"These are landmark advances in international human rights," Boyd said in a statement last month.
But with top fossil fuel producers including the United States arguing that the U.N. resolution is not legally binding, and refusing to join 161 other countries in enshrining the right to a healthy environment for their own citizens, Boyd said his experience as special rapporteur has shown him that "this powerful human right is up against an even more powerful force in the global economy, a system that is absolutely based on the exploitation of people and nature."
"I started out six years ago talking about the right to a healthy environment having the capacity to bring about systemic and transformative changes," Boyd told The Guardian. "And unless we change that fundamental [economic] system, then we're just re-shuffling deck chairs on the Titanic."
The environmental law expert said the failure of world leaders to universally agree to a "human rights-based approach" to the climate, biodiversity, and air pollution crises "has absolutely been the Achilles' heel" of international treaties like the Paris climate agreement, with no mechanisms forcing countries to rapidly draw down their greenhouse gas emissions to help avoid planetary heating above 1.5°C.
"It has driven me crazy in the past six years that governments are just oblivious to history. We know that the tobacco industry lied through their teeth for decades. The lead industry did the same. The asbestos industry did the same."
Governments pledged to phase out "inefficient" fossil fuel subsidies in 2021, but last year subsidies for the industry had risen by $2 million, hitting $7 trillion.
Fossil fuel and other industry lobbyists are still being welcomed to global summits on plastic pollution and the climate, Boyd pointed out.
"It just absolutely boggles my mind that anybody thinks they have a legitimate seat at the table," said Boyd. "It has driven me crazy in the past six years that governments are just oblivious to history. We know that the tobacco industry lied through their teeth for decades. The lead industry did the same. The asbestos industry did the same. The plastics industry has done the same. The pesticide industry has done the same."
Boyd's criticism "hits the nail on the head," said Mark Dummett, deputy program director of Amnesty International.
Boyd said a global grassroots movement is needed to dislodge "the diesel mafia," his term for "powerful interconnected business and political elites" who "are still becoming wealthy from the existing system."
Organizers must continue using "tools like human rights and public protest and every other tool in the arsenal of change-makers," he advised.
Boyd spent his time as special rapporteur traveling to countries including Portugal, the Maldives, Chile, and Fiji, where he spoke to people directly affected by plastic waste, rising sea levels, air pollution, extreme heat, and other climate impacts.
He went on his final mission to the Maldives, the world's lowest lying country, in April, finding "numerous atolls submerged under water, according to The Guardian.
"These islands are just like jewels scattered across the Indian Ocean, and yet for anyone who understands the science of climate change, it's just a heartbreaking place to visit because of sea level rise, storm surges, coastal erosion, acidification, rising ocean temperatures, and heatwaves," Boyd said of the Maldives, 80% of which scientists have said could be uninhabitable by 2050. "The future is really daunting for people in the Maldives... The climate emergency is an existential threat that overshadows all the other issues."
If people in the Maldives and around the world "don't have a living, healthy planet Earth, then all the other rights are just words on paper," said Boyd.
The outgoing rapporteur said environmental legal groups will likely increasingly file lawsuits against governments that aren't doing their part to mitigate the climate crisis—a tactic that the U.N. Environment Program said last year could be a key driver of change in climate policies.
"I expect in the next three or four years, we will see court cases being brought challenging fossil fuel subsidies in some petro-states," said Boyd. "These countries have said time and time again at the G7, at the G20, that they're phasing out fossil fuel subsidies. It's time to hold them to their commitment. And I believe that human rights law is the vehicle that can do that."
Last month, the European Court of Human Rights ruled that the Swiss government violated the human rights of senior citizens by refusing to abide by scientists' warnings and swiftly phase out fossil fuel production.
Environmental law expert Astrid Puentes Riaño stepped into Boyd's former role this month, saying she will prioritize "the implementation of the human right to a clean, healthy, and sustainable environment," following the U.N.'s formal recognition of the right.
The implementation of the right provides "a vital opportunity for greater understanding of the obligations of states to respect, protect, and fulfill this right, as well as the role of non-state actors," she said. "This will be my main task as rapporteur to be implemented through the reports, visits, communications, events and other activities to develop."