Amid calls for reduction of the greenhouse gas emissions that have been warming the planet and intensifying extreme weather events such as droughts, cyclones and floods, Dr. Huq focused on ways to adapt to climate change and mitigate its effects.

He was also a leading advocate of requiring the world’s most developed, industrialized nations — those producing the most emissions — to compensate poorer countries for “loss and damage” from climate change.

He attended all 27 Conference of the Parties (COP) talks of the U.N. Framework Convention on Climate Change. Last November, at COP27 in Sharm el-Sheikh, Egypt, Dr. Huq was instrumental in obtaining an agreement to establish a loss and damage fund.

That accord culminated a 30-year quest to set up such a fund separate from money to be used to help countries adapt to climate change. But meetings and workshops are still underway to “design” the fund and resolve issues such as its location and contributors, said Harjeet Singh, head of global political strategy at the Climate Action Network. Among the other outstanding issues are how much money the fund would contain, who would benefit and who should run it.

“He worked tirelessly for 30 years,” Singh told The Washington Post from New Delhi. “Despite many moments of frustration, he never lost hope.”

“Loss and damage isn’t aid,” Dr. Huq said in an interview last year with the journal Nature, which called him a “climate revolutionary” in naming him as one of 10 people worldwide who helped shape the biggest science stories of 2022. Rather, it is based on the principle of the “polluter pays,” he said. “When money is given as aid, all the power rests with the donor,” creating an unequal relationship, he added.

“The term ‘loss and damage’ is a euphemism for terms we’re not allowed to use, which are ‘liability and compensation,’” Dr. Huq told the New York Times at the COP talks in Glasgow, Scotland, in 2021. “‘Reparations’ is even worse.”

Singh described Dr. Huq as “the leading voice calling for adaptation when the whole world was calling for emissions reductions.” He worked to raise awareness of the needs of communities that are “already impacted and going to be impacted” by climate change, he said.

Dr. Huq was “the intellectual architect of what we now call Locally Led Adaptation,” Patrick Verkooijen, chief executive of the Netherlands-based Global Center on Adaptation, wrote on the research organization’s website. He was “de facto the voice of the voiceless.”

Verkooijen recalled touring Bangladesh with Dr. Huq to better understand the effects of climate change on some of the world’s most vulnerable people, residents of a low-lying, impoverished and densely populated country prone to intense heat, severe tropical storms and flooding.

“Saleem introduced us to local communities who are taking their own steps to protect themselves from rising temperatures, constructing cyclone shelters and building alert systems,” Verkooijen wrote. “We took away the greatest lesson of all, that moving communities from vulnerability to resilience is a goal which is urgent, vital and achievable.”

Saleemul Huq was born in Karachi, Pakistan, on Oct. 2, 1952, to parents who worked in the Pakistani diplomatic service before Bangladesh, formerly East Pakistan, gained independence after a 1971 war. His Bengali parents escaped capture by the Pakistani army by traveling overland on a donkey to India, Nature reported.

He grew up in Europe, Asia and Africa because of his parents’ diplomatic postings and moved to Britain in the 1970s to study at Imperial College London, where he received a doctorate in botany in 1978.

After returning to Bangladesh, he co-founded an independent think tank specializing in environmental policy, the Bangladesh Center for Advanced Studies, and encouraged the establishment of a government department, which became the Ministry of Environment, Forest and Climate Change.

Survivors include his wife, Kashana Huq; a son, Saqib Huq, who is assistant director at the Dhaka center led by his father; and a daughter, Sadaf Huq.

Over the years, Dr. Huq contributed to the United Nations Intergovernmental Panel on Climate Change (IPCC), which shared the 2007 Nobel Peace Prize with former U.S. vice president Al Gore for their work on spreading knowledge of man-made global warming. Last year, Dr. Huq was honored with the Order of the British Empire for his efforts to combat climate change.

In a bleak 2022 report, the IPCC cited a “brief and rapidly closing window of opportunity” for the human race to avoid an increasingly deadly future of unbearable heat, rising sea levels, spreading drought, intensifying violent storms and widespread hunger, among other effects of climate change.

It warned that, left unchecked, greenhouse gas emissions would raise sea levels by several feet, swallowing small island nations and overwhelming even the world’s wealthiest coastal regions, The Post reported. But the more temperatures rise, the wider the gulf between rich and poor is likely to become, the report said.

“That’s one of the clearest things the scientific evidence shows about the impacts of climate change — the injustice of it,” Dr. Huq told The Post after the report was issued. “It affects poor people more than rich people, but it’s caused by rich people’s emissions.”