Tonight, President Obama will deliver a farewell address in his hometown of Chicago. His two terms in office offer many examples of progress for which he deserves thanks and praise. Chief among these examples is the game-changing gains we’ve seen in renewable energy since he took office. Thanks to his commitment to tackling global warming and his leadership, the United States and the world are finally on a path to a future powered entirely by clean, renewable energy.

When President Obama took office in 2009, the U.S. had only 1.2 gigawatts (GW) of solar capacity and 25 GW of wind capacity installed. Since then, there’s nearly three times as much wind power (75 GW), and solar power has increased by an astonishing 2500% clip to 31 GW.

These dramatic increases are, in part, a product of forward-thinking policies by the Obama administration that drove down costs. In early 2009, nearly $90 billion went to renewable energy from the American Recovery and Reinvestment Act. In 2015, Congress extended renewable tax credits for solar and wind. Throughout the past eight years, the Obama administration actively supported the offshore wind energy industry, and ultimately oversaw the first offshore wind farm coming online in 2016. And they aggressively pushed energy savings by finalizing fifty efficiency standards -- more than any previous administration -- saving consumers $550 billion on their utility bills.

As a result of these actions, the cost of solar and wind has decreased in stunning fashion -- exceeding even the more optimistic projections. Land-based wind costs have dropped 41 percent since 2008, and wind now powers over 17 million U.S. households. The cost of rooftop solar has declined by 54 percent, and as of the beginning of 2016, one million households had solar panels. Finally, utility-scale solar costs have been cut by 64 percent, powering two million homes.

There is no denying that solar and wind are booming like never before under President Obama’s leadership. What’s more, a growing body of research indicates that the transition to a low-carbon economy is happening alongside a growing economy. Since the president took office, carbon emissions from electricity fell by 9.5 percent, while the economy grew by more than 10 percent -- and we’re seeing the same pattern on a global scale for the first time.

Of course, we need to go even farther and set even more ambitious renewable energy goals if we want to avoid the worst impacts of global warming. We echo the President’s optimism in a recently-published piece in Science Magazine that despite the uncertain energy policy of the incoming administration, the momentum of clean energy is “irreversible.”

So thank you, President Obama, for laying the foundation for the renewable energy boom. While much work is left to be done, you have helped chart a course for a 100 percent renewable energy future -- and it is crucial that the next administration embrace this path, for the sake of our kids and our grandkids.