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Carbon Critical Net-Zero Challenge

Updated: Apr 21, 2023

Most people are now aware that climate change is a serious problem requiring urgent action. But not many kiwis realize just how important forestry will be in our efforts to reach net-zero emissions in Aotearoa New Zealand.

There is an ongoing debate about what kinds of trees and forests should be eligible to receive carbon credits in the Emissions Trading Scheme, and in particular, whether exotic species should be permitted to remain in the new Permanent Forest (PP89) category. The outcome of this debate will have a profound effect on the time and cost required to meet our climate change targets.

We have created a web tool that allows you to experiment with different land-use options to see if you can set a plan for NZ to reach net zero. You can adjust the amount of additional land allocated to different forestry options to decide which mix results in the best outcome for New Zealand.

The forestry options at your disposal are:

  • Production forestry (mainly pine trees grown and harvested for logs and timber)

  • Permanent exotic forestry (trees grown for carbon storage) - the government is considering banning this option.

  • Native species planting (for carbon storage or wood production)

  • Native regeneration (bare land allowed to revert back to native bush).

Can you find an afforestation strategy that will get Aotearoa NZ to net-zero emissions before the year 2050 without bankrupting the country?


Why does this matter?

New Zealand has been slow to commit to emissions reductions. According to, we are one of the worst countries in the world in terms of our climate targets and progress at decarbonizing. If we are to have any chance of reaching Net-Zero emissions by 2050, it’s going to be because trees help us get there.

Emission reductions at source are, of course, critical. We all need to take action as individuals, businesses, councils and as a nation to reduce our emissions. But even with serious year on year reductions, we are still going to need trees to take some of the burden by removing CO2 from the atmosphere.

Trees are one of the best CO2 removal options available, and bring a wealth of other benefits including biodiversity, erosion control, soil improvement and water filtering. And some trees are far better than others at removing carbon from the atmosphere.

Exotic trees like pine, redwood and eucalyptus (amongst many others) grow quickly and can live for a long time, sucking up carbon and storing it for hundreds of years if we let them. They are cheap to establish and could become a source of export income in future as the planet races to decarbonise.

Native forests are best for increasing biodiversity. They also store carbon too, but at a much slower rate than exotic species. They are also more expensive to plant and look after as they take longer to grow and get established.

Some conservationists believe the best solution is to not plant trees at all, but to just leave nature to do its thing. But this requires a long time horizon, does not always result in a rich forest, and is surprisingly expensive due to the requirement for ongoing and effective management of browsing pests such as deer, goats, pigs and possums.

Many people are concerned that if the 'green rush' of pine tree planting continues then it could create a future 'over-supply' of forestry credits in the ETS, keeping carbon prices low, and reducing the incentive for emitters to make real changes to cut their gross emissions. There are also concerns about the cost and viability of transitioning old-growth pine plantations to native forests.

We believe New Zealand can do much better, by:

  1. taking a more balanced and pragmatic approach to forestry and land-use change, based on the right-tree-right-place principle, and

  2. restructuring the ETS so that forestry removals do not work against genuine gross emissions reductions (e.g. by capping the amount that foresters can earn for selling credits and applying a tax so that emitters pay a lot more to purchase offsets).

An afforestation strategy that mixes native and exotic species (including alternatives to radiata pine) can play a big role in helping Aotearoa NZ to reach, and sustain, net-zero emissions.

What do you think? Do we need exotic tree species to reach net-zero?

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