When President Obama first ran for president, tackling climate change was one of his largest campaign promises. So far, the U.S. has taken some steps, but there has been no ground-breaking legislation.

Today, that appears to be changing as President Obama announced a new target to cut net greenhouse gas emissions 26%-28% below 2005 levels by 2025. A key aspect of this was the accompanying announcement by President Xi Jinping of China. He announced targets to peak carbon dioxide emissions around 2030, with the intention to try to peak early, and to increase the non-fossil-fuel share of all energy to around 20% by 2030. This is such a big deal because China is currently the largest polluter in the world, and to have large-scale change, China needs to be involved.

Together, the U.S. and China account for over one-third of global greenhouse gas emissions. Today’s joint announcement, the culmination of months of bilateral dialogue, highlights the critical role the two countries must play in addressing climate change. The actions they announced are part of the longer-range effort to achieve the deep decarbonization of the global economy over time. These actions will also inject momentum into the global climate negotiations on the road to reaching a successful new climate agreement next year in Paris.

The new U.S. goal will double the pace of carbon pollution reduction from 1.2% per year on average during the 2005-2020 period to 2.3-2.8% per year on average between 2020 and 2025. This ambitious target is grounded in intensive analysis of cost-effective carbon pollution reductions achievable under existing law and will keep the United States on the right trajectory to achieve deep economy-wide reductions on the order of 80% by 2050.

The joint announcement marks the first time China has agreed to peak its carbon dioxide emissions. The United States expects that China will succeed in peaking its emissions before 2030 based on its broad economic reform program, plans to address air pollution, and implementation of President Xi’s call for an energy revolution.

China’s target to expand total energy consumption coming from zero-emission sources to approximately 20% by 2030 is notable. It will require China to deploy an additional 800-1,000 GW of solar, wind, nuclear, and other zero-emission generation capacity by 2030 – more than all the coal-fired power plants that exist in China today and close to total current electricity generation capacity in the United States.

The joint agreement today came as a welcome surprise that sends an important message to the rest of the world. It’s certainly good news, and a step in the right direction. Some are saying it’s not enough — and that the agreement is non-binding and vague. But the Solar Energy Industries Association (SEIA) hailed it as a “historic, breakthrough agreement.” SEIA President and CEO Rhone Resch said it “sends a clear signal to private investors and political leaders here at home and around the world that solving climate change is a top priority on both sides of the globe.”

To achieve the goals set in the agreement, both the U.S. and China will need to greatly expand their clean energy production. Solar stands to benefit greatly from this, with its continued cost declines and increased adoption. Even without this target reduction, solar was predicted to continue rapidly growing. With this target now in place, solar looks to expand even more quickly than previously predicted.