The control of forest browsers can deliver benefits for both the climate and biodiversity. However, the present carbon accounting framework needs revision before those benefits can be monetised through the voluntary carbon market and counted towards Aotearoa’s national emissions reduction commitments.
A June 2025 report commissioned by the Ministry for the Environment (MfE), Evaluation of Carbon Market and NDC Opportunities for ZIP's Management Programme, considered whether the predator-free work of Zero Invasive Predators (ZIP) might result in more atmospheric carbon being stored by tall-growth forest. The report was prepared by Environmental Accounting Services (EAS), a New Zealand auditor specialising in environmental performance and compliance. Formed in 2007, EAS provides advice to NGOs, private sector and government entities.
Their report discussed policy and research pathways for recognising the extra carbon sequestration in the voluntary carbon market (VCM).
Finally, it asked the question: could that extra carbon count towards Aotearoa New Zealand’s obligations to cut emissions under the Paris Climate Agreement?
Wild animal control: the evidence for climate benefits
While ZIP remains focussed on the landscape-scale elimination of invasive predators such as rats, possums and mustelids, it is aware that this work can also impact numbers of pest browsers. In this way, ZIP can restore forest health and enhance carbon sequestration.
ZIP is exploring carbon-based crediting mechanisms to create a virtuous, self-funding conservation programme. The MfE report considered whether ZIP’s evidence for carbon storage benefits is enough to support the monetisation of that work through carbon credits, to be traded on the VCM.
The report found that while ZIP has the skills and experience to deliver robust field measurements, other components, such as dynamic baseline setting, leakage assessments and risk buffers, need further refinement and more extensive datasets to satisfy the requirements of a voluntary carbon project.
It recommended that ZIP find a voluntary carbon programme that explicitly accommodates pest and browser control activities, or develop its own fit-for-purpose methodology to quantify the climate benefits of pest and browser control in existing forests. That work could then generate verifiable carbon credits for on domestic or international markets.
Counting extra forest carbon in Aotearoa’s greenhouse gas budget
All pre-1990 forest lands are monitored through the National Forest Inventory (NFI) which provides an existing mechanism to capture ZIP’s work in national emissions accounting.
Presently, however, the legislation isn’t sufficiently nuanced to accommodate carbon stock increases specifically from browser control. That means the NFI system would need to be refined to better distinguish between different forest types and management regimes, and made sensitive enough to recognise what could be a relatively modest contribution to the National Greenhouse Gas Inventory (NGHGI) over long time frames.
The MfE report recommended further research to gauge any contribution to Aotearoa’s Nationally Determined Contribution (NDC)—the country’s commitment to the global effort to reduce climate emissions (presently a 50 per cent reduction of net emissions below our gross 2005 level by 2030).
Wild animal control could also be included in the next Government emissions reduction plan, which would acknowledge the contribution of ZIP’s data to more accurate NGHGI and NDC reporting.
It would also highlight the importance and co-benefits of this self-funding, nature-based programme to both climate change mitigation and biodiversity.