Blue and Green Water Footprint Assessment for China—A Multi-Region Input–Output Approach

Blue water footprint linked to national consumption and international trade is unsustainable

Increasing pressure on the world's freshwater resources raises serious concerns about global food security and the sustainability of water use in agriculture. Here we quantify and map at a 5-arcmin spatial resolution the blue water footprint of each country's national consumption and where they infringe sustainable environmental flows as defined by the presumptive environmental flow standard or the 80% rule, in which runoff depletion by more than 20% will pose risk to ecosystems. We find that 52% of the blue water footprint of global consumption and 43% of international blue virtual water flows come from places where the sustainable environmental flow is violated. About 22% of the environmental flow infringement of the blue water footprint of global consumption lies outside the specific countries of consumption, indicating that a number of them have externalized their impacts. By establishing a link between the consumption of a product in one place and water scarcity in places far from the place of consumption, our assessment may aid a dialogue on how to assign and share responsibilities concerning water use.

Carbon footprint and water footprint in China: Similarities and differences

Water crisis and carbon emissions are the biggest challenges facing China's environment. International trade has exacerbated the pressures of China's carbon emissions and water consumption. This work establishes a multi-regional input-output model for time series analysis. It aims to understand how human final demands affect an economy's water consumption and carbon emissions by contrasting the similarity and dissimilarity of China's carbon footprint and water footprint. The results show that >90% of China's carbon and water footprints are embodied in trade, and China was a net exporter of embodied carbon and virtual water from 1990 to 2010. This could mean that China is burdened with more environmental pollution and resource pressures in the global supply and demand chain. We find that China's main net export destination of carbon-water-intensive products are developed areas such as North America and Europe, while China's main net import sources are developing areas such as Africa and Southeast Asia. Heavy industry and transportation contain the most carbon footprint in China, while agriculture, fishery and light industry contain the most water footprint. Also, China's embodied carbon and virtual water in diverse sectors in different years vary from region to region. The similarities and differences between China's carbon and water footprints should be considered when making decisions to better governance of climate change and water crisis.

Identification of key sectors of water resource utilization in China from the perspective of water footprint

We identified the key sectors of water resource use in China from the perspective of the water footprint to improve the use of water resources. The empirical results showed that there were six key sectors (including Crop Cultivation; Forestry; Livestock and Livestock Products; Fishery, Technical Services for Agriculture, Forestry, Livestock and Fishing; Other Food Products, and Scrap and Waste) for water consumption in China in 2015.We analyzed the use of green water, blue water, and grey water. These six sectors accounted for 66.15% of the total impact and 90.76% of the direct impact. Seven key sectors (the six sectors above plus Steel Processing)for the consumption of blue water in China can explain 59.70% of the total impact and 86.94% of the direct effect in 2015. Eight key sectors (Crop cultivation, Other food products, Scrap and Waste, Railway Freight Transport, Highway Freight and Passengers Transport, Water Freight and Passengers Transport, Pipeline Transport, and Health Services) responsible for the consumption of grey water in China in 2015 can explain 81.28% of the total impact and 95.73% of the direct impact. Therefore, the Chinese government should focus on the departments that manage water resources in these sectors when designing water-saving policies and improving water-use efficiency, such as promoting water-saving irrigation technology (including sprinkler irrigation and drip irrigation) in the agricultural sector.

Uncovering embodied CO2 flows via North-North trade - A case study of US-Germany trade

With development of globalization, the geographic separation of production caused consumption of a region was linked to pollution emitted by another region. In this process, dramatic growth of CO₂ emissions embodied in international trade attracted attention of relevant studies. Existing literatures have paid much attention on the empirical research of CO₂ flows between developed and developing countries, while studies of CO₂ emissions embodied in North-North trade were often overlooked. To partly fill the research gap, the study assessed CO₂ emissions embodied in Germany-US trade during 2000-2015, which was viewed as an example of the empirical research on CO₂ flows in North-North trade. On the basis of the estimation, we conducted a structural decomposition analysis on CO₂ emissions embodied in Germany-US trade. The decomposition focused on five driving forces that dominated the change of CO₂ emission flows. The result showed that Germany ran both the surplus of export CO₂ emissions and surplus of trade volume with the US. The share of Germany-US export CO₂ emissions to total export CO₂ emissions of Germany was greater than US-Germany export CO₂ emissions to total export CO₂ emissions of the US, which, to some extent, indicated significance of the US in Germany's external trade was greater than importance of Germany in overseas trade of the US. Decline of the two ratios above showed a trend of transferring CO₂ emissions to developing countries by the two countries. By comparison of sectoral CO₂ distribution, the categories of "manufacturing" and "services" dominated most emissions in the trade. According to structural decomposition analysis, CO₂ emission intensity and per capita final consumption caused most growth and reduction of emissions in the first 10 years, while in the next 5 years production structure of two countries played the most important role in change of embodied emissions. And the trend seemed to continue in the future.

Water Footprint and Virtual Water Accounting for China Using a Multi-Regional Input-Output Model

Water footprint (WF) is a measure of the actual appropriation of water resources. WF accounting can provide a scientific basis for the managements of water resources. In this study, a multi-regional input-output model is employed to measure the quantity of blue WF (WF) and inter-provincial virtual water (VW) flows in China for the years of 2007 and 2010. The results show that: (1) China’s total WF increased from 205.42 billion m3 in 2007 to 229.34 billion m3 in 2010. Approximately 42% of the WF was attributed to VW embodied in inter-provincial trade. Xinjiang is the largest province of VW export, whereas Shanghai had the largest net VW inflows. (2) From 2007 to 2010, the share of the agricultural sector in the entire VW trade declined, but was still as high as 82.78%, followed by the industrial sector. (3) The north-to-south and south-to-south patterns were witnessed in the domestic VW flows. The provincial WF variations are found to be affected by the per capital GDP, total water resources, per capita water resources, and urban population. (4) By linking VW with an integrated WAVE+ (water accounting and vulnerability evaluation) factor, it was found that virtual scarce water (VSW) was mainly exported by the provinces in northern China. At the national level, the amounts of VSW inflows were consistently greater than those of VSW outflows for both years, 2007 and 2010, implying an increased pressure on the provinces with water deprivation issues. Overall, these results can provide a basis for refining the spatiotemporal allocation of water resources and mitigating the conflict between water supply and demand in China.