Consultation underway on the Government‘s proposed Zero Carbon Bill

8 MinutesBy NZ Trucking magazineJune 25, 2018

The Government’s proposed Zero Carbon Bill lays out how they plan to transition New Zealand to a low-emission economy by 2050. Public consultation on the Bill opened 7 June, with the discussion document asking citizens what they think the 2050 emissions targets should be.

Each target has different implications for New Zealand’s climate and economy. The options are:

  • net-zero carbon dioxide only;

  • net-zero long-lived gases (e.g. carbon dioxide, nitrous oxide) and stabilised short-lived gases like methane; or

  • net-zero emissions for all greenhouse gases.

Distinguished Professor Robert McLachlan, Applied Mathematics, Massey University, says short-lived gases, such as methane are a flow pollutant, and emitting them at a steady rate leads to steady levels in the atmosphere.

“Long-lived gases – such as carbon dioxide emitted by burning coal, oil, and gas, and nitrous oxide emitted by animal manure and chemical fertilisers – are a stock pollutant. Emitting them at a steady rate leads to steadily increasing levels in the atmosphere.

“Current international rules include all these gases. New Zealand has a particular interest in separating short- and long-lived gases because we make a lot of money from activities that emit the short-lived gas methane.”

McLachlan says modelling commissioned by the Productivity Commission indicates that a net zero target can be achieved, and that it was not any harder for New Zealand than for other countries.

“There are good reasons for including flow pollutants in the target. New forests, which we expect a lot of in all scenarios, are analogous to flows, because the carbon stored by the forest does not build up indefinitely. Methane is responsible for a significant part, about a quarter, of current warming.

“Cutting methane emissions provide an immediate decrease in temperature; cutting carbon dioxide emissions does not. This may be significant as climate change impacts increase nonlinearly and we approach tipping points. Some ways of cutting agricultural and waste emissions are known already we need an incentive to adopt them.”

Professor Ralph Sims, director, Centre for Energy Research, Massey University, says the latest science projections are that we are currently on track to exceed 1.5°C warming in around only 20 years‘ time.

“There is no question that long-lived CO2 has to be reduced by urgently weaning ourselves off fossil fuels. Planting more forests on to marginal pasture land will buy some time to phase out coal, oil and gas, but can only be a temporary option.

“Consultation on the Bill includes discussion around methane (CH4) being treated differently as it is a relatively short-lived gas in the atmosphere compared with CO2 for which each molecule emitted can last for hundreds of years.”

Sims says a simple analogy for cumulating long-lived CO2 emissions is a bath of water slowly filling up as the tap keeps dripping until it overflows, while for the methane bath, the plug is poorly fitted so some water continually leaks out as the dripping tap continues. If the leakage is at the same rate as the tap is dripping, then the water level in the bath remains stable. If the tap is turned on a little further (i.e. the flow of methane emissions increases), the water level will slowly rise a little and the global warming impact will be greater. The argument is being made that stabilising the current stocks of methane in the atmosphere would be sufficient, at least in the short term.

Sims says while this would take pressure off the farming sector having to reduce its emissions, as in spite of much research, identified solutions to date give only small reductions.

“However, the very same methane gas also enters the atmosphere from leakage at coal mines, natural gas fields and pipelines. Indeed NASA has recently confirmed this is the main source of the concentrations of methane that had mysteriously increased in the atmosphere over the past decade or so – especially from fracking.

“As methane molecules break down in the atmosphere over a decade or two, it produces CO2. If the methane is bio-based, it can be argued that the resulting CO2 is recycled back through the growing pasture or rice plants. However, if it is fossil-based methane, then the resulting CO2 is no different from that released from fossil fuel combustion.”

Sims says any mitigation policy that is less stringent on agricultural methane emissions has to consider its impact on fossil methane emissions that cause greater warming. In New Zealand, agricultural methane dominates but elsewhere fossil methane does.

“Under our nationally determined contribution – where countries have stated under the Paris agreement what their emissions reduction will be by 2030 (New Zealand‘s target is 11.2% below 1990 level or 30% below 2005 level) – we can use any means to reduce emissions as deemed most appropriate. But the international debate about whether methane can be treated differently to CO2 will be more challenging.”

Sims says the opportunity provided for businesses, organisations and individuals to consult on the Zero Carbon Bill was commendable.

“The aim of Government to have the Zero Carbon Act and Climate Change Commission in place at some time around the end of this year should be supported. It is encouraging that the National opposition is showing some support as there has to be cross-party agreement to give long-term certainty. In this regard, the UK model has proved to be highly successful over the past 10 years.

“Given the continuing annual increases in New Zealand‘s net greenhouse gas emissions, and the failure of the Emissions Trading Scheme to curb them, stopping offshore oil/gas exploration was a brave start. Further leadership from Government through implementing strong policies is now essential and the Zero Carbon Act will hopefully provide this before it becomes too late.”

For more information on the consultation process, visit