The US rejoins the Paris Agreement on day one
A new administration moved immediately to return the country to the global climate pact and signal renewed ambition.
The United States moved to rejoin the Paris climate agreement on the first day of a new administration this January, reversing its brief withdrawal and signalling a dramatic return of American engagement on climate change after a period of retreat.
The decision to rejoin, enacted within hours of the inauguration, was among the first acts of the new president, underscoring the priority placed on climate. The formal re-entry took effect roughly a month later, restoring the world's largest economy and second-largest emitter to the global pact.
The move was accompanied by a flurry of other climate actions and a pledge to pursue far more ambitious goals, including a commitment to steeply cut US emissions over the coming decade and to decarbonise the economy by mid-century. The administration signalled its intent to weave climate considerations across government policy.
The return was welcomed by allies and climate advocates around the world as a restoration of American leadership, and it injected fresh momentum into international efforts ahead of a major climate summit later in the year.
Yet the whiplash of exit and re-entry within a matter of months also highlighted the fragility of climate commitments subject to domestic political swings, raising questions among international partners about the durability of American pledges. Rebuilding trust and credibility, and translating renewed ambition into lasting policy and emissions cuts, would be the true test of the country's re-engagement with the global climate effort.