Characterizing present and future drought changes over eastern China

Abstract

This study aimed to characterize present and future drought changes over eastern China using observations and Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations. We used the standardized precipitation evapotranspiration index (SPEI) to characterize droughts at the timescales of 3‐ and 12‐month. We distinguished the spatial patterns of drought regimes (DRs) using the rotated empirical orthogonal function (EOF) on the SPEI. Our results identified three DRs centered in northern China (DR1), northeastern China (DR2), and southern China (DR3). Droughts in these regimes have increased in recent decades. Most CMIP5 models reproduce at least two of the DRs. The rotated EOF results indicate that the three DRs can jointly explain 46–68% of the SPEI variance (compared with approximately 60% in the observations). Among the 33 CMIP5 models analysed in this study, 13 simulated all three DRs well and showed a strong correlation pattern (>0.5). Further analysis indicated that both the external natural and greenhouse gas forcing experiments in CMIP5 reproduced the DRs, implying that natural variability and anthropogenic activity play important roles in the formation of these DRs. With continued climate warming, the three DRs over eastern China will persist. Despite the uncertainties in drought changes that mainly depend on the potential evapotranspiration methods, climate model results suggest that droughts would be aggravated under warming scenarios. The probability of severe droughts increase by the end of the century: 33% in DR1, 25% in DR2, 34% in DR3 in RCP4.5 and almost double in RCP8.5 scenario in Thornthwaite method based SPEI estimates.

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

“…In recent years, China has experienced an increase in extreme climate events, some of which present widespread impacts, including deaths, severe ecosystem damage, and large economic losses. These increased extreme events in China have had detectable anthropogenic influences with a high confidence level for temperature‐related extremes but a low confidence level for precipitation‐related extremes (Sun et al, ; Chen and Sun, , , ; Li et al, ; Ma et al, ). Here, we present an analysis of a set of extreme climate events in China, including the wide‐ranging cold event across China in January 2011, extreme hot event over eastern China from July to August 2013, large‐scale heavy rainfall over northern China in July 2012, and severe drought over NC from July to August 2014.…”

“…In China, most weather and climate events have become extreme (Wang et al, 2012;Sun, 2014;Sun et al, 2014;Zhou et al, 2016;Chen and Zhai, 2017) and will be worse in the future (Gao et al, 2011;Chen, 2013;Zhou et al, 2014;Xu et al, 2015;Chen and Sun, 2017a;2017b;2017c) in the context of global warming. Additionally, studies concerning climate responses to the 2 C warming target have been conducted.…”

Drought characterization over India under projected climate scenario

“…SPEI estimation requires monthly water deficit (MWD), that is, the difference of monthly precipitation (P) and monthly potential evapotranspiration (PET). Hargreaves (Rhee et al, 2016;Dibike et al, 2017;Oguntunde et al, 2017;Spinoni et al, 2018), Thornthwaite (Törnros and Menzel, 2014;Smirnov et al, 2016;Wu et al, 2016;Bonsal et al, 2017;Chen and Sun, 2017;Feng et al, 2017;Khan et al, 2017), and Penman-Monteith (Wang et al, 2014;Feng et al, 2017;Gao et al, 2017;Huang et al, 2018;Zhang et al, 2018) are the three most commonly used PET estimation methods employed in SPEI based drought studies under projected scenarios. Penman-Monteith method is the best reported method and data intensive, Hargreaves method utilizes daily maximum and minimum temperature whereas Thonthwaite requires monthly mean temperature.…”

“…According to IPCC (2012) at a medium level of confidence, drought is likely to increase in future where some region may experience more intense drought. Several regional studies performed on various parts of the world (Wang et al, 2011;Yu et al, 2014;Nam et al, 2015;Chen and Sun, 2017;Thilakarathne and Sridhar, 2017;Lee et al, 2018;Spinoni et al, 2018) invariably reported the increase in the drought events in changing climatic conditions. During 1950-2006, Wang et al (2011 observed that soil moisture droughts became longer, more severe and more frequent for central and northeastern China.…”

“…An analysis of drought using Standardized Precipitation Evapotranspiration Index (SPEI) by Yu et al (2014) for period 1951-2010 over China revealed that above moderate droughts have become more serious. Furthermore, SPEI derived using Coupled Model Intercomparison Project Phase 5 (CMIP5) family of climate model infers aggravated drought conditions under projected scenarios (Chen and Sun, 2017) in China. Nam et al (2015) analysed the future drought characteristics over South Korea using SPEI, Standardized Precipitation Index (SPI), and Self-Calibrating Palmer Drought Severity Index (SC-PDSI); they reported an increasing drought severity and magnitude in the region.…”