Extremes In China Research Articles

Detectable Impacts of the Past Half‐Degree Global Warming on Summertime Hot Extremes in China

AbstractAvoided risks in a 1.5°C warmer world as opposed to a 2°C one become urgent to be assessed after the Paris Agreement, especially at regional scales. To provide an observable analog, this study quantified detectable impacts of the past 0.5°C global warming on summertime hot extremes in China. The half‐degree global warming has preferentially facilitated the emergence and prevalence of complex hot extremes (sequential hot day‐night), which experienced a twofold‐fourfold increase in their frequency in Southeast China, lower reaches of the Yangtze River, and northern China, along with a doubling to tripling of duration and intensity. The past global warming of 0.5°C further exacerbated the vulnerability of above hot spots by exposing them to drastically augmented (over 300%) excess heat accumulated during the severest complex events. These observation‐based solid evidences imply that a 0.5°C reduction in future global warming does matter for China to avoid excessively escalated risks of complex hot extremes.

Weak Cooling of Cold Extremes Versus Continued Warming of Hot Extremes in China During the Recent Global Surface Warming Hiatus

AbstractUsing daily maximum temperature (Tmax), minimum temperature (Tmin), and mean temperature data of 437 weather stations in China, we compared variations of the mean with extreme ends of probability distribution of temperatures in China from 1960 to 2015. Our analysis confirmed that annual mean Tmax and Tmin experienced warming hiatus in China after 1998. The warming hiatus is also reflected by the weak cooling of cold extremes across China, but hot extremes continue the significant warming trend nationally and in climate regions of East China, Southwest China, and the Tibetan Plateau. During 1999–2015, the hot day frequency (Tx90, based on base period 1961–1990) and averaged Tmax above the 90th percentile of each year (Txp90) increased significantly by 3.70 d/decade and 0.20°C/decade nationally. But there were significant cooling trends of cold extremes in East China and Southeast China from 1999 to 2015. During the warming hiatus period, the obvious decline in warm season precipitation contributed to the ongoing warming of hot extremes in East China and Southwest China. Both the decrease of warming season solar irradiance and increase of warm season precipitation facilitated the weak cooling trends of hot extremes in Northeast China and North China Plain. Although mean temperature experienced warming hiatus after 1998, the continued warming of hot extremes and reverse from warming to weak cooling of cold extremes imply an increase of temperature variability in China simultaneously.

Heat and Adult Health in China.

Given projected increases in the frequency of precipitation and temperature extremes in China, we examine the extent adults may be vulnerable to climate anomalies. We link nutrition, health, and economic data from the China Health and Nutrition Survey (1989-2011) to gridded climate data to identify which socioeconomic outcomes are particularly susceptible, including adult underweight incidence, body mass index, dietary intake, physical activity, illness, income, and food prices. We find warm temperatures augment the probability of being underweight among adults, with a particularly large impact for the elderly (ages > 60). Extremely dry and warm conditions produce a 3.3-percentage point increase in underweight status for this group. Consequences on nutrition coincide with changes in illness rather than dietary, income or purchasing power shifts. Social protection targeting areas prone to excessive heat may consider supplementing bundles of goods with a suite of health care provisions catering to the elderly.

Projected changes in climate extremes in China in a 1.5 °C warmer world

In December 2015, the Paris Agreement was reached in an effort to limit global warming to below 1.5 °C. However, there is few scientific literature assessing changes in the climate with 1.5 °C of warming over China. We investigated changes in climate extremes in China that generally present high impacts on society. The results indicated that an additional warming of 0.5 °C would lead to significant increases in temperature and precipitation extremes across China. Both the temperatures on the hottest days and the frequencies of heat events across China are estimated to be lower when limiting warming to 1.5 °C compared to 2.0 °C. Events such as the record heat case in the summer of 2013 over eastern China would be approximately 28% less likely to occur if warming was limited to below 1.5 °C. Moreover, China would experience reduced precipitation extremes, although this projection is accompanied by a relatively lower confidence level than for changes in temperature extremes. High‐impact heavy rain events similar to that in the summer of 2012 over northern China (Beijing) that led to severe urban waterlogging and loss of life would be less likely if there is no more than 0.5 °C of warming. Similarly, the odds of wide‐ranging severe droughts, as witnessed in the summer of 2014 over north China, are projected to decrease clearly. The positive effects of limiting warming on changes in climate extremes are thus clear, and limiting warming should be encouraged regardless of the political and socio‐economic goals of a country.

Projected signals in climate extremes over China associated with a 2 °C global warming under two RCP scenarios

ABSTRACTUsing daily output from 29 climate models provided by the Coupled Model Intercomparison Project Phase 5, we project signals in 12 extreme temperature indices and 12 extreme precipitation indices relative to 1986–2005 over China associated with a 2 °C global warming above pre‐industrial levels under representative concentration pathways 4.5 (RCP4.5) and 8.5 (RCP8.5). The model output reflects the following projected changes: (1) It is robust and statistically significant that warm extremes are more frequent, more persistent, and more intense than those during the baseline period of 1986–2005, and local signals emerge from natural internal variability over most of China. In particular, southern China faces severe heat stress in summer based on warm extreme indices. (2) It is robust and statistically significant that there are fewer cold extremes in China. Most models show no significant changes in the longest duration and intensity of most cold extremes in southern China and northwest China. (3) The multi‐model median shows that more frequent and more intense wet extremes that deliver greater amounts of extreme precipitation occur in China, with a regional mean increase of 16.7–42.8 mm (8–42%) in total amount of annual wet extremes, but these changes are not significant and do not exceed natural internal variability over most of the country. Spatially, the Tibetan Plateau and northeast China have robust and significant changes in part of precipitation extremes, and some changes begin to emerge from natural internal variability at local scale. There are benefits to limiting global warming for China, including less frequent and less persistent warm extremes when comparing 1.5 °C with 2 °C of global warming and a later occurrence of significant changes in climate extremes when compared an intermediate mitigation scenario RCP4.5 with a high emission scenario RCP8.5.

Dynamical Downscaling of Temperature and Precipitation Extremes in China under Current and Future Climates

ABSTRACTClimate changes over China from the present (1996–2005) to the future (2046–2055) under Representative Concentration Pathways 4.5 (RCP4.5) and Representative Concentration Pathways 8.5 (RCP8.5) scenarios are projected using the Weather Research and Forecasting (WRF) model, version 3.7.1. The WRF model was driven by the Global 6-Hourly Bias-corrected Coupled Model Intercomparison Project, Phase 5 (CMIP5), Community Earth System Model dataset over China with a resolution of 30 km. The results demonstrate that WRF downscaling generally simulates more reliable spatial distributions of surface air temperature and precipitation in China with higher spatial pattern correlations and closer in magnitude to the Community Climate System Model, version 4.0, simulation results, especially near mountain ranges. The WRF projections for temperature and precipitation for the future under the two emission scenarios are compared with the present simulation. Generally stronger warming, both in mean temperature and extreme statistics, is produced by WRF-RCP8.5 than by WRF-RCP4.5. The projections for precipitation changes are more varied with season and region for both scenarios.

Trends in the consecutive days of temperature and precipitation extremes in China during 1961–2015

Background and aimsConsecutive climatic extremes have more intense impacts on natural ecosystems and human activities than occasional events. There were many studies about the frequency or intensity of extreme weather events, but few focused on the consecutiveness or continuousness of climatic extremes. We analyzed the temporal and spatial distributions and tendencies in the consecutive temperature and precipitation extremes in China during 1961–2015. MethodsDaily temperature and precipitation data at 1867 meteorological stations over China was used and four consecutive indices of climate extremes, i.e. cold spell duration indicator (CSDI), warm spell duration indicator (WSDI), consecutive dry days (CDD) and consecutive wet days (CWD), were calculated by RClimDex 1.0. Linear trends in the time series of consecutive days of temperature and precipitation extremes were examined and their statistical significance was evaluated using Mann–Kendall test. Results and discussionThere were obvious differences in the spatial distributions of consecutive days of climate extremes in China. During 1961–2015, CSDI and CWD decreased significantly at rates of 0.9 and 0.1 days per decade respectively, while WSDI increased significantly at rate of 0.8 days per decade in China. Spatially, CSDI decreased at rates of 0–3.0 days per decade in almost all parts of China, and WSDI increased at rates of 0–2.0 days per decade in most parts of China. The spatial trends of CDD and CWD were significant only in several regions of China. CSDI and WSDI had higher percent changes than those of CDD and CWD. Changes in the CSDI and WSDI were associated with large-scale oceanic and atmospheric circulation oscillations, such as Atlantic Multidecadal Oscillation (AMO), El Niño/Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). With global warming, there will be fewer cold extremes, more frequent hot extremes and precipitation extremes. ConclusionsGiven the increases in the frequency and intensity of some consecutive climatic extremes and an increasing physical exposure and socio-economic vulnerability to such extremes in China, more strategies and capacities of mitigation and adaptation to consecutive climatic extremes are essential for the local government and climate-sensitive sectors.

Implications of differential effects between 1.5 and 2 °C global warming on temperature and precipitation extremes in China's urban agglomerations

ABSTRACTIn the context of global warming, urban areas are more vulnerable to extreme weather conditions. In this study, four key temperature and precipitation extreme indices, defined by the Expert Team on Climate Change Detection and Indices, are selected to investigate implications of differential effects of 1.5 and 2 °C global warming on extreme weather in China's urban agglomerations (CNUAs). Results indicate that bias‐corrected extreme indices derived from downscaled data sets of National Aeronautics and Space Administration (NASA) Earth Exchange Global Daily Downscaled Projections (NEX‐GDDP) of 19 Coupled Model Intercomparison Project Phase 5 (CMIP5) models under RCP4.5 scenario [representative concentration pathways (RCP)] can be used to study the effects of global warming on extreme indices in locations of CNUAs. An increase in the global warming from 1.5 to 2 °C is likely to exacerbate the intensity of extreme maximum temperature (TXx) and decrease extreme minimum temperature (TNn) in CNUAs. Moreover, additional 0.5 °C warming is more likely than not to increase the intensity of total precipitation of very wet days (R95) and maximum 5‐day precipitation (Rx5day). For the very extreme events (>1.5σ), a global warming increase from 1.5 to 2 °C will lead to extra increase in extreme risk for very extreme TXx, R95p and Rx5day by 4.1, 1.8 and 1.0 times, relative to 1986–2005. Thus, it seems that reducing the 2 °C global warming level by 0.5 °C during the remainder of the 21st century would significantly suppress very extreme heat waves and very extreme wet events in CNUAs. Certainly, the urban heat island and aerosol effects are expected to further enhance such extreme events in the urban areas. The combined influence of global warming and urbanization effects on extreme events needs further study in the future.

Nonstationary extreme value analysis of temperature extremes in China

In a changing climate, the common assumption of stationarity of climate extremes has been increasingly challenged, raising the need to incorporate non-stationarity in extreme value modeling. In this study, quantile regression is used to identify the trends of annual temperature extremes and their correlations with two large climate patterns, the western Pacific subtropical high (WPSH) and the Arctic Oscillation (AO) at 357 stations in China. Statistical significant positive trends and correlations between warm (or cold) temperature extremes and WPSH (or AO) have been detected at most stations. The influence of WPSH on warm extremes is significant in southern China, while the AO mainly affects the cold extremes in northern and eastern China. Then, annual temperature extremes are fitted to generalized extreme value (GEV) distributions with time-varying parameters. The summer (or winter) mean daily maximum (or minimum) temperatures and two climate indices, the WPSH index and the AO index, are chosen as covariates. In total, 16 candidate GEV distribution models are constructed, and the best fitting model with the lowest Bayesian information criterion (BIC) is selected. The 20-year return levels of annual warm (or cold) extremes in the period 1961–1980 and 1991–2010 are computed and compared. The changes of 20-year return levels of annual warm and cold extremes are jointly determined by trend and distributional changes of annual temperature extremes. Analysis of large scale atmospheric circulation changes indicate that a strengthening anticyclonic circulation and increasing geopotential height in recent decades may have contributed to the changes in temperature extremes in China.

Ensemble evaluation and projection of climate extremes in China using RMIP models

ABSTRACTUnder the framework of the Regional Climate Model Intercomparison Project (RMIP III), simulation results from six regional climate models (RCMs) and two global climate models (GCMs) were used to generate climate extreme indices for the present and future over China using two ensemble methods. All the models reasonably captured the observed climate extremes, and performance‐based ensemble averaging (PEA) outperformed the individual model and equal‐weighted averaging (MME) for the control climate. However, noticeable cold deficiencies in temperature extremes were found over areas with complex topography, and too frequent heavy precipitation at smaller intensities was simulated using the multiple model ensembles. Under the A1B scenario for 2041–2060, widespread increases in the 90th percentiles of the maximum temperatures (Tmax90p) and the 10th percentile of the minimum temperatures (Tmin10p) were projected, with larger increases in winter than in summer. Greater intensities in precipitation extremes were projected over China, with the exception of Inner Mongolia. Large uncertainties exist in the projected mean diurnal temperature range (Trange), number of days with precipitation exceeding 10 mm (R10) and the maximum number of consecutive dry days (CDD) because of disagreements in both the magnitudes and signs of the climate model projections, and even the two ensemble methods presented opposite signs over some regions.

Changes of extreme precipitation and nonlinear influence of climate variables over monsoon region in China

The El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO) and Pacific decadal oscillation (PDO) are well understood to be major drivers for the variability of precipitation extremes over monsoon regions in China (MRC). However, research on monsoon extremes in China and their associations with climate variables is limited. In this study, we examine the space-time variations of extreme precipitation across the MRC, and assess the time-varying influences of the climate drivers using Bayesian dynamic linear regression and their combined nonlinear effects through fitting generalized additive models. Results suggest that the central-east and south China is dominated by less frequent but more intense precipitation. Extreme rainfalls show significant positive trends, coupled with a significant decline of dry spells, indicating an increasing chance of occurrence of flood-induced disasters in the MRC during 1960–2014. Majority of the regional indices display some abrupt shifts during the 1990s. The influences of climate variables on monsoon extremes exhibit distinct interannual or interdecadal variations. IOD, ENSO and AMO have strong impacts on monsoon and extreme precipitation, especially during the 1990s, which is generally consistent with the abrupt shifts in precipitation regimes around this period. Moreover, ENSO mainly affects moderate rainfalls and dry spells, while IOD has a more significant impact on precipitation extremes. These findings could be helpful for improving the forecasting of monsoon extremes in China and the evaluations of climate models.

Mangrove species' responses to winter air temperature extremes in China

AbstractThe global distribution and diversity of mangrove forests is greatly influenced by the frequency and intensity of winter air temperature extremes. However, our understanding of how different mangrove species respond to winter temperature extremes has been lacking because extreme freezing and chilling events are, by definition, relatively uncommon and also difficult to replicate experimentally. In this study, we investigated species‐specific variation in mangrove responses to winter temperature extremes in China. In 10 sites that span a latitudinal gradient, we quantified species‐specific damage and recovery following a chilling event, for mangrove species within and outside of their natural range (i.e., native and non‐native species, respectively). To characterize plant stress, we measured tree defoliation and chlorophyll fluorescence approximately one month following the chilling event. To quantify recovery, we measured chlorophyll fluorescence approximately nine months after the chilling event. Our results show high variation in the geographic‐ and species‐specific responses of mangroves to winter temperature extremes. While many species were sensitive to the chilling temperatures (e.g., Bruguiera sexangula and species in the Sonneratia and Rhizophora genera), the temperatures during this event were not cold enough to affect certain species (e.g., Kandelia obovata, Aegiceras corniculatum, Avicennia marina, and Bruguiera gymnorrhiza). As expected, non‐native species were less tolerant of winter temperature extremes than native species. Interestingly, tidal inundation modulated the effects of chilling. In comparison with other temperature‐controlled mangrove range limits across the world, the mangrove range limit in China is unique due to the combination of the following three factors: (1) Mangrove species diversity is comparatively high; (2) winter air temperature extremes, rather than means, are particularly intense and play an important ecological role; and (3) due to afforestation and restoration efforts, several species of non‐native mangroves have been introduced beyond their natural range limits. Hence, from a global perspective, mangroves in China provide valuable opportunities to advance understanding of the effects of freezing and chilling temperatures on mangroves. Within the context of climate change, our findings provide a foundation for better understanding and preparing for mangrove species‐specific responses to future changes in the duration and intensity of winter temperature extremes.

Revisiting summertime hot extremes in China during 1961–2015: Overlooked compound extremes and significant changes

AbstractSummertime hot extremes in China are categorized into three distinct types, i.e., independent hot days, independent hot nights, and compound events, based on differing configurations between daily maximum and minimum temperature. Linear trends for multiple indictors of these subtypes and traditionally defined hot days/nights exhibited remarkable differences in significance, magnitude, and even sign, especially for events involving daytime extremes. Thus, some significant changes masked in conventional analyses are successfully uncovered. Particularly, the dominance of independent hot days has decayed significantly, accompanied by a rapid boom of compound events and/or independent hot nights in different regions. These nighttime‐accentuated hot extremes have exhibited significant increases in duration, intensity, and spatial extent, with much stronger trends detected in severest events.

A regional frequency analysis of precipitation extremes in Mainland China with fuzzy c‐means and L‐moments approaches

ABSTRACTOwing to their essential influence on human society and natural environment exerted by inducing disasters, such as floods and droughts, further studies on precipitation extremes in China are needed. This study presents the regional frequency and spatial‐temporal patterns of precipitation extremes in China based on a high‐resolution (0.5° × 0.5°) daily precipitation dataset from 1961 to 2013. With fuzzy c‐means, L‐moments methods and other scientific statistical tests, a regional frequency analysis (RFA) is conducted, aiming to further understand the regional and spatial distribution of precipitation extremes across China. The results show that: (1) the whole Mainland China can be divided into 50 homogeneous regions on the basis of the characteristics of mean annual precipitation and location indices. (2) For most of the regions, Generalized Extreme Value (GEV), Generalized Normal (GNO) and Pearson type III (PE3) distributions of precipitation extremes fit well, according to the results of goodness‐of‐fit (GOF) test. (3) For RX1DAY, GEV has the best‐fit distribution in the east, northeast and southwest of China, whereas GNO distribution mostly fits the northern and parts of southwest and southeast; in addition, regions which fit PE3 and Generalized Logistic (GLO) distribute dispersedly across the country. (4) For RX5DAY, GEV mainly fits in the middle, southwestern and southern; GNO and PE3 apply best to the northeastern and northern, respectively. (5) Return periods of 20, 50 and 100 years for their best‐fit distributions decrease gradually from southeastern China to northwestern China. Compared with the results of GEV distribution fitted to each grid, RFA may provide more accurate estimates of rainfall quantiles. Definitely, the study results will not only benefit further understanding of the unique and complex features of extreme precipitation in the whole Mainland China but also contribute to the nation‐scale flood prevention, control and management in the backdrop of the changing climate.

Simultaneous modulations of precipitation and temperature extremes in Southern parts of China by the boreal summer intraseasonal oscillation

The boreal summer intraseasonal oscillation (BSISO), including a 30–60 day component (BSISO1) and a quasi-biweekly component (BSISO2), is the most prominent form of subtropical intraseasonal variability. Influences of BSISOs on summertime precipitation and temperature extremes in China are examined. Results indicate that BSISOs can simultaneously facilitate precipitation extremes in central-eastern China and extreme high temperatures in South China-Southeast China. During phase 2–4 of active BSISO1, accompanying precipitation extremes in central-eastern China, there is a fourfold-fivefold increase in probability of extreme high temperatures in Southeast China. About 50% of such simultaneous extremes fall into phase 2–3. BSISO2’s influences are pronounced from phase 6 to the next phase 2, with about 58% simultaneous extremes clustered within phase 7 to the next phase 1. It is the BSISO-induced vertical cell, with ascending motion in the Yangtze-Huai River Valley and descending motion in the south, that contributes to simultaneous extremes. Enhanced low-level southwesterlies convey moist and warm air towards southern parts of China. Strengthened ascending branch loaded by anomalously abundant moisture produces precipitation extremes in the north. Concurrently, combined effects of warm advection and descent-triggered adiabatic heating anchors extreme high temperatures well located in South China. The northeastward propagation of the BSISO1 confines influenced regions to eastern-southeastern parts of China, with gradually narrowing spatial extents. The BSISO2-induced simultaneous extremes sweep much broader areas, from southeast coasts to the central inlands. Above analyses on BSISOs-simultaneous extremes relationship lay a crucial scientific basis for predicting these high-impact events on sub-seasonal to seasonal scales.

Projected Changes in Temperature Extremes in China Using PRECIS

Temperature extremes can cause disastrous impacts on ecological and social economic systems. China is very sensitive to climate change, as its warming rate exceeds that of the global mean level. This paper focused on the spatial and temporal changes of the temperature extremes characterized by the 95th percentile of maximum temperature (TX95), the 5th percentile of the minimum temperature (TN5), high-temperature days (HTD) and low-temperature days (LTD). The daily maximum and minimum temperatures generated by PRECIS under different Representative Concentration Pathways (RCPs) are used in the research. The results show that: (1) Model simulation data can reproduce the spatial distribution features of the maximum temperature (Tmax) and minimum temperature (Tmin) as well as that of the extreme temperature indices; (2) By the end of the 21st century (2070–2099), both the Tmax and Tmin are warmer than the baseline level (1961–1990) in China and the eight sub-regions. However, there are regional differences in the asymmetrical warming features, as the Tmin warms more than the Tmax in the northern part of China and the Tibetan Plateau, while the Tmax warms more than the Tmin in the southern part of China; (3) The frequency of the warm extremes would become more usual, as the HTD characterized by the present-day threshold would increase by 106%, 196% and 346%, under RCP2.6, RCP4.5 and RCP8.5, respectively, while the cold extremes characterized by the LTD would become less frequent by the end of the 21st century, decreasing by 75%, 90% and 98% under RCP2.6, RCP4.5 and RCP8.5, respectively. The southern and eastern parts of the Tibetan Plateau respond sensitively to changes in both the hot and cold extremes, suggesting its higher likelihood to suffer from climate warming; (4) The intensity of the warm (cold) extremes would increase (decrease) significantly, characterized by the changes in the TX95 (TN5) by the end of the 21st century, and the magnitude of the increase in the TN5 is larger than that of the TX95 in the national mean value. The changes in both the TX95 and TN5 are larger under the higher versus weaker emission scenario, indicating that it is essential to reduce the GHG emissions and take adaptation measures in the future.

Spatiotemporal variability of extreme temperature frequency and amplitude in China

Temperature extremes in China are examined based on daily maximum and minimum temperatures from station observations and multiple global climate models. The magnitude and frequency of extremes are expressed in terms of return values and periods, respectively, estimated by the fitted Generalized Extreme Value (GEV) distribution of annual extreme temperatures. The observations suggest that changes in temperature extremes considerably exceed changes in the respective climatological means during the past five decades, with greater amplitude of increases in cold extremes than in warm extremes. The frequency of warm (cold) extremes increases (decreases) over most areas, with an increasingly faster rate as the extremity level rises. Changes in warm extremes are more dependent on the varying shape of GEV distribution than the location shift, whereas changes in cold extremes are more closely associated with the location shift. The models simulate the overall pattern of temperature extremes during 1961–1981 reasonably well in China, but they show a smaller asymmetry between changes in warm and cold extremes primarily due to their underestimation of increases in cold extremes especially over southern China. Projections from a high emission scenario show the multi-model median change in warm and cold extremes by 2040 relative to 1971 will be 2.6°C and 2.8°C, respectively, with the strongest changes in cold extremes shifting southward. By 2040, warm extremes at the 1971 20-year return values would occur about every three years, while the 1971 cold extremes would occur once in >500years.

Spatial and temporal changes in daily temperature extremes in China during 1960–2011

Based on daily maximum and minimum temperature data from 437 weather stations over China, this study examined the spatiotemporal change of temperature extremes in China from 1960 to 2011. Results showed a general downward trends in the occurrence of cold days (TX10) and nights (TN10) (base period 1961–1990), but upward tendency on the occurrence of warm days (TX90) and nights (TN90), the temperatures of coldest day (TXn), coldest night (TNn), warmest day (TXx), and warmest night (TNx) in China and most climate regions. At the national scale, TX10 and TN10 have significantly decreased by −1.89 and −4.39 days/decade, and TX90 and TN90 have significantly increased by 2.49 and 4.72 days/decade from 1960 to 2011. The national average trends for TXn, TNn, TXx, and TNx were 0.28, 0.54, 0.17, and 0.27 °C/decade, respectively. The temporal changes of extremes indices showed that changes in cold (warm) relative indices may be primarily related to that of corresponding winter (summer) Tmax and Tmin, respectively. Regionally, the magnitudes of changes in extreme indices decreased from the north to south of China. However, we found significant increase of warm extremes, especially warm days and nights in Southeast China. For most climate regions, the trend magnitudes in warm days/nights were larger than that in cold days/nights, but the trend in coldest temperature was much higher than that in warmest temperature. The trend magnitudes in minimum temperature indices were larger than those based on daily maximum temperature, explaining the faster increase of Tmin than Tmax in China.

Projection of precipitation extremes for eight global warming targets by 17 CMIP5 models

Based on the historical and future outputs of 17 coupled model intercomparison project phase 5 (CMIP5) models, simulation of the precipitation extremes in China was evaluated under baseline climate condition compared to a gridded daily observation dataset CN05.1. The variations in precipitation extremes for eight global warming targets were also projected. The 17 individual models and the multi-model ensemble accurately reproduced the spatial distribution of precipitation extremes, although they were limited in their ability to capture the temporal characteristics. A notable dry bias existed in Southeast China, while a wet bias was present in North and Northwest China. The precipitation extremes in China were projected to be more frequent and more intense as global temperature rise reached the 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 °C warming targets. The projected percentage changes in the annual number of days with precipitation >50 mm (R50) and total precipitation during days in which the daily precipitation exceeds the 99th percentile (R99p) are projected to increase by 25.81 and 69.14 % relative to the baseline climate for a 1.5 °C warming target, and by 95.52 and 162.00 % for a 4.0 °C warming target, respectively. As the global mean temperature rise increased from 1.5 to 5 °C, the subregions considerably affected by the East Asian summer monsoon (e.g., Southwest China, South China, and the Yangtze-Huai River Valley) were projected to experience a more dramatic increase in extreme precipitation events, in both number of days and intensity, while North and Northwest China were projected to suffer from relatively slight increases. The model uncertainties in the projected precipitation extremes in China by 17 CMIP5 models increase as global temperature rise increases.

Can reanalysis datasets describe the persistent temperature and precipitation extremes over China?

The persistent temperature and precipitation extremes may bring damage to the economy and human due to their intensity, duration and areal coverage. Understanding the quality of reanalysis datasets in descripting these extreme events is important for detection, attribution and model evaluation. In this study, the performances of two reanalysis datasets [the twentieth century reanalysis (20CR) and Interim ECMWF reanalysis (ERA-Interim)] in reproducing the persistent temperature and precipitation extremes in China are evaluated. For the persistent temperature extremes, the two datasets can better capture the intensity indices than the frequency indices. The increasing/decreasing trend of persistent warm/cold extremes has been reasonably detected by the two datasets, particularly in the northern part of China. The ERA-Interim better reproduces the climatology and tendency of persistent warm extremes, while the 20CR has better skill to depict the persistent cold extremes. For the persistent precipitation extremes, the two datasets have the ability to reproduce the maximum consecutive 5-day precipitation. The two datasets largely underestimate the maximum consecutive dry days over the northern part of China, while overestimate the maximum consecutive wet days over the southern part of China. For the response of the precipitation extremes against the temperature variations, the ERA-Interim has good ability to depict the relationship among persistent precipitation extremes, local persistent temperature extremes, and global temperature variations over specific regions.