The long-term relationship between temperature and hydroclimate has remained uncertain due to the short length of instrumental measurements and inconsistent results from climate model simulations. This lack of understanding is particularly critical with regard to projected drought and flood risks. Here we assess warm-season co-variability patterns between temperature and hydroclimate over Europe back to 850 CE using instrumental measurements, tree-ring based reconstructions, and climate model simulations. We find that the temperature–hydroclimate relationship in both the instrumental and reconstructed data turns more positive at lower frequencies, but less so in model simulations, with a dipole emerging between positive (warm and wet) and negative (warm and dry) associations in northern and southern Europe, respectively. Compared to instrumental data, models reveal a more negative co-variability across all timescales, while reconstructions exhibit a more positive co-variability. Despite the observed differences in the temperature–hydroclimate co-variability patterns in instrumental, reconstructed and model simulated data, we find that all data types share relatively similar phase-relationships between temperature and hydroclimate, indicating the common influence of external forcing. The co-variability between temperature and soil moisture in the model simulations is overestimated, implying a possible overestimation of temperature-driven future drought risks.

The drivers of multidecadal‐ to centennial‐scale variability in East Asian temperature, apparent in temperature reconstructions, are poorly understood. Here we apply a multivariate regression analysis to distinguish the influences of large‐scale modes of internal variability (Atlantic Multidecadal Oscillation and Pacific Multidecadal Oscillation) and external natural (orbital, solar, and volcanic) and anthropogenic (greenhouse gas concentrations, aerosols, and land use changes) forcings on East Asian warm‐season temperature over the period 850–1999 CE (Common Era). We find that ~80% of the temperature change on time scales longer than 30 years can be explained including all drivers over the full‐length period. The Pacific Multidecadal Oscillation was the most important driver of multidecadal temperature variability during the Medieval Climate Anomaly (here 950–1250), while solar contribution was important during the Little Ice Age (here 1350–1850). Since 1850, two thirds of temperature change can be explained with anthropogenic forcing, whereas one third was related mainly to the Atlantic Multidecadal Oscillation and volcanic forcing.

Accurate projections of moisture variability across the Tibetan Plateau (TP) are crucial for managing regional water resources, ecosystems, and agriculture in densely populated downstream regions. Our understanding of how moisture conditions respond to increasing temperatures over the TP is still limited, due to the short length of instrumental data and the limited spatial coverage of high-resolution paleoclimate proxy records in this region. This study presents a new, early-summer (May–June) self-calibrating Palmer drought severity index (scPDSI) reconstruction for the southeastern TP (SETP) covering 1135–2010 CE using 14 tree-ring records based on 1669 individual width sample series. The new reconstruction reveals that the SETP experienced the longest period of pluvial conditions in 1154–75 CE, and the longest droughts during the periods 1262–80 and 1958–76 CE. The scPDSI reconstruction shows stable and significant in-phase relationships with temperature at both high and low frequencies throughout the past 900 years. This supports the hypothesis that climatic warming may increase moisture by enhancing moisture recycling and convective precipitation over the SETP; it is also consistent with climate model projections of wetter conditions by the late twenty-first century in response to global warming.