The Agriculture Minister says our climate obligations trump the productivity of farmers.

The recently detailed Zero Carbon Bill aims to reduce biological methane emissions by as little as a quarter, or as much as a half by 2050.

Damien O'Connor told Mike Hosking it's not ideal to put pressure on farmers to stunt their operations.

"We do have to meet our international obligations and if 50 per cent of our total emissions in agriculture are always going to be a big challenge, we're putting a lot of money into scientific research across the livestock sector."

However, he says our climate goals are getting our farmers on-side with big overseas markets.

O'Connor says some countries might not accept our agricultural products if we're not being seen to do our bit to prevent climate change.

"We're a very small country. Our total emissions relative to others are small. The problem is, in Europe consumers want to be part of a global action on climate change. So if we're going to sell the best and get the best money for it, we're going to have to be meeting our international obligations."