He served as chairman of the thirteenth session of the Commission on Sustainable Development, which met at United Nations Headquarters on 11–22 April 2005.

[citation needed] In April 2009, he was elected chair of the Ad Hoc Working Group on Further Commitments for Annex I Parties under the Kyoto Protocol (AWG-KP), and was responsible for overseeing negotiations leading up to and including the final phase at the 2009 United Nations Climate Change Conference in Copenhagen.

[citation needed] According to Farrukh Khan, the Program Manager on Climate Finance at the UN Secretary General's Office, Ashe played a central role in the negotiations for the Sustainable Development Goals (SDGs).

The complaint accused Ashe of using "his official position to obtain for Ng potentially lucrative investments in Antigua" as part of an alleged broader scheme to funnel more than $1 million in bribes from Chinese sources to facilitate business dealings, particularly in real estate.

The Westchester County, New York medical examiner's office reported that Ashe died of injuries (specifically, traumatic asphyxia, and laryngeal fractures) suffered when a barbell he was lifting from a bench dropped on his neck.