Oxford University's Professor Gideon Henderson has been appointed by the UK government's Department for Environment, Food and Rural Affairs (Defra) to be its new Chief Scientific Adviser (CSA).
Professor Henderson, Professor of Earth Sciences at Oxford and until recently head of the Earth Sciences department, will join Defra in October this year.
He will replace Sir Ian Boyd, who is leaving Defra after seven years in the post.
Environment Secretary Michael Gove said: "Sir Ian Boyd's contribution to Defra's work has been invaluable, and I am immensely grateful for all the advice he has provided over the past seven years, informing key government policies.
"I warmly welcome Professor Henderson to the role and look forward to working with him and seeing his positive impact on science in the department going forward.
"It is absolutely crucial that all our policies are based on sound scientific advice to ensure we are addressing the UK's most pressing environmental issues in a targeted and innovative way, and Defra's Chief Scientific Adviser is vital to this process."
Commenting on his appointment, Professor Henderson said: "I am thrilled to be joining Defra at a time when the environment is such a strong priority and there is an ever-growing public level of environmental awareness.
"The UK faces many challenges - among them responding to climate change and helping meet a net-zero emissions goal, as well as ensuring our food's security and realising the goals of the 25-year environment plan.
"I look forward to working closely with colleagues to help achieve these ambitions with the support of the UK's excellent scientific research."
Tamara Finkelstein, Permanent Secretary at Defra, said: "I am delighted that Gideon Henderson is joining us as the new CSA for Defra, bringing with him strong experience in geochemistry, ocean sciences and climate. I look forward to working with him as part of the Defra executive committee and as a leader of our superb scientist community."
The CSA sits on Defra's board and is responsible for overseeing the quality of evidence that the department relies on for policy decisions. The CSA also provides Ministers with scientific advice and sets the priorities for scientific research and evidence-gathering.
Professor Henderson has been Professor of Earth Sciences at Oxford's Department of Earth Sciences since 2006. His awards and accolades include election as a Fellow of the Royal Society.
His research uses geochemistry to understand surface earth processes - particularly those relating to climate, the ocean and the carbon cycle. Two major themes have been the use of past climate to assess climate issues relevant to the future, and assessment of the cycles of metals in the modern ocean, including contaminants and nutrients. His present work includes researching the potential and risks of accelerating natural processes to remove CO2 from the atmosphere.