In New Zealand, its not so much people, but methane-producing livestock that's the problem. A revived government proposal would tax farmers for their animal's gas emissions.
"Methane, which accounts for about half of New Zealand's total annual greenhouse emissions, had to be brought under control, said panel members at last night's Hot Science event in Christchurch.
"Although the Government had shelved earlier proposals for fart taxes on farmers and carbon taxes on business, one or both might still be necessary.
"We need to face up to the fact that we are producing a lot of greenhouse gases in New Zealand and we need to move away from that," Cullen said.
Moderator Kim Hill asked about the contributions to methane production from different rural sectors.
"Is it dairy farmers that produce the most methane? The cows, I mean?"
Cullen said the country's approximately 40 million sheep and six to seven million cattle produced about the same amount of methane."