After years of dragging their feet, lawmakers in Washington advanced a pair of major bills this week that include significant provisions for tackling climate change as scientists continue to ring alarm bells about the state of the planet.

The Senate approved on Tuesday a sweeping bipartisan $1.2 trillion infrastructure bill with funding for many public works meant to cut climate-warning emissions. A day later, Democrats in the chamber took a major step to adopt an even bigger, $3.5 trillion budget bill supporting yet more programs for cleaning up power plants and cars.

Each, if passed, would invest billions of dollars in the sort of clean energy transition the United States must make to have any chance of hitting the goal set by President Biden to cut the nation’s emissions by at least 50 percent by the end of this decade.

“This was one of the most significant legislative days we’ve had in a long time here,” Senate Majority Leader Charles E. Schumer (D-N.Y.) told reporters Wednesday.

But both bills face a potentially bumpy road ahead. Democrats still need to draft in committees the details of their massive budget reconciliation package over the coming weeks, with not a single vote to spare in the 50-50 split Senate. The bipartisan public-works bill, meanwhile, still needs approval from the House, where progressive Democrats hold significant sway.

The moves on Capitol Hill come as hundreds of scientists detailed this week the intensifying fires, floods and other catastrophes that will continue to worsen until humans dramatically scale back greenhouse gas emissions.

Scientists assembled by the United Nations made clear in a landmark report Monday that time is running out for the world to make immediate and dramatic cuts to emissions produced by the burning of fossil fuels and other human activities. U.N. Secretary General António Guterres called the sobering, sprawling report from the Intergovernmental Panel on Climate Change a “code red for humanity.”

But it remains unclear whether the new findings alone will be enough to spur new action in a Washington as politically divided as ever.

Psychological research shows that climate change can alter an individual's mental health both directly and indirectly, impacting how we respond to this crisis. (John Farrell/The Washington Post)

Climate change remains a distinctly fraught issue in the United States compared with many other countries, with the de facto leader of one of the two major parties — former president Donald Trump — dismissing the scientific consensus about human-caused climate change and downplaying its risks throughout his term.

Even if Congress passes bills with big climate provisions, regulations from the Biden administration are vulnerable to being reined in by federal court judges appointed by Trump and the most conservative Supreme Court in a generation. And the fate of many of the administration’s climate initiatives could depend on the Democratic Party retaining control of Congress — and on how Biden himself fares if he runs again in 2024.

If Biden and his Democratic allies in Congress succeed in shifting the nation rapidly toward a greener future, the math of climate change means that the rest of the world would have to follow suit, and quickly. The United States accounts for only about one-seventh of global emissions. The rest of the world — particularly the world’s largest emitter, China — would need to set more aggressive goals for reducing footprints as well.

Other countries have taken steps to do that. The European Union, for instance, agreed earlier this year to cut carbon emissions as a bloc by at least 55 percent by 2030. But how aggressively China, India, Russia and other nations will move in the years ahead remains an open question.

World leaders already faced mounting pressure to arrive at a major U.N. climate conference scheduled this fall in Scotland with more ambitious, concrete plans to slow greenhouse gas pollution. That pressure grew only more intense after Monday’s IPCC assessment, which found that the world is quickly running out of time to meet the goals of the 2015 Paris agreement.

The report found that humans can only unleash less than 500 additional gigatons of carbon dioxide — the equivalent of about 10 years of current global emissions — to have an even chance of limiting warming to 1.5 degrees Celsius (2.7 Fahrenheit) above preindustrial levels.

The hopes of hitting that target, the most aspirational goal outlined in the Paris accord, will soon slip away without rapid action, the report made clear. After all, the world has already warmed more than 1 degree Celsius (1.8 degrees Fahrenheit), with few signs of slowing unless nations begin to cut emissions at a rate unprecedented in history.

For Biden to live up to his promises to reduce U.S. emissions sharply in coming years, transition to electric vehicles and eliminate the carbon footprint of the power sector by 2035, his administration needs a helping hand from Congress.

The infrastructure package, which the Senate approved in a 69-to-30 vote with the support of 19 Senate Republicans, apportions billions of dollars for building new transmission lines, public transit and electric-car charging stations.

Meanwhile, the separate $3.5 trillion budget reconciliation bill, which Democrats plan to pass on their own, includes more far-reaching provisions for tackling climate change.

That measure would impose new import fees on polluters and give tax breaks for wind turbines, solar panels and electric vehicles. It would also seek to electrify vehicles used by the U.S. Postal Service and other federal agencies and create a new Civilian Climate Corps to enlist young people in planting trees and other conservation work.

Perhaps most crucially, the legislation would put new requirements on electricity providers to use cleaner forms of energy — something President Barack Obama’s administration tried but failed to do.

Dan Lashof, U.S. director of the World Resources Institute, called Tuesday’s bipartisan infrastructure package “a down payment” on the fight against climate change but not nearly enough going forward. He said it is essential for the Senate to also pass the budget-reconciliation package that funds a broader array of climate-focused measures to create jobs and shift the nation’s infrastructure toward one no longer reliant on fossil fuels.

“The forthcoming reconciliation package could be our best opportunity for advancing climate action this decade,” he said. “Kicking the can down the road is no longer an option as extreme weather wreaks havoc across our nation and around the world.”

Passing both bills, along with tighter regulations from the Environmental Protection Agency, “puts us within shooting distance” reducing emissions by 50 percent by 2030, according to Collin O’Mara, president of the National Wildlife Federation.

Yet the fate of each bill remains unsettled.

Democrats need the approval of the Senate parliamentarian, Elizabeth MacDonough, to include the clean energy requirements in the budget bill. Some parliamentary experts expect her to reject it because the primary aim of the policy is not related to federal revenue.

And Sen. Joe Manchin III (D-W.Va.), a moderate who chairs the Senate Energy and Natural Resources Committee, is already raising concerns about inflation and the size of the Democratic-only package. “Given the current state of the economic recovery, it is simply irresponsible to continue spending at levels more suited to respond to a Great Depression or Great Recession — not an economy that is on the verge of overheating,” he said in a statement Wednesday.

House Democrats, meanwhile, are pressing for more climate spending in that same budget package.

More than 180 lawmakers urged Democratic leaders to prioritize investments in clean energy, energy efficiency and tax incentives for cleaner transportation into the legislation. They specifically cited the IPCC report, which they said only increases the urgency to act to address climate change.

“These incentives will play a critical role in America’s economic recovery, alleviate some of the pollution impacts that have been borne by disadvantaged communities, and help the country build back better and cleaner,” the group wrote in a letter to House Speaker Nancy Pelosi (D-Calif.) and Majority Leader Steny H. Hoyer (D-Md.).

GOP lawmakers, meanwhile, are poised to oppose the Democratic budget bill at every turn. Sen. John Barrasso (Wyo.), the top Republican on the Senate Energy Committee, called the measure a “reckless tax and spending spree to impose this green new disaster on every American.”

At the same time, Republicans risk forgoing the chance to shape major climate legislation, according to Paul Bledsoe, a strategic adviser at the Progressive Policy Institute.

“The clean energy transition that climate science requires will be the biggest economic story over the coming decade, but Republicans will have less influence on it because they are now purposefully sitting out the reconciliation bill, which will contain the most crucial policy measures,” Bledsoe, who served as a climate adviser under President Bill Clinton, said in an email.

On the Senate floor Monday, hours after the IPCC released its findings and before the passage of the bipartisan infrastructure package, Schumer made clear that climate change had to remain a priority and a focus for Congress.

“Without immediate and bold action, we are staring down ever-worsening floods and heat waves, droughts and sea-level rise,” Schumer said. “The future of our planet looks bleak until we do something, right now.”

The fight over how to fund efforts to recover from the coronavirus pandemic — and how much public money should go to boost the transition to a greener economy — is playing out all over the world.

As of the second quarter of 2021, according to the International Energy Agency, governments around the world have allocated around $380 billion for clean energy measures as part of their economic response as they begin to emerge from the pandemic.

That amounts to only “around 2 percent of the total fiscal support in response to covid-19,” the IEA found. The investments the world has committed to appear unlikely to meaningfully alter the trajectory of global emissions in the way scientists say is critical to avoid continued warming.

Sen. Thomas R. Carper (D-Del.), a Biden ally who chairs the Senate Environment and Public Works Committee, was among the Democrats who had hoped for more funding for more climate-related initiatives in the infrastructure bill. But he also insisted that Democrats on Capitol Hill would keep pushing for what they and Biden have said is a critical priority for the nation.

“Let me be clear — this legislation isn’t perfect. It certainly doesn’t go far enough on advancing equity and tackling the existential crisis of climate change,” Carper said Tuesday. But for now, he added, “let’s not make the perfect the enemy of the good.”