Biden is off to a great start. But there’s a lot of work to be done on climate.

(Editor’s Note: This Opinion piece is being published as a companion article to the essays in the January issue of our magazine, on “Advice to the Next President.”)

My one most important piece of advice to President Biden about climate change is to reengage the international community. This goes beyond rejoining the Paris Climate Agreement. The United States has to reclaim the mantle as a global leader on climate action. If we lead, others will follow.

Our country’s history of international climate engagement is decidedly contentious. Bruising home-turf battles over an early attempt at a carbon tax—the so-called BTU tax, defeated in Congress in 1993—led to a much too timid climate agenda for the Clinton administration. The United States initially refused to commit to binding greenhouse gas emission reductions during the international community’s first efforts on climate change mitigation—the Kyoto treaty negotiations. In 1997, just a few months prior to the United States finally agreeing to sign the Kyoto Protocol, the US Senate unanimously passed the Byrd-Hagel Resolution which opposed any international agreement that did not require developing countries to commit to legally binding greenhouse pollution reductions if developed countries did. Any hope for the Senate to officially ratify Kyoto was dead-on-arrival. George W. Bush, who early on in his administration refused to acknowledge the growing scientific consensus on global warming and opposed all efforts to limit greenhouse gas emissions, finally pulled the plug on US involvement in Kyoto in 2001.

Hope was the operative word when Barack Obama took office in 2009, having promised to address a broad range of environmental problems. But his first term was spent dealing with the Great Recession and economic recovery. Political capital was expended in the effort to pass the Affordable Care Act, and much like in the early days of the Clinton administration, President Obama was handed a bruising climate blow when his landmark climate change legislation died in the Senate in 2010. International engagement on climate wasn’t just tepid, it was arguably a failure. The United Nations Framework Convention on Climate Change 15th Conference of Parties (COP15) in Copenhagen concluded in December 2009 with no binding treaty to curtail greenhouse pollutants—thanks in good part to the US delegation’s too-little-too-lateapproach.

Evidence of how quickly climate policy can change—akin to what’s about to happen starting on January 20—came during Obama’s second term. At a speech at Georgetown University in June 2013, Obama outlined a strategy to combat climate change that included dozens of proposals, specifically including a reassertion of American international leadership on climate with the goal of seeking a new global treaty to cut carbon pollution. Among a strong batch of strong environmental second-term appointments, which included Gina McCarthy as EPA head, Obama brought in John Podesta, a former Clinton chief of staff, as special adviser. He, along with then Secretary of State John Kerry, played crucial roles in negotiating a 2014 U.S. agreement with China pledging to reduce carbon emissions. It was the first time China had ever agreed to limit its use of fossil fuels. In attaining this accord, the United States and China paved the way for the broader set of international agreements reached about a year later in December 2015.

Make no mistake—Paris is not enough. But despite its flaws, the COP21 climate accord amounts to the biggest and greatest global effort to avert a climate crisis. In rejoining it on Day One of his presidency, Joe Biden will symbolically restore our country’s place among the international community. More importantly, I expect the United States to ably maneuver to take on a climate-leadership role like it had during Obama’s second term. John Kerry, having proven that he is more than capable, can lead America out of an intercontinental shadow and help spur the urgent action needed to improve upon the Paris Agreement.

There will be hurdles, of course. Biden’s administration just barely has control of the US Senate. Byrd-Hagel stands in the way of the Senate ratifying any international treaty in which industrialized countries don’t pledge to cut dependence on fossil fuels within the same compliance period as the United States. Even knowing that there will be a huge return on investment, the funding required to transition to a renewable-energy economy is daunting. That is the case domestically, but especially internationally, where developing countries will need help.

The urgency in mitigating global greenhouse gas emissions cannot be understated. Whether its floods, droughts, wildfires or major hurricanes, billion-dollar disasters driven in part by global warming are increasing in the United States. The raging symptoms of the growing climate crisis are hitting the most vulnerable here and abroad the hardest, especially in the world’s poorest countries.

I commend President-elect Biden and Vice President-elect Harris in assembling an experienced, knowledgeable, broadly respected and diverse group of leaders to take on the greatest challenge facing mankind this century: anthropogenic climate change. Now I exhort the new president and his team to hit the ground running, reengage the global community, and immediately seek to set and adhere to new and binding emissions targets that will keep global warming from becoming much worse.