Early warning of the Indian Ocean Dipole using climate network analysis.

SignificanceThe Indian Ocean Dipole (IOD), an air-sea coupled phenomenon over the tropical Indian Ocean, has substantial impacts on the climate, ecosystems, and society. Due to the winter predictability barrier, however, a reliable prediction of the IOD has been limited to 3 or 4 mo in advance. Our work approaches this problem from a new data-driven perspective: the climate network analysis. Using this network-based method, an efficient early warning signal for the IOD event was revealed in boreal winter. Our approach can correctly predict the IOD events one calendar year in advance (from December of the previous year) with a hit rate of higher than 70%, which strongly outperforms current dynamic models.

A global daily evapotranspiration deficit index dataset for quantifying drought severity from 1979 to 2022.

Droughts cause multiple ecological and social damages. Drought indices are key tools to quantify drought severity, but they are mainly limited to timescales of monthly or longer. However, shorter-timescale (e.g., daily) drought indices enable more accurate identification of drought characteristics (e.g., onset and cessation time) and help timely potential mitigation of adverse effects. Here, we propose a dataset of a daily drought index named daily evapotranspiration deficit index (DEDI), which is produced for global land areas from 1979 to 2022 using actual and potential evapotranspiration data. Validation efforts show that the DEDI dataset can well identify dry and wet variations in terms of spatial patterns and temporal evolutions when compared with other available drought indices on a daily scale. The dataset also has the capability to capture recent drying trends and to detect ecology- or agriculture-related droughts. Overall, the DEDI dataset is a step forward in facilitating drought monitoring and early warning at higher temporal resolution than other compared existing products.

Assessing the regional climate impact on terrestrial ecosystem over East Asia using coupled models with land use and land cover forcing during 1980-2010.

The coupled model AVIM-RIEMS2.0 is employed to examine the effects of climate change on the terrestrial ecosystem over East Asia during three decades since the 1980s. The vegetation parameters present significantly different responses to climate change in subregions, since the effects of climate change trigger seasonal signals on land surface processes at the regional scale. In the 1980s, the increasing temperature and rainfall lead to a decrease in biomass and leaf area index (LAI) in winter, but a slight increase in net primary productivity (NPP) over China. However, summertime precipitation shows interval changes of cyclic increase-decrease pattern over eastern China, and the similar pattern also occurs for the variations in biomass and LAI. In the 1990s, the temperature and precipitation over the most regions in East Asia demonstrate the opposite changes compared to the 1980s, which results in converse variations in LAI and vegetation carbon flux. In the 2000s, biomass and LAI in the mid-lower reaches of Yangtze River basin and southeast coastal regions exhibit the same changes as precipitation in winter, and NPP shows a similar response to temperature. The biomass and LAI show consistent responses to regional climate change in summer, while different responses are seen for NPP. In general, climate change had a great impact on the vegetation in the 1990s, which produced the remarkable influences on LAI and biomass in winter and the significant impacts on NPP in summer. Over the regions affected significantly by East Asian monsoon, e.g. South China, the terrestrial ecosystem displays a roughly consistent response to regional climate change.

Sharing tableware reduces waste generation, emissions and water consumption in China's takeaway packaging waste dilemma.

China has a rapidly growing online food delivery and takeaway market, serving 406 million customers with 10.0 billion orders and generating 323 kilotonnes of tableware and packaging waste in 2018. Here we use a top-down approach with city-level takeaway order data to explore the packaging waste and life-cycle environmental impacts of the takeaway industry in China. The ten most wasteful cities, with just 7% of the population, in terms of per capita waste generation, were responsible for 30% of the country's takeaway waste, 27-34% of the country's pollutant emissions and 30% of the country's water consumption. We defined one paper substitution and two sharing tableware scenarios to simulate the environmental mitigation potentials. The results of the scenario simulations show that sharing tableware could reduce waste generation by up to 92%, and environmental emissions and water consumption by more than two-thirds. Such a mechanism provides a potential solution to address the food packaging waste dilemma and a new strategy for promoting sustainable and zero-waste lifestyles.

Satellite-based analysis of evapotranspiration and water balance in the grassland ecosystems of Dryland East Asia.

The regression tree method is used to upscale evapotranspiration (ET) measurements at eddy-covariance (EC) towers to the grassland ecosystems over the Dryland East Asia (DEA). The regression tree model was driven by satellite and meteorology datasets, and explained 82% and 76% of the variations of ET observations in the calibration and validation datasets, respectively. The annual ET estimates ranged from 222.6 to 269.1 mm yr(-1) over the DEA region with an average of 245.8 mm yr(-1) from 1982 through 2009. Ecosystem ET showed decreased trends over 61% of the DEA region during this period, especially in most regions of Mongolia and eastern Inner Mongolia due to decreased precipitation. The increased ET occurred primarily in the western and southern DEA region. Over the entire study area, water balance (the difference between precipitation and ecosystem ET) decreased substantially during the summer and growing season. Precipitation reduction was an important cause for the severe water deficits. The drying trend occurring in the grassland ecosystems of the DEA region can exert profound impacts on a variety of terrestrial ecosystem processes and functions.