UN secretary-general Kofi Annan has been given one of the most prestigious environmental awards, the Zayed Prize.
UN chief Kofi Annan: "Deservedly the global winner"
The citation noted his "personal leadership" on sustainable development.
The 1,360 scientists whose research contributed to the Millennium Ecosystem Assessment were also honoured, as were activists from Trinidad and Indonesia.
The winners of the prize, which honours former UAE President Sheikh Zayed, share $1m (£564,000); previous awards have gone to Jimmy Carter and the BBC.
Mr Annan's prize, for Global Leadership on the Environment, nets him $500,000.
"One person has done more than most to catalyse political and public opinion to an understanding that the environment is a fundamental pillar of sustainable development," said the jury in its citation.
"That person is Mr Kofi Annan."
Jury chair Klaus Toepfer, executive director of the United Nations Environment Programme, added: "When you look at the overall global impact on politics, business and civil society of Mr Annan's environment and sustainable development-related initiatives, we came to the conclusion that he is deservedly the global winner."
Among the instances given of the UN chief's leadership was his decision to set up the Millennium Ecosystem Assessment, a global research project aimed at producing a definitive snapshot of the planet's environmental health.
The scientists who contributed share the second element of the Zayed prize worth $300,000, for Scientific and Technological Achievement.
The jury described it as a "landmark study" which "demonstrates that the degradation of ecosystems is progressing at an alarming and unsustainable rate".
The $200,000 third segment, for Environmental Action Leading to Positive Change in Society, is shared between Angela Cropper, co-president of the Cropper Foundation in Trinidad and Tobago, and Emil Salim, a former Indonesian minister who is now involved with a range of environmental organisations.
This is the third round of Zayed Prizes, named after Sheikh Zayed Bin-Sultan Al Nahyan, who died just over a year ago.
Former US president Jimmy Carter won the inaugural award in 2001, while the BBC and the Intergovernmental Panel on Climate Change were among the winners of the second round.