Dr Steve Mohr

Given recent circular economy policy and waste minimisation targets, there is a significant opportunity to fundamentally change the way waste is managed in Australia, and re-focus waste management to promote resource recovery and efficiency. Detailed data on household waste generation can assist decision makers in targeting waste minimisation incentives, improving resource recovery and circularity, identifying specific technology and infrastructure gaps and informing future development. Unfortunately, high-resolution spatial estimates of waste generation at the property lot scale is typically unavailable. This study presents a novel spatial model developed to estimate waste generation data at the property lot level. Utilising census data at multiple spatial scales and council waste generation data, we apply our model to estimate quantities of residual waste, dry recyclables and garden waste generated for more than 1,200,000 property lots in the Sydney metropolitan area, Australia. Results show the spatial distribution of estimated household waste generation, achieving a high degree of accuracy when compared to validation data. To illustrate the application of our results in the context of identifying ideal areas for waste processing facilities, we analyse the spatial distribution of available garden waste arising from property lots. An area of intense garden waste generation was identified, indicating a supply area of approximately 13km2 in northern Sydney that can support a facility of approximately 20,000t throughput a year. Our analytical approach presented is novel, and has practical application for locating waste processing facilities; analysing efficient kerbside waste collection services; and in informing data driven urban waste management strategies.

Emission inventories are widely used by the climate community, but their uncertainties are rarely accounted for. In this study, we evaluate the uncertainty in projected climate change induced by uncertainties in fossil-fuel emissions, accounting for non-CO2 species co-emitted with the combustion of fossil-fuels and their use in industrial processes. Using consistent historical reconstructions and three contrasted future projections of fossil-fuel extraction from Mohr et al we calculate CO2 emissions and their uncertainties stemming from estimates of fuel carbon content, net calorific value and oxidation fraction. Our historical reconstructions of fossil-fuel CO2 emissions are consistent with other inventories in terms of average and range. The uncertainties sum up to a ±15% relative uncertainty in cumulative CO2 emissions by 2300. Uncertainties in the emissions of non-CO2 species associated with the use of fossil fuels are estimated using co-emission ratios varying with time. Using these inputs, we use the compact Earth system model OSCAR v2.2 and a Monte Carlo setup, in order to attribute the uncertainty in projected global surface temperature change (T) to three sources of uncertainty, namely on the Earth system's response, on fossil-fuel CO2 emission and on non-CO2 co-emissions. Under the three future fuel extraction scenarios, we simulate the median T to be 1.9, 2.7 or 4.0 °C in 2300, with an associated 90% confidence interval of about 65%, 52% and 42%. We show that virtually all of the total uncertainty is attributable to the uncertainty in the future Earth system's response to the anthropogenic perturbation. We conclude that the uncertainty in emission estimates can be neglected for global temperature projections in the face of the large uncertainty in the Earth system response to the forcing of emissions. We show that this result does not hold for all variables of the climate system, such as the atmospheric partial pressure of CO2 and the radiative forcing of tropospheric ozone, that have an emissions-induced uncertainty representing more than 40% of the uncertainty in the Earth system's response.

Phosphorus is an essential element for food production whose main global sources are becoming scarce and expensive. Furthermore, losses of phosphorus throughout the food production chain can also cause serious aquatic pollution. Recycling urban organic waste resources high in phosphorus could simultaneously address scarcity concerns for agricultural producers who rely on phosphorus fertilisers, and waste managers seeking to divert waste from landfills to decrease environmental burdens. Recycling phosphorus back to agricultural lands however requires careful logistical planning to maximize benefits and minimize costs, including processing and transportation. The first step towards such analyses is quantifying recycling potential in a spatially explicit way. Here we present such inventories and scenarios for the Greater Sydney Basin's recyclable phosphorus supply and agricultural demand. In 2011, there was 15 times more phosphorus available in organic waste than agricultural demand for phosphorus in Sydney. Hypothetically, if future city residents shifted to a plant-based diet, eliminated edible food waste, and removed animal production in the Greater Sydney Basin, available phosphorus supply would decrease to 7.25 kt of phosphorus per year, even when accounting for population growth by 2031, and demand would also decrease to 0.40 kt of phosphorus per year. Creating a circular phosphorus economy for Sydney, in all scenarios considered, would require effective recycling strategies which include transport outside of the Greater Sydney Basin. These spatially explicit scenarios can be used as a tool to facilitate stakeholders engagement to identify opportunities and barriers for appropriate organic waste recycling strategies.

Lead and zinc are used extensively in the construction and automotive industries, and require sustainable supply. In order to understand the future availability of lead and zinc, we have projected global supplies on a country-by-country basis from a detailed global assessment of mineral resources for 2013. The model GeRS-DeMo was used to create projections of lead and zinc production from ores, as well as recycling for lead. Our modelling suggests that lead and zinc production from known resources is set to peak within 15 years (lead 2025, zinc 2031). For lead, the total supply declines relatively slowly post peak due to recycling. If additional resources are found, these peaks would shift further into the future. These results suggest that lead and zinc consumers will need to plan for the future, potentially by: seeking alternative supplies (e.g., mine tailings, smelter/refinery slags); obtaining additional value from critical metals contained in lead-zinc ore deposits to counter lower grade ores; identifying potential substitutes; redesigning their products; or by contributing to the development of recycling industries.

This paper reports on the short- and long-term impacts of online water-use feedback provided via a smart metering trial involving 120 households in New South Wales, Australia. Near-real time water consumption feedback was provided via an online portal to half of the sample. Water consumption was uniquely analysed one year pre- and post-intervention, and in conjunction with login data. During one year of available access, the intervention group saved an overall average of 24.1 litres per household per day (L/hh/d) (4.2%). Regression analysis showed the significant savings of active users related specifically to portal login activity. Significant short-term effects persisted for 42¿days, averaging at 63.1 L/hh/d. The article discusses the implications for research and practice, including a consideration of how, in addition to providing ongoing access, online portals could be leveraged further by water authorities to help meet urgent short-term supply constraints such as in drought.

China is vigorously promoting the development of its unconventional gas resources because natural gas is viewed as a lower-carbon energy source and because China has relatively little conventional natural gas supply. In this paper, we first evaluate how much unconventional gas might be available based on an analysis of technically recoverable resources for three types of unconventional gas resources: shale gas, coalbed methane and tight gas. We then develop three alternative scenarios of how this extraction might proceed, using the Geologic Resources Supply Demand Model. Based on our analysis, the medium scenario, which we would consider to be our best estimate, shows a resource peak of 176.1 billion cubic meters (bcm) in 2068. Depending on economic conditions and advance in extraction techniques, production could vary greatly from this. If economic conditions are adverse, unconventional natural gas production could perhaps be as low as 70.1. bcm, peaking in 2021. Under the extremely optimistic assumption that all of the resources that appear to be technologically available can actually be recovered, unconventional production could amount to as much as 469.7. bcm, with peak production in 2069. Even if this high scenario is achieved, China's total gas production will only be sufficient to meet China's lowest demand forecast. If production instead matches our best estimate, significant amounts of natural gas imports are likely to be needed.

The impact of global phosphorus scarcity on food security has increasingly been the focus of scientific studies over the past decade. However, systematic analyses of alternative futures for phosphorus supply and demand throughout the food system are still rare and provide limited inclusion of key stakeholders. Addressing global phosphorus scarcity requires an integrated approach exploring potential demand reduction as well as recycling opportunities. This implies recovering phosphorus from multiple sources, such as food waste, manure, and excreta, as well as exploring novel opportunities to reduce the long-term demand for phosphorus in food production such as changing diets. Presently, there is a lack of stakeholder and scientific consensus around priority measures. To therefore enable exploration of multiple pathways and facilitate a stakeholder dialog on the technical, behavioral, and institutional changes required to meet long-term future phosphorus demand, this paper introduces an interactive web-based tool, designed for visualizing global phosphorus scenarios in real time. The interactive global phosphorus scenario tool builds on several demand and supply side measures that can be selected and manipulated interactively by the user. It provides a platform to facilitate stakeholder dialog to plan for a soft landing and identify a suite of concrete priority options, such as investing in agricultural phosphorus use efficiency, or renewable fertilizers derived from phosphorus recovered from wastewater and food waste, to determine how phosphorus demand to meet future food security could be attained on a global scale in 2040 and 2070. This paper presents four example scenarios, including (1) the potential of full recovery of human excreta, (2) the challenge of a potential increase in non-food phosphorus demand, (3) the potential of decreased animal product consumption, and (4) the potential decrease in phosphorus demand from increased efficiency and yield gains in crop and livestock systems.

The argument that human society can decouple economic growth-defined as growth in Gross Domestic Product (GDP)-from growth in environmental impacts is appealing. If such decoupling is possible, it means that GDP growth is a sustainable societal goal. Here we show that the decoupling concept can be interpreted using an easily understood model of economic growth and environmental impact. The simple model is compared to historical data and modelled projections to demonstrate that growth in GDP ultimately cannot be decoupled from growth in material and energy use. It is therefore misleading to develop growth-oriented policy around the expectation that decoupling is possible. We also note that GDP is increasingly seen as a poor proxy for societal wellbeing. GDP growth is therefore a questionable societal goal. Society can sustainably improve wellbeing, including the wellbeing of its natural assets, but only by discarding GDP growth as the goal in favor of more comprehensive measures of societal wellbeing.

Due to the expected importance of unconventional oil in China's domestic oil supply, this paper first investigates the four types of China's unconventional oil resources comprehensively: heavy and extra-heavy oil, oil sands, broad tight oil and kerogen oil. Our results show that OIP (Oil-in-Place) of these four types of resources amount to 19.64Gt, 5.97Gt, 25.74Gt and 47.64Gt respectively, while TRRs (technically recoverable resources) amount to 2.24Gt, 2.26Gt, 6.95Gt and 11.98Gt respectively. Next, the Geologic Resources Supply-Demand Model is used to quantitatively project the long-term production of unconventional oil under two resource scenarios (TRR scenario and Proved Reserve+Cumulative Production scenario). Our results indicate that total unconventional oil production will peak in 2068 at 0.351Gt in TRR scenario, whereas peak year and peak production of PR (proved reserves)+CP (Cumulative Production) scenario are 2023 and 0.048Gt, significantly earlier and lower than those of TRR scenario. The implications of this growth in production of unconventional oil for China are also analyzed. The results show that if the TRR scenario can be achieved, it will increase total supply and improve oil security considerably. However, achieving the production in TRR scenario has many challenges, and even if it is achieved, China will still need to rely on imported oil.

A comprehensive country-by-country projection of world iron ore production is presented along with alternative scenarios and a sensitivity analysis. The supply-driven modelling approach follows Mohr (Projection of world fossil fuel production with supply and demand interactions, PhD Thesis, http://www.theoildrum.com/node/6782, 2010) using an ultimately recoverable resource of 346 Gt of iron ore. Production is estimated to have a choppy plateau starting in 2017 until 2050 after which production rapidly declines. The undulating plateau is due to Chinese iron ore production peaking earlier followed by Australia and Brazil in turn. Alternative scenarios indicate that the model is sensitive to increases in Australian and Brazilian resources, and that African iron ore production can shift the peak date only if the African Ultimately Recoverable Resources (URR) is 5 times larger than the estimate used. Changes to the demand for iron ore driven by substitution or recycling are not modelled. The relatively near-term peak in iron ore supply is likely to create a global challenge to manufacturing and construction and ultimately the world economy.

A model for estimating world natural gas production to peak in 2043 has been developed and takes into account the conventional natural gas production peak by 2038, the world unconventional natural gas production peak in 2038 as well the decline in methane hydrate. The model approximates coalbed methane while natural gas demand is modeled by analyzing demand per person and population forecasts. Estimating the worldwide coalbed methane resource and the determination of a reasonable recovery factor yields he coalbed methane unconventional ultimately recoverable resources (URR) estimate. Another input comes from the determination of conventional natural gas URR estimate. The model estimates that methane hydrate resources are about 1,000 tcm.