Tag Archives: China

Urbanization impacts China surface temperature trends

Willie Wei-Hock Soon, Ronan Connolly, Michael Connolly, Peter O’Neill,
Jingyun Zheng, Quansheng Ge, Zhixin, Hao, Hong Yan. Comparing the current and early 20th century warm periods in China. Earth-Science Reviews Volume 185, October 2018, Pages 80-101

Most estimates of Chinese regional Surface Air Temperatures since the late-19th century have identified two relatively warm periods – 1920s–40s and 1990s–present. However, there is considerable debate over how the two periods compare to each other. Some argue the current warm period is much warmer than the earlier warm period. Others argue the earlier warm period was comparable to the present. In this collaborative paper, including authors from both camps, the reasons for this ongoing debate are discussed. Several different estimates of Chinese temperature trends, both new and previously published, are considered. A study of the effects of urbanization bias on Chinese temperature trends was carried out using the new updated version of the Global Historical Climatology Network (GHCN) – version 4 (currently in beta production). It is shown that there are relatively few rural stations with long records, but urbanization bias artificially makes the early warm period seem colder and the recent warm period seem warmer. However, current homogenization approaches (which attempt to reduce non-climatic biases) also tend to have similar effects, making it unclear whether reducing or increasing the relative warmth of each period is most appropriate. A sample of 17 Chinese temperature proxy series (12 regional and 5 national) is compared and contrasted specifically for the period since the 19th century. Most proxy series imply a warm early-20th century period and a warm recent period, but the relative warmth of these two periods differs between proxies. Also, with some proxies, one or other of the warm periods is absent.

Urban heat waves linked to urban heat island effect

The urban heat island effect is a significant confounding problem for global surface temperature measurements. Heat waves in a particular location may not be driven by external atmospheric changes but locally from surface development. Consequently, an increase in surface temperatures may not be driven by changes in climate but rather by changes on the earth’s surface. More on this paper here at WUWT.

Xiaojuan Liu, Guangjin Tian, Jinming Feng, Bingran Ma, Jun Wang, Lingqiang Kong. Modeling the Warming Impact of Urban Land Expansion on Hot Weather Using the Weather Research and Forecasting Model: A Case Study of Beijing, China. Advances in Atmospheric Sciences, June 2018, Volume 35, Issue 6, pp 723–736.

The impacts of three periods of urban land expansion during 1990–2010 on near-surface air temperature in summer in Beijing were simulated in this study, and then the interrelation between heat waves and urban warming was assessed. We ran the sensitivity tests using the mesoscale Weather Research and Forecasting model coupled with a single urban canopy model, as well as high-resolution land cover data. The warming area expanded approximately at the same scale as the urban land expansion. The average regional warming induced by urban expansion increased but the warming speed declined slightly during 2000–2010. The smallest warming occurred at noon and then increased gradually in the afternoon before peaking at around 2000 LST—the time of sunset. In the daytime, urban warming was primarily caused by the decrease in latent heat flux at the urban surface. Urbanization led to more ground heat flux during the day and then more release at night, which resulted in nocturnal warming. Urban warming at night was higher than that in the day, although the nighttime increment in sensible heat flux was smaller. This was because the shallower planetary boundary layer at night reduced the release efficiency of near-surface heat. The simulated results also suggested that heat waves or high temperature weather enhanced urban warming intensity at night. Heat waves caused more heat to be stored in the surface during the day, greater heat released at night, and thus higher nighttime warming. Our results demonstrate a positive feedback effect between urban warming and heat waves in urban areas.

Fluoride Exposure and Cognitive Functions, Chinese Children

Choi AL, Zhang Y, Sun G, Bellinger DC, Wang K, Yang XJ, Li JS, Zheng Q, Fu Y, Grandjean P. Association of lifetime exposure to fluoride and cognitive functions in Chinese children: a pilot study. Neurotoxicol Teratol. 2015 Jan-Feb;47:96-101. doi: 10.1016/j.ntt.2014.11.001. Erratum in Neurotoxicol Teratol. 2015 Sep-Oct;51():89.

BACKGROUND: A systematic review and meta-analysis of published studies on developmental fluoride neurotoxicity support the hypothesis that exposure to elevated concentrations of fluoride in water is neurotoxic during development.

METHODS: We carried out a pilot study of 51 first-grade children in southern Sichuan, China, using the fluoride concentration in morning urine after an exposure-free night; fluoride in well-water source; and dental fluorosis status as indices of past fluoride exposure. We administered a battery of age-appropriate, relatively culture-independent tests that reflect different functional domains: the Wide Range Assessment of Memory and Learning (WRAML), Wechsler Intelligence Scale for Children-Revised (WISC-IV) digit span and block design; finger tapping and grooved pegboard. Confounder-adjusted associations between exposure indicators and test scores were assessed using multiple regression models.

RESULTS: Dental fluorosis score was the exposure indicator that had the strongest association with the outcome deficits, and the WISC-IV digit span subtest appeared to be the most sensitive outcome, where moderate and severe fluorosis was associated with a digit span total score difference of -4.28 (95% CI -8.22, -0.33) and backward score with -2.13 (95% CI -4.24, -0.02).

CONCLUSIONS: This pilot study in a community with stable lifetime fluoride exposures supports the notion that fluoride in drinking water may produce developmental neurotoxicity, and that the dose-dependence underlying this relationship needs to be characterized in detail.

Warming Results in Decreasing Trend in Severe Weather Occurrence, China

Qinghong Zhang, Xiang Ni, Fuqing Zhang. Decreasing trend in severe weather occurrence over China during the past 50 years. Scientific Reports 7, Article number: 42310 (2017)

Understanding the trend of localized severe weather under the changing climate is of great significance but remains challenging which is at least partially due to the lack of persistent and homogeneous severe weather observations at climate scales while the detailed physical processes of severe weather cannot be resolved in global climate models. Based on continuous and coherent severe weather reports from over 500 manned stations, for the first time, this study shows a significant decreasing trend in severe weather occurrence across China during the past five decades. The total number of severe weather days that have either thunderstorm, hail and/or damaging wind decrease about 50% from 1961 to 2010. It is further shown that the reduction in severe weather occurrences correlates strongly with the weakening of East Asian summer monsoon which is the primary source of moisture and dynamic forcing conducive for warm-season severe weather over China.

Assessment of the Municipal Water Cycle in China

Tao Wang, Shuming Liu, Xuepeng Qian, Toshiyuki Shimizu, Sébastien M.R. Dente, Seiji Hashimoto, Jun Nakajima. Assessment of the municipal water cycle in China. Science of The Total Environment Volumes 607–608, 31 December 2017, Pages 761-770.

Water produced from municipal utilities accounts for nearly 10% of the sum water demand in China. The municipal water cycle that integrates processes of urban water supply, water use, sewage treatment, and water reclamation has been assessed for 655 cities across nine drainage areas in mainland China in 2012. These cities in total extracted 55 km3 raw water for municipal use from surface waterbodies and ground aquifers, approximate to the countrywide freshwater extraction of Russia or Italy. After purification and transmission, 45 km3 water was distributed to industrial, service, and domestic users. 36 km3 of post-use sewage was collected and environmentally safely treated; merely 3.2 km3 of the treated water was reclaimed. Driven by increasing urbanization, the municipal water demand in cities of China may grow 70% by 2030. The Hai River and the Huai River basins, which harbor 137 cities and occupy a majority of the densely populated North China Plain, are most exposed to physical water scarcity. The municipal water abstraction in these cities can remain constant by promoting demand-side and process conservation in the next two decades. Interbasin transfer and unconventional sources will provide municipal water double than the cities’ need. Whereas the urban water security can be technically enhanced, the challenges are to better improve water use efficiency and mitigate economic and environmental costs of the municipal system.

China Economic Impact Study Distorts Reality

This study is an exercise in statistical manipulation that distorts reality. Many factors affect productivity such that any correlation between TFP and atmospheric temperature is inconclusive. A correlation even if present is not indicative of causation or even that one is the “primary driver” of the other.

Peng Zhang, Olivier Deschenes, Kyle Meng, Junjie Zhang. Temperature effects on productivity and factor reallocation: Evidence from a half million chinese manufacturing plants. Journal of Environmental Economics and Management Volume 88, March 2018, Pages 1-17

This paper uses detailed production data from a half million Chinese manufacturing plants over 1998–2007 to estimate the effects of temperature on firm-level total factor productivity (TFP), factor inputs, and output. We detect an inverted U-shaped relationship between temperature and TFP and show that it primarily drives the temperature-output effect. Both labor- and capital- intensive firms exhibit sensitivity to high temperatures. By mid 21st century, if no additional adaptation were to occur, we project that climate change will reduce Chinese manufacturing output annually by 12%, equivalent to a loss of $39.5 billion in 2007 dollars. This implies substantial local and global economic consequences as the Chinese manufacturing sector produces 32% of national GDP and supplies 12% of global exports.

Organic Pollutants in Drinking Water, Eastern China

Shi P, Zhou S, Xiao H, Qiu J, Li A, Zhou Q, Pan Y, Hollert H. Toxicological and chemical insights into representative source and drinking water in eastern China. Environmental pollution 2017 Oct 17;233:35-44. doi: 10.1016/j.envpol.2017.10.033.

Drinking water safety is continuously threatened by the emergence of numerous toxic organic pollutants (TOPs) in environmental waters. In this study, an approach integrating in vitro bioassays and chemical analyses was performed to explore toxicological profiles of representative source and drinking water from waterworks of the Yangtze River (Yz), Taihu Lake (Th), and the Huaihe River (Hh) basins in eastern China. Overall, 34 of 96 TOPs were detected in all water samples, with higher concentrations in both source and drinking water samples of Hh, and pollutant profiles also differed across different river basins. Non-specific bioassays indicated that source water samples of Hh waterworks showed higher genotoxicity and mutagenicity than samples of Yz and Th. An EROD assay demonstrated dioxin-like toxicity which was detected in 5 of 7 source water samples, with toxin concentration levels ranging from 62.40 to 115.51 picograms TCDD equivalents per liter of water (eq./L). PAHs and PCBs were not the main contributors to observed dioxin-like toxicity in detected samples. All source water samples induced estrogenic activities of 8.00-129.00 nanograms 17β-estradiol eq./L, and estrogens, including 17α-ethinylestradiol and estriol, contributed 40.38-84.15% of the observed activities in examined samples. While drinking water treatments efficiently removed TOPs and their toxic effects, and estrogenic activity was still observed in drinking water samples of Hh. Altogether, this study indicated that the representative source water in eastern China, especially that found in Hh, may negatively affect human health, a finding that demonstrates an urgent requirement for advanced drinking water treatments.