Climate Change Minister Simon Watts. Photo: RNZ / Angus Dreaver
Officials warned against the government's decision to lower New Zealand's methane emissions target, saying it could increase the country's contribution to global warming.
The "primary beneficiary" of a lower target was the farming sector and there was "negligible" benefit to overall economic growth from doing so, they said.
They also noted that the potential effects on the economy did not take into account the actual costs of climate change to the country.
The comments are included in the regulatory impact statement (RIS) prepared ahead of the government's decision to reject advice from the Climate Change Commission to instead strengthen the country's emissions targets for 2050.
The commission had advised setting a 35-47 percent reduction in methane emissions from 2017 levels, up from the existing target of 24-47 percent.
It also recommended strengthening the 2050 net-zero target for carbon dioxide and other long-lived gases, to a net-negative target that would mean New Zealand would remove more of those gases from the atmosphere than it produced.
The government last week rejected both targets.
It opted to retain the net-zero target for carbon dioxide, and confirming an earlier plan to lower the methane target to a 14-24 percent reduction.
In both cases, it cited a small negative effect on economic growth as the main reason for rejecting the advice.
Officials from the Ministry for Primary Industries and the Ministry for the Environment advised that the commission's recommendations were the least feasible of all the options, "due to the significant policy change, market drivers, and private sector action required to achieve the technological uptake and system shifts".
However, they also warned that the lower end of the government's preferred target could be seen as "inconsistent" with New Zealand's obligations under the Paris Agreement.
Instead, officials recommended a methane reduction target of 24 percent - the lower end of the existing target and the upper end of the government's chosen option.
"This option strikes a balance between economic growth and climate change objectives," they said.
The government's choice of target would mean there was no obligation to reduce methane emissions by any more than 14 percent, they said.
"If the lower end of the target (14 percent) is achieved, it will increase the warming caused by New Zealand by [about] 3.3 per cent by 2050 and by [about] 6.2 per cent by 2100 when compared with our current trajectory."
Lowering the target could also "dampen the ambition of mitigation actions and behaviours, including investment decisions by businesses".
The RIS said modelling showed that going ahead with the Climate Change Commission's recommendations could mean a 0.4 percent reduction in economic growth in 2035, and a 2.2 reduction in 2050, partly because of emissions pricing.
It could result in a 17 percent reduction in output from the agriculture sector, and smaller reductions in some other sectors like mining.
But the analysis showed that would largely be offset by large increases in the electricity (52 percent) and utilities (35 percent) sectors, from electrifying the economy.
The negative economic impact could be overstated, officials said.
"In reality we would expect the high emissions prices to drive innovation and result in new emissions-reduction technologies."
There were other important limitations to the economic modelling.
"The modelling also does not account for the impacts of climate change on the economy or society, or the long-term benefits of reducing climate risks and successfully transitioning New Zealand's economy," officials said.
"Recent reports have found the economic costs of climate change to be significant and that there are strong net economic benefits for mitigation policies."
The economic impact of going ahead with the commission's recommended targets was a $12.4 billion decrease in GDP in 2050.
Treasury has previously estimated the total costs to New Zealand's economy from Cyclone Gabrielle were $9-14.5b.
Climate change advocates have previously warned that lowering New Zealand's targets could be seen as a breach of the country's international obligations, including clauses in free trade agreements with the European Union and the UK.
Officials said it was "uncertain" how the international community would respond.
"[New Zealand] be seen as out of step with partner countries who have all gas net-zero targets."
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