Mr de Boer who has led UNFCCC since September 2006, says: "It was a difficult decision to make, but I believe the time is ripe for me to take on a new challenge, working on climate and sustainability with the private sector and academia."

A UNFCCC spokesperson told Renewable Energy Focus that no further reason for de Boer's departure is available.

"I have always maintained that while governments provide the necessary policy framework, the real solutions must come from business.

“Copenhagen [COP15] did not provide us with a clear agreement in legal terms, but the political commitment and sense of direction toward a low-emissions world are overwhelming. This calls for new partnerships with the business sector and I now have the chance to help make this happen", he adds.

Yvo de Boer will remain in his current position as head of the UNFCCC until 1 July and help negotiations move forward ahead of the Climate Change Conference in Mexico (COP16) in November this year.

"Countries responsible for 80% of energy related CO2 emissions have submitted national plans and targets to address the climate change. This underlines their commitment to meet the challenge of climate change and work towards an agreed outcome in Cancun", he says.

Yvo de Boer will be joining the consultancy group KPMG as Global Adviser on Climate and Sustainability, as well as working with a number of universities.

Yvo de Boer’s speech can be downloaded from the right hand side of this page.