Governments promised on 30 November to almost double global funding for clean-energy research (see go.nature.com/n4qdsw). Meanwhile, the very act of deploying emissions-cutting technologies to meet countries' climate pledges at the recent United Nations summit in Paris is likely to spur major innovation.
Such technological advances mean that cutting emissions can drive down the cost of further cuts in emissions (see go.nature.com/j8ueaj). For example, the price of photovoltaic modules for solar energy has fallen by 85% since 2000 as markets have grown; electricity costs from wind are now comparable to those from coal; and energy-storage technologies are improving.
Publicly funded research and development, early investment by the private sector, and efficient deployment are all crucial for innovation. Market growth in renewable energy is largely driven by government policies, which have unleashed private companies' research ingenuity and achieved economies of scale and greater productivity (see also 300–302; 2014). Nature 507,
Recognizing the mutual reinforcement of cutting emissions and improving clean energy is essential for negotiating a long-term, ambitious climate deal. As global efforts add up, falling costs should allow for an international agreement to phase in emissions cuts at a rate that matches each nation's stage of economic development.