Guoyu Ren

Bio: Guoyu Ren is an academic researcher from China Meteorological Administration. The author has contributed to research in topics: Climatology & Climate change. The author has an hindex of 35, co-authored 71 publications receiving 4329 citations. Previous affiliations of Guoyu Ren include China University of Geosciences (Wuhan).

Rapid increase in the risk of extreme summer heat in Eastern China

Abstract: Mean summer temperature in Eastern China has increased by 082 °C since the 1950s and five of the hottest summers have occurred since 2000 This study estimates anthropogenic influence to have caused a greater than 60-fold increase in the likelihood of extreme summer heat and projects that hot summers will continue to increase in frequency

Urbanization Effects on Observed Surface Air Temperature Trends in North China

Abstract: A dataset of 282 meteorological stations including all of the ordinary and national basic/reference surface stations of north China is used to analyze the urbanization effect on surface air temperature trends. These stations are classified into rural, small city, medium city, large city, and metropolis based on the updated information of total population and specific station locations. The significance of urban warming effects on regional average temperature trends is estimated using monthly mean temperature series of the station group datasets, which undergo inhomogeneity adjustment. The authors found that the largest effect of urbanization on annual mean surface air temperature trends occurs for the large-city station group, with the urban warming being 0.16°C (10 yr) 1 , and the effect is the smallest for the small-city station group with urban warming being only 0.07°C (10 yr) 1 . A similar assessment is made for the dataset of national basic/reference stations, which has been widely used in regional climate change analyses in China. The results indicate that the regional average annual mean temperature series, as calculated using the data from the national basic/reference stations, is significantly impacted by urban warming, and the trend of urban warming is estimated to be 0.11°C (10 yr) 1 . The contribution of urban warming to total annual mean surface air temperature change as estimated with the national basic/reference station dataset reaches 37.9%. It is therefore obvious that, in the current regional average surface air temperature series in north China, or probably in the country as a whole, there still remain large effects from urban warming. The urban warming bias for the regional average temperature anomaly series is corrected. After that, the increasing rate of the regional annual mean temperature is brought down from 0.29°C (10 yr) 1 to 0.18°C (10 yr) 1 , and the total change in temperature approaches 0.72°C for the period analyzed.

Palaeovegetation of China: a pollen data‐based synthesis for the mid‐Holocene and last glacial maximum

Abstract: Pollen data from China for 6000 and 18,000 C-14 yr BP Were compiled and used to reconstruct palaeovegetation patterns, using complete taxon lists where possible and a biomization procedure that entailed the assignment of 645 pollen taxa to plant functional types. A set of 658 modern pollen samples spanning all biomes and regions provided a comprehensive test for this procedure and showed convincing agreement between reconstructed biomes and present natural vegetation types, both geographically and in terms of the elevation gradients in mountain regions of north-eastern and south-western China. The 6000 C-14 yr BP map confirms earlier studies in showing that the forest biomes in eastern China were systematically shifted northwards and extended westwards during the mid-Holocene. Tropical rain forest occurred on mainland China at sites characterized today by either tropical seasonal or broadleaved evergreen/warm mixed forest. Broadleaved evergreen/warm mixed forest occurred further north than today, and at higher elevation sites within the modern latitudinal range of this biome. The northern limit of temperate deciduous forest was shifted c. 800 km north relative to today. The 18,000 C-14 yr BP map shows that steppe and even desert vegetation extended to the modem coast of eastern China at the last glacial maximum, replacing today's temperate deciduous forest. Tropical forests were excluded from China and broadleaved evergreen/warm mixed forest had retreated to tropical latitudes, while taiga extended southwards to c. 43 degreesN.

Detection, causes and projection of climate change over China: An overview of recent progress

Abstract: This article summarizes the main results and findings of studies conducted by Chinese scientists in the past five years It is shown that observed climate change in China bears a strong similarity with the global average The country-averaged annual mean surface air temperature has increased by 11°C over the past 50 years and 05–08°C over the past 100 years, slightly higher than the global temperature increase for the same periods Northern China and winter have experienced the greatest increases in surface air temperature Although no significant trend has been found in country-averaged annual precipitation, interdecadal variability and obvious trends on regional scales are detectable, with northwestern China and the mid and lower Yangtze River basin having undergone an obvious increase, and North China a severe drought Some analyses show that frequency and magnitude of extreme weather and climate events have also undergone significant changes in the past 50 years or so Studies of the causes of regional climate change through the use of climate models and consideration of various forcings, show that the warming of the last 50 years could possibly be attributed to an increased atmospheric concentration of greenhouse gases, while the temperature change of the first half of the 20th century may be due to solar activity, volcanic eruptions and sea surface temperature change A significant decline in sunshine duration and solar radiation at the surface in eastern China has been attributed to the increased emission of pollutants Projections of future climate by models of the NCC (National Climate Center, China Meteorological Administration) and the IAP (Institute of Atmospheric Physics, Chinese Academy of Sciences), as well as 40 models developed overseas, indicate a potential significant warming in China in the 21st century, with the largest warming set to occur in winter months and in northern China Under varied emission scenarios, the country-averaged annual mean temperature is projected to increase by 15–21°C by 2020, 23–33°C by 2050, and by 39–60°C by 2100, in comparison to the 30-year average of 1961–1990 Most models project a 10%–12% increase in annual precipitation in China by 2100, with the trend being particularly evident in Northeast and Northwest China, but with parts of central China probably undergoing a drying trend Large uncertainty exists in the projection of precipitation, and further studies are needed Furthermore, anthropogenic climate change will probably lead to a weaker winter monsoon and a stronger summer monsoon in eastern Asia

Contribution of urbanization to warming in China

Abstract: The contribution of urbanization to warming in China has been difficult to quantify owing to the proximity of rural stations to urban areas. A novel detection and attribution analysis separates the contribution of all external forcings, and shows that urbanization accounts for about one-third (0.5 °C) of the total warming signal in China (1.4 °C).

The impacts of climate change on water resources and agriculture in China

Abstract: China is the world's most populous country and a major emitter of greenhouse gases. Consequently, much research has focused on China's influence on climate change but somewhat less has been written about the impact of climate change on China. China experienced explosive economic growth in recent decades, but with only 7% of the world's arable land available to feed 22% of the world's population, China's economy may be vulnerable to climate change itself. We find, however, that notwithstanding the clear warming that has occurred in China in recent decades, current understanding does not allow a clear assessment of the impact of anthropogenic climate change on China's water resources and agriculture and therefore China's ability to feed its people. To reach a more definitive conclusion, future work must improve regional climate simulations-especially of precipitation-and develop a better understanding of the managed and unmanaged responses of crops to changes in climate, diseases, pests and atmospheric constituents.

Different glacier status with atmospheric circulations in Tibetan Plateau and surroundings

Abstract: Glacial melting in the Tibetan Plateau affects the water resources of millions of people. This study finds that—partly owing to changes in atmospheric circulations and precipitation patterns—the most intensive glacier shrinkage is in the Himalayan region, whereas glacial retreat in the Pamir Plateau region is less apparent.

Indices for monitoring changes in extremes based on daily temperature and precipitation data

Abstract: Indices for climate variability and extremes have been used for a long time, often by assessing days with temperature or precipitation observations above or below specific physically-based thresholds. While these indices provided insight into local conditions, few physically based thresholds have relevance in all parts of the world. Therefore, indices of extremes evolved over time and now often focus on relative thresholds that describe features in the tails of the distributions of meteorological variables. In order to help understand how extremes are changing globally, a subset of the wide range of possible indices is now being coordinated internationally which allows the results of studies from different parts of the world to fit together seamlessly. This paper reviews these as well as other indices of extremes and documents the obstacles to robustly calculating and analyzing indices and the methods developed to overcome these obstacles. Gridding indices are necessary in order to compare observations with climate model output. However, gridding indices from daily data are not always straightforward because averaging daily information from many stations tends to dampen gridded extremes. The paper describes recent progress in attribution of the changes in gridded indices of extremes that demonstrates human influence on the probability of extremes. The paper also describes model projections of the future and wraps up with a discussion of ongoing efforts to refine indices of extremes as they are being readied to contribute to the IPCC's Fifth Assessment Report. WIREs Clim Change 2011, 2:851–870. doi: 10.1002/wcc.147 For further resources related to this article, please visit the WIREs website.