Spatially extensive and persistent drought episodes have repeatedly influenced human history, including the 'Strange Parallels' drought event in monsoon Asia during the mid-18th century. Here we explore the dynamics of sustained monsoon failure using observed and tree-ring reconstructed drought patterns and a 1300-year pre-industrial community earth system model control run. Both modern observational and climate model drought patterns during years with extremely weakened South Asian monsoon resemble those reconstructed for the Strange Parallels drought. Model analysis reveals that this pattern arises during boreal spring over Southeast Asia, with decreased precipitation and moisture flux, while related summertime climate anomalies are confined to the Indian subcontinent. Years with simulated South Asian drying exhibit canonical El Niño conditions over the Pacific and associated shifts in the Walker circulation. In contrast, multi-year drought periods, resembling those sustained during the Strange Parallels drought, feature anomalous Pacific warming around the dateline, typical of El Niño Modoki events.

The North American Monsoon (NAM) dominates the annual cycle of rainfall over the southwest United States and western Mexico, feeding into economic and environmental resources, including agricultural practices, water management, and fire season variability. The peak monsoon season is observed between July through September, with the largest rainfall occurrence over the elevated terrain of the Sierra Madre Occidental (SMO) and accounts for 70%-80% of the mean annual rainfall (Pascale et al., 2019). Variations in NAM timing and magnitude can have significant impacts on the region's hydroclimate and water resources, especially under anthropogenic climate change. However, uncertainty remains regarding the NAM's response to climate change, including its seasonal cycle, among previous generations of global climate models (GCMs) due, in part, to model parameterizations and coarse resolutions that can influence their ability to simulate complex terrain and dynamical features and produce striking biases within climate simulations such as the double Intertropical Convergence Zone (ITCZ)

Acclimation to different light regimes is at the base of survival for photosynthetic organisms, regardless of their evolutionary origin. Previous research efforts largely focused on acclimation events occurring at the level of photosynthetic apparatus and often highlighted species-specific mechanisms. Here, we investigated the consequences of acclimation to different irradiances in Chlorella vulgaris, a green alga that is one of the most promising species for industrial application, focusing on both photosynthetic and mitochondrial activities. Moreover, proteomic analysis of cells acclimated to high light (HL) or low light (LL) allowed identification of the main targets of acclimation in terms of differentially expressed proteins. The results obtained demonstrate photosynthetic adaptation to HL vs. LL that were only partially consistent with previous findings in Chlamydomonas reinhardtii, a model organism for green algae, but in many cases similar to vascular plant acclimation events. Increased mitochondrial respiration measured in HL-acclimated cells mainly relied on alternative oxidative pathway dissipating the excessive reducing power produced due to enhanced carbon flow. Finally, proteins involved in cell metabolism, intracellular transport, gene expression, and signaling —including an heliorhodopsin homolog — were identified as strongly differentially expressed in HL vs. LL, suggesting their key roles in acclimation to different light regimes.

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