Greenhouse gases
Outcome: Improved measurement and mitigation of greenhouse gas emissions from the terrestrial biosphere.
New Zealand must meet its international greenhouse gas reporting obligations and decrease net emissions of greenhouse gases from terrestrial systems to below ‘business as usual’ levels. To achieve this, it is necessary to have (1) a robust inventory of net emissions and carbon storage and (2) effective mitigation options for reducing net emissions. Changes in emissions and carbon storage as a consequence of management, land use and global change can then be forecasted and appraised. New Zealand is required, under the UNFCCC (United Nations Framework Convention on Climate Change), to produce an annual inventory of greenhouse gas emissions.
While there has been a lot of research effort to estimate changes in above-ground carbon storage in vegetation with land-use management, much less is known about the effects on soil carbon storage. Although New Zealand’s commitment to reduce net greenhouse gas emissions does not include changes in soil carbon storage, we are required to report such changes annually in relation to land management and land-use change.
Research is needed to improve methodologies for measuring soil carbon storage and for reducing uncertainty in estimating and scaling emissions, and quantifying changes in emissions as a consequence of key land-use and management change. This allows mitigation strategies to be developed and approaches for increasing carbon storage to be identified and adopted. This is an area in which the science challenges are substantial and we are developing new national and international collaborations to address them. We have a significant role to play and are acknowledged internationally for our expertise in carbon and nitrous oxide science.
Impact 1: Terrestrial greenhouse gas emissions and removals are understood and quantified so that changes in relation to management strategies, land-use policies and global change can be predicted.
KPI:
MPI and MfE are using verified estimates of greenhouse gas (GHG) emissions and carbon storage to reduce uncertainty in national inventories.
2010/11 baseline situation:
Estimates of greenhouse gas emissions, and how these change with altered land use, contained many uncertainties.
Progress 2011/12:
- Afforestation was greater than deforestation (579,000 ha ± 2% and 75,000 ha ± 6% respectively) in New Zealand between 1990 and 2008. The difference gave MPI an estimate of carbon emissions due to forest changes.
- Modelling the growth of pine stands and kānuka/mānuka stands is providing MPI with carbon sequestration rates and how these vary regionally and temporally.
- The uncertainty in estimating soil carbon for perennial croplands in MfE’s Soil Carbon Monitoring System has been significantly reduced.
Progress 2012/13:
- Greater certainty in New Zealand’s national GHG inventory has been achieved through more accurate measurements of N2O from pastoral hill country, and updated emission factors; these N2O emissions are less than previously reported.
- MfE has greater confidence in carbon estimates from the LUCAS plot network and understand the accuracy of carbon change that can be detected.
- MfE has improved information on the impact of erosion on soil carbon stocks and the need to incorporate the effect of erosion into the Soil Carbon Monitoring System.
Impact 2: Strategies for land use and asset management increase carbon storage, mitigate greenhouse gas emissions and balance environmental, economic and social benefits
KPI:
Agricultural land managers and DOC are, where appropriate, using validated methodologies and land-use practices to mitigate greenhouse gas emissions and increase carbon storage and adapt to likely climate change effects.
2010/11 baseline situation:
Models of carbon dynamics were largely inadequate for understanding wider implications of land use.
Progress 2011/12:
- The effectiveness of the nitrification inhibitor DCD in reducing nitrous oxide emissions from stock effluent can be optimised for use by agricultural land managers.
- Land managers have an improved basis for incorporating variability in carbon stocks when planning emissions management for natural forests.
Progress 2012/13:
- Land management strategies and the National Greenhouse Gas Inventory benefit from new data on the long-term relative warming and cumulative effects of CO2, N2O and CH4 emissions attributed to land use change.
- The agricultural sector has updated-information on the effectiveness of the urease inhibitor Agrotain® in reducing NH3 emissions.
- National-scale indirect measures of the likelihood of, and average time taken for, gorse or broom to become ‘forest land’ could enhance assessment of eligibility for entry into the Emissions Trading Scheme.
