The Government has reached consensus on a split-gas target for reducing emissions in its Zero Carbon Bill, a landmark piece of legislation that is designed to set targets for up to 2050. 

This effectively means agriculture will be covered by the law, but the methane generated by animals will be treated differently to carbon. It sets a legally binding “objective” of reducing warming to no more than 1.5 degrees.

The all-important emissions target has actually been split in two: one for long-lived gases like carbon dioxide, and another for short-lived gases like methane. 

This will come as a blow to activists, whose submissions on the Zero Carbon Bill last year overwhelmingly favoured reducing all emissions to net zero, but it is consistent with advice from both the Parliamentary Commissioner for the Environment and the Productivity Commission whose latest reports both backed split gas targets .

Long-lived gases like carbon dioxide are less immediately harmful but persist in the atmosphere for hundreds of thousands of years, effectively locking-in the warming they create.

The targetin the bill  for carbon is net-zero by 2050. This will require both reductions in emissions, and the creation of more “carbon sinks”, like forests. 

Short-lived gases like methane are very damaging in the short-term but mostly leave the atmosphere within decades. These will not be reduced to net zero. 

An often-used metaphor is that of a bubble bath: where the carbon dioxide represents water slowly filling the bath, while methane represents the bubbles, which quickly add to the level of the bath, but disappear just as fast. 

The target for these gases will be a 10 percent reduction in biological methane emissions by 2030, aiming for a 24 to 47 percent reduction by 2050.

Treating agriculture differently is both politically and economically contentious. While New Zealand’s economy is massively reliant on agricultural exports, agriculture is also responsible for 48 percent of our emissions. 

The bill had been delayed last year as Shaw struggled to reach consensus with both New Zealand First and National’s climate change spokesperson Todd Muller. The bill is designed to be bipartisan, which will give it a chance of surviving changes in Government.

National has not yet committed to supporting the bill through Parliament as it needs to be taken to its caucus first, however its support is likely. 

Six emissions budgets to get to zero. 

The Zero Carbon Bill will actually be an amendment to the Climate Change Response Act. It will be tabled later today and read for a first time later this month, before heading to a select committee in June. 

The bill will create a Climate Change Commission, which will set emissions budgets every five years to act as stepping stones to the long-term target. The first target will be for 2022-25. Five subsequent budgets will have the difficult task of pushing New Zealand to net-zero by 2050. 

The Government says these will help New Zealand meet its Paris Agreement target of reducing greenhouse gas emissions to 30 percent below 2005 levels by 2030.

Once the Commission has set emissions budgets, the Government must then respond to its advice and establish a plan to meet the budget set by the commission. Crucially, the goals do not form a legal obligation on the Government, which will rely on political power to see them enforced. 

The Government will also have the ability to amend budgets but only if there have been significant changes.

Each budget will state the quantity of greenhouse gases permitted, expressed as a CO2 equivalent. It will cover all greenhouse gases: CO2, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride, and nitrogen trifluoride. 

Another note of contention: nitrous oxides will be treated as long-lived gases under the law, even though they are considered to fall somewhere between carbon and methane in the level of damage they cause. 

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