The conservation charity WWF-UK has appointed the environmentalist Tony Juniper as executive director for advocacy and campaigns.
Juniper, who is a fellow of the University of Cambridge Institute for Sustainability Leadership and a co-founder of the sustainability consultancy group Robertsbridge, will join the charity in January.
He has been working as an independent environment and sustainability adviser, writer and campaigning since he left Friends of the Earth in 2008, after five years as executive director.
Juniper, who was appointed CBE this year for services to conservation, is president of the Wildlife Trusts and the Society for the Environment.
"It is an honour to be joining WWF and to be able to help in achieving its vitally important mission of protecting life on Earth," he said in a statement.
"What we humans choose to do during the coming years will determine outcomes with profound ramifications, not only for our living planet but for people too. I very much look forward to working with my new colleagues in making the most of all the opportunities we have for shaping our choices in positive directions."