Saleemul Huq, a climate-change expert with a global reputation and adviser to the presidency of the COP-28 climate summit that is to begin in Dubai within a month, died in Dhaka on Saturday night.

The Bangladeshi-British scientist was 71 and is survived by his wife, son and daughter as well as hundreds of climate followers he had mentored.

"Saleemul Huq sir is no more, we lost our guardian," wrote Noor Elahi, a close associate of Huq at the International Centre for Climate Change & Development, Dhaka, of which Huq was founding director.

Sources close to Huq said he had been suffering from lung ailments for nearly a month and had to be hospitalised. He was scheduled to travel to Bangkok soon for treatment but died of cardiac arrest.

Huq had highlighted issues of adaptation -- as well as loss and damage --- relating to climate change. He was a strong advocate of developed countries providing support for areas like the Sunderbans in India and Bangladesh, where millions suffer despite contributing virtually nothing to carbon emission.

"I am perhaps one of few who have been part of all the COPs since they began. I hope that every COP is successful. Sometimes (the hope) is fulfilled, but mostly it is not," Huq had recently told The Telegraph.

"The latest IPCC (Intergovernmental Panel on Climate Change) report clearly shows that the disasters around the world are attributable to climate change, and there should be action on the ground. Industrialised countries should walk the talk and support climate action in the least developed and developing countries."

He had added: "I am hopeful the COP-28 will deliver, including in the key areas of adaptation and loss and damage which are so important to South Asian countries, including areas like the Sunderbans."

Last year, Huq was nominated as one of the top 10 global scientists by the scientific journal Nature, and appointed an Officer of the Order of the British Empire (OBE).

He had contributed to several IPCC and other premier UN reports.

"Saleemul Huq was one of the world's greatest climate adaptation science experts. We were enriched by his engagement in (the) UNEP-hosted World Adaptation Science programme…. May he rest in peace," said Inger Anderson, executive director of the United Nations Environment Programme (UNEP).

Harjeet Singh, a global climate expert attached to the Climate Action Network International, told this newspaper: "Saleem was a leading voice in favour of adaptation for decades; in fact, he started talking about it even before the COP process was initiated in the early '90s.

"He was undertaking research, advising the least developed countries including Bangladesh, and training negotiators simultaneously. His sudden demise is a great loss to the global climate movement."

Sanjay Vashist, director of Climate Action Network South Asia of which Huq was a key member, recalled Huq’s contribution to mentoring others and his crucial role since 2012-13 in the loss and damage sector, which relates to the climate liability of developed countries.

"I still remember how we fought shoulder to shoulder for days at the Sharm el Sheikh COP last year, demanding the loss and damage finance facility, and finally got it. He played a key role," Singh said.