Farmers are abandoning their fields and taking to the streets of New Zealand’s cities on Thursday to protest nationwide against plans to tax greenhouse gas emissions from livestock.

Convoys of tractors, four-wheel drive vehicles and farm vehicles disrupted traffic in Wellington, Auckland and other major transport hubs as protesters demanded the centre-left government drop plans for a “burp and fart” tax on animals.

Earlier this month Prime Minister Jacinda Ardern announced a “world-first” levy on methane and nitrous oxide emissions produced by the country’s 6 million cows and 26 million sheep as a step to combat climate change.

Thousands of farmers rallied on Thursday, waving signs saying the policy “stinks” and warning that the tax would make food more expensive while jeopardizing their livelihoods.

“Most farmers have enough,” said a protester from Wellington, who gave his name only as Chris. “It’s going to be difficult to continue farming and this government isn’t really supporting us – it’s a tough job at the moment.”

Animals produce methane and nitrous oxide as a by-product of eating grass and forage.

Methane is much rarer than carbon dioxide and doesn’t stay in the atmosphere as long, but it’s a much more potent warming agent.

Scientists believe that methane is responsible for about 30 percent of global temperature rise, even though it makes up only a fraction of the greenhouse gas mix.

Ardern has argued that the tax is necessary to meet climate targets and could even benefit farmers if they could charge more for climate-friendly meat.

She also signaled a possible willingness to compromise.

“We are talking to our farmers and food producers about the best possible design,” she told reporters in Auckland.

Bryan McKenzie, of protest organizers Groundswell NZ, said the tax was “punitive” and “an existential threat to rural communities”.

“After years of false consultations, the government has given up any pretensions to a fair and workable agricultural emissions policy.”

While the government hopes the tax will reduce animal emissions by 20 percent, McKenzie argues that any “reductions will be replaced by less efficient foreign farmers.”

City supporters also joined the protest in some regions, with a sign in the southern city of Dunedin reading “Farm tax affects us all”.

In a joint statement, several mayors from remote regions of New Zealand’s west coast said they “strongly support” the protest.

Environmentalists argue that protesting farmers are stuck in the mud.

“This country’s rural and agricultural sector has been badly hit by floods, violent storms and droughts this year alone,” said Emily Bailey of Climate Justice Taranaki.

“This has cost millions in damage and heaps of stress and heartache for those who have lost homes, sheds, supplies and fences… It’s only going to get worse,” she said.

“Farmers can either adapt and cut their emissions quickly, or they and everyone else will suffer more.”