(Bloomberg) -- President Joe Biden pledged to cut U.S. greenhouse gas emissions in half by 2030 as he convened 40 world leaders in a virtual summit intended to demonstrate renewed American resolve to fight climate change and pressure wary nations to raise their own ambitions.Biden announced in opening remarks for the two-day summit that the U.S. will reduce its own greenhouse gas emissions 50%-52% from 2005 levels by the end of the decade -- significantly boosting a commitment made under former President Barack Obama that was scrapped by former President Donald Trump.“No nation can solve this crisis on our own,” Biden said Thursday from the White House. “All of us, and particularly those of us who represent the world’s largest economies, we have to step up.”The new U.S. pledge is aimed at encouraging industrializing countries including China, India and Brazil that account for much of the world’s carbon output to set their own aggressive emissions-reductions targets. But Biden is likely to face a cool reception from leaders worried about committing to emissions cuts that could slow economic growth.Biden must also confront overseas skeptics who have watched U.S. climate policy shift dramatically depending on the occupant of the White House and wonder whether the latest U.S. president’s promises can be trusted.Biden’s pledge would require changes that would touch the lives of nearly every American. But Republicans in Congress are unlikely to support legislation that would make major reductions in U.S. emissions, for example by penalizing fossil fuel use or mandating renewable power, and any regulations Biden’s administration issues are sure to face challenges from industry.“The message he’s sending to the country and, frankly, to the world is that he feels that the climate crisis we’re facing around the world and certainly in this country, as the world’s largest emitters, is so significant that within 100 days of his presidency, he’s convening the world’s largest economies to have a discussion about that,” White House Press Secretary Jen Psaki said Wednesday.All 40 of the leaders invited, from British Prime Minister Boris Johnson to Chinese President Xi Jinping and Russian President Vladimir Putin, agreed to attend and are expected to speak, as are Pope Francis, members of indigenous groups from around the world, and current and former corporate executives including Bill Gates and Michael Bloomberg, the co-founder and chief executive of Bloomberg LP.The gathering is aimed at driving more aggressive climate action that may keep average global temperatures from rising more than 1.5 degrees Celsius (2.7 degrees Fahrenheit), a key tipping point.“The world is way behind where we need to be and this is going to take very dramatic efforts from all of us,” former Secretary of State John Kerry, Biden’s special presidential envoy for climate, said at a Washington Post event on Wednesday.Biden is committing the U.S. to cutting emissions by at least half from 2005 levels by 2030, according to administration officials who asked not to be identified discussing the plans. That compares with the pledge former President Barack Obama made to cut emissions 26%-28% from 2005 levels by 2025.The target is intended to put the U.S. on track to reach net-zero emissions by 2050. Biden has frequently highlighted that goal -- a point where the greenhouse gases added to the atmosphere by the U.S. are completely offset by reductions.The 50%-52% pledge stemmed from an analysis of the potential for different sectors of the economy to pare greenhouse gases, according to the officials. The cuts build on more than a decade of innovation and technological progress that has unlocked new opportunities in green hydrogen and carbon capture systems, while driving down the cost of renewable power and batteries, administration officials said.Although the pledge describes emissions cuts in only broad terms, Biden’s national climate task force will outline a sector-by-sector strategy for paring that planet-warming pollution later this year, an administration official said.The Biden administration opted not to make an explicit commitment to pare emissions of methane as part of the pledge, despite entreaties from environmentalists.Pledges of AlliesSome U.S. allies have signaled plans to pitch in with their own pledges, while major polluters that have a more adversarial relationship with the Biden administration have been more opaque about their intentions.Kerry said China’s Xi is expected “to make some announcements” about Beijing’s plans to address emissions between now and 2030. He pointed to a statement including the word “crisis” that China signed during his recent trip to Shanghai as evidence that the world’s leading polluter realizes the immediacy of the challenge.“Obviously we have differences with China on certain issues, and climate has to be treated separately,” Kerry said, referring to rifts on trade and human rights, among other issues. “They didn’t just talk about plateauing or peaking, they have now agreed there must be actions between 2020 and 2030.”Biden’s pledge is less ambitious than the European Union’s target of reducing its emissions 55% from 1990 levels by 2030, and it falls below a coming U.K goal to achieve a 78% reduction by 2035 from 1990 levels. A 50% cut from 2005 emissions would amount to just a 40% cut for the U.S. when recalibrated to the same 1990 baseline.By contrast, current emissions-intensity goals laid out by China and India are not aggressive enough to keep global temperature increase below 2 degrees Celsius, according to BloombergNEF.In a sharp turnaround from his typically dismissive rhetoric about climate change, Russia’s Putin said during his annual address to the nation on Wednesday that the cumulative volume of the country’s net emissions should be less than those of the European Union over the next three decades. Analysts were deeply skeptical that Putin’s statement will amount to a real policy change, noting Russia’s emphasis on continuing to extract fossil fuels from the Arctic.Japan, Canada, the U.K. and other countries are expected to outline more stringent carbon-cutting plans. But none of the pledges are binding, and meeting the most ambitious targets will require dramatic changes in the way the world generates and uses energy. It would also require emissions reductions from hard-to-decarbonize sectors of the economy, from cement-making to agriculture.Environmentalists argue Biden’s planned emissions reduction is both achievable and ambitious -- a sweet spot essential to U.S. credibility. However, fulfilling the commitment still depends on a slew of yet-to-be-written environmental regulations that can be ripped up by future presidents, Biden’s multitrillion-dollar infrastructure package that faces stiff opposition in Congress and a rapid transformation of the U.S. electrical sector.U.S. Political DisputesBiden’s efforts come after Trump pulled the U.S. back from the climate fight. He withdrew from the Paris Agreement on climate and his administration systematically dialed back Obama-era climate policies, including efficiency standards to curb electricity use and rules cutting greenhouse gas emissions from power plants, automobiles and oil wells.Asked how Americans and the rest of the world could be assured Biden would deliver on his commitments, Psaki said “the president has every intention of getting re-elected, and certainly ensuring that he is implementing policies where climate, addressing our climate crisis, putting Americans back to work go hand-in-hand, which is absolutely his desire and his commitment, it will be a part of his continuing agenda.”Biden also faces concerns within his own domestic political base as he tries to navigate competing pressures from Senator Joe Manchin, a Democrat from coal-rich West Virginia, and progressives such as Representative Alexandria Ocasio-Cortez and the Sunrise Movement.On the eve of the summit, Sunrise’s political director, Evan Weber, took a swipe at Biden’s planned emissions cut, arguing that a 50% reduction falls far short of what the U.S. needs to do as “the richest country in the world and the biggest historical polluter.”“The science is clear – if the U.S. does not achieve much, much more by the end of this decade, it will be a death sentence for our generation and the billions of people at the front lines of the climate crisis in the U.S. and abroad,” Weber said in a statement.The Biden administration is building its target on a foundation of domestic climate programs and policies, including investments in renewable power and electric vehicles as well as regulations throttling greenhouse gas emissions from power plants, oil wells and automobiles.Still, there are technical and economic barriers to achieving the deep cuts the U.S. and other countries are laying out. To meet just its commitment, the U.S. would need to curtail emissions from across all reaches of its economy, including the energy, transportation and industrial sectors. The country would have to rapidly scale up renewable power, shift more of the nation’s vehicles to zero-emitting electric varieties and quickly deploy carbon-capture technology at manufacturing facilities.Oil industry advocates, including Republicans on Capitol Hill, have already panned Biden’s expected pledge as too aggressive, with Senator John Barrasso, a Republican from Wyoming, describing it as a “punishing” target that “will cost working families a fortune in higher energy bills” while harming America’s competitiveness.Anne Bradbury, chief executive of the American Exploration and Production Council that represents independent oil producers, warned that American consumers could pay a price if cuts are too aggressive.“Implementing policies that go beyond the capabilities of current technologies with unrealistic timeframes,” she said in an email, “will only penalize consumers, our industry and our country’s energy security.For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.