Group 2i Isochrysidales produce characteristic alkenones reflecting sea ice distribution

Alkenones are biomarkers produced solely by algae in the order Isochrysidales that have been used to reconstruct sea surface temperature (SST) since the 1980s. However, alkenone based SST reconstructions in the northern high latitude oceans show significant bias towards warmer temperatures in core-tops, diverge from other SST proxies in down core records, and are often accompanied by anomalously high relative abundance of the C37 tetra-unsaturated methyl alkenone (%C37:4). Elevated %C37:4 is widely interpreted as an indicator of low sea surface salinity from polar water masses, but its biological source has thus far remained elusive. Here we identify a lineage of Isochrysidales that is responsible for elevated C37:4 methyl alkenone in the northern high latitude oceans through next-generation sequencing and lab-culture experiments. This Isochrysidales lineage co-occurs widely with sea ice in marine environments and is distinct from other known marine alkenone-producers, namely Emiliania huxleyi and Gephyrocapsa oceanica. More importantly, the %C37:4 in seawater filtered particulate organic matter and surface sediments is significantly correlated with annual mean sea ice concentrations. In sediment cores from the Svalbard region, the %C37:4 concentration aligns with the Greenland temperature record and other qualitative regional sea ice records spanning the past 14 kyrs, reflecting sea ice concentrations quantitatively. Our findings imply that %C37:4 is a powerful proxy for reconstructing sea ice conditions in the high latitude oceans on thousand- and, potentially, on million-year timescales.publishedVersio

China's Food Security

From 2006 to 2008, soaring global food prices impaired stability and development in the developing world. China, the most populous country, was able to provide sufficient food because of its domestic production. China's experiences and lessons of avoiding food crises are important for its future food policy and can serve as lessons for other emerging economies. This paper shows that China's food sufficiency is in danger of becoming lower than the target of 95 percent self-sufficiency. Based on the analysis of the current situation, challenges to China's food market can arise because of actions adopted by policymakers and inefficient allocation of agricultural resources.

Global trade and water: lessons from China and the WTO

Agricultural trade and water use are intrinsically linked. The case of China illustrates how (1) trade liberalization may impact water use; and (2) failure to consider water resources may distort analysis of trade liberalization. This article incorporates water constraints into forecasts of future agriculture in China and thereby creates a new set of scenarios that explicitly examine linkages between agriculture, water, and global trade. These new assessments show that many existing projections regarding agriculture in China are unrealistic due to water scarcity. For instance, China may import more wheat and export fewer vegetables and fruits than has typically been predicted. The findings also indicate that WTO accession provides China with opportunities to better manage demand for water in its agricultural sector while still addressing key food security concerns. The article emphasizes that it is crucial to include water as a factor of production when analyzing global agricultural trade. Global governance mechanisms of trade, such as the WTO, need to fulfill their key role in the design of effective water resources policy

Biofuels and implications for agricultural water use: blue impacts of green energy

Rising energy prices, geopolitics and concerns over the impact of greenhouse gas emissions on climate change are increasing the demand for biofuel production. At present biofuel production is estimated at 35 billion liters, accounting only for a small part (,2%) of the 1200 billion liters of annual gasoline consumption worldwide. But the contribution of biofuels to energy supply is expected to grow fast with beneficial impacts including reductions in greenhouse gasses, improved energy security and new income sources for farmers. However, biomass production for energy will also compete with food crops for scarce land and water resources, already a major constraint on agricultural production in many parts of the world. China and India, the world's two largest producers and consumers of many agricultural commodities, already face severe water limitations in agricultural production, yet both have initiated programs to boost biofuel production. This paper explores the land and water implications of increased biofuel production globally and with special focus on these two important countries, using the WATERSIM model. It concludes that, although of lesser concern at the global level, local and regional impact could be substantial. In fact, the strain on water resources would be such in China and India that it is unlikely that policy makers will pursue biofuel options, at least those based on traditional field crops

Phylogeny, alkenone profiles and ecology of Isochrysidales subclades in saline lakes: Implications for paleosalinity and paleotemperature reconstructions

Long-chain alkenones (LCAs) produced by phylogenetically classified Groups 1 and 3 Isochrysidales are increasingly used for paleotemperature and/or paleosalinity reconstructions in oligohaline lakes and marine environments. However, there are considerable difficulties in the paleoenvironmental interpretation of LCAs from Group 2 Isochrysidales thriving in saline lakes. The biggest challenge lies in our poor understanding of the complexity and ecological niches of individual Group 2 subclades in saline lakes. Here, we perform comprehensive analysis of haptophyte-specific 18S rRNA sequences and distributions of LCAs, and long-chain alkenoates (LCEs) in surface sediments and suspended particulate matter (SPM) from 37 saline lakes in northern China. These lakes span a large salinity gradient from 0.5 to 308%. Combined with published genomic data of Group 2 Isochrysidales, our phylogenetic analysis reveals three Group 2 subclades occupying distinct ecological niches: one ice-related bloomer Group 2i and two warm-season bloomers Groups 2w1 and 2w2. Group 2i, the earliest seasonal bloomer, frequently co-occurs with Group 2w1 in sediments from saline lakes with relatively low to intermediate salinity waters, whereas Group 2w2 blooms in hypersaline waters. Based on existing data, C-39:4 methyl alkenone is a chemotaxonomic biomarker for Group 2i. %C-3(7:)4 (relative abundance of C(3)(7:)(4 )to the total C-37 alkenones) values in the three Group subclades follow the order: Group 2i > Group 2w2 > Group 2w1. The %C(37:4 )in sediment cores of saline lakes does not directly record past salinity changes, but instead reflects variable contributions in production by these three subclades. This could indirectly and partially reflect overall salinity changes in some lakes dominated by Groups 2i and 2w1, but can be more complicated in lakes dominated by other assemblages. For our sites, we also demonstrate that direct use of C(37 )alkenone unsaturation indices (U-37(K), U-37(K'), and U-37(K '')) for paleotemperature reconstructions in saline lakes is generally not feasible, except for cases where alkenone-producing Isochrysidales are dominated by one single species/subclade and seasonal production effects can be circumvented. We propose two possible alternative proxies for paleotemperature reconstructions in saline lakes: 1) unsaturation ratios of C-41 and C-42 alkenones, as these compounds are predominantly produced by a limited number of Group 2 species, such as Isochrysis nuda (Liao et al., 2020) 2) C38Et/C36OEt ratio (ratio of C-38 ethyl alkenones and C-36 ethyl alkenoates), which appears to have similar temperature sensitivity for Groups 2w1 and 2w2, in lakes with no Group 2i inputs. Our study provides new insights into the phylogenetic classifications of Group 2 Isochrysidales and their ecological/environmental niches, which are fundamental for more quantitative and rigorous applications of LCAs and LCEs in saline lakes as paleosalinity and paleotemperature proxies. (C) 2021 Elsevier Ltd. All rights reserved

China?s water pricing reforms for irrigation: effectiveness and impact

Irrigation occupies a central position in China?s crop production. However, due to low per capita water resources, much worse, unevenly distributed over regions and time and the rapid increase of water diversions to non-irrigation sectors, irrigation water shortages have become a very serious problem. Without the adoption of effective measures this problem may even threaten China?s food security. Currently, irrigation efficiency is very low in general, irrigation water prices cannot fully recover water supply costs, and irrigation facilities are aging due to the lack of funding for O&M (operation & maintenance). Since water prices are regulated by the government, and not determined by the market, water prices did not work effectively in water allocation. The adoption of more economic incentive measures, such as increasing water prices, has become the main strategy of the Chinese government. Since 1 January 2004, China has carried out a new water pricing regulation. The main objectives of this regulation are that water price should be increased to fully recover water supply cost and that water should be treated as a market good. In non-irrigation sectors, the consensus is that water price could be charged to fully recover water supply cost. However, there is still controversy over the charge of irrigation water pricing. Indeed, increasing water price to fully recover supply cost may seriously affect grain production, and farmers? income. Past studies in China on these issues mainly focused on the theoretical aspects of the problem, analyzing whether irrigation water price should be increased or not. Little studies have quantified the potential impact of the reforms in China. The following questions need to be elaborated: Are irrigation water pricing reforms effective?; What are the attitudes of the farmers towards the reforms?; How do farmers respond to water pricing reforms?; What comprehensive methods should be adopted to achieve the goals of the reforms?This project is based on the analysis of three case studies (Wudu, Jinghuiqu, and Shijin irrigation districts). Jinghuiqu is located in an arid region, Shijin is located in a semi-arid region and Wudu is located in the more humid Southwest. All the issues mentioned above, have been studied using econometric methods on the basis of the data gathered at the household, field canal, pump, and village level. The study reveals that the farmers? ability to pay for irrigation water is still low and that the current water prices reflect the farmers? willingness to pay, which implies that it is in fact very difficult to increase water prices further, let alone fully recover water supply cost. Farmers do not really participate in the irrigation management process, even at the field canal level, which limits the farmers? willingness to pay. In areas confronted with severe water shortages, such as in the Jinghuiqu and Shijin irrigation districts, it is estimated that the volume of water use significantly affects wheat and maize yields, and the reduction of field water use will lead to the decline of grain production. In such cases, although increasing irrigation water price will encourage farmers to reduce water use, it may also force them to decrease their grain production. These measures affect the farmers? revenues, which are largely dependent on crop production, thus increasing social inequities. Other policies need to protect weaker groups, such as poor farmers and farmers whose income mainly depends on crops. For instance, water property has still not been initialized and both irrigation bureaus and farmers lack incentives to adopt water-saving technologies. Initiating water property, expanding low-cost water-saving technologies, reforming irrigation management and fostering a water market are all important measures to achieve the policy goals of water-saving. At this point, it is necessary to emphasize that surface water price reforms may deeply affect groundwater resources use, especially in the conjunctive irrigation areas. Without the enhancement of groundwater resources management, saving surface water may lead to more overexploitation of groundwater resources, such was the case in the Jinghuiqu and Shijin irrigation districts.All in all, irrigation water price reforms represent a revolution when compared with traditional irrigation water resource management in China. Comprehensive and integrated policies should be carried out. China being such a large country, reforms cannot be uniform in all areas. Different areas, with different precipitation levels, should adopt different measures. In most parts of South China, volumetric water pricing is not appropriate, since this method requires large infrastructure investments. Collecting water fees on the basis of the farmers? irrigated area is an alternative policy, although it requires involving farmers in the irrigation management process. Even in the northern regions, the standards of irrigation infrastructure should not be overemphasized and more attention should be paid to the cost-benefits analysis of irrigation investments

China’s water pricing reforms for irrigation: effectiveness and impact

Irrigation occupies a central position in China’s crop production. However, due to low per capita water resources, much worse, unevenly distributed over regions and time and the rapid increase of water diversions to non-irrigation sectors, irrigation water shortages have become a very serious problem. Without the adoption of effective measures this problem may even threaten China’s food security. Currently, irrigation efficiency is very low in general, irrigation water prices cannot fully recover water supply costs, and irrigation facilities are aging due to the lack of funding for O&M (operation & maintenance). Since water prices are regulated by the government, and not determined by the market, water prices did not work effectively in water allocation. The adoption of more economic incentive measures, such as increasing water prices, has become the main strategy of the Chinese government. Since 1 January 2004, China has carried out a new water pricing regulation. The main objectives of this regulation are that water price should be increased to fully recover water supply cost and that water should be treated as a market good. In non-irrigation sectors, the consensus is that water price could be charged to fully recover water supply cost. However, there is still controversy over the charge of irrigation water pricing. Indeed, increasing water price to fully recover supply cost may seriously affect grain production, and farmers’ income. Past studies in China on these issues mainly focused on the theoretical aspects of the problem, analyzing whether irrigation water price should be increased or not. Little studies have quantified the potential impact of the reforms in China. The following questions need to be elaborated: Are irrigation water pricing reforms effective?; What are the attitudes of the farmers towards the reforms?; How do farmers respond to water pricing reforms?; What comprehensive methods should be adopted to achieve the goals of the reforms? This project is based on the analysis of three case studies (Wudu, Jinghuiqu, and Shijin irrigation districts). Jinghuiqu is located in an arid region, Shijin is located in a semi-arid region and Wudu is located in the more humid Southwest. All the issues mentioned above, have been studied using econometric methods on the basis of the data gathered at the household, field canal, pump, and village level. The study reveals that the farmers’ ability to pay for irrigation water is still low and that the current water prices reflect the farmers’ willingness to pay, which implies that it is in fact very difficult to increase water prices further, let alone fully recover water supply cost. Farmers do not really participate in the irrigation management process, even at the field canal level, which limits the farmers’ willingness to pay. In areas confronted with severe water shortages, such as in the Jinghuiqu and Shijin irrigation districts, it is estimated that the volume of water use significantly affects wheat and maize yields, and the reduction of field water use will lead to the decline of grain production. In such cases, although increasing irrigation water price will encourage farmers to reduce water use, it may also force them to decrease their grain production. These measures affect the farmers’ revenues, which are largely dependent on crop production, thus increasing social inequities. Other policies need to protect weaker groups, such as poor farmers and farmers whose income mainly depends on crops. For instance, water property has still not been initialized and both irrigation bureaus and farmers lack incentives to adopt water-saving technologies. Initiating water property, expanding low-cost water-saving technologies, reforming irrigation management and fostering a water market are all important measures to achieve the policy goals of water-saving. At this point, it is necessary to emphasize that surface water price reforms may deeply affect groundwater resources use, especially in the conjunctive irrigation areas. Without the enhancement of groundwater resources management, saving surface water may lead to more overexploitation of groundwater resources, such was the case in the Jinghuiqu and Shijin irrigation districts. All in all, irrigation water price reforms represent a revolution when compared with traditional irrigation water resource management in China. Comprehensive and integrated policies should be carried out. China being such a large country, reforms cannot be uniform in all areas. Different areas, with different precipitation levels, should adopt different measures. In most parts of South China, volumetric water pricing is not appropriate, since this method requires large infrastructure investments. Collecting water fees on the basis of the farmers’ irrigated area is an alternative policy, although it requires involving farmers in the irrigation management process. Even in the northern regions, the standards of irrigation infrastructure should not be overemphasized and more attention should be paid to the cost-benefits analysis of irrigation investments