New Delhi: Environmentalist RK Pachauri, a former TERI chief under whose chairmanship the UN's Intergovernmental Panel on Climate Change won the Nobel Peace Prize in 2007, passed away on Thursday after a prolonged cardiac ailment. He was 79.

In a statement, his family said Pachauri underwent a major heart surgery before succumbing to his deteriorating health on Thursday. He was admitted to Escorts Heart Institute here on Tuesday.

Pachauri passed away at his residence in the national capital with wife, daughter and son by his side.

"His courageous leadership allowed climate change to be recognized world over as the most pressing issue confronting the world and launched a new era of international deliberations and actions," said his family.

The Energy and Resources Institute (TERI) expressed grief over the passing away of its founding director.

"It is with immense sadness that we announce the passing away of R K Pachauri, the founder Director of TERI. The entire TERI family stands with the family of Dr Pachauri in this hour of grief," TERI director general Ajay Mathur said in the statement.

"TERI is what it is because of Dr Pachauri's untiring perseverance. He played a pivotal role in growing this institution and making it a premier global organisation in the sustainability space," said Mathur, who succeeded Pachauri at TERI in 2015.

In 2015, Pachauri was accused of allegedly sexually harassing a woman colleague after which he had to quit the post at TERI.

An FIR was lodged against him following which a case was filed in Saket district court.

With his death, the case is likely to be abated.

But before this episode, he had a distinguished career whose highest point came in October 2007 when he collected the Nobel peace prize as the head of the United Nation's Intergovernmental Panel on Climate Change (IPCC), jointly with former US vice president Al Gore.

Pachauri won the Padma Bhushan in 2001 and the Padma Vibhushan in 2008, the third and second highest civilian awards of the country.

In the statement issued by TERI on Thursday, its chairman Nitin Desai hailed Pachauri's contribution to global sustainable development as "unparalleled".

"His leadership of the Intergovernmental Panel on Climate Change (IPCC) laid the ground for climate change conversations today," Desai said.

Pachauri was born on August 20, 1940 in Nainital, Uttarakhand, and studied at La Martiniere College in Lucknow and at the Indian Railways Institute of Mechanical and Electrical Engineering in Jamalpur, Bihar.

With PTI Inputs