Condemnation of the Government's plans to address climate change is growing within the rural sector with claims stock would have to be culled to reach the proposed targets.
The Climate Change Response (Zero Carbon) Amendment Bill will create a legally binding objective to limit global warming to no more than 1.5degC with a net zero carbon approach.
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A specific target for biogenic methane has also been created with Climate Change Minister James Shaw saying the Government needed to work with the agriculture industry to manage emissions.
The bill sets out a 10 percent reduction in biological methane emissions by 2030, with a provisional reduction ranging from 24 percent to 47 percent the aim by 2050.
However Federated Farmers said the targets would send the message to farmers that New Zealand is prepared to give up on pastoral farming.
"This decision is frustratingly cruel, because there is nothing I can do on my farm today that will give me confidence I can ever achieve these targets," said vice president and Climate Change spokesperson Andrew Hoggard.
He said New Zealand farmers are already playing their part in tackling global warming, and are willing to do more.
"But hearing the Government setting arbitrary targets based on a random selection of reports and incomplete data will leave some farmers wondering; 'what is the point?'" he said.
"The 10 percent reduction target for methane by 2030 gives us a deadline for going beyond net zero more than 20 years earlier than for any other sector of New Zealand. It is unheard of anywhere else on the planet."
He said the targets are significantly higher than what is necessary to be equivalent to net-zero carbon dioxide.
"The announced methane reduction target for 2050 of 24-50 percent, when coupled with the target of net zero for nitrous oxide, requires the New Zealand agriculture sector to reduce its emissions by 43-60 percent."
"Let's be clear, the only way to achieve reductions of that level, is to cut production. There are no magic technologies out there waiting for us to implement."
"At this point in time we have no idea how to achieve reductions of this level, without culling significant stock numbers."
Meanwhile New Zealand's meat processors and exporters are also alarmed at the proposed methane emissions reduction target.
Chief executive of the Meat Industry Association (MIA) Tim Ritchie said the Government appears to have based its target on a range of global emissions scenarios in the IPCC report.
"We are concerned the Government has cherrypicked aspects of a report summarising global emission pathway scenarios and applied it to New Zealand," he said.
"Their target is contrary to science-based policy. The science indicates that to achieve a goal of no increased global warming from agriculture, nitrous oxide emissions from agriculture must come down to net zero as quickly as possible, but methane only requires a slow decline in the order of 0.3 percent a year."
He said the proposed emissions targets are simply not possible with current technologies and farming methods, short of a significant decrease in pastoral agriculture.
"This will impose enormous economic costs on the country and threaten many regional communities who depend on pastoral agriculture."