"A lot can be done to reduce greenhouse gas emissions from transport," he said yesterday.
Transport had a crucial role to play, and he urged "more promotion of public transport, with introduction of "free city transport offered by local governments, paid by ratepayers, at least as a trial exercise".
Some fare-free public transport had been offered in Auckland and he would like to see this extended and offered elsewhere.
Sir Alan is a University of Otago botanist and chairman of the Wise Response Society, a group that promotes sustainable approaches and a "wise response" to climate change challenges.
There was "no substitute for reducing emissions", rather than simply trying to capture carbon through extensive exotic tree planting, he said yesterday.
Such emission cuts required promotion, policies and regulations by central and local governments.
And cuts were vital "in effectively addressing global warming and associated climate disruption", he added.
"Permanent forests, exotic or native, would be more effective in sequestering carbon, " he said.
- This story is part of the Otago Daily Times contribution to Covering Climate Now, an international campaign by more than 170 media organisations to draw attention to the issue of climate change ahead of a United Nations summit on September 23. To read more of our coverage, go to odt.co.nz/climate.