Rajendra Pachauri, chairman of the UN's Intergovernmental Panel on Climate Change since 2002, has been under fire on two fronts: a glaring error in the body's reporting on glaciers and his business dealings.
He has rejected calls to resign, arguing that he is being targeted by countries and companies reluctant to embrace greener technology for economic reasons, and insisting that money he earns as a consultant goes straight back into a research institute which he heads.
The IPCC chairman is Indian and his office's website portrays the 69-year-old engineer and economist as an "incredible" success story for his country.
"The name of Dr Rajendra K Pachauri... has become synonymous with climate change and the environment," its biography says.
"Dr Pachauri is now on everyone's wish list for their climate change events."
Born on 20 August 1940 in the Nainital district of the outer Himalayas, Dr Pachauri is the son of a London University-educated educational psychologist, according to the biography.
He attributes to his mother his "well-known work ethic, entailing strict punctuality and completion of all tasks".
Privately educated in Lucknow, he went on to study mechanical engineering and, after managerial work at an Indian railway company, pursued an academic career which led to US teaching posts, in North Carolina and Virginia.
The year 1982 saw him in the Indian capital, Delhi, where he took over as director of The Energy Research Institute (Teri), a think tank promoting sustainable development.
In the 1990s, Dr Pachauri began working in various capacities for the UN and helped with the research that resulted in the Kyoto Protocol of 1997.
In 2002, he was serving as a vice-chairman of the IPCC when he was elected to the chairman's post itself, ousting Robert Watson.
Dr Pachauri, who was returned to the post in 2008, was the favoured candidate of the US Bush administration which reportedly disliked Dr Watson's willingness to tell governments what he believed to be the unvarnished truth - that human activities were contributing dangerously to climate change.
The Indian chairman has been honoured for his work on climate change with state awards in India and France.
His biography says he relaxes by composing poetry and playing cricket.
A prolific writer of academic reports, he raised eyebrows in January 2010 with the publication of a steamy novel about an Indian climate expert's life and times in India, Peru and the US.
A review of Return to Almora in the Daily Telegraph newspaper notes the novel's initial theme of deforestation, then quips that "talk of 'denuding' is a clue of what is to come", and details the book's sex scenes.
'Not a penny'
In January 2010, the IPCC admitted it had made a mistake in asserting that Himalayan glaciers could disappear by 2035, a date it included in its 2007 assessment of climate impacts.
With the UN climate convention process struggling to forge a binding international agreement on reducing greenhouse gases, the error boosted sceptics who accuse climate campaigners of alarmism, and led to calls for Dr Pachauri to resign.
Speaking to the BBC, the IPCC chairman said the mistake had been publicly corrected and insisted that there was a huge volume of evidence validating the science of global warming.
He denied that controversy surrounding his position was distracting from the work of the IPCC.
"I don't think the world is going to be distracted," he said. "I don't think the scientific community is going to be distracted."
Dr Pachauri also dismissed UK press allegations that he has made a fortune from carbon trading thanks to links between Teri and private companies.
Any money he earned from advising companies went to Teri, he said, adding: "Not a single penny goes into my pocket."