My friend and colleague, Keith Briffa, who has died aged 64, was a climate scientist whose influential work helped drive the international acceptance of global warming as being due to human agency.

His scientific investigations ranged widely but his most influential and sustained contributions lay in decoding the complex climatic signals encrypted by annual tree rings and thereby positioning the science of dendro-climatology on rigorously tested foundations.

His methods were adopted by researchers worldwide and this led to the growth of a global network of tree-ring data, providing estimates of annual temperature stretching back centuries and in many cases millennia before modern instrumental records began.

Collective international efforts in which Keith played a leading role eventually enabled the average temperature of the Earth to be estimated on an annual basis over the past 1,000 years. This showed that modern global warming has exceeded any of the natural variations in that time.

Tree rings alone could not pinpoint the cause but they proved conclusively that something new was afoot, and confirmed the wealth of other evidence that was presented to governments via the five-yearly assessment reports of the Intergovernmental Panel on Climate Change. Keith made important contributions to four of these including the 2007 assessment that was followed by the collective award of the Nobel peace prize to the IPCC scientists.

Keith was born in Liverpool to Raphael Briffa, a machinist from Malta, and his English wife, Dorothy (nee Campbell), a catering manager. He grew up in Speke, attending St Francis Xavier’s college before studying biological sciences at the University of East Anglia. He joined UEA’s climatic research unit in 1977, remaining for 40 years and becoming professor, deputy director and emeritus professor.

In 1983 he married Sarah Raper, a fellow climate scientist. They brought up two daughters on a run-down farmstead that provided ample opportunities for his passion for renovation and building. He brought enormous enthusiasm to all his interests and became extremely knowledgable at each, knowledge that extended to the care and management of a small flock of sheep, later replaced by alpacas. He also had an interest in the arts, and latterly took up metal detecting with a small group of friends, researching the artefacts that can be seen on the website Detecting Norfolk History.

Keith was fun to be with. His capacity for hard work, good humour and affability infected everything he did, while his generosity to fellow scientists and students did much to promote the spirit of collaboration on which modern climate science thrives.

In 2009 he was struck by the first of several bouts of cancer. An optimist, he was determined to keep on living and working with the aid of his doctors, which he did for nearly a decade. The last of his 130 scientific papers was published a few months ago.

He is survived by Sarah, their daughters, Amy and Kirsten, and his sister, Dianne.