor-share forecasts through 2100. A
zero SDR reconciles inter-generational equity with intra-generational efficiency and unlocks a portfolio of “long-horizon public goods”
(LHPGs)—from atmospheric restoration to asteroid defense—that markets at positive discount rates chronically under-supply.