Policy-driven growth of technologies to accelerate climate action

More than 70% of climate policies target low-carbon technologies, with hopes that policy support will trigger tipping points and self-reinforcing growth. In practice, however, trajectories of policy-driven technologies remain difficult to explain and anticipate because their growth is nonlinear and often constrained by backlash, policy reversals and systemic barriers. In this Perspective, we develop a framework to explain, diagnose, and anticipate the growth of policy-driven technologies through four phases. In the formative phase, rapid innovation, uncertainties and frequent failures lead to erratic growth; in the accelerating growth phase, increasing economic and political returns progressively increase deployment speed; in the steady growth phase, emerging barriers dampen acceleration leading to a pattern in which growth pulsates around its peak; and in the slowdown phase, barriers stall growth and technology reaches its limits. Surprisingly, the scale and complexity of supporting policies do not necessarily diminish as technologies mature. Effective acceleration requires phase-specific policies to support technical and commercial viability in the formative phase, amplify increasing returns in the accelerating growth phase, manage barriers in the steady growth phase, and withdraw or reinvigorate support during the slowdown phase. Further advancing this phase-aware understanding of the co-evolution of policy and technology is essential for improving climate policy design and for developing more realistic technology projections and climate mitigation scenarios.