On Dec. 2, 2016, Mexico’s environment minister Rafael Pacchiano Alamán faced the thousands of participants and delegates who traveled to Cancun for the 13th conference of the United Nations Convention on Biological Diversity, and opened the high-level meeting by addressing the elephant in the room.

“Warnings have been made on all the problems that this wall could cause,” Pacchiano said, noting the biological impacts of US president-elect Donald Trump’s promised border wall between Mexico and the United States. Mexico and the UN, Pacchiano optimistically added, would wait until the new US administration takes office, at which point they will start working together “hand in hand.” Erik Solheim, executive director of the UN Environment Programme, followed up Pacchiano’s comments by urging the US, Mexico, Europe, and China to work together for common solutions, like the media-darling Paris Agreement that arose from the United Nations Framework Convention on Climate Change (UNFCCC).

The little-known Convention on Biological Diversity (pdf) is an international treaty adopted in 1992—one day after the UNFCCC. It’s designed to address international conservation concerns, such as mass extinctions and ecosystem degradation. The Convention on Biological Diversity’s main mechanism of action is incentives for conservation and sustainable use, and importantly, developing countries can apply for funding from other nations signed on to the convention for critical biodiversity conservation projects.

Over the past 24 years, 196 parties have ratified the agreement, including the European Union, three non-UN states, and all the UN states, with the exception of one: the United States.

The US refusal to ratify the agreement could weaken biodiversity conservation both at home and abroad.

Up until now, analysts agree America’s absence hasn’t much mattered. Independent national commitments mimic those already in the convention; the US has sent a full-fledged observing delegation to every conference; and every administration has chosen to financially support the convention’s programs. But now, as Trump prepares to take office, the country’s refusal to ratify the agreement could weaken biodiversity conservation both at home and abroad.

Throughout the 1980s, it was the US that championed the idea of a biodiversity treaty. But when the papers finally hit the desk of then-president George H. W. Bush in 1992 following successful negotiations at the Rio de Janeiro Earth Summit, he refused to sign amid the tumultuous presidential election.

AP Photo/Eduardo DiBaia At the 1992 Earth Summit, in Rio de Janeiro, Brazil, nearly all global leaders signed on to the Convention on Biological Diversity. US president George H.W. Bush did not.

When Bill Clinton took office in 1993, he did provide his signature, but the agreement failed to get Senate approval (pdf). Though the Senate Foreign Relations Committee voted to support ratification, Republican senators were strongly against the convention and announced their intention to vote against it. Ultimately, a vote on the Senate floor never occurred and the Convention on Biological Diversity has languished among a backlog of more than 40 treaties for decades since.

Prior to the Senate’s rejection of the Convention, Clinton proudly stated, “There are hundreds of state and federal laws and programs and an extensive system of Federal and State wildlife refuges, marine sanctuaries, wildlife management areas, recreation areas, parks, and forests. These existing programs and authorities are considered sufficient to enable any activities necessary to effectively implement our responsibilities under the Convention.” At the time, he likely couldn’t conceive of Donald Trump coming to power; of Exxon Mobil CEO Rex Tillerson as the president’s pick for Secretary of State; or known climate-change denier Scott Pruitt heading up the Environmental Protection Agency.

At the time, Clinton likely couldn’t conceive of Donald Trump coming to power.

With no binding international treaty holding the US accountable, now the “extensive system” Clinton spoke of is in jeopardy. “Even though the US hasn’t been a party to the Convention on Biological Diversity, we have been sending observers and for a while there was a still a lot of energy around it,” says William Snape, senior legal counsel for the US-based nonprofit Center for Biological Diversity, and an expert on the Convention. “Now, I worry.”

In 2010, the Convention on Biological Diversity announced their 2011-2020 strategic plan that included 20 global biodiversity goals, known as the Aichi Targets. The lofty goals include a target of conserving 17% of total terrestrial and inland water on Earth; preventing the extinction of known threatened species; and at least halving the current the rate of loss of all natural habitats.

But biodiversity conservation isn’t just about losing cute or interesting animals. Extinction and degradation have the potential to seriously harm human health and survival. “Look at the Great Barrier Reef,” says Snape, “which within the past month has been forecasted to perhaps be destroyed. This is something that would have great human impacts, not only with regard to people visiting the reef, but the whole food chain.”

“The idea that we’re no longer going to follow the rule of law is highly disturbing.”

Snape believes the Convention wouldn’t impact conservation in the US one way or the other—that will be determined by standing national laws, and the usual efforts of citizens, activists, and lawyers. But a Trump administration is worrying. “The idea that [under Trump] we’re no longer going to follow the rule of law, or be flippant with the rule of law, is highly disturbing,” says Snape.

Further, Trump can do serious damage in the developing world. Already, he has promised to withdraw all funding from the UNFCCC, and redirect money from climate programming to infrastructure projects. Those promises have not gone unnoticed by the Global Environment Facility (GEF).

Not unlike the World Bank’s Green Climate Fund, the GEF is the primary funding mechanism for the Convention on Biological Diversity. It sources money from 39 nations to fund biodiversity projects in developing and transitioning economies. They’ve financed projects ranging from sustainable forest management in Cameroon to reducing the illegal wildlife trade in South Sudan to snow leopard conservation in Afghanistan.

Historically, the US has been the largest global donor to the GEF, says spokesperson Christian Hofer. Between 1994 and 2013, the US contributed about $1.8 billion to the GEF alone, and hundreds of millions more for other climate-related projects. In the most recent GEF money-replenishment cycle, the US financial pledge comprised about 15% of the total $4.4 billion allocation between 2014 and 2018. Of this, $1.3 billion will go toward biodiversity specifically. Thus far, Hofer says the amount pledged by the US has been paid every year, “without any problem.”

But Congress has sole oversight of US involvement in these programs. And though Aichi Target 20 aims to “substantially” increase funding for the GEF, it stands to reason the mechanism could face a sudden and precipitous shortfall of funds under the Trump administration. ”I predict if things continue the way they appear to be going, those funds are all in severe jeopardy,” says Snape. “All. Every single last dime of foreign aid.”

Reporting for this story was supported by a travel fellowship granted by the Earth Journalism Network.