Explore the vast range of titles available.

Climate strongly shapes plant diversity over large spatial scales, with relatively warm and wet (benign, productive) regions supporting greater numbers of species. Unresolved aspects of this relationship include what causes it, whether it permeates to community diversity at smaller spatial scales, whether it is accompanied by patterns in functional and phylogenetic diversity as some hypotheses predict, and whether it is paralleled by climate-driven changes in diversity over time. Here, studies of Californian plants are reviewed and new analyses are conducted to synthesize climate–diversity relationships in space and time. Across spatial scales and organizational levels, plant diversity is maximized in more productive (wetter) climates, and these consistent spatial relationships are mirrored in losses of taxonomic, functional, and phylogenetic diversity over time during a recent climatic drying trend. These results support the tolerance and climatic niche conservatism hypotheses for climate–diversity relationships, and suggest there is some predictability to future changes in diversity in water-limited climates.

Aridity, which is increasing worldwide because of climate change, affects the structure and functioning of dryland ecosystems. Whether aridification leads to gradual (versus abrupt) and systemic (versus specific) ecosystem changes is largely unknown. We investigated how 20 structural and functional ecosystem attributes respond to aridity in global drylands. Aridification led to systemic and abrupt changes in multiple ecosystem attributes. These changes occurred sequentially in three phases characterized by abrupt decays in plant productivity, soil fertility, and plant cover and richness at aridity values of 0.54, 0.7, and 0.8, respectively. More than 20% of the terrestrial surface will cross one or several of these thresholds by 2100, which calls for immediate actions to minimize the negative impacts of aridification on essential ecosystem services for the more than 2 billion people living in drylands.

Midlatitude Asia (MLA), strongly influenced by westerlies-controlled climate, is a key source of global atmospheric dust, and plays a significant role in Earth’s climate system . However, it remains unclear how the westerlies, MLA aridity, and dust flux from this region evolved over time. Here, we report a unique high-resolution eolian dust record covering the past 3.6 Ma, retrieved from the thickest loess borehole sequence (671 m) recovered to date, at the southern margin of the Taklimakan desert in the MLA interior. The results show that eolian dust accumulation, which is closely related to aridity and the westerlies, indicates existence of a dry climate, desert area, and stable land surface, promoting continuous loess deposition since at least ∼3.6 Ma. This region experienced long-term stepwise drying at ∼2.7, 1.1, and 0.5 Ma, coeval with a dominant periodicity shift from 41-ka cyclicity to 100-ka cyclicity between 1.1 Ma and 0.5 Ma. These features match well with global ice volume variability both in the time and frequency domains (including the Mid-Pleistocene Transition), highlighting global cooling-forced aridity and westerlies climate changes on these timescales. Numerical modeling demonstrates that global cooling can dry MLA and intensify the westerlies, which facilitates dust emission and transport, providing an interpretive framework. Increased dust may have promoted positive feedbacks (e.g., decreasing atmospheric CO₂ concentrations and modulating radiation budgets), contributing to further cooling. Unraveling the long-term evolution of MLA aridity and westerlies climate is an indispensable component of the unfolding mystery of global climate change.

The upper sandy loess unit L9 on the Chinese Loess Plateau (CLP) corresponds to marine isotope stages 22–24, and it represents aeolian deposition under conditions of extreme aridification. However, the forcing mechanism remains controversial. Numerous paleomagnetic studies in the eastern CLP show that the coarsest part of L9 is remagnetized and has a normal geomagnetic polarity. However, our results show that in loess sections in the western CLP the coarsest part of L9 records a primary reverse polarity. This spatially inconsistent magnetization pattern originates mainly from the different magnetic carriers of the characteristic remanent magnetization (hematite in the western CLP and magnetite in the eastern CLP), which suggests a different dust provenance between the western and eastern CLP. We ascribe this spatial contrast in dust provenance to the episodic uplift of the northeastern Tibetan Plateau, which also led to the extreme aridification of the East Asian interior at ∼900 ka. Plain Language Summary Climatic extremes have destructive impacts on human society and the natural environment. In the wind‐blown dust deposits (loess) of the Chinese Loess Plateau (CLP), several loess layers are exceptionally coarse‐grained, representing deposition under conditions of extreme aridification. Among these loess beds, the upper sandy loess layer L9, corresponding to marine isotope stages 22–24, has attracted much research attention. An important reason for this is the widely reported remagnetization of the coarsest part of L9 in loess sections in the eastern CLP. However, our present work found that for the coarsest part of L9 in the loess sections in the western CLP, the reported remagnetization is disappeared. This spatially inconsistent magnetization pattern originates mainly from the different magnetic carriers of the characteristic remanent magnetization, hematite in the western Loess Plateau and magnetite in the eastern Loess Plateau. We propose that the enhanced glacial grinding and the denudation of mountains caused by the uplift of the northeastern Tibetan Plateau led to the production of enormous quantities of fluvial and fluvioglacial materials rich in hematite, which were supplied specifically to the western CLP. This uplift also resulted in the occurrence of extreme aridification in the East Asian interior at ∼900 ka. Key Points The coarsest part of L9 in the western Loess Plateau has a reverse geomagnetic polarity, unlike the normal polarity in the eastern part This spatially inconsistent magnetization results mainly from a spatial difference in magnetic carriers Uplift of the northeastern Tibetan Plateau at ∼900 ka caused the enrichment of detrital hematite specifically in the western Loess Plateau

In an increasingly globalized and warming world, drought can have devastating impacts on regional agriculture, water resources, and the ecological environment. Reliable prediction of future drought changes is especially important within the context of rapid warming. However, the extent and future trends of drought changes are variable and incomplete in the CMIP6 forcing scenarios. Based on the CMIP6 data, we chose the standardized precipitation-evapotranspiration index to predict future global drought. The results show that when emissions increase under the three shared socioeconomic pathway (SSP) scenarios (SSP126, SSP245 and SSP585), the global climate environment becomes drier and drought grow more severe and longer-lasting. Regions already classified as arid will suffer even more severe drought under high-emission SSPs. Specifically, 36.2% of global land will experience increased drought under SSP126, including 67.0% of regions designated as arid, with droughts intensifying significantly. Under SSP585, 68.3% of global land will suffer increased drought, with 93.2% of the arid regions experiencing significant drought intensification. Furthermore, the global duration of drought is estimated to be 4.4 months, 5.7 months, and 8.6 months for the time periods 1960–2000, 2021–2060, and 2061–2100, respectively. Notably, for the SSP585 scenario, regions that are already arid may become universally drought-stricken by the late 21st century. The most severe aridification trends may occur in the arid regions of Australia, Middle East, South Africa, Amazon basin, North Africa, Europe, and Central Asia. Additionally, Europe and the Amazon River Basin are also facing the threat of future drought. Increased aridification will put these regions and countries at risk of further land and ecological degradation, as well as increased poverty. The results of this study have far-ranging implications not only for how we deal with the impacts of climate warming-induced drought disaster, but also for how these impacts affect socio-economic and ecological security.

The Thal and Cholistan Deserts in Pakistan are ecologically significant yet face numerous environmental challenges, including desertification, vegetation decline, and water scarcity. This study aims to assess the spatial-temporal dynamics and environmental challenges of these deserts through a multi-disciplinary approach. A combination of remote sensing, field surveys, and socio-economic assessments was employed. Multispectral satellite imagery from 2015 to 2023 was analyzed to detect land-use and land-cover changes, while vegetation indices such as NDVI and EVI were used to monitor vegetation dynamics. Soil and water samples were analyzed for degradation patterns, and household surveys assessed socio-economic impacts. The study revealed a 43% increase in built-up areas and a corresponding decline of 8% in vegetation cover in the Cholistan Desert, with similar trends in Thal. Groundwater levels declined by 1.5 meters per decade, and soil erosion rates were highest in areas with sparse vegetation. Socio-economic surveys showed that 70% of Cholistan households and 65% of Thal households rely on livestock and agriculture, respectively, highlighting community vulnerability to environmental changes. The findings underscore the critical impact of anthropogenic activities, overgrazing, and climate variability on these ecosystems. Sustainable management strategies integrating scientific and traditional knowledge are essential to mitigate these challenges and ensure ecosystem resilience.

Trait-based approaches are increasingly used to predict ecological consequences of climate change, yet seldom have solid links been established between plant traits and observed climate-driven community changes. Most analyses have focused on aboveground adult plant traits, but in warming and drying climates, root traits may be critical, and seedlings may be the vulnerable stage. Relationships of seedling and root traits to more commonly measured traits and ecological outcomes are poorly known. In an annual grassland where winter drought-induced seedling mortality is driving a long-term decline in native diversity, using a field experiment during the exceptionally dry winter of 2017–2018, we found that seedling mortality was higher and growth of seedlings and adults were lower in unwatered than watered sites. Mortality of unwatered seedlings was higher in species with shorter seedling roots, and also in species with the correlated traits of small seeds, high seedling specific leaf area (SLA), and tall seedlings. Adult traits varied along an axis from short-stature, high SLA and foliar N, and early flowering to the opposite values, and were only weakly correlated with seedling traits and seedling mortality. No evidence was found for adaptive plasticity, such as longer roots or lower SLA in unwatered plants. Among these species, constitutive variation in seedling root length explained most of the variation in survival of a highly vulnerable life stage under winter drought. Selective loss of species with high adult SLA, observed in this community and others under drought stress, may be the byproduct of other correlated traits.

Global aridification is projected to intensify. Yet, our knowledge of its potential impacts on species ranges remains limited. Here, we investigate global aridity velocity and its overlap with three sectors (natural protected areas, agricultural areas, and urban areas) and terrestrial biodiversity in historical (1979 through 2016) and future periods (2050 through 2099), with and without considering vegetation physiological response to rising CO₂. Both agricultural and urban areas showed a mean drying velocity in history, although the concurrent global aridity velocity was on average +0.05/+0.20 km/yr−1 (no CO₂ effects/with CO₂ effects; “+” denoting wetting). Moreover, in drylands, the shifts of vegetation greenness isolines were found to be significantly coupled with the tracks of aridity velocity. In the future, the aridity velocity in natural protected areas is projected to change from wetting to drying across RCP (representative concentration pathway) 2.6, RCP6.0, and RCP8.5 scenarios. When accounting for spatial distribution of terrestrial taxa (including plants, mammals, birds, and amphibians), the global aridity velocity would be -0.15/-0.02 km/yr−1 (“-” denoting drying; historical), -0.12/-0.15 km/yr−1 (RCP2.6), -0.36/-0.10 km/yr−1 (RCP6.0), and -0.75/-0.29 km/yr−1 (RCP8.5), with amphibians particularly negatively impacted. Under all scenarios, aridity velocity shows much higher multidirectionality than temperature velocity, which is mainly poleward. These results suggest that aridification risks may significantly influence the distribution of terrestrial species besides warming impacts and further impact the effectiveness of current protected areas in future, especially under RCP8.5, which best matches historical CO₂ emissions [C. R. Schwalm et al., Proc. Natl. Acad. Sci. U.S.A. 117, 19656–19657 (2020)].

Aridity—the ratio of atmospheric water supply (precipitation; P) to demand (potential evapotranspiration; PET)—is projected to decrease (that is, areas will become drier) as a consequence of anthropogenic climate change, exacerbating land degradation and desertification1–6. However, the timing of significant aridification relative to natural variability—defined here as the time of emergence for aridification (ToEA)—is unknown, despite its importance in designing and implementing mitigation policies7–10. Here we estimate ToEA from projections of 27 global climate models (GCMs) under representative concentration pathways (RCPs) RCP4.5 and RCP8.5, and in doing so, identify where emergence occurs before global mean warming reaches 1.5 °C and 2 °C above the pre-industrial level. On the basis of the ensemble median ToEA for each grid cell, aridification emerges over 32% (RCP4.5) and 24% (RCP8.5) of the total land surface before the ensemble median of global mean temperature change reaches 2 °C in each scenario. Moreover, ToEA is avoided in about two-thirds of the above regions if the maximum global warming level is limited to 1.5 °C. Early action for accomplishing the 1.5 °C temperature goal can therefore markedly reduce the likelihood that large regions will face substantial aridification and related impacts.