Citation: Millar, R. J., Nicholls, Z. R., Friedlingstein, P., and Allen, M. R. 2017. A modified impulse-response representation of the global near-surface air temperature and atmospheric concentration response to carbon dioxide emissions, Atmospheric Chemistry and Physics, 17, 7213-7228, https://doi.org/10.5194/acp-17-7213-2017.
Abstract: Projections of the response to anthropogenic emission scenarios, evaluation of some greenhouse gas metrics, and estimates of the social cost of carbon often require a simple model that links emissions of carbon dioxide (CO2) to atmospheric concentrations and global temperature changes. An essential requirement of such a model is to reproduce typical global surface temperature and atmospheric CO2 responses displayed by more complex Earth system models (ESMs) under a range of emission scenarios, as well as an ability to sample the range of ESM response in a transparent, accessible and reproducible form. Here we adapt the simple model of the Intergovernmental Panel on Climate Change 5th Assessment Report (IPCC AR5) to explicitly represent the state dependence of the CO2 airborne fraction. Our adapted model (FAIR) reproduces the range of behaviour shown in full and intermediate complexity ESMs under several idealised carbon pulse and exponential concentration increase experiments. We find that the inclusion of a linear increase in 100-year integrated airborne fraction with cumulative carbon uptake and global temperature change substantially improves the representation of the response of the climate system to CO2 on a range of timescales and under a range of experimental designs.
Abstract: Atmospheric greenhouse gas (GHG) concentrations are at unprecedented, record-high levels compared to the last 800 000 years. Those elevated GHG concentrations warm the planet and – partially offset by net cooling effects by aerosols – are largely responsible for the observed warming over the past 150 years. An accurate representation of GHG concentrations is hence important to understand and model recent climate change. So far, community efforts to create composite datasets of GHG concentrations with seasonal and latitudinal information have focused on marine boundary layer conditions and recent trends since the 1980s. Here, we provide consolidated datasets of historical atmospheric concentrations (mole fractions) of 43 GHGs to be used in the Climate Model Intercomparison Project – Phase 6 (CMIP6) experiments. The presented datasets are based on AGAGE and NOAA networks, firn and ice core data, and archived air data, and a large set of published studies. In contrast to previous intercomparisons, the new datasets are latitudinally resolved and include seasonality. We focus on the period 1850–2014 for historical CMIP6 runs, but data are also provided for the last 2000 years. We provide consolidated datasets in various spatiotemporal resolutions for carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), as well as 40 other GHGs, namely 17 ozone-depleting substances, 11 hydrofluorocarbons (HFCs), 9 perfluorocarbons (PFCs), sulfur hexafluoride (SF6), nitrogen trifluoride (NF3) and sulfuryl fluoride (SO2F2). In addition, we provide three equivalence species that aggregate concentrations of GHGs other than CO2, CH4 and N2O, weighted by their radiative forcing efficiencies. For the year 1850, which is used for pre-industrial control runs, we estimate annual global-mean surface concentrations of CO2 at 284.3 ppm, CH4 at 808.2 ppb and N2O at 273.0 ppb. The data are available at https://esgf-node.llnl.gov/search/input4mips/ and http://www.climatecollege.unimelb.edu.au/cmip6. While the minimum CMIP6 recommendation is to use the global- and annual-mean time series, modelling groups can also choose our monthly and latitudinally resolved concentrations, which imply a stronger radiative forcing in the Northern Hemisphere winter (due to the latitudinal gradient and seasonality).
Abstract: With the publication of the 9th March 2017 Gas Statement of Opportunities (GSOO), the Australian Energy Market Operator (AEMO) cautioned that within 18 months, “shortfalls” of gas supply could lead to shortfalls in the supply of electricity generated by burning gas. AEMO suggested solutions to potential shortfalls that included the construction of new pipelines or Coal Seam Gas (CSG) fields.
Our report investigates AEMO’s gas-and-electricity-system modelling results as well as the communications that followed. We explore reasonable alternate conclusions that can be drawn by analysing AEMO’s published modelling inputs, assumptions, and results, and by contemplating future real-world events.
We find that although a “gas-price crisis” exists in eastern-Australia, a gas-supply shortfall is very unlikely to occur. Our review finds that the size of AEMO’s forecast shortfall is very small, amounting to no more than around 0.2% of annual supply.
In addition, only eleven days after announcing its supply-gap concerns, AEMO essentially closed the gap when it published, on its website, updated (lower) electricity-demand forecasts that therefore lead to less demand for electricity generated by burning gas.
In this report we also consider alternative solutions to gas shortfalls, and find that there is no need to expand gas-supply infrastructure.
Citation: Palmer, G. 2017. Biophysical Economics and Resource Quality 2(6) doi:10.1007/s41247-017-0022-3
Abstract: The contribution from variable renewable energy (VRE) to electricity generation is projected to increase. At low penetration, intermittency can usually be accommodated at low cost. High-penetration VRE will displace conventional generation, and require increased grid flexibility, geographic and technology diversity, and the use of electrical storage. Energy return on investment (EROI) is a tool that gives greater weight to the principles of energetics over market prices, and may provide a long-term guide to prospective energy transitions. The EROI of electrical storage may be critical to the efficacy of high-penetration renewable scenarios. However, there is no generally agreed upon methodology for incorporating storage into EROI. In recent years, there have been important contributions to applying net-energy analysis to storage, including the development of storage-specific net-energy metrics. However, there remains uncertainty as to how to apply these metrics to practical systems to derive useful or predictive information. This paper will introduce a framework for evaluating storage at a system level. It introduces the surplus energy-storage synergy hypothesis as a general principle for exploring the role of storage. It is argued that the useful energy available to society is determined by both the net-energy of the energy source and the stored energy as stocks. This hypothesis is translated across to electricity systems with the use of electrical reliability indices to evaluate the value of storage. A case study applies the framework to a suite of VRE simulations. The case study was modelled as a limiting case of VRE plus storage, and is therefore not intended as a comprehensive cost-optimised solution to high-penetration VRE. A shift from an electrical system based mostly on energy stocks to one based mostly on natural flows is constrained by the quantity of storage required, and the quantity of VRE overbuild to charge the stores. The application of the framework shows that the value of electrical storage and overbuild exhibits a marked diminishing returns behaviour at rising VRE penetration and therefore the first units of storage are the most valuable. The framework is intended to stimulate further research into using EROI to better understand the role of VRE and storage in prospective energy transitions.
Abstract: The potential for decoupling of energy and resources from economic growth should enable economic development while improving environmental sustainability indicators. Relative decoupling of energy has been a characteristic of developed nations as a consequence of efficiency gains and productivity growth. The trend has strengthened in recent decades as economies have advanced further into the service economy phase. The next phase of development (the so-called ‘Infotronics’ phase) is being enabled by the rapid growth of information and communications technology (ICT), and artificial intelligence. The question explored in this commentary is whether the Infotronics phase will shift energy consumption in absolute rather than relative terms (so-called ‘strong’ vs. ‘weak’ decoupling), using Australia as a case study. In this context, weak decoupling is defined as a relative reduction in energy consumption per unit of GDP, whereas strong decoupling is also an absolute reduction in national energy consumption. Historic data on Australian primary energy consumption, gross domestic product, GDP deflator, and industrial sectors have been assembled for the period 1900–2014. A time-series linear regression between energy and real GDP was undertaken to explore the historic relationship between changes in the changing structure of the Australian economy and energy consumption. Despite a significant shift towards a service economy, primary energy consumption has remained strongly connected to GDP, but overlaid with distinct long-run trends in energy intensity.
Abstract: Streamflows in key catchments across the State of Victoria, Australia, are projected into the future utilising a previously developed multiple linear regression. The regression uses a temporal range of rainfall and temperature parameters to compute monthly streamflows, and is applied to an ensemble of 22 statistically downscaled global climate models. This method reproduced historical streamflows well: on average the reconstruction overestimated the observed mean by 1% and underestimated the observed variance by 2%, although this varied on a catchment-to-catchment basis. Despite the accurate reconstruction of the mean streamflow, no events of similar magnitude to the most severe drought on record (the Millennium drought, 1997−2009) were found in the historical reconstruction for the current climate. Furthermore the reconstructed streamflow did not exhibit declining trends similar to what has been observed, due to the absence of declining rainfall in the climate model simulations for the historical record. Future projections under a high emissions pathway indicate a large reduction (24−87%) in streamflow by the end of the century, with conditions similar to the Millennium drought becoming the norm. The driest 10 yr mean streamflow was found to be 78% worse than the Millennium drought under a high emissions pathway. The greatest reductions in streamflow are seen through the May−November period. This is an important step in understanding how Victoria’s water security will be affected by climate change.
Citation:Fiddes, S. and B. Timbal. 2017. Future impacts of climate change on streamflows across Victoria, Australia: making use of statistical downscaling. Climate Research. 71:219–236.
Authors: Yann Robiou du Pont, M. Louise Jeffery, Johannes Gütschow, Joeri Rogelj, Peter Christoff & Malte Meinshausen
Abstract: Benchmarks to guide countries in ratcheting-up ambition, climate finance, and support in an equitable manner are critical but not yet determined in the context of the Paris Agreement1. We identify global cost-optimal mitigation scenarios consistent with the Paris Agreement goals and allocate their emissions dynamically to countries according to five equity approaches. At the national level, China’s Nationally Determined Contribution (NDC) is weaker than any of the five equity approaches, India’s NDC is aligned with two, and the EU’s and the USA’s with three. Most developing countries’ conditional (Intended) NDCs (INDCs) are more ambitious than the average of the five equity approaches under the 2°C goal. If the G8 and China adopt the average of the five approaches, the gap between conditional INDCs and 2°C-consistent pathways could be closed. For an equitable, cost-optimal achievement of the 1.5°C target, emissions in 2030 are 21% lower (relative to 2010) than for 2°C for the G8 and China combined, and 39% lower for remaining countries. Equitably limiting warming to 1.5°C rather than 2°C requires that individual countries achieve mitigation milestones, such as peaking or reaching net-zero emissions, around a decade earlier.
Citation: Robiou du Pont, Y., Jeffery, M. L., Gütschow, J., Rogelj, J., Christoff, P., & Meinshausen, M. (2016). Equitable mitigation to achieve the Paris Agreement goals. Nat. Clim. Change , advance online publication. doi:10.1038/nclimate3186
Authors: Alexander Nauels, Malte Meinshausen, Matthias Mengel, Katja Lorbacher, and Tom M. L. Wigley
Abstract: Sea level rise is one of the major impacts of global warming; it will threaten coastal populations, infrastructure, and ecosystems around the globe in coming centuries. Well-constrained sea level projections are needed to estimate future losses from Sea Level Rise (SLR) and benefits of climate protection and adaptation. Process-based models that are designed to resolve the underlying physics of individual sea level drivers form the basis for state-of-the-art sea level projections. However, associated computational costs allow for only a small number of simulations based on selected scenarios that often vary for different sea level components. This approach does not sufficiently support sea level impact science and climate policy advice, which require a sea level projection methodology that is flexible with regard to the climate scenario yet comprehensive and bound to the physical constraints provided by process-based models. To fill this gap, we present a sea level model that emulates global mean long-term process-based model projections for all major sea level components. Thermal expansion estimates are calculated with the hemispheric upwelling-diffusion ocean component of the simple carbon cycle-climate model MAGICC, which has been updated and calibrated against CMIP5 ocean temperature profiles and thermal expansion data. Global glacier contributions are estimated based on a parameterization constrained by transient and equilibrium process-based projections. Sea level contribution estimates for Greenland and Antarctic ice sheets are derived from surface mass balance and solid ice discharge parameterizations reproducing current output from ice-sheet models. The land water storage component replicates the latest hydrological modeling results. For 2100, we project 0.38 m to 0.59 m (66 % range) total SLR based on the RCP2.6 scenario, 0.48 m to 0.68 m for RCP4.5, 0.48 m to 0.72 m for RCP6.0, and 0.67 m to 0.97 m for RCP8.5. These projections lie within the range of the latest IPCC SLR estimates. SLR projections for 2300 yield median responses of 0.97 m for RCP2.6, 1.66 m for RCP4.5, 2.32 m for RCP6.0, and 5.12 m for RCP8.5. The MAGICC sea level model provides a powerful and efficient platform for probabilistic uncertainty analyses of long-term SLR projections. It can be used as a tool to directly investigate the SLR implications of different mitigation pathways and may also serve as input for regional SLR assessments via component-wise sea level pattern scaling.
Citation: Nauels, A., Meinshausen, M., Mengel, M., Lorbacher, K., and Wigley, T. M. L.: Synthesizing long-term sea level rise projections – the MAGICC sea level model, Geosci. Model Dev. Discuss., doi:10.5194/gmd-2016-233, in review, 2016.
Authors: Annabelle Workman, Grant Blashki, David Karoly, and John Wiseman
Abstract: Reducing domestic carbon dioxide and other associated emissions can lead to short-term, localized health benefits. Quantifying and incorporating these health co-benefits into the development of national climate change mitigation policies may facilitate the adoption of stronger policies. There is, however, a dearth of research exploring the role of health co-benefits on the development of such policies. To address this knowledge gap, research was conducted in Australia involving the analysis of several data sources, including interviews carried out with Australian federal government employees directly involved in the development of mitigation policies. The resulting case study determined that, in Australia, health co-benefits play a minimal role in the development of climate change mitigation policies. Several factors influence the extent to which health co-benefits inform the development of mitigation policies. Understanding these factors may help to increase the political utility of future health co-benefits studies.
Citation:Workman, A., Blashki, G., Karoly, D., & Wiseman, J. (2016). The Role of Health Co-Benefits in the Development of Australian Climate Change Mitigation Policies. International Journal of Environmental Research and Public Health 13(9), 927.
Abstract:This article analyzes the contested politics of including (and accounting for) land-based mitigation in a post-2020 climate agreement. Emissions from land have been only partially included to date within the United Nations Framework Convention on Climate Change and its Kyoto Protocol. The Paris Agreement, adopted in December 2015 and “applicable to all” for the post-2020 period, raises the possibility of unprecedented reliance on land-based mitigation. This has significant consequences for furthering both ambition and equity in global climate mitigation efforts. Yet, what are these consequences, and how have they manifested themselves in the existing (pre-2020) multilateral climate regime? What role do accounting rules for land-based mitigation play herein? In addressing these questions, we identify key dimensions of what we term the “governance by expertise” approach taken to land-based mitigation to date, which has served to reduce the environmental integrity of existing (developed country) mitigation efforts. Specifically, we analyze land-use accounting rules as a site of politics and highlight the “technicalization of politics” underway in this realm, which obscures the political implications of how land has been included to date. We conclude by considering whether the Paris Agreement institutionalizes similar dynamics, and the environmental integrity and equity implications of doing so.
Citation: Dooley, K. & Gupta, A. Int Environ Agreements (2016). doi:10.1007/s10784-016-9331-z
Abstract:This paper analyses normative change in electricity supply in order to understand the challenges associated with the introduction of a non-negotiable environmental norm, a change necessary to ensure long-term environmental sustainability of the supply system. The analysis combines the work of Wolfgang Streeck together with that of ecological modernisation to trace the fate of an environmental norm as it emerges within a complex pre-existing institutional context comprising social norms around accessibility, affordability and reliability as well as the more recent emphasis on the benefits of competition. The analysis shows how ‘strong’ forms of ecological modernist policy change, policies in which environmental norms were explicit, were vulnerable to carbon intensive businesses arguing that they posed too significant a social risk. Yet, solar PV has been associated with ‘weaker’ forms of ecological modernist policy development where solar proponents have succeeded in demonstrating, despite significant opposition, how solar PV can be embedded within the competition norm thereby promoting both competition and environmental goals. This weaker form of ecological modernist change may have far reaching unintended consequences as solar PV on residential houses enhances the capacity of those households as ‘prosumers’ to ensure their interests are better supported. An environmental norm may be established here but social norms around rights to an essential service may also be placed at risk.
Direct link: http://www.tandfonline.com/doi/full/10.1080/23251042.2016.1155690#.VzQJrBV97WY
Citation: National contributions for decarbonizing the world economy in line with the G7 agreement Yann Robiou du Pont, M Louise Jeffery, Johannes Gütschow, Peter Christoff and Malte Meinshausen 2016 Environ. Res. Lett. 11 054005 doi:10.1088/1748-9326/11/5/054005
In June 2015, the G7 agreed to two global mitigation goals: ‘a decarbonization of the global economy over the course of this century’ and ‘the upper end of the latest Intergovernmental Panel on Climate Change (IPCC)recommendation of 40%–70% reductions by 2050 compared to 2010’. These IPCC recommendations aim to preserve a likely (>66%) chance of limiting global warming to 2 °C but are not necessarily consistent with the stronger ambition of the subsequent Paris Agreement of ‘holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels’. The G7 did not specify global or national emissions scenarios consistent with its own agreement. Here we identify global cost-optimal emissions scenarios from Integrated Assessment Models that match the G7 agreement. These scenarios have global 2030 emissions targets of 11%–43% below 2010, global net negative CO2 emissions starting between 2056 and 2080, and some exhibit net negative greenhouse gas emissions from 2080 onwards. We allocate emissions from these global scenarios to countries according to five equity approaches representative of the five equity categories presented in the Fifth Assessment Report of the IPCC(IPCCAR5): ‘capability’, ‘equality’, ‘responsibility-capability-need’, ‘equal cumulative per capita’ and ‘staged approaches’. Our results show that G7 members’Intended Nationally Determined Contribution (INDCs) mitigation targets are in line with a grandfathering approach but lack ambition to meet various visions of climate justice. The INDCs of China and Russia fall short of meeting the requirements of any allocation approach. Depending on how their INDCs are evaluated, the INDCs of India and Brazil can match some equity approaches evaluated in this study.
Abstract: Decarbonising the electrical power system holds a critical role in climate change mitigation. Recent developments in technology are helping change the current centralized paradigm into one of integrated distributed clean energy resources. In spite of these developments, radical transformation is not occurring at a speed to effectively meet environmental targets, mostly due to the incumbent carbon lock-in trajectory. We argue that business model (BM) innovation dynamics are key drivers in accelerating the low carbon power system transition, often operating irrespective of the underlying technology. We combine BM theory with the multi-level perspective on sociotechnical transitions to present a useful framework to analyze this potential transition. This paper presents the application of this framework characterizing relevant BM dynamics of niche and regime business actors, and supporting these with illustrative examples. Particularly, we find that new actors in the distributed energy business are achieving market scale by offering financially innovative BMs that do not require upfront costs from customers. Higher penetrations of renewable energy sources in liberalized electricity markets are destabilizing the historical BM of large centralized utilities through erosion of wholesale prices. Furthermore, a shift towards distributed and dynamic energy resources further challenges incumbents and might bring opportunities for BMs focused on active customer participation and social value creation. As these tendencies are expected to accelerate, we find analyses of BMs will have important relevance for future power system transition research.
Citation: Wainstein, Martin E.and Bumpus, Adam G. 2016. Business Models as Drivers of the Low Carbon Power System Transition: A Multi-Level Perspective. Journal of Cleaner Production. In Press. doi:10.1016/j.jclepro.2016.02.095
Authors: Rachelle Meyer, Brendan R. Cullen, and Richard J., Eckard
Abstract: Sequestering carbon (C) in soil organic matter in grassland systems is often cited as a major opportunity to offset greenhouse gas (GHG) emissions. However, these systems are typically grazed by ruminants, leading to uncertainties in the net GHG balance that may be achieved. We used a pasture model to investigate the net balance between methane (CH4), nitrous oxide (N2O) and soil C in sheep-grazed pasture systems with two starting amounts of soil C. The net emissions were calculated for four soil types in two rainfall zones over three periods of 19 years. Because of greater pasture productivity, and consequent higher sheep stocking rates, high-rainfall sites were associated with greater GHG emissions that could not be offset by C sequestration. On these high-rainfall sites, the higher rate of soil organic carbon (SOC) increase on low-SOC soils offset an average of 45% of the livestock GHG emissions on the modelled chromosol and 32% on the modelled vertosol. The slow rate of SOC increase on the high-SOC soils only offset 2–4% of CH4 and N2O emissions on these high-rainfall sites. On low-rainfall sites, C sequestration in low-SOC soils more than offset livestock GHG emissions, whereas the modelled high-C soils offset 75–86% of CH4 and N2O emissions. Greater net emissions on high-C soils were due primarily to reduced sequestration potential and greater N2O emissions from nitrogen mineralisation and livestock urine. Annual variation in CH4 and N2O emissions was low, whereas annual SOC change showed high annual variation, which was more strongly correlated with weather variables on the low-rainfall sites compared with the high-rainfall sites. At low-soil C concentrations, with high sequestration potential, there is an initial mitigation benefit that can in some instances offset enteric CH4 and direct and indirect N2O emissions. However, as soil organic matter increases there is a trade-off between diminishing GHG offsets and increasing ecosystem services, including mineralisation and productivity benefits.
Authors: Stephen Pollard, Kate Dooley, Dylan McConnell, Malte Meinshausen, Rachelle Meyer, Annabelle Workman
SUMMARY OF SUBMISSION
The Paris agreement on climate change explicitly recognises that national contributions are not sufficient to hold global warming to the guardrails of 2 degrees and 1.5 degrees Celsius. The agreement includes a process for nations to regularly revise and increase the ambition of targets. Accordingly, the Authority must assess policies on the basis of how quickly they will have an impact on emissions and how rapidly they can be ratcheted up in order to achieve deeper emissions cuts than Australia’s current targets.
The Authority should broaden its assessment of climate change mitigation policies to consider the wider social impacts of policies, in addition to cost-effectiveness, environmental effectiveness and equity considerations.
To ensure that policies are designed to work for conditions that will be encountered in the real world, a strategic approach to emissions reductions should be developed, rather than a narrowly defined framework of economic optimization. This should involve the pursuit of mitigation across all sectors of policy and levels of government, recognising that emissions reductions will not always be the primary aim of policies.
It follows that the introduction of market mechanisms such as emissions trading or carbon taxes should be considered in conjunction with other policy approaches, including targeted support for renewable energy, regulations, funding for research and development, and well-designed programs to understand and support changes to social practices.
In addition to providing incentives for the phase-in of renewables technologies and energy efficiency, the Climate Change Authority should examine innovative complimentary policies to regulate the least efficient electricity production capacity.
The impact of policies on Australia’s international competitiveness should be assessed in the context of the Paris agreement and the creation of opportunities for Australia to participate and lead in developing solutions to the causes of climate change and adapt to its inevitable impacts.
The Authority should also examine further policy opportunities that could bring significant benefits to Australia, including emissions reductions, such as reform of the national electricity market to support a greater share of renewable and distributed energy, reviewing industry support mechanisms for fossil fuel producers, incorporating climate change considerations into all major policy decisions and halting the approval of new coal mines.
Authors: Michael Schreiber, Martin E. Wainstein, Patrick Hochloff, Roger Dargaville
Abstract: Renewable energy is increasingly replacing carbon-based technologies worldwide in electricity networks. This increases the challenge of balancing intermittent generation with demand fluctuation. DR (Demand response) is recognized as a way to address this by adapting consumption to supply patterns. By using DR technology, grid withdrawal of DSM (demand side management) devices such as heat pumps, electric vehicles or stationary batteries can be temporally shifted. Yet, the development of an accurate control and market design is still one of the greatest remaining DR challenges. We present a range of flexible price signals that can address this by acting as effective demand control mechanisms. The different tariffs consist of combinations of flexible energy and power price signals. Their impact on the unit commitment of automatable DSM devices is tested for a set of German households. The financial outcome for the respective stakeholders are quantified. Our results suggest flexible power pricing can reduce overall demand peaks as well as limit simultaneous grid withdrawals caused by real time pricing incentives. Furthermore, we prove that inefficient designs of flexible power pricing can lead to undesired bidding of automatable devices. We propose a specific tariff design that shows robust network perfomance and reduces energy procurement costs.
Citation: Schreiber, Michael; Wainstein, Martin E.; Hochloff, Patrick; Dargaville, Roger. 2015. Flexible electricity tariffs: Power and energy price signals designed for a smarter grid. Energy 93:2568-2581.
Authors: Malte Meinshausen, Louise Jeffery, Johannes Guetschow, Yann Robiou du Pont, Joeri Rogelj, Michiel Schaeffer, Niklas Höhne, Michel den Elzen, Sebastian Oberthür, and Nicolai Meinshausen
Abstract: Achieving the collective goal of limiting warming to below 2C or 1.5C compared to pre-industrial levels requires a transition towards a fully decarbonized world. Annual greenhouse gas emissions on such a path in 2025 or 2030 can be allocated to individual countries using a variety of allocation schemes. We reanalyse the IPCC literature allocation database and provide country-level details for three approaches. At this stage, however, it seems utopian to assume that the international community will agree on a single allocation scheme. Here, we investigate an approach that involves a major-economy country taking the lead. In a bottom-up manner, other countries then determine what they consider a fair comparable target, for example, either a ‘per-capita convergence’ or ‘equal cumulative per-capita’ approach. For example, we find that a 2030 target of 67% below 1990 for the EU28, a 2025 target of 54% below 2005 for the USA or a 2030 target of 32% below 2010 for China could secure a likely chance of meeting the 2C target in our illustrative default case. Comparing those targets to post-2020 mitigation targets reveals a large gap. No major emitter can at present claim to show the necessary leadership in the concerted effort of avoiding warming of 2C in a diverse global context.
Citation: Meinshausen, M., L. Jeffery, J. Guetschow, Y. Robiou du Pont, J. Rogelj, M. Schaeffer, N. Hohne, M. den Elzen, S. Oberthur and N. Meinshausen (2015). "National post-2020 greenhouse gas targets and diversity-aware leadership." Nature Clim. Change advance online publication.
Authors: Joeri Rogelj, Michiel Schaeffer, Malte Meinshausen, Reto Knutti, Joseph Alcamo, Keywan Riahi, and William Hare
Abstract: Recently, assessments have robustly linked stabilization of global-mean temperature rise to the necessity of limiting the total amount of emitted carbon-dioxide (CO2). Halting global warming thus requires virtually zero annual CO2 emissions at some point. Policymakers have now incorporated this concept in the negotiating text for a new global climate agreement, but confusion remains about concepts like carbon neutrality, climate neutrality, full decarbonization, and net zero carbon or net zero greenhouse gas (GHG) emissions. Here we clarify these concepts, discuss their appropriateness to serve as a long-term global benchmark for achieving temperature targets, and provide a detailed quantification. We find that with current pledges and for a likely (>66%) chance of staying below 2 °C, the scenario literature suggests net zero CO2 emissions between 2060 and 2070, with net negative CO2 emissions thereafter. Because of residual non-CO2 emissions, net zero is always reached later for total GHG emissions than for CO2. Net zero emissions targets are a useful focal point for policy, linking a global temperature target and socio-economic pathways to a necessary long-term limit on cumulative CO2 emissions.
Citation: Joeri, R., S. Michiel, M. Malte, K. Reto, A. Joseph, R. Keywan and H. William (2015). "Zero emission targets as long-term global goals for climate protection." Environmental Research Letters 10(10): 105007.
Authors: D.J. Rasmussen, Malte Meinshausen, Robert E. Kopp
Abstract: Quantitative assessment of climate change risk requires a method for constructing probabilistic time series of changes in physical climate parameters. Here, we develop two such methods, Surrogate/Model Mixed Ensemble (SMME) and Monte Carlo Pattern/Residual (MCPR), and apply them to construct joint probability density functions (PDFs) of temperature and precipitation change over the 21st century for every county in the United States. Both methods produce likely (67% probability) temperature and precipitation projections consistent with the Intergovernmental Panel on Climate Change's interpretation of an equal-weighted Coupled Model Intercomparison Project 5 (CMIP5) ensemble, but also provide full PDFs that include tail estimates. For example, both methods indicate that, under representative concentration pathway (RCP) 8.5, there is a 5% chance that the contiguous United States could warm by at least 8°C. Variance decomposition of SMME and MCPR projections indicate that background variability dominates uncertainty in the early 21st century, while forcing-driven changes emerge in the second half of the 21st century. By separating CMIP5 projections into unforced and forced components using linear regression, these methods generate estimates of unforced variability from existing CMIP5 projections without requiring the computationally expensive use of multiple realizations of a single GCM.
Authors: Vogel, E., Deumlich, D., & Kaupenjohann, M.
Abstract: In the last decade, legislative incentives have led to a significant increase in maize cultivation for the generation of energy from biomass in Germany. The expansion of maize acreage resulted in an increased risk of water erosion due to the low vegetative soil cover after the seeding of the maize and the linear structure and great distance of the maize rows. Soil erosion is considered a major threat to food security and causes damages both on-site and off-site, i.e., to adjacent infrastructures and surface waters. In this study we investigated the effectiveness of six main erosion control concepts in terms of their reduction of damages using the physically based model Erosion-3D. Simulations were carried out based on an agricultural site in Brandenburg, Germany, for three different rainfall events with average recurrence intervals of 2, 20 and 100 years. No-tillage and conservation tillage showed the strongest erosion mitigation potential with reduction rates of up to 90 to 100%. Contour buffer strips and vegetated waterways have only very small erosion mitigation effects. Medium erosion reduction rates were simulated for the division of the field into smaller parcels or strips (alternating maize and winter cereal crops). We conclude that no-tillage or conservation tillage is the most recommendable erosion control measure. However, further research needs to be done on the potential of no-tillage and conservation tillage to increase preferential flow paths, their effect on the vertical outflow rate of pesticides and herbicides into groundwater resources and ways to mitigate these adverse effects. Vegetated waterways and contour buffer strips can be combined with other erosion control measures and entail only a minimal reduction in cultivation area. Their installation is relatively low priced, however, additional maintenance costs may be incurred. Noteworthy reduction rates could only be shown for rainfall events with short return periods. The division of the field into winter grain and maize cultivation areas leads to substantial erosion mitigation rates, but has to be seen in context with the reduction of maize cultivation area. The long-term benefits of decreasing maize acreage under specific circumstances might, however, outweigh the reduced benefits of maize production.
Citation: Vogel, E., Deumlich, D., & Kaupenjohann, M. (2016). Bioenergy maize and soil erosion—Risk assessment and erosion control concepts. Geoderma, 261, 80-92.
Authors: Joeri Rogelj, Andy Reisinger, David L McCollum, Reto Knutti, Keywan Riahi, and Malte Meinshausen
Abstract: Global-mean temperature increase is roughly proportional to cumulative emissions of carbon-dioxide (CO2). Limiting global warming to any level thus implies a finite CO2 budget. Due to geophysical uncertainties, the size of such budgets can only be expressed in probabilistic terms and is further influenced by non-CO2 emissions. We here explore how societal choices related to energy demand and specific mitigation options influence the size of carbon budgets for meeting a given temperature objective. We find that choices that exclude specific CO2 mitigation technologies (like Carbon Capture and Storage) result in greater costs, smaller compatible CO2 budgets until 2050, but larger CO2 budgets until 2100. Vice versa, choices that lead to a larger CO2 mitigation potential result in CO2 budgets until 2100 that are smaller but can be met at lower costs. In most cases, these budget variations can be explained by the amount of non-CO2 mitigation that is carried out in conjunction with CO2, and associated global carbon prices that also drive mitigation of non-CO2 gases. Budget variations are of the order of 10% around their central value. In all cases, limiting warming to below 2 °C thus still implies that CO2 emissions need to be reduced rapidly in the coming decades.
Citation: Joeri, R., R. Andy, L. M. David, K. Reto, R. Keywan and M. Malte (2015). "Mitigation choices impact carbon budget size compatible with low temperature goals." Environmental Research Letters 10(7): 075003.
Authors: Dylan McConnell, Tim Forcey, M. Sandiford
Abstract: Price volatility and increasing renewable energy generation have raised interest in the potential opportunities for storage technologies in energy-only electricity markets. In this paper we explore the value of a price-taking storage device in such a market, the National Electricity Market (NEM) in Australia. Our analysis suggests that under optimal operation, there is little value in having more than six hours of storage in this market. However, an inability to perfectly forecast wholesale prices, particularly extreme price spikes, may warrant some additional storage. We found that storage devices effectively provide a similar service to peak generators and are similarly dependent on and exposed to extreme price events, with revenue for a merchant generator highly skewed to a few days of the year. As a consequence of this finding, and in contrast to previous studies, the value of storage was found to be relatively insensitive to the round trip efficiency. We also found that the variability of revenue and exposure to extreme prices could be reduced using common hedging strategies, such as those currently used by peak generators. We present a case study that demonstrates storage technologies using such strategies may have a competitive advantage over other peaking generators in the NEM, due to the ability to earn revenue outside of extreme peak events. Similar to traditional peak generators, a main driver for storage options in an energy-only electricity market is extreme prices, which in turn is dependent on capacity requirements. However storage technologies can receive additional revenue streams, which may be improved by increased integration of renewable energy.
McConnell, D., Forcey, T. & Sandiford, M. Estimating the value of electricity storage in an energy-only wholesale market. Applied Energy159, 422–432 (2015). doi:10.1016/j.apenergy.2015.09.006
Authors: Mike Sandiford; Tim Forcey; Alan Pears; Dylan McConnell
THE ELECTRICITY JOURNAL, Volume: 28, Issue 7, Pages: 1-22, DOI: 10.1016/j.tej.2015.07.007, Published: AUG 2015
Abstract: For decades, consumption of grid-supplied electricity increased in line with a growing economy. In the five years since 2009, however, annual consumption in eastern Australia declined by 7 percent, even while the Australian economy grew by 13 percent. Declining consumption was not forecast by the planning authority nor by market participants. The authors review reasons for declining consumption, the failure of planning authorities to forecast this structural change, and ongoing consequences. Fuel switching from oil and gas offers one means of partly arresting the rapidly declining use of electricity grid infrastructure.
Authors: Rachelle Meyer; Brendan R Cullen; Ian R Johnson; Richard J Eckard
Abstract: Soil carbon is often cited as having potential to provide both climate change mitigation and adaptation benefits. Given the extensive ecosystem service benefits of soil organic matter (SOM), including increasing N supply and plant-available water-holding capacity (PAWHC), we hypothesized that on-farm benefits provide ample justification for maintaining high levels of SOM, separate to its carbon sequestration potential. To investigate this we used whole-farm system modelling to simulate pastures with high SOM (initial carbon amount similar to long-term pasture) and low SOM (initial carbon condition similar to long-term cropping). These scenarios are deliberately confounded with land use change, as this allowed for comparison of the mineralization, PAWHC, and associated productivity benefits on high and low carbon soils with the same management. Low-carbon soils were modelled with two amounts of PAWHC to investigate the importance of this effect in isolation. These three scenarios (one high carbon and two low carbon with differing PAWHC) were run for two climatic zones each with two soil types. Across both climatic zones and soil types, soil C accumulated at a rate of 0.30-0.48 t C ha-1 year-1 (0-30 cm) over the first 20 years in soils with low initial carbon amounts. On soils in a high-rainfall climate, annual pasture production in low-SOM soil was 560 to 900 kg DM ha-1 less than for high-SOM soil, attributable primarily to increased N mineralization (68 to 77 kg N ha-1 year-1) overcoming an N limitation in spring. On low-rainfall sites, a reduction in annual pasture production of 280 to 770 kg DM ha-1 on low carbon soils compared to high carbon soils was attributable to reduced PAWHC. The increased pasture production associated with higher SOM was valued between AUD 26 and 95 ha-1, across the soils and sites. The entire value on low-rainfall sites (AUD 26-85) was attributable to differences in PAWHC, while on high-rainfall sites, increased pasture production was attributed to N mineralization valued from AUD 85 to 105 ha-1. These results indicate that soil carbon sequestration, through increased SOM, can provide substantial on-farm benefits that contribute to future productivity.
Citation: R. Meyer, BR. Cullen, IR Johnson, RJ Eckard (2015) "Process modelling to assess the sequestration and productivity benefits of soil carbon for pasture", Agriculture, Ecosystems and Environment (2015), pp. 272-280, DOI: 10.1016/j.agee.2015.07.024
Revised: 01 Jun 2015 – Accepted: 11 Aug 2015 – Published: 02 Sep 2015
Abstract. Thermal expansion of seawater is one of the most important contributors to global sea level rise in the past 100 years. Yet, observational estimates of thermal expansion are sparse, mostly limited to the upper ocean layers, and only a part of the available climate model data is sufficiently diagnosed to complete our quantitative understanding of thermosteric sea level rise (thSLR). In order to support usage of results of the Coupled Model Intercomparison Project Phase 5 (CMIP5), complement observations and enable the development of surrogate techniques to project thSLR, we complete diagnostics of CMIP5 models. We obtain 30% more thermal expansion time series than currently published. We find that upper 700 m (2000 m) observational estimates need to be augmented by 36 ± 9% (15 ± 6%) on average to be considered for a global sea level budget. Half of the total expansion originates from depths below 480 ± 250 m – with the range indicating scenario-to-scenario variations. Lastly, to support the development of surrogate methods to project thermal expansion, we calibrate two simplified parameterisations against CMIP5 estimates of thSLR: one parameterisation is suitable for scenarios where only hemispheric ocean temperature profiles are available, the other, where total ocean heat uptake is known (goodness-of-fit: ±5 and ±9%, respectively).
Abstract: Changes in the Atlantic overturning circulation have a strong influence on European temperatures, North American sea level and other climate phenomena worldwide. A meaningful assessment of associated societal impacts needs to be based on the full range of its possible future evolution. This requires capturing both the uncertainty in future warming pathways and the inherently long-term response of the ocean circulation. While probabilistic projections of the global mean and regional temperatures exist, process-based probabilistic assessments of large-scale dynamical systems such as the Atlantic overturning are still missing. Here we present such an assessment and find that a reduction of more than 50 % in Atlantic overturning strength by the end of the 21 (s t) century is within the likely range under an unmitigated climate change scenario (RCP8.5). By combining linear response functions derived from comprehensive climate simulations with the full range of possible future warming pathways, we provide probability estimates of overturning changes by the year 2100. A weakening of more than 25 % is found to be very unlikely under a climate protection scenario (RCP2.6), but likely for unmitigated climate change. The method is able to reproduce the modelled recovery caused by climatic equilibration under climate protection scenarios which provides confidence in the approach. Within this century, a reduction of the Atlantic overturning is a robust climatic phenomena that intensifies with global warming and needs to be accounted for in global adaptation strategies.
Link to full article: http://link.springer.com/article/10.1007%2Fs10584-014-1265-2
Rogelj, J; Schaeffer, M; Meinshausen, M; Shindell, DT; Hare, W; Klimont, Z; Velders, GJM; Amann, M; Schellnhuber, HJ
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Volume: 111, Issue: 46, Pages: 16325-16330, DOI: 10.1073/pnas.1415631111, Published: NOV 18 2014
Abstract: Anthropogenic global warming is driven by emissions of a wide variety of radiative forcers ranging from very short-lived climate forcers (SLCFs), like black carbon, to very long-lived, like CO2. These species are often released from common sources and are therefore intricately linked. However, for reasons of simplification, this CO2-SLCF linkage was often disregarded in long-term projections of earlier studies. Here we explicitly account for CO2-SLCF linkages and show that the short-and long-term climate effects of many SLCF measures consistently become smaller in scenarios that keep warming to below 2 degrees C relative to preindustrial levels. Although long-term mitigation of methane and hydrofluorocarbons are integral parts of 2 degrees C scenarios, early action on these species mainly influences near-term temperatures and brings small benefits for limiting maximum warming relative to comparable reductions taking place later. Furthermore, we find that maximum 21st-century warming in 2 degrees C-consistent scenarios is largely unaffected by additional black-carbon-related measures because key emission sources are already phased-out through CO2 mitigation. Our study demonstrates the importance of coherently considering CO2-SLCF coevolutions. Failing to do so leads to strongly and consistently overestimating the effect of SLCF measures in climate stabilization scenarios. Our results reinforce that SLCF measures are to be considered complementary rather than a substitute for early and stringent CO2 mitigation. Near-term SLCF measures do not allow for more time for CO2 mitigation. We disentangle and resolve the distinct benefits across different species and therewith facilitate an integrated strategy for mitigating both short and long-term climate change.
Abstract: In this paper we analyze the interaction between climate and air pollution policies using the integrated assessment model REMIND coupled to the reduced-form climate model MAGICC. Since overall, aerosols tend to cool the atmosphere, there is a concern that a reduction of pollutant emissions could accelerate global warming and offset the climate benefits of carbon dioxide emission reductions.
We investigate scenarios which independently reduce emissions from either large-scale sources, such as power plants, or small-scale sources, such as cooking and heating stoves. Large-scale sources are likely to be easier to control, but their aerosol emissions are characterized by a relatively high sulfur content, which tends to result in atmospheric cooling. Pollution from small-scale sources, by contrast, is characterized by a high share of carbonaceous aerosol, which is an important contributor to global warming.
We find that air pollution policies can significantly reduce aerosol emissions when no climate policies are in place. Stringent climate policies lead to a large reduction of fossil fuel use, and therefore result in a concurrent reduction of air pollutant emissions. These reductions partly reduce aerosol masking, thus initially counteracting the reduction of greenhouse gas forcing, however not overcompensating it. If climate policies are in place, air pollution policies have almost no impacts on medium- and long-term radiative forcing. Therefore there is no conflict of objectives between clean air and limiting global warming. We find that the stringency of air pollution policies may influence the rate of global temperature change in the first decade. Afterwards climate change mitigation policies are of greater importance. (C) 2014 Elsevier Ltd. All rights reserved.
Abstract: In electricity markets that use a merit order dispatch system, generation capacity is ranked by the price that it is bid into the market. Demand is then met by dispatching electricity according to this rank, from the lowest to.the highest bid. The last capacity dispatched sets the price received by all generation, ensuring the lowest cost provision of electricity. A consequence of this system is that significant deployments of low marginal cost electricity generators, including renewables, can reduce the spot price of electricity. In Australia, this prospect has been recognized in concern expressed by some coalfired generators that delivering too much renewable generation would reduce wholesale electricity prices. In this analysis we calculate the likely reduction of wholesale prices through this merit order effect on the Australian National Electricity Market. We calculate that for 5 GW of capacity, comparable to the present per capita installation of photovoltaics in Germany, the reduction in wholesale prices would have been worth in excess of A$1.8 billion over 2009 and 2010, all other factors being equal. We explore the implications of our findings for feed-in tariff policies, and find that they could deliver savings to consumers, contrary to prevailing criticisms that they are a regressive form of taxation. (C) 2013 Elsevier Ltd. All rights reserved.