The decisions the incoming Trump Administration makes on how the U.S. government will address these challenges will have a great impact on the course of climate change not just over the next four years, but for decades to come. It may be too soon to know what these decisions will be, but President-elect Donald Trump’s words, his actions during his first term as U.S. president and his nominees for key positions in his new administration provide some guidance.

Forestalling the worst impacts of climate change means dramatically reducing humans’ emissions of greenhouse gases, particularly the climate-warming gases carbon dioxide and methane, from activities such as burning fossil fuels.

The best-case scenario sketched out by scientists was to limit the average warming of the planet to 1.5 degrees Celsius above preindustrial levels by the end of the century — a threshold that has increasingly felt further away as many of the world’s most powerful nations dragged their feet on limiting their own emissions. Achieving that goal means that by 2030, the world must reduce emissions to 57 percent of 2019 levels (SN: 4/4/22). That target quantity is roughly equivalent to the combined 2023 emissions of China, the United States, Russia and India.

Achieving net-zero carbon emissions — reducing the world’s emissions to the point where new emissions are balanced out by carbon removed from the atmosphere — is possible but would require global and concerted actions by the world’s governments, researchers say.

Progress on that has been maddeningly slow — but there were some hopeful signs of movement. In December 2023, world leaders meeting in Dubai for a climate summit agreed for the first time to set their global emissions goal according to the numbers cited by scientists. That agreement also called on nations to speed up their climate actions by increasing global renewable energy generation and phasing out fossil fuel subsidies.

President Joe Biden’s administration had pledged to reduce U.S. net greenhouse gas emissions by 50 to 52 percent, relative to 2005 levels, by 2030. One aim was to reduce U.S. transportation emissions, in part by dramatically increasing the relative proportion of electric vehicles on the road.

These policies are likely to be on the chopping block. During his previous administration, Trump repeatedly rejected any calls to reduce emissions, instead promising to end the “war on coal.” He called for opening up public lands for oil and gas development, and for reducing energy research and development by the federal government’s national laboratories.

How the incoming Trump administration will address climate change loomed over COP29, a climate summit held in November in Baku, Azerbaijan. The meeting concluded November 24 with an agreement that, by 2035, developed nations will deliver $300 billion a year to developing countries to reduce the burden of climate change impacts. That target date, a decade out, was intended to extend the deal beyond the next four years, U.S. State Department officials told Politico.