In the last general election, policy to tackle our greenhouse gas emissions was put front-and-centre with a Climate Voter movement and a televised debate devoted to the issue.

That demand for action hasn't waned - and this year Waikato University student Sarah Thompson felt compelled to sue the Government over what she argued was a lack of commitment to the global effort.

Weeks later, celebrities, scientists, doctors, businesspeople and thousands of other Kiwis came together to launch a fresh push, calling on the Government to phase out the extraction and burning of fossil fuels by 2050, and adopt tougher policy.

And now, environmental groups have been furious to learn the Government has been sitting on an official report estimating that $19 billion of property is at risk from the effects of climate change.

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Yet the Goliath issue has been oddly absent from the first two televised leader's debates.

For New Zealand, the impacts of climate change would be serious and wide-ranging: sea levels could rise by up to 1m and temperatures could increase by several degrees before the end of the century.

Climate change would bring us more floods - about two-thirds of Kiwis live in areas prone to flooding - make our freshwater problems worse and put more pressure on rivers and lakes.

Our primary industries would be transformed, even more species would be put at risk, and New Zealand would experience flow-on effects from climate change's potential global impacts, spanning from disease and famine to regional conflict and the mass displacement of millions.

Many Maori, who have a unique relationship with the natural environment and advocate its preservation through the principles of kaitiakitanga, are particularly interested in what climate change will mean for their land and people.

While New Zealand contributes just 0.15 per cent of the world's emissions - a fact often pushed by those who argue against taking a more ambitious stance - a recent international ranking found the 24 per cent increase our country registered between 1990 and 2014 placed the rise as the seventh worst out of 41 industrialised nations.

And although about a third of our emissions come from transport and electricity generation, the greatest proportion - around half of the inventory - comes from agriculture, and much of that from methane belched from ruminant livestock like sheep and cows.

It's a headache the National-led Government has been trying to solve by spending around $20 million each year on agricultural greenhouse gas research.

But to meet its agreed pledge to cut emissions by 30 per cent from 2005 levels and 11 per cent from 1990 levels by 2030, the Government will largely rely on carbon trading and our main climate mechanism, the Emissions Trading Scheme.

That includes buying around $14b worth of international carbon credits over the next decade to offset what emissions we produce here.

Under the ETS, companies are required to match each unit of emissions they report with an allowance, or credits, they must pay to the Government.

People who plant forests, meanwhile, can report the carbon dioxide they take out of the air and claim credits, which they can sell, thus creating a trading market and an incentive to lower emissions.

Introduced in 2008 to meet Kyoto obligations, the ETS has gone through multiple reforms.

Just a year after it was established, the scheme was overhauled by National, ushering in a raft of amendments many argued gave polluters an easier ride.

At the time, the Government called its new ETS "workable and affordable" - but the Herald dismissed it as a "miserable offering to the international effort".

The latest moves have scrapped low-credibility "hot air" credits that could long be bought cheaply from other countries and phased out a two-for-one measure, and proposed units to be auctioned and for participants' use of international units to be limited when the ETS eventually reopens to international carbon markets.

Elsewhere in the climate space, National plans to phase down the use of hydrofluorocarbons by 80 per cent, spend $2b on public transport, increase renewable electricity to 90 per cent by 2025, eliminate fossil fuel subsidies, plant millions more trees, and work toward doubling the number of electric vehicles registered every year to reach 64,000 by 2021.

It's set up three new expert groups to look at adaptation, agriculture and forestry to address climate change, spent $31m on research into understanding climate change and its impacts, pledged up to $200m in international aid for climate-related support and signed the Climate Change Action Plan with China.

But critics say New Zealand has been nowhere near bold enough.

Labour, whose leader Jacinda Ardern has called climate change her generation's "nuclear-free moment", would establish an independent Climate Change Commission to track progress on the transition to a zero-carbon economy by 2050, and offer expert advice.

Further, it would set emissions targets in law, forcing governments to meet them, and extend the ETS to cover all forms of gases and sectors, including agriculture, which green groups have argued to be folded into the scheme.

Labour also wants the public sector to lead the way on reducing emissions, and it would require state-owned enterprises and other government departments to pursue low-carbon options and technologies.

Under the policy, the public sector could only buy electric cars for their fleet unless there were "exceptional reasons" not to do so.

Some parties would scrap the ETS altogether.

The Greens advocate replacing it with a polluter-pays carbon tax - initially set at $25 per tonne for all sectors except agriculture, which would start at $12.50 - and NZ First argue it should be swapped for a UK-style Climate Change Act and a parliamentary commission which would set three-yearly carbon budgets starting in 2021.

The Greens also back establishing a new commission, along with a goal to have electricity 100 per cent sourced from renewable energy by 2030, and a legally-binding target to make our economy carbon neutral by 2050.

The party would set up a state-owned "Green Investment Fund" to help launch new clean energy and infrastructure projects, with its initial $100m line of credit raised by hiking royalties on oil extraction from 46 per cent to 70 per cent.

It would also electrify rail between Auckland, Hamilton and Tauranga to move freight off the road, and incentivise businesses to choose clean transport options for staff, while ensuring that at least 20 per cent of the vehicles the Government buys in the next seven years are electric.

Act would replace petrol taxes with a user-pays road pricing system, alongside new lanes for high-occupancy vehicles like buses.

NZ First would go further and require that all government vehicles be electric within a decade, and also bring in "net metering", where electricity retailers are required to buy power generated by customers at the price at which it's typically sold to them.

The Maori Party wants emissions goals set into law, also through a new commission; to offer tax breaks for research on renewable energy; to close all coal-fired plants by 2025; and to plant 100,000ha of forest over the next decade.

It's also promoting incentives to low-income families and remote communities, offering solar power and energy storage such as home batteries, while also helping displaced Pacific communities through a visa scheme.

The Opportunities Party (Top) is campaigning to cover much more ground - reforesting 1.1 million hectares of erosion-prone land.

Elsewhere in its comprehensive climate policy, Top, which also has set a 2050 carbon-neutral goal and a 2035 target to achieve 100 per cent renewable electricity, would ensure all large new investments take into account a low carbon future.

While the party wouldn't scrap the ETS, it would dump "junk" credits held by the Government by cancelling surplus credits as at 2020 and ensuring the scheme stays closed to international trade.

All revenue from a higher carbon price would go back toward helping households and businesses become more energy efficient, slashing their costs and emissions.

An 'increasingly disastrous phenomenon'

Young Aucklander Will McKay is a Blake Ambassador with the Sir Peter Blake Trust. Photo / Supplied
Young Aucklander Will McKay is a Blake Ambassador with the Sir Peter Blake Trust. Photo / Supplied

Will McKay has more reason than most to care about climate change.

Not only does the University of Auckland PhD candidate's research area, aquaculture, hinge on what's going to happen to our planet, but he's young enough to potentially see some of global warming's most significant near-future impacts.

"Human-induced climate change to me is a result of a long-term misunderstanding of how our actions impact the planet and more recently, poor management of Earth's resources," McKay said.

"Although an increasingly disastrous phenomenon, I find climate change an interesting challenge because if we are to avoid the worst we will need to research, experiment, innovate and challenge the norm."

But in the political realm, McKay, a Blake Ambassador with the Sir Peter Blake Trust, feels issues around the environment have sat somewhere behind personalities, personal accusations and economic policy at election time.

"Environmental issues are often polarising, particularly as they raise discussion on rangatiratanga and kawanatanga and affect industry and large voting bases such as agriculture.

"These issues require multifaceted approaches encompassing environmental, social, cultural and economic considerations.

"Because no one currently has the answer to solve these issues and keep all affected parties happy it appears parties avoid bringing on more trouble amongst the chaos that election time brings."

He'd like to see policy that improves the Emissions Trading Scheme to ensure incentives or penalties are reflective of businesses' emissions, economic tools to promote businesses undertaking R&D to improve their operations, and policy making solar power more accessible in homes.

"Policy on environmental issues has a large influence on who I will vote for because I care about it and its health immensely," he said.

"But also as a country we rely heavily on our land and waters for the economic gains that agriculture, fisheries, tourism, bring as well as for social, cultural and spiritual well-being so I believe it is in New Zealand's best interest that environmental policy is at the forefront of decision-making."

Policies by party

NATIONAL:

Continue NZ's Paris Agreement pledge to cut emissions 30 per cent below 2005 levels; review and improve the Emissions Trading Scheme; fund agricultural greenhouse gas research; increase the amount of electricity that comes from renewable energy from 80 per cent currently to 90 per cent; spend $2b on public transport and encourage the uptake of electric vehicles.

LABOUR: Back carbon emissions targets being cemented into legislation, requiring the government to set carbon budgets for itself; establish an independent Climate Commission to work toward net zero carbon by 2050; bring all gas forms and sectors into the Emissions Trading Scheme and use revenue to move to a low-carbon economy; require state-owned enterprises and other government departments to pursue low-carbon options and technologies.

GREENS: Set a legally-binding target to make New Zealand carbon-neutral by 2050 and achieve 100 per cent renewable electricity by 2030; boost investment in green tech with an investment fund; replace the Emissions Trading Scheme with an emissions tax and use revenue as tax credits for households; establish a Climate Commission to track progress and set carbon prices.

NZ FIRST: Oppose the Emissions Trading Scheme; support programmes and goals to cut emissions as with the UK's Climate Change Act; Support "net metering" whereby electricity retailers buy power generated by customers at the price it's normally sold to the customer.

MAORI PARTY: Set emissions goals into law with a climate commission; offer tax breaks for renewables research; close coal-fired plants by 2025; plant 100,000ha of new forests over the next 10 years; support displaced Pacific communities through a special visa scheme; offer solar power and energy storage, like home batteries, to low-income families and remote communities.

ACT: Replace petrol taxes with a user-pays road pricing system to reduce congestion and emissions; encourage ride-sharing and car-sharing.

OPPORTUNITIES PARTY: Aim to be carbon neutral by 2050 and for 100 per cent renewable electricity by 2035; reform the Emissions Trading Scheme by setting a carbon budget, removing the current upper limit on the carbon price, and keeping the scheme closed to international credits; cancel the surplus of emissions permits held as at 2020; reforest all erosion-prone land by 2030; scrap fossil fuel subsidies and electrify cars and trains.