Sen. Bernie Sanders’ presidential campaign has become the first in the 2020 race to promise to offset the planet-warming gases produced while traveling the country.

In a statement to HuffPost, the campaign said it plans to fund renewable energy projects to compensate for the carbon dioxide spewed by the planes and automobiles in which Sanders and his staff will travel while they barnstorm the nation ahead of the Democratic National Convention in July 2020.

“Bernie Sanders is a champion in the fight for climate justice and, like him, we know we need to address our emissions through action, not just rhetoric,” Faiz Shakir, Sanders’ campaign manager, said in a statement. “We are proud to lead the way in the fight against climate change by acting boldly to move our energy system away from fossil fuels and towards sustainable energy sources.”

Climate change is already a central plank of Sanders’ second White House bid. In December, two months before he announced his candidacy, the senator from Vermont hosted a televised town hall with climate scientists and advocates to discuss the crisis. In February, he attacked Trump for ignoring climate change in his State of the Union address. During his stump speeches, Sanders routinely skewers the fossil fuel industry and promises to enact a Green New Deal if elected.

Over the past two years, he’s introduced legislation to set a national target for 100 percent renewable electricity by 2050 and spend $146 billion rebuilding hurricane-ravaged Puerto Rico and the U.S. Virgin Islands with climate-resilient infrastructure and clean energy.

The announcement boosts Sanders’ bona fides on the issue and gives him a leg up in a crowded field of Democrats putting more attention on climate change than ever before. The move comes a week after the Sanders campaign became the first to unionize.

Sanders has also drawn heat recently for his uncertain stance on reparations for the descendants of slaves and for quietly hiring a journalist who frequently attacked his 2020 opponents on Twitter as an adviser.

Carbon offsets represent a drop in the bucket on an issue that requires unprecedented systemic change to avert climate disaster. But transportation emissions make up the largest share of the United States’ climate pollution. Sanders’ announcement steels the campaign against accusations of hypocrisy, often made by Republicans who take an ideological stance against the scientific realities of climate change.