Sir John Houghton, the respected physicist and climate scientist, has died from Covid-19 complications. He was 88 and had been suffering from dementia.
A committed Christian, he was widely respected for his activism and research on climate change.
He was the first co-chair of the influential Intergovernmental Panel on Climate Change, a role he held from 1988 to 2002.
He was also a professor in atmospheric physics at the University of Oxford and a former Director General at the Met Office.
He was brought up in a Christian family in Wales and his faith would remain an important part of his life, with Sir John going on to serve as an elder at Aberdovey Presbyterian Church.
In a moving tribute on Twitter, his granddaughter Hannah Malcolm said he had become committed to his faith at university, where he also became "interested in how faith and science intersected".
She quoted him as saying, "Science was a voyage of discovery to the way the universe worked, and it was God's universe, then it was studying the works of God, and that's something that stuck with me."
She said of her grandfather: "My granddad died yesterday from COVID-19. He was an atmospheric physicist and committed Christian who devoted his career to climate justice, including chairing the IPCC and changing the mind of a major U.S. evangelical lobbyist."
She was referring to Richard Cizik, the then head of the National Association of Evangelicals who, at a time when many American evangelicals were sceptical or indifferent to climate change, embraced a "creation care" position after hearing Sir John speak.
Malcolm paid tribute to her grandfather's commitment to climate justice and his Christian faith.
"When I was younger, my consistent memory of him was warnings over the devastation waiting us if we didn't act on climate change. And I remember thinking how glad I was that scientists like him were in charge. But of course it isn't the scientists in charge," she said.
"He faced a lifetime of lobbyists and corporations trying to undermine his work, question his motives, and distract from evidence. But my other consistent memory will be his deep faith that he was doing work in service of the God he loved, and in service of the world he loved."