With deepest sadness, we share with you that Geert Jan van Oldenborgh (59), initiator, creator and maintainer of the Climate Explorer, sadly passed away on Tuesday 12 October. Geert Jan's contribution to climate science is immense and he will be sorely missed.

Geert Jan has received a lot of recognition for his work in recent years. For example, this year he is on the list of 100 most influential people of the American TIME Magazine, together with climate scientist Friederike Otto. His response to this: "It has never been our intention to be influential, we are only providing scientific answers to questions of how climate change affects extreme weather". In April he was awarded a Knight of the Order of the Netherlands Lion for his major contribution to climate science.

After studying theoretical physics in Leiden, Geert Jan obtained his doctorate in particle physics at the NIKHEF in Amsterdam in the late 1980s. After a few temporary appointments in that field of research, he joined the KNMI in 1996. His work initially focused on the dynamics and predictability of El Niño, the warming of sea water in the eastern Pacific Ocean. As a 'by-product' of this work, he wrote a computer program with which he could link and analyze weather and climate data: the KNMI Climate Explorer. It became a great success. He received the Technology Achievement Award 2021 from the European Meteorological Society (EMS).

Geert Jan was at the origin of a young branch of climate science: climate attribution, explaining the relationship of extreme weather with climate change. He is one of the driving forces behind the international team of scientists at World Weather Attribution (WWA). In recognition of this work, he was appointed professor by special appointment at the University of Oxford in 2020. In addition, Geert Jan has contributed to assessment reports of the IPCC, the climate panel of the United Nations.

Geert Jan was very concerned about the climate and was able to explain the causes and consequences of climate change in a clear and accessible manner. That is why he was frequently asked to explain extreme weather events in the media. He saw it as his duty to share his scientific knowledge. He said of himself, "If Geert Jan gives figures, they will be correct. That is the reputation I hope to have."

Eight years ago Geert Jan was diagnosed with Kahler's disease, an incurable cancer. "On even days I am optimistic and I see the innovations with sun and wind. But on the odd day I think: it's not enough, we won't make it. That's frustrating too. Given my life expectancy, I will never know how this will end."