Professor Richard Wood

Plastics are among the most versatile materials in the world but pose a threat to the environment due to pollution of land, water, and air. Research has focused on developing natural substitutes for fossil-derived, non-degradable plastics, principally by replacing oil-based feedstocks with renewable feedstocks and by producing biodegradable alternatives, preferably from such feedstocks. With a resultant significant growth in production capacity for biobased plastics, there is a need to better understand the global implications of such a transition. Here we conduct a global multi-regional input-output analysis of plastic supply chains, with specific consideration of technological requirements of conventional and biobased plastic resources, monomers, polymers and final plastic products. We analyse a set of scenarios with varying levels of replacement of conventional processes with biobased processes. Under a full replacement scenario, we find greenhouse gas emission savings of 369 Mt (¿1% of global emissions), an increase in land use of 65 Mha (+1.2% of global land use), and the generation of an additional 18 million jobs (+0.6% of global employment). Whilst principally these results show positive emission and employment outcomes, policy will be needed to further guide the transition in order to increase uptake, and to guard against potential negative outcomes related to increased land requirements.

Estimating comprehensive toxicity footprints, encompassing potential impacts of toxic releases from consumption on human health and ecosystems, remains challenging due to the absence of complete emission inventories and disaggregation in global economic sectors. This study proposes an integrative approach to evaluate the global toxicity footprint by combining multiple databases, inventorying methods gap-filling/extrapolation techniques, and environmentally extended multi-region input¿output models. We incorporated industrial, residential, and agricultural emissions of 693 chemicals into air, water, and soil, assessing the toxicity footprints of 49 countries and regions and revealing the displacement of toxic impacts across regions and nations. Our results emphasize the significant sensitivity of emission inventories and toxicity footprints to the choice of extrapolation procedures in regionalized chemical inventory development. Despite considerable progress in consolidating emission data, major gaps persist in publicly available datasets, impeding accurate extrapolation of global pollutant releases and comprehensive analysis of toxicity footprints. Primary data require refinement, harmonization, and expansion to enhance toxicity footprints' accuracy, particularly concerning pesticide emissions and national Pollutant Release and Transfer Registers initiatives. This study offers crucial insights for national and regional policymakers, facilitating the creation of targeted regulations and incentives to mitigate toxic substances' environmental impact. Future research should prioritize developing input¿output table projections, deriving forward-looking time series of national emission inventories, and establishing absolute thresholds for toxic impacts within the framework of environmentally sustainable societies.

Cities are at the forefront of the battle against climate change. However, intercity comparisons and responsibility allocations among cities are hindered because cost- and time-effective methods to calculate the carbon footprints of global cities have yet to be developed. Here, we establish a hybrid method integrating top-down input¿output analysis and bottom-up crowdsourced data to estimate the carbon footprints of global cities. Using city purchasing power as the main predictor of the carbon footprint, we estimate the carbon footprints of 465 global cities in 2020. Those cities comprise 10% of the global population but account for 18% of the global carbon emissions showing a significant concentration of carbon emissions. The Gini coefficients are applied to show that global carbon inequality is less than income inequality. In addition, the increased carbon emissions that come from high consumption lifestyles offset the carbon reduction by efficiency gains that could result from compact city design and large city scale. Large climate benefits could be obtained by achieving a low-carbon transition in a small number of global cities, emphasizing the need for leadership from globally important urban centres.

Non-technical summary The distribution of household carbon footprints is largely unequal within and across countries. Here, we explore household-level consumption data to illustrate the distribution of carbon footprints and consumption within 26 European Union countries, regions and social groups. The analysis further sheds light on the relationships between carbon footprints and socially desirable outcomes such as income, equality, education, nutrition, sanitation, employment and adequate living conditions. Technical summary We need a good understanding of household carbon distributions in order to design equitable carbon policy. In this work, we analyse household-level consumer expenditure from 26 European Union (EU) countries and link it with greenhouse gas (GHG) intensities from the multiregional input¿output database EXIOBASE. We show carbon footprint distributions and elasticities by country, region and socio-economic group in the context of per capita climate targets. The top 10% of the population with the highest carbon footprints per capita account for 27% of the EU carbon footprint, a higher contribution to that of the bottom 50% of the population. The top 1% of EU households have a carbon footprint of 55 tCO2eq/cap. The most significant contribution is from air and land transport, with 41% and 21% among the top 1% of EU households. Air transport has a rising elasticity coefficient across EU expenditure quintiles, making it the most elastic, unequal and carbon-intensive consumption category in this study. Only 5% of EU households live within climate targets, with carbon footprints below 2.5 tCO2eq/cap. Our analysis points to the possibility of mitigating climate change while achieving various well-being outcomes. Further attention is needed to limit trade-offs between climate change mitigation and socially desirable outcomes. Social media summary EU top 1% of households emit 22 times the per capita climate targets. Only 5% of EU households live within the targets.

Multiregional input¿output (MRIO) databases are used to analyze the impact of resource use and environmental impacts along global supply chains. To accurately account for pressures and impacts that are highly concentrated in specific sectors or regions of the world, such as agricultural and land-use-related impacts, MRIO databases are being fueled by increasingly more detailed data. To date no MRIO database exists which couples a high level of harmonized sector detail with high country resolution. Currently available databases either aggregate minor countries into rest-of-the-world (WIOD and EXIOBASE 3), or the high country resolution is achieved at the cost of non-harmonized or lower sectoral detail (Eora, OECD-ICIO or the GTAP-MRIO). This aggregation can cause potentially significant differences in environmental and socioeconomic impact calculations. In this paper, we describe the development of an EXIOBASE 3 variant that expands regional coverage from 49 regions to 214 countries, while keeping the high and harmonized sectoral detail. We show the relevance of disaggregation for land-use accounting. Previous rest-of-the-world regions supply one-third of global land, which is used to produce a large range of different products under very different levels of productivity. We find that the aggregation of regions leads to a difference in the balance of land embodied in trade of up to 6% and a difference of land embodied in imports of up to 68% for individual countries and up to 600% for land-use-relevant sectors. Whilst the database can still be considered experimental, it is expected to increase the accuracy of estimates for environmental footprint studies of the original EXIOBASE countries, and provides the first estimates for the countries in the previous rest-of-the world.

After the publication of various multi-regional input¿output (MRIO) databases over the past years and related environmental and socio-economic footprint analyses, the interest in these global value chain analyses is ever increasing. In order to provide forward-looking analysis of policy impacts, it is necessary to take MRIO data one step further, projecting them into the future. This paper introduces a simple approach to implementing existing climate change scenarios, such as the IEA energy technology perspective scenarios, in MRIO models. Rather than forecasting the world economy, the methodology is based on a mix of econometric estimations on the demand side and using specific information regarding technology development and its classical implementation in input¿output tables. We apply this ¿what if¿ scenario approach to the most recent version of the MRIO system EXIOBASE. We compare the development of consumption- and production-based CO2 emissions up to 2030. As an additional example, we show that the energy dependency of Europe is reduced in the 2-degree scenario compared to the 6-degree scenario, while the material dependency is higher. We discuss the major shortcoming of the model, the assumption of constant shares if no better information is available, and suggest that this actually is an advantage for deducing policy implications.

In the context of the transformation toward a ¿green economy,¿ issues related to natural resource use have rapidly increased in importance in European and international policy debates. The large number of studies applying economy-wide material flow analysis so far mostly produced aggregated national indicators, making the results difficult to connect to policies, which are often designed for single sectors or consumption areas. This paper provides a detailed assessment of the composition of EU¿s material footprint in its global context, aiming at identifying the main product groups contributing to overall material consumption and specifying the geographical sources for the raw materials required to satisfy EU¿s final demand. Based on multi-regional input¿output (MRIO) modeling, we apply production layer decomposition to assess supply chains and their structural changes from 1995 to 2011. The global MRIO database used in this study is EXIOBASE 3, which disaggregates 200 products and 163 industries, of which 33 represent material extraction sectors. By that means, we increase the level of detail to a degree where policies can more easily connect to. We find that the generally growing material footprint of the EU was characterized by a dramatic shift regarding the origin of raw materials, with the share of materials extracted within the EU territory falling from 68¿% in 1995 to 35¿% in 2011. In 2011, raw materials extracted in China to produce exports to the EU already contributed an equal share to EU¿s material footprint as material extraction within the EU itself. Import dependency is most critical for the material group of metal ores, with only 13¿% of all metals required as inputs to EU final demand stemming from within the EU. Regarding product composition, construction was confirmed as the most important sector contributing to the material footprint, followed by the group of manufacturing products based on biomass. Materials embodied in service sector activities together contributed a quarter to the total material footprint in 2011, making services an important, but currently disregarded area for European resource policies. We also find that supply chain structures became more complex over time, with a growing part located outside the EU territory.