Mr Brown said climate change was a critical issue for Auckland's future with a target of reducing greenhouse gas emissions by 40 per cent by 2040.
The mayor's annual scorecard across a number of measures over the past year showed a deterioration in greenhouse gas emissions, freshwater quality and air quality. Marine water quality improved.
Last year, it was revealed that Mr Brown's Holden Calais V6 limousine had a carbon footprint more than 70 per cent bigger than some alternative vehicles. He dismissed an electric car as too small for carrying up to five adults and providing space to work.
Mr Brown said his travel costs were being covered by Bloomberg Philanthropies.
Environment, Climate Changes and Natural Heritage committee chairman Wayne Walker and council's overseas investment champion Sir Bob Harvey are paying their own costs to attend the conference.
The other members of the council party are chief sustainability officer John Mauro and mayoral environment portfolio manager Dr Megan Howell.