A dangerous trend: How anthropogenically driven climate change is affecting heat waves and drought is one of the most important environmental issues facing societies around the globe. Zhang et al. present a 260-year-long record of temperature and soil moisture over inner East Asia that reveals an abrupt shift to hotter and drier conditions (see the Perspective by Zhang and Fang). Extreme episodes of hotter and drier climate over the past 20 years, which are unprecedented in the earlier records, are caused by a positive feedback loop between soil moisture deficits and surface warming and potentially represent the start of an irreversible trend. Science , this issue p. 1095 ; see also p. 1037

The 2013–2014 California drought was initiated by an anomalous high-amplitude ridge system. The anomalous ridge was investigated using reanalysis data and the Community Earth System Model (CESM). It was found that the ridge emerged from continual sources of Rossby wave energy in the western North Pacific starting in late summer and subsequently intensified into winter. The ridge generated a surge of wave energy downwind and deepened further the trough over the northeast U.S., forming a dipole. The dipole and associated circulation pattern is not linked directly with either El Niño–Southern Oscillation (ENSO) or Pacific Decadal Oscillation; instead, it is correlated with a type of ENSO precursor. The connection between the dipole and ENSO precursor has become stronger since the 1970s, and this is attributed to increased greenhouse gas loading as simulated by the CESM. Therefore, there is a traceable anthropogenic warming footprint in the enormous intensity of the anomalous ridge during winter 2013–2014 and the associated drought.

Western Nepal has experienced consecutive and worsening winter drought conditions since 2000, culminating in a severe drought episode during 2008/09. In this study, the meteorological conditions and a historical perspective of the winter droughts in western Nepal were analyzed using instrumental records, satellite observations, and climate model simulations. Meteorological diagnosis using atmospheric reanalysis revealed that 1) winter drought in western Nepal is linked to the Arctic Oscillation and its decadal variability, which initiates a tropospheric short-wave train across Eurasia and South Asia; and that 2) the persistent warming of the Indian Ocean likely contributes to the suppression of rainfall through enhanced local Hadley circulation. Simulations from the phase 5 of the Coupled Model Intercomparison Project (CMIP5) sets of historical single-forcing experiments indicated that the increased loading of anthropogenic aerosols is also a compounding factor in the precipitation decline during the later decades. It is therefore conceivable that the recent spells of decadal drought in Nepal are symptomatic of both natural variability and anthropogenic influences. Given the observations that winter precipitation has declined to near zero while groundwater has hardly been replenished, appropriate management of western Nepal's water resources is both critical and necessary.

Southern Japan suffered from a succession of extreme events in summer 2018. Climatological 10‐day precipitation in southern Japan depict the three‐phase lifecycle of the East Asian summer monsoon (EASM) and the corresponding timing of the 2018 consecutive extreme events (indicated in the bottom). The sequential yet contrasting extreme events in Japan therefore reflect an amplified EASM projected in a warmer climate.