Environmental impacts of the nutrition transition and potential hunger eradication in emerging countries

Industrial Ecolog

China's potential SO2 emissions from coal by 2050

Global Challenges (FGGA)Industrial Ecolog

The energy-water nexus of China’s interprovincial and seasonal electric power transmission

Industrial Ecolog

Linking global crop and livestock consumption to local production hotspots

International trade plays a critical role in global food security, with global consumption having highly localized environmental impacts. It has been difficult to gain insights into these effects due to the diversity of food production, and complexity of supply chains in international trade. We present a Spatially-explicit Multi-Regional Input-Output (SMRIO) model which couples primary crops and livestock at a high spatial resolution with a global Multi-Regional Input-Output (MRIO) model. We then identify hotspots (the most significant production regions) for primary crops and livestock driven by international consumption. We present the method and data behind this approach, and provide illustrative case studies for Indonesian palm oil and Brazilian soy and beef production. Regionally, China is the largest primary crop consumer, while the EU28 is the largest livestock consumer. Primary crops and livestock hotspots are highly unequal, and the embodied primary crops and livestock for high-income countries are distributed over larger areas when compared to lower-income countries since high-income countries have more numerous trade links. Identified hotspots could allow for increased cooperation between consumers (high-income countries) and producers (lower-income countries) to improve sustainability programs for global food security.Industrial Ecolog

Water use of electricity technologies: A global meta-analysis

Understanding the water use of power production is an important step to both a sustainable energy transition and an improved understanding of water conservation measures. However, there are large differences across the literature that currently present barriers to decision making. Here, the compiled inventory of the blue water use of power production from existing studies allowed to uncover the characteristics of water use and to investigate current uncertainties. The results show that photovoltaics, wind power, and run-of-the-river hydropower consume relatively little water, whereas reservoir hydropower and woody and herbaceous biomass can have an extremely large water footprint. The water consumption of power production can differ greatly across countries due to different geographic conditions. Only a few studies provided the values for the influencing factors of water use, such as the capacity factor. Values that are reported came mainly from assumptions and other literature rather than direct measurement. Omitting a life cycle stage may lead to significant underestimations. Water scarcity is attracting more attention, but the few existing results are not useable for a regional comparison due to data gaps and inconsistent measurements. In the future, a clear and detailed definition of the water footprint and system boundary of power production is essential to improving comparisons and energy systems modelling.Industrial Ecolog

Global human consumption threatens key biodiversity areas

Key biodiversity areas (KBAs) are critical regions for preserving global biodiversity. KBAs are identified by their importance to biodiversity rather than their legal status. As such, KBAs are often under pressure from human activities. KBAs can encompass many different land-use types (e.g., cropland, pastures) and land-use intensities. Here, we combine a global economic model with spatial mapping to estimate the biodiversity impacts of human land use in KBAs. We find that global human land use within KBAs causes disproportionate biodiversity losses. While land use within KBAs accounts for only 7% of total land use, it causes 16% of the potential global plant loss and 12% of the potential global vertebrate loss. The consumption of animal products accounts for more than half of biodiversity loss within KBAs, with housing the second largest at around 10%. Bovine meat is the largest single contributor to this loss, at around 31% of total biodiversity loss. In terms of land use, lightly grazed pasture contributes the most, accounting for around half of all potential species loss. This loss is concentrated mainly in middle- and low-income regions with rich biodiversity. International trade is an important driver of loss, accounting for 22-29% of total potential plant and vertebrate loss. Our comprehensive global, trade-linked analysis provides insights into maintaining the integrity of KBAs and global biodiversity.Industrial Ecolog

Shared and environmentally just responsibility for global biodiversity loss

Industrial Ecolog

Environmental responsibility for sulfur dioxide emissions and associated biodiversity loss across Chinese provinces

Recent years have witnessed a growing volume in Chinese interregional trade, along with the increasing disparities in environmental pressures. This has prompted an increased attention on where the responsibilities for environmental impacts should be placed. In this paper, we quantify the environmental responsibility of SO2 emissions and biodiversity impacts due to terrestrial acidification at the provincial level for the first time. We examine the environmental responsibility from the perspectives of production, consumption, and income generation by employing a Multi-Regional Input-Output (MRIO) model for 2007, 2010, and 2012. The results indicate that ~40% of SO2 emissions were driven by the consumption in provinces other than where the emissions discharged. In particular, those developed provinces were net importers of SO2 emissions and mainly outsourced their emissions to nearby developing provinces. Over the period of analysis, environmental inequality among 30 provinces was larger than GDP inequality. Furthermore, environmental inequality continued to increase while GDP inequality decreased over the time period. The results of a shared income- and consumption-based responsibility approach suggest that the environmental responsibility of SO2 emissions and biodiversity impacts for developed provinces can reach up to ~4- to 93-fold the environmental pressure occurred within those provinces. This indicates that under these accounting principles the developed northern provinces in China would bear a much larger share of the environmental responsibility.Global Challenges (FGGA)Industrial Ecolog

A convex polynomial that is not sos-convex

A multivariate polynomial $p(x)=p(x_1,...,x_n)$ is sos-convex if its Hessian $H(x)$ can be factored as $H(x)= M^T(x) M(x)$ with a possibly nonsquare polynomial matrix $M(x)$. It is easy to see that sos-convexity is a sufficient condition for convexity of $p(x)$. Moreover, the problem of deciding sos-convexity of a polynomial can be cast as the feasibility of a semidefinite program, which can be solved efficiently. Motivated by this computational tractability, it has been recently speculated whether sos-convexity is also a necessary condition for convexity of polynomials. In this paper, we give a negative answer to this question by presenting an explicit example of a trivariate homogeneous polynomial of degree eight that is convex but not sos-convex. Interestingly, our example is found with software using sum of squares programming techniques and the duality theory of semidefinite optimization. As a byproduct of our numerical procedure, we obtain a simple method for searching over a restricted family of nonnegative polynomials that are not sums of squares.Comment: 15 page

On Correctness of Data Structures under Reads-Write Concurrency

Abstract. We study the correctness of shared data structures under reads-write concurrency. A popular approach to ensuring correctness of read-only operations in the presence of concurrent update, is read-set validation, which checks that all read variables have not changed since they were first read. In practice, this approach is often too conserva-tive, which adversely affects performance. In this paper, we introduce a new framework for reasoning about correctness of data structures under reads-write concurrency, which replaces validation of the entire read-set with more general criteria. Namely, instead of verifying that all read conditions over the shared variables, which we call base conditions. We show that reading values that satisfy some base condition at every point in time implies correctness of read-only operations executing in parallel with updates. Somewhat surprisingly, the resulting correctness guarantee is not equivalent to linearizability, and is instead captured through two new conditions: validity and regularity. Roughly speaking, the former re-quires that a read-only operation never reaches a state unreachable in a sequential execution; the latter generalizes Lamport’s notion of regular-ity for arbitrary data structures, and is weaker than linearizability. We further extend our framework to capture also linearizability. We illus-trate how our framework can be applied for reasoning about correctness of a variety of implementations of data structures such as linked lists.