In this year’s Gates Foundation annual letter, Bill and Melinda Gates outline their goals for the next 15 years. Central to achieving this progress and safeguarding development gains over time is an immediate transformation of energy to climate-safe, zero-emission sources that keep energy prices low, they say.

 The long-term threat is so serious that the world needs to move much more aggressively — right now — to develop energy sources that are cheaper, can deliver on demand, and emit zero carbon dioxide.

Read the complete 2015 Gates Annual Letter Our Big Bet for the Future here.