Those protein sources have less impact on the natural world than livestock farming.
As the OECD (Organisation for Economic Co-operation and Development) country most dependent on the natural world for its economy, New Zealand needs to react quickly.
The country's farmers have proved adaptable and Mr Oram thinks they can do it.
"People will continue to be able to earn a living from that land, but they will be farming different things, in different ways."
The world has to move to net zero greenhouse gas emissions by 2050 to avoid catastrophic global warming. At this stage Mr Oram doesn't think the warming can be limited to 2C.
Nearly half (49 per cent) of New Zealand's greenhouse gases are methane and nitrous oxide from farming ruminant animals: sheep, cattle, deer and goats.
The methane is emitted mainly by burping, and most of the nitrous oxide is gassed off when micro-organisms act on urine in soils.
The country loses almost 200 million tonnes of topsoil a year through erosion, and 80 per cent of farm soils are compacted.
Maintaining large areas in grass has reduced biodiversity, and New Zealand has one of the highest percentages of threatened species in the world.
The grass and crops are fed with manure and artificial fertiliser. When those nutrients are not taken up by plants they pollute water. New Zealand has the worst and fastest growing nitrogen imbalance in the OECD.
A group of New Zealand MPs commissioned British consultancy Vivid Economics to consider what the country can do to get to zero emissions.
Electrifying transport, increasing renewable energy and 500,000ha of new forest would reduce emissions by only between 10 and 20 per cent. Land use will have to change more drastically than that.
Vivid's report, www.vivideconomics.com/publications/net-zero-in-new-zealand, says all those technical improvements plus 1 million ha of new forest and 25 to 30 per cent fewer and low-emitting animals would cut emissions 70 to 80 per cent.
If the right technology doesn't come through then more forest will be needed, 1.6 million ha, creating a bigger upheaval in the countryside.
Where trees are concerned, Mr Oram strongly favours native ones. And on hill country, the parliamentary Commissioner for the Environment's 2016 report Climate Change and Agriculture says, natives will regenerate once grazing stops.
Farmers will find ways to appreciate the new land uses.
"When monoculture ends there are a greater variety of plants and animals. I think if you love your land you will quite quickly find all sorts of other things to love about it," Mr Oram said.
Making these changes would increase productivity, add to biodiversity, take the pressure off water and soil and keep the country attractive for tourists. It would also resonate with the outdoorsy image New Zealanders have of themselves.
"Whilst I am positive about all that, my biggest concerns are that we will not figure out how to move and change things in complex ways, and fast enough," Mr Oram said.
Read more: Editorial: Climate change to transform farming
