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The impact of climate change policy on the risk of water stress in southern and eastern Asia

Abstract: The adequacy of freshwater resources remains a critical challenge for a sustainable and growing society. We present a self-consistent risk-based assessment of water availability and use under future climate change and socioeconomic growth by midcentury across southern and eastern Asia (SEA). We employ large ensemble scenarios from an integrated modeling framework that are consistent across the spectrum of regional climate, population, and economic projections. We find socioeconomic growth contributes to an increase in water stress across the entire ensemble. However, climate change drives the ensemble central tendency toward an increase in water stress in China but a reduction in India, with a considerable spread across the ensemble. Nevertheless, the most deleterious unabated climate-change impact is a low probability but salient extreme increase in water stress over China and India. In these outcomes, annual withdrawals will routinely exceed water-storage capacity. A modest greenhouse gas mitigation pathway eliminates the likelihood of these extreme outcomes and also benefits hundreds of millions of people at risk to various levels of water stress increase. Over SEA we estimate an additional 200 million people under threat of facing at least heavily water-stressed conditions from climate change and socioeconomic growth, but the mitigation scenario reduces the additional population-under-threat by 30% (60 million). Nevertheless, there remains a 1-in-2 chance that 100 million people across SEA experience a 50% increase in water stress and a 1-in-10 chance they experience a doubling of water stress. Therefore, widespread adaptive measures may be required over the coming decades to meet these unavoidable risks in water shortfalls.

The ECCO‐Darwin Data‐Assimilative Global Ocean Biogeochemistry Model: Estimates of Seasonal to Multidecadal Surface Ocean pCO2 and Air‐Sea CO2 Flux

Summary: Data‐driven estimates of how much carbon dioxide the ocean is absorbing (the so‐called “ocean carbon sink”) have improved substantially in recent years. However, computational ocean models that include biogeochemistry continue to play a critical role as they allow us to isolate and understand the individual processes that control ocean carbon sequestration. The ideal scenario is a combination of the above two methods, where data are ingested and then used to improve a model's fit to the observed ocean, also known as, data assimilation. While the physical oceanographic community has made great progress in developing data assimilation systems, for example, the Estimating the Circulation and Climate of the Ocean (ECCO) consortium, the biogeochemical community has generally lagged behind.

The ECCO‐Darwin model presented in this paper represents an important technological step forward as it is the first global ocean biogeochemistry model that (1) ingests both physical and biogeochemical observations into the model in a realistic manner and (2) considers how the nature of the ocean carbon sink has changed over multiple decades. As the ECCO ocean circulation estimates become more accurate and lengthen in time, ECCO‐Darwin will become an ever more accurate and useful tool for climate‐related ocean carbon cycle and mitigation studies.

The Importance of the Phytoplankton ‘Middle Class’ to Ocean Net Community Production

Abstract: The net balance between photosynthesis and respiration in the surface ocean is a key regulator of ocean‐atmosphere CO2 partitioning, and by extension, Earth's climate. The slight excess of photosynthesis over community respiration in sunlit waters, known as net community production (NCP), sets the upper bound on the sequestration of carbon via biological pump export. Prevailing paradigms suggest a high/low binary where net primary production (NPP), NCP, and export are highest in ecosystems characterized by microplankton (>20 μm) and lowest in ecosystems dominated by picoplankton (<2 μm). This bifurcation model neglects the potential importance of nanoplankton (2‐20 μm) – i.e. the “middle” size class – toward global biological pump functioning.

Here, we show a relationship between the biomass of nanoplankton and oxygen‐based estimates of NCP across natural ecological gradients in the North Pacific Ocean. Using a suite of high‐resolution optical imaging approaches including SeaFlow, Imaging FlowCytobot, and laser‐based scattering, nanoplankton dynamics are observed to dominate the particle size distribution throughout a ~1000 km transition between the subtropical and subpolar North Pacific, where NCP rates are 3 to 5‐fold higher than subtropical values.

Based on ecological theory applied to the Darwin size‐based ecosystem model, we hypothesize that intermediate size‐class organisms are capable of high rates of production via an optimization of bottom‐up and top‐down control inherent to the ‘middle class’. More broadly, the model indicates the global importance of nanoplankton for ocean biological production.

Utility-scale portable energy storage systems

Abstract: Battery storage is expected to play a crucial role in the low-carbon transformation of energy systems. The deployment of battery storage in the power grid, however, is currently limited by its low economic viability, which results from not only high capital costs but also the lack of flexible and efficient utilization schemes and business models.

Making utility-scale battery storage portable through trucking unlocks its capability to provide various on-demand services. We introduce the potential applications of utility-scale portable energy storage and investigate its economics in California using a spatiotemporal decision model that determines the optimal operation and transportation schedules of portable storage.

We show that mobilizing energy storage can increase its life-cycle revenues by 70% in some areas and improve renewable energy integration by relieving local transmission congestion. The life-cycle revenue of spatiotemporal arbitrage can fully compensate for the costs of a portable energy storage system in several regions in California.

For much of 2020, Covid-19 has captured the world’s attention. The pandemic has impacted billions of lives, and with over a million deaths and counting, continues to drive home a profound message that the survival and well-being of our growing and complex society hinges on our willingness to confront environmental threats with global consequences. Key to protecting lives and making our communities more resilient to such threats will be an emphasis on proactive, science-based decision-making at all levels of society.

Covid-19: A teachable moment for how we confront climate change and economic challenges

Many world regions face increasing pressures from global and regional changes in climate, population growth, urban-area expansion, and the socio-economic impacts of fossil-based development. Human interference in the global climate system contributes significantly to changes in regional and local extreme weather and climate patterns.

Navigating the energy transition

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