5 Conclusions and recommendations

This report has assessed the extent to which recommendations made in the 2005 review (NP 2005) have been implemented in the 2007 emission projection methodology and 2007 net position report. In general we consider that the basis for the 2007 projections is more robust than the basis for the 2005 projections, and the projections are better documented. The progress made in implementing each of the recommendations from the 2005 review is summarised in Tables 8 and 9 (for high priority recommendations and lower priority recommendations respectively). Overall there has been significant progress towards implementing the recommendations. In the energy and transport sectors, as well as key improvements to the modelling suggested in the review, there have been additional improvements. However, recommendations on modelling of the residential sector have still to be implemented. In the LULUCF all recommendations have been implemented, although in some cases implementation is not complete as data is required from the LUCAS project, which is due to become operational in 2010. Similarly, high priority recommendations in the agriculture sector have been implemented. The compilation process has been improved, with the introduction of a steering group, requirements for ‘sign-off’ by departments of projections and improved documentation, but improvements to quality assurance and quality control (QA/QC) could still be made. Documentation and explanation of how the effects of policy on emissions are estimated could also be improved further, as could the treatment of uncertainty.

Recommendations from the 2005 review, which have not yet been implemented and are still valid are:

Energy: use bottom up model of residential sector to cross-check results from SADEM and consider incorporating more bottom-up detail within SADEM for this sector.
Energy: improve the treatment of uncertainty (see below).
Energy: consider cooling and heating degree-days separately in the residential energy model. It is accepted however that this is not of key importance and that it will be addressed in the proposed improvements to the model.

Recommendations which have been implemented but where some further improvements could be made, together with new recommendations arising from this review, are detailed below:

Compilation: improve project planning and documentation and introduce and implement a formal QA/QC plan for project compilation. Each department contributing projections should produce a written QA/QC document and the Ministry for the Environment should produce one for the compilation process.
Compilation: produce a written plan, to improve over the next two-to-three years, the quality of the projections.
Policies: continue to improve the documentation available concerning the basis of emissions savings anticipated from policies, ensuring that it is transparent and comprehensive.
Energy: improve the representation of transmission and distribution losses in GEM.
Energy: consider whether the treatment of hydro storage can be better addressed in GEM.
Transport: consider whether the growing use of air transport requires that it is modelled using drivers of demand rather than using a time series model.
Transport: consider if a split between freight and passenger transport demand would allow a better characterisation of transport demand.
Transport: consider improving modelling of effect on emissions of biofuels sales obligation (bioethanol element).
Industry: consider explicit modelling of fluorinated gas emissions.
Agriculture: continue to keep the trends in ruminant methane and nitrogen excretion factors under review and consider an alternative approach to modelling if the linear trend becomes less strong.
LULUCF: data from LUCAS should be used to reduce uncertainties in the projections as soon as they become available.
LULUCF: more information about the LUCAS project should be included in the LULUCF section in the net position report.
LULUCF: documentation should be kept up-to-date with the latest methodological developments.

This review also looked in some detail at how uncertainty is modelled and made the following recommendations:

Modellers in the Ministry of Economic Development and the Ministry of Agriculture and Forestry should develop the most likely estimates of the emissions for the energy and agricultural sectors for each of the most likely, optimistic and pessimistic scenarios.
The uncertainty in the energy and agricultural emissions associated with non-economic factors should be assessed.
The estimates of the uncertainty from each of the sectors can be combined by Monte Carlo simulation, provided that the potential correlation between sectors resulting from economic factors is taken into account.
The uncertainty over effectiveness with which the Government’s current policy to cap the Crown’s deforestation liability for pre-1990 forests at 21.0 million tonnes of carbon dioxide is implemented should not be included in the analysis of the overall uncertainty. Instead two scenarios, one where the target is reached, and one where deforestation emissions rise above this level should be considered separately.
The use of Monte Carlo simulation within the LULUCF sector should be considered as this has the potential to reduce the uncertainty in the net removal and the overall net position substantially.

While it is not possible to judge conclusively, overall, on the basis of the information available at the time of this review, we believe that implementation of the outstanding recommendations and proposals for further improvements are unlikely to make a substantial change to the ‘most likely’ estimate of the net position result at the current time. The largest uncertainty in the net position arises from the LULUCF sector, where there is considerable uncertainty in future outcomes, measurement uncertainty, knowledge gaps and high natural variability in the factors affecting emissions. However, the approach taken to estimating the sector’s contribution is reasonable given the current data limitations.

Table 8: Assessment of progress on high priority recommendations from 2005 review

View assessment of progress on high priority recommendations from 2005 review (large table).

Table 9: Assessment of progress on lower priority recommendations from 2005 review

View assessment of progress on lower priority recommendations from 2005 review (large table).

Previous|Next