Takuma Watari

National Institute for Environmental Studies · Material Cycles Division

China, as the largest global producer of bulk materials, confronts formidable challenges in mitigating greenhouse gas emissions arising from their production. Yet the emission savings resulting from circular economy strategies, such as improved scrap recovery, more intensive use and lifetime extension, remain underexplored. Here we show that, by 20...

Concrete production poses multiple sustainability challenges, including resource over-exploitation and climate change. Here we show that growing global demand for buildings and infrastructure over the past three decades has quadrupled concrete production, reaching ∼26 Gt/year in 2020. As a result, annual requirements for virgin concrete aggregates...

Achieving a zero-emission future depends greatly on how steel production is decarbonized within a limited time frame. Here we show that the production of zero-emission steel is possible but that the quantity and quality of steel may be limited by scrap downcycling. Using Japan as a case study, our analysis shows that most steel scrap is currently d...

Decarbonization strategies for the cement and concrete sector have relied heavily on supply-side technologies, including carbon capture and storage (CCS), masking opportunities for demand-side intervention. Here we show that cross-cutting strategies involving both the supply and demand sides can achieve net-zero emissions by 2050 across the entire...

Purpose Assessing the potential impacts (characterization) of mineral resource use in life cycle impact assessment (LCIA) has long been debated. One of the most crucial challenges in the characterization models for mineral resource use is the consideration of the changing demand and availability of in-use stocks in the future, which is relevant to...

In Vietnam, an increase in construction activities together with the absence of recycling-oriented demolition techniques is giving rise to an alarming generation of construction and demolition waste. This study scrutinized the current state of building demolition approaches in Hanoi, Vietnam and evaluated the potential for the selective dismantling...

Moving towards a 1.5 °C world could fundamentally alter the future copper cycle through two key drivers: the implementation of decarbonization technologies and the imposition of an emissions budget on production activities. This study explores the impact of these drivers on the global copper cycle using a dynamic material flow analysis, coupled wit...

With the aim of achieving a carbon-neutral society by 2050 and in response to the Paris Agreement, Japan has raised its targets for greenhouse gas (GHG) emission reductions and declared that it will limit its total emissions to approximately 760 million tonnes by 2030. The materials industry, which accounts for about 20% of Japan’s GHG emissions, i...

The global transition to fundamentally decarbonized electricity and transport systems will alter the existing resource flows of both fossil fuels and metals; however, such a transition may have unintended consequences. Here we show that the decarbonization of both the electricity and transport sectors will curtail fossil fuel production while parad...

The foundations of modern society are based on metals, yet their production is currently placing considerable strain on the Earth’s carrying capacity. Here, we develop a century-long scenario for six major metals (iron, aluminum, copper, zinc, lead, and nickel) harmonized with climate goals, with the goal of establishing science-based targets. We s...

In-use stocks of metals underpin essential services in the world's economy and drive long-term anthropogenic metal cycles. Given this fact, the global distribution patterns of metal stocks provide a fundamental basis for examining ways to satisfy the basic needs of an expanding global population within the Earth's carrying capacity. Here we show th...

Sustainable metal supply requires well-coordinated strategy and policy packages based on a sound scientific understanding of anticipated long-term demand, supply, and associated environmental implications. Such information , however, is highly fragmented among various case studies. Accordingly, this extensive review explores the projected long-term...

Climate change is an urgent global challenge, and greenhouse gas (GHG) emissions from metal production contribute to a substantial part of total emissions. Metals play an essential role in human life, and their demand will increase with global population and economic growth. Therefore, projecting future GHG emissions associated with metal productio...

Metal consuming countries depend on mining activity in other countries, which may impose potential pressure on sustainable metal supply. This study proposes an approach to analyze the responsibility of consuming countries for mining activities based on the decomposition analysis of scarcity-weighted metal footprints (S-MFs) of Japan. The applicatio...

Metals underpin essential functions in modern society, yet their production currently intensifies climate change. This paper develops global targets for metal flows, stocks, and use intensity in the global economy out to 2100. These targets are consistent with emissions pathways to achieve a 2 °C climate goal and cover six major metals (iron, alumi...

Critical metals are technologically vital to the functionality of various emerging technologies, yet they have a potentially unstable supply. This condition calls for strategic planning based on the expected long-term demand and supply of these metals and the implications attached. Here, we provide the first systematic review of studies (88 studies...

Growing modern economies are built on a variety of resources, and transitioning to the type of societies that are targeted by the Sustainable Development Goals (SDGs) will require a dramatic increase of clean energy (SDG 7) and resources consumption (SDG 12). At the same time, they must be provided within the limits of local environments, with a co...

Electrification of the transport sector will support its decarbonization, yet significantly change material requirements. This calls for an integrated modeling approach internalizing metal demand-supply dynamics in low-carbon scenarios to support the Paris agreement on climate change and sustainable material circulation. Here we develop a step towa...

Global energy transitions could fundamentally change flows of both minerals and energy resources over time. It is, therefore, increasingly important to holistically and dynamically capture the impacts of large-scale energy transitions on resource flows including hidden flows such as mine waste, as well as direct flows. Here we demonstrate a systema...

This chapter explores the magnitude of the changes in patterns of material use that will be associated with the increasing deployment of renewable energy and discusses the implications for sustainable development. In particular, this chapter focuses on the increased use of lithium and cobalt, metals which are used extensively in battery technologie...

As environmental problems associated with energy systems become more serious, it is necessary to address them with consideration of their interconnections—for example, the energy-mineral nexus. Specifically, it is unclear whether long-term energy scenarios assuming the expansion of low carbon energy technology are sustainable in terms of resource c...