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.