New Zealand Agricultural Greenhouse Gas Research Center

Palmerston North, New Zealand

New Zealand Agricultural Greenhouse Gas Research Center

Palmerston North, New Zealand
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Reisinger A.,New Zealand Agricultural Greenhouse Gas Research Center | Ledgard S.F.,Agresearch Ltd. | Falconer S.J.,Agresearch Ltd.
Ecological Indicators | Year: 2017

Milk production is responsible for emitting a range of greenhouse gases (GHGs), mainly carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). In Life Cycle Assessments (LCA), the Global Warming Potential with a time horizon of 100 years (GWP100) is used almost universally to aggregate emissions of individual gases into so-called CO2-equivalent emissions that are used to calculate the overall carbon footprint of milk production. However, there is growing awareness that, depending on the purpose of the LCA, metrics other than GWP100 could be justified and some would give a very different weighting for the short-lived gas CH4 relative to the long-lived gases CO2 and N2O when calculating the carbon footprint. Pastoral dairy production systems at different levels of intensification differ in the balance of short- and long-lived GHGs associated with on- and off-farm emissions. Differences in the carbon footprint of different production systems could therefore be highly sensitive to the choice of GHG metric. Here we explore the extent to which alternative GHG metric choices would alter the carbon footprint of New Zealand milk production at different levels of intensification at national, regional and individual farm scales and compared to the carbon footprint of milk of selected European countries. We find that the ranking of different production systems and individual farms in terms of their carbon footprint is relatively robust against the choice of GHG metric, despite significant differences in their utilisation of pastures versus supplementary off-farm feed, fertiliser use and energy consumption at various stages of farm operations. However, there are instances where alternative GHG metric choices would fundamentally change the conclusions of LCA of different production systems, including whether a move towards higher or lower input systems would increase or decrease the average carbon footprint of milk production in New Zealand. Greater transparency about the implications of alternative GHG metrics for LCA, and the often inadvertent and implicit value judgements embedded in these metrics, would help ensure that policy decisions and consumer choices based on LCA indeed deliver the climate outcomes intended by end-users. © 2017 Elsevier Ltd

PubMed | University of Minnesota, Center for International Forestry Research, Scottish Food Security Alliance Crops, Pacific Northwest National Laboratory and 14 more.
Type: Journal Article | Journal: Global change biology | Year: 2016

More than 100 countries pledged to reduce agricultural greenhouse gas (GHG) emissions in the 2015 Paris Agreement of the United Nations Framework Convention on Climate Change. Yet technical information about how much mitigation is needed in the sector vs. how much is feasible remains poor. We identify a preliminary global target for reducing emissions from agriculture of ~1GtCO

Smith P.,University of Aberdeen | Haberl H.,University of Vienna | Popp A.,Potsdam Institute for Climate Impact Research | Erb K.-H.,University of Vienna | And 24 more authors.
Global Change Biology | Year: 2013

Feeding 9-10 billion people by 2050 and preventing dangerous climate change are two of the greatest challenges facing humanity. Both challenges must be met while reducing the impact of land management on ecosystem services that deliver vital goods and services, and support human health and well-being. Few studies to date have considered the interactions between these challenges. In this study we briefly outline the challenges, review the supply- and demand-side climate mitigation potential available in the Agriculture, Forestry and Other Land Use AFOLU sector and options for delivering food security. We briefly outline some of the synergies and trade-offs afforded by mitigation practices, before presenting an assessment of the mitigation potential possible in the AFOLU sector under possible future scenarios in which demand-side measures codeliver to aid food security. We conclude that while supply-side mitigation measures, such as changes in land management, might either enhance or negatively impact food security, demand-side mitigation measures, such as reduced waste or demand for livestock products, should benefit both food security and greenhouse gas (GHG) mitigation. Demand-side measures offer a greater potential (1.5-15.6 Gt CO2-eq. yr-1) in meeting both challenges than do supply-side measures (1.5-4.3 Gt CO2-eq. yr-1 at carbon prices between 20 and 100 US$ tCO2-eq. yr-1), but given the enormity of challenges, all options need to be considered. Supply-side measures should be implemented immediately, focussing on those that allow the production of more agricultural product per unit of input. For demand-side measures, given the difficulties in their implementation and lag in their effectiveness, policy should be introduced quickly, and should aim to codeliver to other policy agenda, such as improving environmental quality or improving dietary health. These problems facing humanity in the 21st Century are extremely challenging, and policy that addresses multiple objectives is required now more than ever. © 2013 John Wiley & Sons Ltd.

Reisinger A.,New Zealand Agricultural Greenhouse Gas Research Center | Meinshausen M.,Potsdam Institute for Climate Impact Research | Manning M.,Victoria University of Wellington
Environmental Research Letters | Year: 2011

Global warming potentials (GWPs) are the metrics currently used to compare emissions of different greenhouse gases under the United Nations Framework Convention on Climate Change. Future changes in greenhouse gas concentrations will alter GWPs because the radiative efficiencies of marginal changes in CO2, CH4 and N2O depend on their background concentrations, the removal of CO2 is influenced by climate-carbon cycle feedbacks, and atmospheric residence times of CH4 and N 2O also depend on ambient temperature and other environmental changes. We calculated the currently foreseeable future changes in the absolute GWP of CO2, which acts as the denominator for the calculation of all GWPs, and specifically the GWPs of CH4 and N2O, along four representative concentration pathways (RCPs) up to the year 2100. We find that the absolute GWP of CO2 decreases under all RCPs, although for longer time horizons this decrease is smaller than for short time horizons due to increased climate-carbon cycle feedbacks. The 100-year GWP of CH4 would increase up to 20% under the lowest RCP by 2100 but would decrease by up to 10% by mid-century under the highest RCP. The 100-year GWP of N2O would increase by more than 30% by 2100 under the highest RCP but would vary by less than 10% under other scenarios. These changes are not negligible but are mostly smaller than the changes that would result from choosing a different time horizon for GWPs, or from choosing altogether different metrics for comparing greenhouse gas emissions, such as global temperature change potentials. © 2011 IOP Publishing Ltd.

Rogelj J.,International Institute For Applied Systems Analysis | Rogelj J.,ETH Zurich | Reisinger A.,New Zealand Agricultural Greenhouse Gas Research Center | McCollum D.L.,International Institute For Applied Systems Analysis | And 5 more authors.
Environmental Research Letters | Year: 2015

Global-mean temperature increase isroughly proportionalto cumulative emissions of carbon dioxide (CO2). Limiting global warming toany level thus implies a finite CO2budget. Due to geophysical uncertainties, the size of such budgets can only be expressed in probabilistic terms and is further influenced by non-CO2emissions. We here explore how societal choices related to energy demand and specific mitigation options influence the size of carbon budgets for meetingagiven temperature objective. We find that choices that exclude specific CO2mitigation technologies (like Carbon Capture and Storage) result in greater costs, smaller compatible CO2budgets until 2050, but larger CO2budgets until 2100. Vice versa, choices that lead to a larger CO2mitigation potential result in CO2budgets until 2100 that are smaller but can bemet at lower costs. Inmost cases, these budget variations canbe explained bythe amount of non-CO2mitigation that iscarried out in conjunction with CO2,and associated global carbon prices that also drive mitigation of non-CO2gases. Budget variations are of the order of 10% around their central value. In all cases, limiting warming to below 2 °Cthus still implies that CO2emissions needto bereduced rapidly inthe coming decades. © 2015 IOP Publishing Ltd.

Clark H.,New Zealand Agricultural Greenhouse Gas Research Center | Kelliher F.,Agresearch Ltd. | Pinares-Patino C.,Agresearch Ltd.
Asian-Australasian Journal of Animal Sciences | Year: 2011

Almost half of New Zealand's greenhouse gas emissions arise from agriculture and enteric methane (CH4) emissions arising from ruminant animals constitute 30% of total CO2-e emissions. Enteric CH4 emissions have increased by 9% since 1990. Extensive research has been undertaken to develop reliable methods for measuring enteric CH4 emissions. New Zealand studies using the SF6 tracer technique suggest that on average this technique yields similar values to the 'gold' standard of calorimetry, but with a larger variance. National inventory estimates based on results obtained using the SF6 technique will therefore overestimate the uncertainty. Mitigating emissions can be achieved by changing feed type but there are practical and cost barriers to the use of alternative feeds. Forages containing condensed tannins do reduce emissions but are agronomically inferior to the forages currently used. Rumen additives have shown some success in-vitro but results from in-vivo trials with both monensin and fumaric acid have been disappointing. The development of methods for directly manipulating rumen microorganisms are at an early stage and work to develop vaccines that can inhibit methanogenesis has yielded mixed results. The successful identification of sheep with contrasting CH4 yields raises the possibility that, in the long term, a breeding approach to CH4 mitigation is feasible.

Allen M.R.,University of Oxford | Fuglestvedt J.S.,CICERO Center for International Climate and Environmental Research | Shine K.P.,University of Reading | Reisinger A.,New Zealand Agricultural Greenhouse Gas Research Center | And 2 more authors.
Nature Climate Change | Year: 2016

Parties to the United Nations Framework Convention on Climate Change (UNFCCC) have requested guidance on common greenhouse gas metrics in accounting for Nationally determined contributions (NDCs) to emission reductions. Metric choice can affect the relative emphasis placed on reductions of 'cumulative climate pollutants' such as carbon dioxide versus' short-lived climate pollutants' (SLCPs), including methane and black carbon. Here we show that the widely used 100-year global warming potential (GWP 100) effectively measures the relative impact of both cumulative pollutants and SLCPs on realized warming 20-40 years after the time of emission. If the overall goal of climate policy is to limit peak warming, GWP 100 therefore overstates the importance of current SLCP emissions unless stringent and immediate reductions of all climate pollutants result in temperatures nearing their peak soon after mid-century, which may be necessary to limit warming to "well below 2 °C" (ref.). The GWP 100 can be used to approximately equate a one-off pulse emission of a cumulative pollutant and an indefinitely sustained change in the rate of emission of an SLCP. The climate implications of traditional CO2 -equivalent targets are ambiguous unless contributions from cumulative pollutants and SLCPs are specified separately. © 2016 Macmillan Publishers Limited.

Orwin K.H.,Lancaster University | Kirschbaum M.U.F.,Landcare Research | Kirschbaum M.U.F.,New Zealand Agricultural Greenhouse Gas Research Center | St John M.G.,Landcare Research | Dickie I.A.,Landcare Research
Ecology Letters | Year: 2011

Understanding the factors that drive soil carbon (C) accumulation is of fundamental importance given their potential to mitigate climate change. Much research has focused on the relationship between plant traits and C sequestration, but no studies to date have quantitatively considered traits of their mycorrhizal symbionts. Here, we use a modelling approach to assess the contribution of an important mycorrhizal fungal trait, organic nutrient uptake, to soil C accumulation. We show that organic nutrient uptake can significantly increase soil C storage, and that it has a greater effect under nutrient-limited conditions. The main mechanism behind this was an increase in plant C fixation and subsequent increased C inputs to soil through mycorrhizal fungi. Reduced decomposition due to increased nutrient limitation of saprotrophs also played a role. Our results indicate that direct uptake of nutrients from organic pools by mycorrhizal fungi could have a significant effect on ecosystem C cycling and storage. © 2011 Blackwell Publishing Ltd/CNRS.

Reisinger A.,New Zealand Agricultural Greenhouse Gas Research Center | Havlik P.,International Institute For Applied Systems Analysis | Havlik P.,Kenya International Livestock Research Institute | Riahi K.,International Institute For Applied Systems Analysis | And 3 more authors.
Climatic Change | Year: 2013

100-year Global Warming Potentials (GWPs) are used almost universally to compare emissions of greenhouse gases in national inventories and reduction targets. GWPs have been criticised on several grounds, but little work has been done to determine global mitigation costs under alternative physics-based metrics. We used the integrated assessment model MESSAGE to compare emission pathways and abatement costs for fixed and time-dependent variants of the Global Temperature Change Potential (GTP) with those based on GWPs, for a policy goal of limiting the radiative forcing to a specified level in the year 2100. We find that fixed 100-year GTPs would increase global abatement costs (discounted and aggregated over the 21st century) under this policy goal by 5-20 % relative to 100-year GWPs, whereas time-varying GTPs would reduce costs by about 5 %. These cost differences are smaller than differences arising from alternative assumptions regarding agricultural mitigation potential and much smaller than those arising from alternative radiative forcing targets. Using the land-use model GLOBIOM, we show that alternative metrics affect food production differently in different world regions depending on regional characteristics of future land-use change to meet growing food demand. We conclude that under scenarios of complete participation, the choice of metric has a limited impact on global abatement costs but could be important for the political economy of regional and sectoral participation in collective mitigation efforts, in particular changing costs and gains over time for agriculture and energy-intensive sectors. © 2012 Springer Science+Business Media Dordrecht.

Clark H.,New Zealand Agricultural Greenhouse Gas Research Center
Animal | Year: 2013

Concentrations of methane (CH4) in the atmosphere have almost doubled since the mid 1700s, and it is estimated that ∼30% of the global warming experienced by the planet in the last century and a half can be attributed to CH4. Between 25% and 40% of anthropogenic CH4, emissions are estimated to arise from livestock farming. Mitigating absolute emissions from livestock is extremely challenging technically and is made more difficult because of the need to increase food production to meet the demands of a burgeoning world population. Opportunities for manipulating the diet of intensively managed ruminant to reduce absolute CH4 exist, but in grazing livestock the opportunities are constrained practically and economically. Mitigating emissions per unit of product is more tractable, especially in the short term. Although the formation of CH4 is an anaerobic microbiological process, the host animal does seem to exert an influence, as animals differ in the quantity of CH4 they emit when fed the same diet. The reasons for this are not yet clear, but evidence is accumulating that these differences are consistent and have a genetic basis. Exploiting these between animal differences by animal breeding is an attractive mitigation option as it is potentially applicable to all animals and is open to continuous improvement. However, identifying the desired phenotype poses severe practical constraints. Vaccinating the host animal to produce antibodies that can modulate the activities of the organisms responsible for CH4 formation also presents a novel mitigation option. © 2011 The Animal Consortium.

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