How hot will the summers get in India and Pakistan, and how will tens of thousands of deaths from extreme heat impact the stability of the region (both nations have nuclear weapons)? How close is the West Antarctic ice sheet to collapse, and what does the risk of five or six feet of sea-level rise mean for people living in mobile homes on the Gulf Coast? The truth is, no one knows for sure. We are in uncharted terrain. “We’re now in a world where the past is no longer a good guide to the future,” said Jesse Jenkins, an assistant professor of engineering at Princeton University. “We have to get much better at preparing for the unexpected.”

By all indications, President Biden and his team understand all this. And it’s hard not to feel that after 30 years of dithering and denial and hypocrisy, the fight to save the climate has finally begun in earnest. In the 2020 election, nearly 70 percent of Biden’s voters said climate change was a top issue for them. Biden has staffed his administration with the climate A-team, from Gina McCarthy as domestic climate czar to John Kerry as international climate envoy. He has made racial and environmental justice a top priority. And perhaps most important of all, he sees the climate crisis as an opportunity to reinvent the U.S. economy and create millions of new jobs.

“I think in Obama’s mind, it was always about tackling the climate challenge, not making the climate challenge the central element of your economic policy,” says John Podesta, a Democratic power broker and special adviser to President Obama who played a key role in negotiating the Paris Agreement. “Biden’s team is different. It is really the core of their economic strategy to make transformation of the energy systems the driver of innovation, growth, and job creation, justice and equity.”

Of course, there have been hopeful moments before: the signing of the Kyoto Protocol in 1997, when the nations of the world first came together to limit CO2 emissions; the success of Al Gore’s documentary An Inconvenient Truth in 2006; the election of Obama in 2008 (“This was the moment when the rise of the oceans began to slow and our planet began to heal,” Obama said in his speech accepting the Democratic presidential nomination that year); the Paris Agreement in 2015, when China finally engaged in climate talks. But all of these moments, in the end, led to nothing. If you look at the only metric that really matters—a graph of the percentage of CO2 molecules in the atmosphere—it has been on a long, steady upward climb. More CO2 equals more heat. To put it bluntly, all our scientific knowledge, all the political speeches, all the activism and protest marches have done zero to stop the accumulation of CO2 in the atmosphere from the burning of fossil fuels.