Rajendra Pachauri, 79, Dies; Led Nobel-Winning Climate Agency

Rajendra K. Pachauri, a charismatic voice on the risks of global warming who led the United Nations’ climate science agency when it won the Nobel Peace Prize, but whose career ended amid accusations of sexual harassment, died on Thursday at his home in New Delhi. He was 79.

His death was announced by the Energy and Resources Institute in India, the influential policy organization he had headed for 34 years until being replaced in 2015 under the cloud of the harassment accusations, which also led to his departure from the U.N. agency. No cause of death was given, but he had recently undergone surgery for “a prolonged cardiac ailment,” according to India Today, a major news outlet.

The institute’s chairman, Nitin Desai, said in a statement that Dr. Pachauri’s leadership of the United Nations Intergovernmental Panel on Climate Change “laid the ground for climate change conversations today.”

Dr. Pachauri was chairman of the panel from 2002 to 2015. In 2007, the Norwegian Nobel Committee jointly awarded the Nobel Peace Prize to the group and former Vice President Al Gore “for their efforts to build up and disseminate greater knowledge about man-made climate change.”

The panel’s reports have detailed the overwhelming scientific evidence in support of climate change. In a statement, the panel noted that a report, known as the Fifth Assessment and published in 2014 under Dr. Pachauri’s leadership, provided “the scientific foundation of the Paris Agreement,” the 2015 deal among nearly 200 nations to reduce greenhouse gas emissions.

The agreement was hailed as a landmark in international cooperation on climate issues, but President Trump is withdrawing the United States from it.

Dr. Pachauri stepped down as chairman of the U.N. panel in 2015, when a researcher at the Indian energy institute, a 29-year-old woman, said he had made lewd advances and sent graphic emails and text messages to her.

Dr. Pachauri denied the accusations, saying he had been hacked. But at least one other employee made similar accusations against him. A case based on the allegations remained unresolved at his death.

The U.N. group said at the time that the decision to replace Dr. Pachauri would “ensure that the I.P.C.C.’s mission to assess climate change continues without interruption.” In a letter to the United Nations secretary general, Ban Ki-moon, Dr. Pachauri wrote, “For me the protection of Planet Earth, the survival of all species and sustainability of our ecosystems, is more than a mission” — it was “my religion and my dharma,” or duty, he said.

Like many other prominent figures in climate science, Dr. Pachauri faced criticism from climate-change denial groups and their allies. Even within the scientific community he was sometimes criticized as having a tendency to combine science and advocacy.

A 2010 review of the U.N. panel’s procedures warned that “straying into advocacy can only hurt I.P.C.C.’s credibility.” However, many well-regarded climate scientists argue that advocacy is an essential part of raising alarms about the threat of climate change.

The researcher who led the 2010 review, Robbert Dijkgraaf, the director of the Institute for Advanced Study in Princeton, N.J., said that the I.P.C.C. “was very open to suggestions to strengthen the organization” and that he “was impressed with Chairman Pachauri’s emphasis on scientific rigor and careful processes.”

A former colleague offered a mixed portrait of Dr. Pachauri. Jean-Pascal van Ypersele of the Catholic University of Louvain in Belgium, a former vice president of the I.P.C.C., praised him in a statement on Twitter for having “put the climate change challenge and the science behind it on top of the international agenda.”

But be added that Dr. Pachauri “was sometimes overconfident, as when he refused to quickly acknowledge and correct” an erroneous estimate in the panel’s 2007 report, known as the Fourth Assessment, saying it was “very likely” that Himalayan glaciers would disappear by 2035 if current warming trends continued.

“This led to escalated and undue criticism of the organization he chaired,” Dr. van Ypersele wrote.

Through a spokesman, Mr. Gore said Dr. Pachauri’s “dedication to advance the science and raise global awareness of the climate crisis will endure.”

Rajendra Kumar Pachauri was born on Aug. 20, 1940, in Nainital, a hill station in the foothills of the Himalayas. He said that the stunning setting there had given him a deep affection for nature and made him sensitive to the fragility of the natural world.

He worked variously as an engineer, scientist and economist, with an academic career that took him to the Indian Railways Institute of Mechanical and Electrical Engineering in Jamalpur, in Bihar state, and to North Carolina State University in Raleigh, where he earned a master’s degree in industrial engineering in 1972 and a joint doctorate in industrial engineering and economics in 1974.

In 1981 he became chief executive of what would become known as the Energy and Resources Institute, or TERI. Over his career, he wrote or co-wrote some 25 books.

Dr. Panchauri’s survivors include his wife, Saroj (Puri) Pachauri, who is a doctor and researcher on family planning and reproductive health; two daughters, Rashmi Pachauri-Rajan and Shonali Pachauri; and a son, Ash Pachauri.

Dr. Pachauri, known familiarly as Patchy, was a vegetarian, both because of his religious commitment as a Hindu and because of his views on the impact of meat production on the climate. He recommended vegetarianism as a way to fight global warming.

“In terms of immediacy of action and the feasibility of bringing about reductions in a short period of time,” he said in a 2008 interview with The Guardian, “it clearly is the most attractive opportunity.”

In an interview after the 2007 Peace Prize was announced, Dr. Pachauri urged the nations of the world to act quickly to stop climate change.

“The price of waiting is enormous,” he said.