ALBERT

Description: The continued climate warming has increased the drought risk for ecosystems in many areas of the globe. However, in cold regions, climate warming brings a more complicated impact on drought and ecosystems. A warmer climate and shorter snow duration may extend vegetation phenology and increase productivity, while increased evaporative demand may aggravate the vulnerability of the ecosystem to drought. In this study, we select the Qilian Mountains (QLMs) in northwestern China as a case study area, which has experienced intense climate change. We utilized a long-term and downscaled normalized difference vegetation index (NDVI) product to investigate how climate change, drought, and snow variability jointly affect the fine-scale greenness dynamics of different vegetation types. Results suggest that most areas in the QLMs experienced a greening trend while the western part displayed a browning. The grass and shrub demonstrated a decreased sensitivity to drought over the medium altitudes but increased drought sensitivity at the lower and upper altitudes. The broadleaf forests showed intensifying drought sensitivity at all elevations. Coniferous forests and alpine meadows respectively displayed decreasing and increasing trends of sensitivity to drought along elevations. The increased vulnerability of vegetation to drought over the lowest and highest elevations is likely attributed to a combination of the fastest warming and mildest wetting trends. Snow cover shows a significant effect in maintaining vegetation growth through increasing soil moisture in dry periods. These findings provide insights into how these cold-region vegetation communities may respond to drought under a warmer and snow-less climate in the future.

Description: Over recent decades, the rate of global mean sea-level (GMSL) rise has increased, though the magnitude of current and projected GMSL change by the end of this century – tens of centimeters – remains small from a geological perspective. Such modest GMSL rise presents challenges when attempting to assess its global climate impacts, as the signal is weak. However, in previous warmer geological periods, GMSL was several or tens of meters higher than the present. These paleoclimate periods offer a unique opportunity to investigate the climate effects of high GMSL. Here, using climate simulations of the Last Interglacial period and a set of present-day sea-level sensitivity experiments, we highlight the importance of GMSL rise in modulating global climate. Lifting a sea-level datum – lowering terrestrial elevation and deepening oceanic bathymetry – reorganizes atmospheric and oceanic circulations. Our simulations of the Last Interglacial show that considering this aspect of GMSL rise, in isolation from changes associated with land-sea masks or freshwater input, reduces the long-lasting model-data mismatch in the Southern Hemisphere. Furthermore, the present-day sensitivity experiments demonstrate that a slight GMSL uplift causes significant adjustments in the global climate, particularly at mid-high latitudes.

Description: Global mean sea level (GMSL) rose at an accelerated rate in recent decades. As one of the areas most vulnerable to GMSL rise, Maritime Continent (MC) has numerous sea ways and low-lying island nations, need more attention. Here, our modeling study demonstrates that sea-level datum uplift (even tens of centimeters) rise can alter the oceanic circulation and cause the Sea Surface Temperature (SST) near Guinea and Java warming significantly, which enhances convection and increases summer precipitation over southern MC. Meanwhile, the upward flow driven by warm SST anomaly move northward in the upper troposphere, and then converge and subside over the northern MC. The downdraft suppresses local precipitation, as well as excites the Pacific–Japan (PJ) pattern on decadal time scales, which decreases/increases summer precipitation over Southeast China/North China.