More than 100 climate and development organisations, along with 70,000 people, have called on Barack Obama to help secure the future of the Paris agreement by transferring the remaining $2.5bn committed by the US.

The Green Climate Fund was a key aspect of the historic Paris agreement signed in 2015, which aims to keep global warming “well below” 2C and aspires to keep warming to 1.5C.

The fund, established in 2010, is financed by wealthy countries and used to assist developing countries with adaptation and mitigation. It was widely seen as a key measure to bring both rich and poor countries to the negotiating table.

The US pledged $3bn towards the fund, making up nearly a third of the $10.3bn pledged in total. But so far, it has only transferred $500m.

“This is one of the only things Obama can do now that Trump can’t undo,” said Jesse Bragg from Corporate Accountability International, the group that organised the petitions. “Once those funds are transferred, Trump won’t be able to take them back.”

As of today, 117 organisations including 350.org, Friends of the Earth and the League of Conservation Voters have joined with Corporate Accountability International to deliver a petition signed by more than 70,000 to the Obama administration.

The organisations signed a letter saying: “The world cannot afford Donald Trump’s steps backward on climate. Right now, people around the world are mobilising to counter Trump’s anticipated actions. You can help us protect your climate legacy by fulfilling your pledge to contribute $3bn to fund climate justice measures in the Global South.”

The petition those organisations delivered said: “Donald Trump plans to do everything he can to reverse progress on climate change. His policies threaten disaster for people and the planet. But there’s one thing President Obama can do before he leaves office that Trump cannot undo.”

Trump has nominated a series of climate deniers to his cabinet, including Rex Tillerson, the chief executive of Exxon Mobil, as secretary of state. He has also nominated Scott Pruitt, who is known for suing the Environmental Protection Agency, to direct that agency.

Tamar Lawrence-Samuel, associate research director at Corporate Accountability International, said: “Donald Trump’s administration will be of, by and for the fossil fuel industry and if we don’t act now, millions will suffer.”

“President Obama must do whatever it takes to fulfil the US’s commitment to the Green Climate Fund before Donald Trump and his Big Oil cabinet take over,” she said.

350.org’s founder, Bill McKibben, said: “The debt for the damage inflicted on the global climate by American carbon will never be fully repaid – and the Trump administration can be counted on to do nothing for the most vulnerable people on the planet … so this call makes both practical and moral sense.”

The first $500m was transferred through a State Department fund, which Obama could use without congressional support. Corporate Accountability International argues that Obama could draw from several relevant funds to fulfill his pledge, including those within the State Department, Treasury Department, Defense Department and other agencies.