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Journal Article•DOI•

Enhancing life cycle impact assessment from climate science: Review of recent findings and recommendations for application to LCA

Annie Levasseur1, Otávio Cavalett2, Jan S. Fuglestvedt3, Thomas Gasser4, Thomas Gasser5, Daniel J.A. Johansson6, Susanne Vedel Jørgensen, Marco Raugei7, Andy Reisinger, Greg Schivley8, Anders Hammer Strømman9, Katsumasa Tanaka10, Francesco Cherubini9 •
École Polytechnique de Montréal1, State University of Campinas2, University of Oslo3, Agro ParisTech4, Centre national de la recherche scientifique5, Chalmers University of Technology6, Oxford Brookes University7, Carnegie Mellon University8, Norwegian University of Science and Technology9, National Institute for Environmental Studies10
01 Dec 2016-Ecological Indicators (Elsevier)-Vol. 71, pp 163-174
TL;DR: In this article, a systematic review of available midpoint metrics (i.e., using an indicator situated in the middle of the cause-effect chain from emissions to climate change) for well-mixed greenhouse gases and near-term climate forcers based on the current literature is performed.
About: This article is published in Ecological Indicators.The article was published on 2016-12-01 and is currently open access. It has received 108 citations till now. The article focuses on the topics: IPCC Fifth Assessment Report.

Summary (4 min read)

Jump to: [1. Introduction] – [2. Emission metrics for climate change impacts] – [2.1.1. The cause-effect chain] – [2.2.1. Metrics based on radiative forcing] – [3. Discussion of some key metric choices] – [3.1. Instantaneous versus cumulative metrics] – [3.2. Constant versus variable background atmosphere and climate] – [3.3. Climate-carbon cycle feedbacks] – [3.4. Regional variations] – [3.5. The time dimension] – [3.5.2. Discount rates] – [3.5.3. Considering the timing of emissions] – [4. Recommendations] – [4.1. Improving climate change impact assessment in LCA] and [4.2.1. Consideration of climate-carbon cycle feedbacks for non-CO 2 components]

1. Introduction

  • The objectives of this paper are to perform a systematic review of available midpoint metrics for WMGHGs and NTCFs based on the current literature, to provide recommendations for the development and use of climate change CFs in LCA, and to identify research needs.
  • The authors primarily discuss research findings on metrics presented in the IPCC 5 th AR, which emphasized GWP and GTP, and under which circumstances these metrics could be applied to improve current climate change midpoint characterization factors in LCA.
  • This work is part of the 'Global Guidance on Environmental Life Cycle Impact Assessment' project held by the UNEP/SETAC Life Cycle Initiative and is intended to support a consensus finding workshop.

2. Emission metrics for climate change impacts

  • They can be used in different contexts such as multi-component climate policies, comparison of emissions between regions or sectors, and LCA, amongst others (Kolstad et al., 2014; Myhre et al, 2013) .
  • As stated in the IPCC 5 th AR, "the most appropriate metric will depend on which aspects of climate change are most important" (Myhre et al, 2013) .
  • Indeed, no single metric can adequately and simultaneously assess the impact of different climate forcers on different aspects of climate change such as the rate of change or long-term temperature increase.
  • This section presents an overview of different midpoint emission metrics used to estimate the impact of climate forcers.

2.1.1. The cause-effect chain

  • Figure 1 presents a simplified diagram of the cause-effect chain from emissions to impacts as described above.
  • The diagram shows only the most important pathways by omitting more detailed feedbacks such as climate-carbon cycle feedbacks (Friedlingstein et al., 2006) .

2.2.1. Metrics based on radiative forcing

  • 14 Sterner et al. (2014) have developed instantaneous and cumulative metrics to compare the impact of different climate forcers on sea level rise: the Global Sea level rise Potential (GSP) and the Integrated Global Seal level rise Potential (IGSP).
  • They have shown that all climate forcers, including very short-lived ones, have considerable influence on sea level rise on the century time scale per unit emissions.
  • Shine et al. (2015) present a new metric concept named the Global Precipitation change Potential (GPP), which estimates the effect of various emissions on the global water cycle.
  • The formulation of GPP consists of two terms, one dependent on the surface temperature change and the other dependent on the atmospheric component of the radiative forcing.
  • For some forcing agents, and notably for CO 2 , these two terms oppose each other.

3. Discussion of some key metric choices

  • These choices may have significant impacts on the LCA results.
  • Using GWP values for a 20-year time horizon may lead to different conclusions than if GTP and a 100-year time horizon is used.
  • It cannot objectively determine which ones are ultimately better because it depends on policy context and involves value judgments so that there is no single scientifically correct choice.

3.1. Instantaneous versus cumulative metrics

  • Cumulative metrics based on temperature or radiative forcing are relevant when assessing potential climate impacts associated with cumulative warming, which are for instance loss of permanent ice and associated sea-level rise (Vermeer & Rahmstorf, 2009) or shut-off of thermohaline circulation (Lenton et al., 2008) .
  • Finally, the rate of change of atmospheric and oceans temperature strongly influences whether species and humans have time to adapt to climate change (Peck & Teisberg, 1994) .
  • A relevant metric for this type of impacts would be based on the derivative of the function describing an instantaneous metric (Hammit et al., 1996) , but can also be reflected by the choice of shorter time horizons when using a cumulative metric.

3.2. Constant versus variable background atmosphere and climate

  • GWP and GTP values proposed in the IPCC ARs have been calculated for respective present-day constant background atmosphere concentrations (391 ppm CO 2 for the 5 th AR) and climate conditions.
  • The dependence of metrics on background conditions also implies that metrics values inevitably change over time as background concentrations change as a result of human activities, posing a challenge for the consistency of LCIA results with emissions that take place over time.
  • Reisinger et al. (2011) have found a 100-year GWP value 20% higher than today for methane under the lowest RCP for an emission occurring in 2100 and 10% lower by mid-century than today under the highest RCP.
  • This further exemplifies that LCA practitioners cannot avoid subjective judgments when choosing a metric; they can only assess the consequences of alternative choices and communicate to end-users whether the results of LCA are robust across a wide range of different metric approaches or highly contingent on particular choices.

3.3. Climate-carbon cycle feedbacks

  • Feedback mechanisms are very complex and can increase the uncertainty in a metric value.
  • The uncertainty in AGWP associated with climate-carbon cycle feedbacks may reach ±100% of its best estimate (Myhre et al., 2013) .
  • In other words, uncertainties related to feedback effect are comparable in magnitude to the strength of the feedback itself.
  • The consideration of these feedbacks thus results in a trade-off between accuracy, consistency and comprehensiveness, but there is a clear case that climate-carbon cycle feedbacks should be treated consistently as they are a well-understood (even if difficult to quantify) feature of the climate system.

3.4. Regional variations

  • On the other hand, the climate response also varies from one region to another.
  • These regional variations may be addressed using different metric values for region where climate impacts occur (Collins et al., 2013; Shindell & Faluvegi, 2009) .
  • The conclusions from the IPCC 5 th AR are that additional studies are still needed to ensure their robustness (Myhre et al., 2013) .

3.5. The time dimension

  • A short time horizon will put emphasis on short-term impacts (or rate of change) and thus gives a higher relative importance to short-lived WMGHGs and NTCFs, while a longer time horizon will do the opposite.
  • The choice of a time horizon for instantaneous metrics can be aligned with, in the case of GTP, the estimated peaking year of the global mean surface temperature.
  • In that case, this would reflect a primary goal of limiting peak warming.
  • For LCAs that consider emissions occurring over several years, fixing the end of the time horizons to a given calendar year requires the use of a variable time horizon for climate metrics depending on the timing of each emission relative to that calendar year as shown in Figure 3b .

3.5.2. Discount rates

  • Some forms of discounting are usually present in such metrics and the selection of any discount rate requires value judgments and cannot be based on science alone, as the economic literature amply attests (e.g.
  • This choice of discount rate is in terms of value judgements similar to the choice of time horizon when using cumulative metrics.
  • At the same time, selection of an instantaneous metric such as GTP evaluates warming only in one specific year and thus discounts entirely the warming for any other year before or after this target year (Tol et al., 2012) .

3.5.3. Considering the timing of emissions

  • Timing is also critical when assessing the climate impacts of emissions of different forcers in relation to a climate stabilisation limit, e.g. the 2°C limit.
  • The GWP has been criticised as being economically inefficient and indeed inconsistent with the ultimate objective of the UNFCCC to 25 stabilise greenhouse gas concentrations at a given level (Manne & Richels, 2001; Myhre et al., 2013; Shine et al., 2007; Johansson, 2012; Tol et al., 2012) .
  • Other approaches, where the metric time horizon is based on the time left to the year a prescribed limit is reached, exist as well, e.g. the climate tipping potential (CTP) proposed by Jørgensen et al. (2014) .
  • For this approach, a 'planteray boundary' context is included, as the absolute, cumulative impacts of GHG emissions, up until the year in which a predefined limit will be reached, are expressed as a fraction of the 'capacity' left before exceeding the predefined limit.
  • As shown by Persson et al. (2015) , adopting a timedependent metric implies a commitment to significantly higher metric values for NTCFs and short-lived WMGHGs as the authors get closer to the time when peak temperatures are reached.

4. Recommendations

  • The use of GWP with a fixed time horizon has come under increased scrutiny as awareness of its limitations has become more widespread over the recent past.
  • GWP was the only metric presented and discussed in the IPCC First AR.
  • The IPCC 4 th AR was the first to introduce and discuss an alternative metric, i.e., GTP, but still considered that GWP was a "useful metric for comparing the potential climate impact of the emissions of different [long-lived gases]" (Forster et al., 2007) .
  • This metric is thus less suitable to account for long-term climate change impacts.
  • The authors first provide recommendations for a more robust assessment and interpretation of potential climate change impacts in LCA following the most recent climate research findings presented in this review.

4.1. Improving climate change impact assessment in LCA

  • 29 Some choices must be made when selecting emission metrics regarding the characteristics and modelling conditions presented in the previous sections: type of effect modelled (radiative forcing, temperature, etc.), instantaneous vs. cumulative, time horizon and/or discounting, constant vs. variable background, etc.
  • Some of these choices are scientific, while others are more policy-related and cannot be based solely on scientific studies (Tanaka et al., 2010) .
  • The choice of metric type and time horizon as proposed in this step-by-step approach may have much larger effects on decisions than the improvement of input parameters to the metrics (Myhre et al., 2013) .

4.2.1. Consideration of climate-carbon cycle feedbacks for non-CO 2 components

  • As a rule of thumb, the inclusion of climate-carbon cycle feedbacks tends to have a smaller effect on metric values for NTCFs and short-lived WMGHGs than alternative metric choices (e.g. GTP instead of GWP) and time horizons.
  • If the sensitivity test regarding alternative metrics shows little effect on the overall LCA result, then testing for the sensitivity of climate-carbon cycle feedbacks could perhaps be omitted.

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Citations
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Journal Article•DOI•
Blockchain-based life cycle assessment: An implementation framework and system architecture

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Abraham Zhang1, Abraham Zhang2, Ray Y. Zhong3, Muhammad Farooque1, Muhammad Farooque4, Kai Kang3, V.G. Venkatesh5 •
Auckland University of Technology1, Indiana Wesleyan University2, University of Hong Kong3, Sukkur Institute of Business Administration4, École de management de Normandie5
01 Jan 2020-Resources Conservation and Recycling
TL;DR: This research develops a framework to guide the implementation of Blockchain-based LCA and proposes a system architecture that integrates the use of Blockchain, IoT, and big data analytics and visualization.
Abstract: Life cycle assessment (LCA) is widely used for assessing the environmental impacts of a product or service. Collecting reliable data is a major challenge in LCA due to the complexities involved in the tracking and quantifying inputs and outputs at multiple supply chain stages. Blockchain technology offers an ideal solution to overcome the challenge in sustainable supply chain management. Its use in combination with internet-of-things (IoT) and big data analytics and visualization can help organizations achieve operational excellence in conducting LCA for improving supply chain sustainability. This research develops a framework to guide the implementation of Blockchain-based LCA. It proposes a system architecture that integrates the use of Blockchain, IoT, and big data analytics and visualization. The proposed implementation framework and system architecture were validated by practitioners who were experienced with Blockchain applications. The research also analyzes system implementation costs and discusses potential issues and solutions, as well as managerial and policy implications.

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Journal Article•DOI•
Environmental impact of biodegradable food packaging when considering food waste

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Leela Dilkes-Hoffman1, Joe Lane1, Tim Grant, Steven Pratt1, Paul Lant1, Bronwyn Laycock1 •
University of Queensland1
10 Apr 2018-Journal of Cleaner Production
TL;DR: In this article, the authors quantify the greenhouse gas (GHG) trade-offs associated with using the proposed biodegradable packaging and identify the important design considerations, including food wastage.

120 citations

Cites background from "Enhancing life cycle impact assessm..."

  • ...However, the need to check the sensitivity of an LCA's conclusions to different modeling choices is discussed by Levasseur et al. (2016)....

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  • ...Methane is a short-lived GHG, and because of this using a twenty year time horizon places greater emphasis on its emissions and its associated global warming potential than using a 100-year time horizon (Levasseur et al., 2016)....

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Journal Article•DOI•
On the Oxidation State of Manganese Ions in Li-Ion Battery Electrolyte Solutions

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Anjan Banerjee1, Yuliya Shilina1, Baruch Ziv1, Joseph M. Ziegelbauer2, Shalom Luski1, Doron Aurbach1, Ion C. Halalay2 •
Bar-Ilan University1, General Motors2
30 Jan 2017-Journal of the American Chemical Society
TL;DR: It is demonstrated that Mn3+ and not Mn2+, as commonly accepted, is the dominant dissolved manganese cation in LiPF6-based electrolyte solutions of Li-ion batteries with lithium manganate spinel positive and graphite negative electrodes chemistry.
Abstract: We demonstrate herein that Mn3+ and not Mn2+, as commonly accepted, is the dominant dissolved manganese cation in LiPF6-based electrolyte solutions of Li-ion batteries with lithium manganate spinel positive and graphite negative electrodes chemistry. The Mn3+ fractions in solution, derived from a combined analysis of electron paramagnetic resonance and inductively coupled plasma spectroscopy data, are ∼80% for either fully discharged (3.0 V hold) or fully charged (4.2 V hold) cells, and ∼60% for galvanostatically cycled cells. These findings agree with the average oxidation state of dissolved Mn ions determined from X-ray absorption near-edge spectroscopy data, as verified through a speciation diagram analysis. We also show that the fractions of Mn3+ in the aprotic nonaqueous electrolyte solution are constant over the duration of our experiments and that disproportionation of Mn3+ occurs at a very slow rate.

114 citations

Journal Article•DOI•
How much do direct livestock emissions actually contribute to global warming

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Andy Reisinger, Harry Clark
01 Apr 2018-Global Change Biology
TL;DR: These estimates demonstrate that expanding the mitigation potential and realizing substantial reductions of direct livestock non-CO2 emissions through demand and supply side measures can make an important contribution to achieve the stringent mitigation goals set out in the Paris Agreement, including by increasing the carbon budget consistent with the 1.5°C goal.
Abstract: Agriculture directly contributes about 10%-12% of current global anthropogenic greenhouse gas emissions, mostly from livestock. However, such percentage estimates are based on global warming potentials (GWPs), which do not measure the actual warming caused by emissions and ignore the fact that methane does not accumulate in the atmosphere in the same way as CO2 . Here, we employ a simple carbon cycle-climate model, historical estimates and future projections of livestock emissions to infer the fraction of actual warming that is attributable to direct livestock non-CO2 emissions now and in future, and to CO2 from pasture conversions, without relying on GWPs. We find that direct livestock non-CO2 emissions caused about 19% of the total modelled warming of 0.81°C from all anthropogenic sources in 2010. CO2 from pasture conversions contributed at least another 0.03°C, bringing the warming directly attributable to livestock to 23% of the total warming in 2010. The significance of direct livestock emissions to future warming depends strongly on global actions to reduce emissions from other sectors. Direct non-CO2 livestock emissions would contribute only about 5% of the warming in 2100 if emissions from other sectors increase unabated, but could constitute as much as 18% (0.27°C) of the warming in 2100 if global CO2 emissions from other sectors are reduced to near or below zero by 2100, consistent with the goal of limiting warming to well below 2°C. These estimates constitute a lower bound since indirect emissions linked to livestock feed production and supply chains were not included. Our estimates demonstrate that expanding the mitigation potential and realizing substantial reductions of direct livestock non-CO2 emissions through demand and supply side measures can make an important contribution to achieve the stringent mitigation goals set out in the Paris Agreement, including by increasing the carbon budget consistent with the 1.5°C goal.

110 citations

Cites background from "Enhancing life cycle impact assessm..."

  • ...policy contexts, and the choice of metric and time horizon depends (or should depend) on the type of application and policy context (IPCC 2014b, Box 3.2; Levasseur et al., 2016)....

    [...]

  • ...There is broad consensus that no single metric is optimal in all policy contexts, and the choice of metric and time horizon depends (or should depend) on the type of application and policy context (IPCC 2014b, Box 3.2; Levasseur et al., 2016)....

    [...]

Journal Article•DOI•
Development of a life-cycle impact assessment methodology linked to the Planetary Boundaries framework

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Morten Ryberg1, Mikolaj Owsianiak1, Katherine Richardson2, Michael Zwicky Hauschild1•
Technical University of Denmark1, American Museum of Natural History2
01 May 2018-Ecological Indicators
TL;DR: In this paper, the authors present a methodology, referred to as PB-LCIA, which can be used to quantify the share of the safe operating space that human activities occupy, as was illustrated by calculating indicator scores for about 10,600 products, technologies and services exemplifying several sectors, including materials, energy, transport, and processing.

109 citations

Cites background from "Enhancing life cycle impact assessm..."

  • ...An exception is Global Temperature change Potential from a pulse emission (GTPP) (Shine et al., 2005; Levasseur et al., 2016) which express change in surface temperature at a point time as a result of a pulse GHG emission....

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  • ...The magnitude of the GTPP indicator is, however, highly sensitive to the specific time point and the indicator will approach zero after sufficiently long time due to removal of the GHG from the atmosphere....

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  • ...An exception is Global Temperature change Potential from a pulse emission (GTPP) (Shine et al. 2005; Levasseur et al. 2016) which express change in surface temperature at a point time as a result of a pulse GHG emission....

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Journal Article•DOI•
Bounding the role of black carbon in the climate system: A scientific assessment

[...]

Tami C. Bond1, Sarah J. Doherty2, David W. Fahey3, Piers M. Forster4, Terje Koren Berntsen5, Benjamin DeAngelo6, Mark Flanner7, Steven J. Ghan8, Bernd Kärcher9, Dorothy Koch10, Stefan Kinne11, Yutaka Kondo12, Patricia K. Quinn13, Marcus C. Sarofim6, Martin G. Schultz14, Michael Schulz15, Chandra Venkataraman16, Hua Zhang17, Shiqiu Zhang18, Nicolas Bellouin19, Sarath K. Guttikunda20, Philip K. Hopke21, Mark Z. Jacobson22, Johannes W. Kaiser23, Zbigniew Klimont24, Ulrike Lohmann, Joshua P. Schwarz3, Drew Shindell25, Trude Storelvmo26, Stephen G. Warren27, Charles S. Zender28 •
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TL;DR: In this paper, the authors provided an assessment of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice.
Abstract: Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr−1 in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m−2 with 90% uncertainty bounds of (+0.08, +1.27) W m−2. Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m−2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m−2 with 90% uncertainty bounds of +0.17 to +2.1 W m−2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m−2, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (−0.50 to +1.08) W m−2 during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (−0.06 W m−2 with 90% uncertainty bounds of −1.45 to +1.29 W m−2). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.

4,591 citations

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Gunnar Myhre, Drew Shindell, Julia Pongratz
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3,684 citations

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Frequently Asked Questions (1)
Q1. What are the contributions mentioned in the paper "Enhancing life cycle impact assessment from climate science: review of recent findings and recommendations for application to lca" ?

36 Since the Global Warming Potential ( GWP ) was first presented in the Intergovernmental Panel on 37 Climate Change ( IPCC ) First Assessment Report, the metric has been scrutinized and alternative 38 metrics have been suggested. The IPCC Fifth Assessment Report gives a scientific assessment of 39 the main recent findings from climate metrics research and provides the most up-to-date values 40 for a subset of metrics and time horizons. The objectives of this paper are to perform a systematic 41 review of available midpoint metrics ( i. e. using an indicator situated in the middle of the cause42 effect chain from emissions to climate change ) for well-mixed greenhouse gases and near-term 43 climate forcers based on the current literature, to provide recommendations for the development 44 and use of characterization factors for climate change in life cycle assessment ( LCA ), and to 45 identify research needs. This work is part of the ‘ Global Guidance on Environmental Life Cycle 46 Impact Assessment ’ project held by the UNEP/SETAC Life Cycle Initiative and is intended to 47 support a consensus finding workshop. In an LCA context, it can make sense to use several 48 complementary metrics that serve different purposes, and from there get an understanding about 49 the robustness of the LCA study to different perspectives and metrics. The authors propose a step-by-step 50 approach to test the sensitivity of LCA results to different modelling choices and provide 51 recommendations for specific issues such as the consideration of climate-carbon feedbacks and 52 the inclusion of pollutants with cooling effects ( negative metric values ).