Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

A focus on climate change

Surinder Saggar and Jagrati Singh measuring soil methane levels in pasture

Surinder Saggar and Jagrati Singh measuring soil methane levels in pasture

Climate change is an issue that runs through all of the economy,the environment and our communities. Our science – from understanding the ecological and anthropogenic processes causing (and in–turn affected by) climate change through to the much wider implications for natural, productive, urban, social and business environments – underpins New Zealand’s ability to reduce greenhouse gas emissions, develop mitigation options and adapt to the effects of a changing climate.

Much of our work is for national policy agencies such as MAF and MfE. We are also leading a multi–agency group to model possible policy scenarios for climate change negotiations post–2012. The group includes Motu Economics, universities (Waikato, Massey, Lincoln, Otago), NZIER, Infometrics, AgResearch, and MFAT.

Land Use & Carbon Analysis System

Landcare Research completed a major project determining Kyoto land use changes between 1990 and 2008 for MfE’s Land Use and Carbon Analysis System (LUCAS). Mapping the changes required comprehensive interpretation and analysis of satellite imagery and aerial photographs by a team of about 15 image processing and GIS specialists. Our scientists met weekly with MfE’s technical team to ensure we delivered exactly what was expected, on time, and to the data quality standards expected by the Intergovernmental Panel on Climate Change (IPCC) and MfE. The results of this work are of substantial political, environmental and economic importance to New Zealand.

These satellite data are good news in that they accurately confirm the area of post–1989 forests is sufficient to offset New Zealand’s increase in emissions and meet our Kyoto obligations in the first commitment period from 2008 to 2012.’ Hon Nick Smith, Minister for Climate Change Issues.

Meauring & Modelling Greenhouse Gases

Data on biophysical functioning of ecosystems and greenhouse gas exchange processes support the development of sophisticated computer models that are essential for analysing ecosystem responses to climate change, feedback effects, and the resilience of natural and managed terrestrial systems.

While no sector can escape global change, pastoral farming is often at the centre of public debate – largely because our national emissions inventory is dominated by methane and nitrous oxide emissions from our extensive and intensive agricultural industry. Both these gases have a ‘global warming potential’ many times that of carbon dioxide.

We have continued to develop techniques for measuring emissions and removals of carbon dioxide, methane and nitrous oxide from grazed pasture, shrubland and forest systems. While technology is well advanced for carbon dioxide, measurements of methane and nitrous oxide are much more challenging because of the low ambient concentrations. Nevertheless, we have developed techniques that provide direct estimates of emissions for an entire herd but which are non–obtrusive for stock.

Methane Mitigation Technologies

Methane comprises 35% of New Zealand’s total greenhouse gas emissions. The main source is from bacteria that digest plant material in the rumen of grazing animals, but other agricultural sources, including anaerobic decomposition of effluent from piggeries and dairy farms, are also important. There are currently no viable mitigation options to reduce agricultural methane emissions apart from reducing livestock numbers.

However, we are researching novel technologies that have the potential to signifi cantly reduce agricultural methane emissions, including a methane biofi lter to convert methane to the less potent carbon dioxide.

The biofilter uses naturally occurring soil bacteria called methanotrophs that consume methane as an energy source. Experiments in one of our laboratories revealed the huge potential of landfill–covering soils to oxidise the methane released by decomposing waste. The methanotrophs removed 98% of the methane entering the soil chamber. Even when the soils were intentionally saturated with methane, the microbe populations adapted rapidly to the high gas concentrations. This has important implications for designing biofilters that can effectively mitigate point–sources of high methane concentrations, such as at effluent ponds. The performance of a prototype for a paddock–scale biofilter at an effluent pond on Massey University’s dairy farm is being assessed.

Improving Nitrous Oxide Inventories

New Zealand currently reports its annual emissions of nitrous oxide from agriculture using a set of ‘emission factors’ set by the IPCC. These specify the fractions of total nitrogen from a particular farming activity that are converted either directly to nitrous oxide or to a precursor that subsequently causes further (indirect) emissions. Some of these factors have been quantified specifically for New Zealand conditions. Our process–based ‘NZ–DNDC’ (denitrification–decomposition) model not only estimates nitrous oxide emissions and identifies emission ‘hot–spots’ but is useful for assessing the efficacy of mitigation strategies.

A recent review, commissioned by MAF, suggests that one of these default emission factors overestimates the true indirect emissions under New Zealand farming conditions. Our measurements have contributed to reducing emissions liabilities by recommending a reduction in indirect emissions factors for nitrous oxide losses from waterways and from the use of urease inhibitors on pasture.