Intense surface melt and subsequent meltwater ponding are the key triggers for the disintegration of ice shelves in the Antarctic Peninsula (AP). Although a long-term decline in AP surface melt has been evident since the early 1990s, episodes of intense surface melt events have frequently been reported in recent years. Here, using 1979-2023 daily surface melt rates from regional climate models, we show that this declining trend has reversed, with November-February surface melt increasing significantly by 3% year-1 (p < 0.05) between 2009 and 2022. Decomposition of trends based on circulation classification indicates that changes in the frequency of atmospheric circulation patterns cannot account for this enhancement. Instead, the thermodynamics-linked to variations in the surface energy budget independent of atmospheric circulation contribute 80% of the positive trend in AP surface melt. Analysis of extreme surface melt events further supports the dominant thermodynamic contribution.

As global greenhouse gases continue rising, the urgency of more ambitious action is clearer than ever before. China is the world's biggest emitter of greenhouse gases and one of the countries affected most by climate change. The evidence about the impacts of climate change on the environment and human health may encourage China to take more decisive action to mitigate greenhouse gas emissions and adapt to climate impacts. This article aimed to review the evidence of environmental damages and health risks posed by climate change and to provide a new science-based perspective for the delivery of sustainable development goals. Over recent decades, China has experienced a strong warming pattern with a growing frequency of extreme weather events, and the impacts of climate change on China's environment and human health have been consistently observed, with increasing O 3 air pollution, decreases in water resources and availability, land degradation, and increased risks for both communicable and non-communicable diseases. Therefore, China's climate policy should target the key factors driving climate change and scale up strategic measures to curb carbon emissions and adapt to inevitable increasing climate impacts. It provides new insights for not only China but also other countries, particularly developing and emerging economies, to ensure climate and environmental sustainability whilst pursuing economic growth.

Abstract Although mercury (Hg) is a neurotoxic metal of global relevance, its Antarctic biogeochemical cycles are not well characterized. Here, we present the total Hg (THg) distribution and stable isotopic fractionation between the Zhongshan Station and Dome A (1,248 km), in eastern Antarctica, to characterize THg sources and controlling factors. Surface snow samples and snow blocks similarly exhibited higher THg concentrations in the coastal and interior sections than the intermediate section. From the THg distribution and stable isotopic fractionation (notably for 200Hg and 202Hg), we inferred an adjacent oceanic Hg source for the coastal section and primary oceanic sources at 63°S–55°S and 50°S–45°S for the intermediate and interior sections, respectively. Snow drifting and postdepositional effects also influenced THg concentrations and stable isotopic fractionation, particularly in areas with marked terrain slope variations. Finally, the stratospheric contribution of THg near Dome A was negligible, with a possible transport pathway through the lower troposphere.

Surface melt and subsequent runoff have been the main contributors to recent Greenland mass loss. However, previous studies mainly focused on the extent and persistence of surface melt. The variations in surface melt rates and extreme events have not been adequately known, especially the role of extremes in the long-term surface melt changes. Here, using two high-resolution regional climate models (RACMO2.3p2 and MARv3.14), we analyzed the variations in Greenland surface melt in 1958-2023. Both models (RACMO/MAR) show that annual surface melt is rapidly increasing post-1990 at a rate of 8.6 +/- 4.9/7.2 +/- 4.4 Gt per year. The northern regions show the strongest relative regional increase rate (3.9% +/- 1.9%/3.4% +/- 1.6% per year), contributing more surface melt to the whole Greenland. Based on the 90th percentile of the daily distribution, we found that extreme surface melt events from May to September (M-S) have become more frequent post-1990 (0.7/0.8 +/- 0.5 d per year). Compared with 1958-1990, M-S surface melt from extreme events has increased by 134/105 Gt per year and dominates the increase in the total surface melt. During extreme surface melt events, we found an increase in downward longwave radiation, net shortwave radiation and sensible heat flux. The rise in surface melt and extreme events post-1990 is linked to more frequent atmospheric blocking. This study improves our understanding of the role in ice sheet mass balance played by long-term variations in ice sheet surface melt and extreme events.

Polar amplification-the phenomenon whereby anthropogenic warming is accentuated relative to the global average-has emerged as a central focus of climate research. While Arctic amplification is well-established, the presence and drivers of Antarctic amplification remain contentious. Using Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations, we demonstrate a robust emergence of Antarctic amplification under the 2 degrees C goal of the Paris Agreement. Sensitivity experiments identify a pivotal role for sea surface temperature (SST) changes in mediating this anthropogenic response. Positive SST anomalies influence Antarctic temperature through dynamic and thermodynamic processes, exerting distinct and contrasting effects. Dynamic processes, characterized by intensification of the Southern Annular Mode (SAM), generally induce continental-scale cooling. In contrast, thermodynamic processes, specially through enhanced sensible and latent heat fluxes, take precedence over the dynamic effect and drive widespread warming. In a warming climate, these thermodynamic processes are expected to intensify substantially, thereby amplifying the anthropogenic climate signal over Antarctica.

Climate warming is causing rapid permafrost degradation, including thaw-induced subsidence, potentially resulting in heightened carbon release. Nevertheless, our understanding of the levels and variations of carbon components in permafrost, particularly during the degradation process, remains limited. The uncertainties arising from this process lead to inaccurate assessments of the climate effects during permafrost degradation. With vast expanses of permafrost in the Tibetan Plateau, there is limited research available on SOC components, particularly in the central Tibetan Plateau. Given remarkable variations in hydrothermal conditions across different areas of the Tibetan Plateau, the existing limited studies make it challenging to assess the overall SOC components in the permafrost across the Tibetan Plateau and simulate their future changes. In this study, we examined the properties of soil organic carbon (SOC) and microbial necromass carbon (MicrobialNC) in a representative permafrost thaw-subsidence area at the southern edge of continuous permafrost in the central Tibetan Plateau. The results indicate that prior to the thaw-subsidence, the permafrost had a SOC content of 72.68±18.53 mg g−1, with MicrobialNC accounting for 49.6%. The thaw-subsidence of permafrost led to a 56.4% reduction in SOC, with MicrobialNC accounting for 70.0% of the lost SOC. MicrobialNC constitutes the primary component of permafrost SOC, and it is the main component that is lost during thaw-subsidence formation. Changes in MicrobialNC are primarily correlated with factors pH, plant input, and microbial properties. The present study holds crucial implications for both the ecological and biogeochemical processes associated with carbon release from permafrost, and it furnishes essential data necessary for modeling the global response of permafrost to climate warming. Based on this study and previous research, permafrost thawing in the Tibetan Plateau causes substantial loss of SOC. However, there's remarkable heterogeneity in SOC component changes across different regions, warranting further in-depth investigation.

Safe and just Earth system boundaries (ESBs) for surface water and groundwater (blue water) have been defined for sustainable water management in the Anthropocene. Here we assessed whether minimum human needs could be met with surface water from within individual river basins alone and, where this is not possible, quantified how much groundwater would be required. Approximately 2.6 billion people live in river basins where groundwater is needed because they are already outside the surface water ESB or have insufficient surface water to meet human needs and the ESB. Approximately 1.4 billion people live in river basins where demand-side transformations would be required as they either exceed the surface water ESB or face a decline in groundwater recharge and cannot meet minimum needs within the ESB. A further 1.5 billion people live in river basins outside the ESB, with insufficient surface water to meet minimum needs, requiring both supply- and demand-side transformations. These results highlight the challenges and opportunities of meeting even basic human access needs to water and protecting aquatic ecosystems.

In the divided changing world, there is a pressing need for a global science program to promote the delivery of sustainable development goals (SDGs), even though Future Earth is an international science program that was launched to strengthen research and society collaboration to accelerate transformations to global sustainability. Future Earth’s role in and impact on setting the international science agenda on transdisciplinary research for global sustainability may not have been so clear to the research or broader stakeholder communities. Therefore, we present future directions that could help the global change program to play a more eminent role in strengthening global sustainability science to fill in research gaps and address uncertainties in our knowledge of global environmental risks, to establish a better science–policy interface for effective communication with policymakers and other stakeholders, and to contribute to innovative and sustainable solutions for human well-being and the environment.

Tipping points of about 16 elements have been identified in Earth system, yet cryospheric tipping point of specific Alpine region has not been studied. Here we analyzed three tipping elements (mountain glacier, snow cover, and permafrost) identified in recent years, evidenced by the facts of frequent occurrence of abrupt massive collapse of glacier mass and the widespread thermakarst of permafrost. Since 2015, strikingly abrupt cryosphere events (ACEs) have been consistently observed over a large range of High Mountain Asia (HMA). Those events were unprecedentedly significant in history, leading to collapses of glaciers following by disconnection of glacier tongue from accumulation basin and recession of thermakarst towards higher elevation. Strong decreasing of snow depth in 2022 was also observed since 2021/2022 winter, coinciding with extreme warming of the year. The widespread high warming rates in the last two decades over HMA might have triggered above ACEs. The dynamic thresholds of ACEs depend largely on high temperature, especially extreme heat wave, for both glaciers and permafrost, closely related to meltwater as a key factor for reaching initial conditions of abrupt changes, suggesting HMA cryosphere is a tipping element under the global warming level of 1.1 degrees C. The ACEs can cause tremendous damage to local ecosystem and socioeconomy, measures to mitigate risks should be taken when the tipping points are reached.

The Shared Socio-economic Pathways (SSPs) and Representative Concentration Pathways (RCPs) describe how and to what extent greenhouse gases generated by future human socio-economic activities drive climate change. The coupling of the SSP and RCP pathways (SSP scenarios) forms a scientific loop for assessing the climate change science-impacts-risks-adaptation-mitigation. A scenario is a tool for describing the future development and change possibilities of the world.

Adaptation and mitigation are two main ways to address climate change. Adaptation is the process of adjustment to actual or expected climate change and its effects. In human systems, adaptation seeks to moderate harm or exploit beneficial opportunities; in natural systems, human interventions may speed up adjustment to the expected climate change and its effects. Mitigation involves human interventions to reduce emission sources or enhance the sinks of greenhouse gases. The objective of mitigation is to limit the global average temperature increase to a certain target above pre-industrial levels so as to reduce climate change risks and impacts. There are both synergies and trade-offs between adaptation and mitigation measures; adaptation and mitigation actions should be advanced within the framework of sustainable development.

Safe and just Earth System Boundaries (ESBs) for surface and groundwater (blue water) have been defined for sustainable water management in the Anthropocene. We evaluate where minimum human needs can be met within the surface water ESB and, where this is not possible, identify how much groundwater is required. 2.6 billion people live in catchments where groundwater is needed because they are already outside the surface water ESB or have insufficient surface water to meet human needs and the ESB. Approximately 1.4 billion people live in catchments where demand side transformations are required as they either exceed the surface water ESB or face a decline in groundwater recharge and cannot meet minimum needs within the ESB. A further 1.5 billion people live in catchments outside the ESB with insufficient surface water to meet needs, requiring both supply and demand-side transformations. These results highlight the challenges and opportunities of meeting even basic human access needs to water and protecting aquatic ecosystems.

Thaw slumps can lead to considerable carbon loss in permafrost regions, while the loss of components from two major origins, i.e., microbial and plant-derived carbon, during this process remains poorly understood. Here, we provide direct evidence that microbial necromass carbon is a major component of lost carbon in a retrogressive permafrost thaw slump by analyzing soil organic carbon (SOC), biomarkers (amino sugars and lignin phenols), and soil environmental variables in a typical permafrost thaw slump in the Tibetan Plateau. The retrogressive thaw slump led to a ∼61% decrease in SOC and a ∼25% SOC stock loss. As evident in the levels of amino sugars (average of 55.92 ± 18.79 mg g-1 of organic carbon, OC) and lignin phenols (average of 15.00 ± 8.05 mg g-1 OC), microbial-derived carbon (microbial necromass carbon) was the major component of the SOC loss, accounting for ∼54% of the SOC loss in the permafrost thaw slump. The variation of amino sugars was mainly related to the changes in soil moisture, pH, and plant input, while changes in lignin phenols were mainly related to the changes in soil moisture and soil bulk density.

As the largest valley glacier in the Qilian Mountains, the Laohugou glacier No. 12 (LHG12) has shrunk significantly since 1957. In this study, two topographic maps and a WorldView-2 satellite stereopair image data were used to assess the volume and cumulative mass balance of LHG12 located at the western Qilian Mountains during 1957–2015. During the study period, the LHG12 exhibited changes in two processes: slightly ablation and stability in a brief period during 1957–1989 and strong melting and accelerated ablation during 1989–2015. During 1957–2015, the volume of LHG12 decreased by 0.38 km3, the average thickness decreased by 17.23 m, the cumulative mass balance (MB) was −14.69 ± 3.00 m w. e., and ablation was found glacier-wide. By comparing the previous MB simulation and digital elevation model (DEM) differencing results, it was found that the MB simulation results underestimated the strong melting trend of LHG12 since the 1990s. Temperature rose, especially in autumn and winter, and could cause the ice temperature of LHG12 to increase, and LHG12 may become more sensitive to climate change.

南极地区被视为地球气候的稳定器,近年来南极极端天气事件的变化已引起全球关注.由于气象观测资料不足,对全南极极端事件的研究较少.Wei等 [1]发现2000年后西南极极端天气事件的强度和频率显著减少;Turner等 [2]指出1979—2019年南极半岛地区极端天气事件显著减少,南极沿岸地区则存在较大不确定性.而东南极冰穹地区(海拔3000 m以上区域)的极端天气事件变化,目前仍未有清晰的认识;南极极端天气事件发生原因的研究则更有限,且结论各异.现有研究仅对南极半岛异常高温产生的原因得到相对一致的认识,即南极半岛高温往往和焚风效应有关 [3].

Laohugou glacier No. 12 (LHG12), located in the northeast of the Qinghai–Tibet Plateau, is the largest valley glacier in the Qilian mountains. Since 1957, LHG12 has shrunk significantly. Due to the limitations of in situ observations, simulations and investigations of LHG12 have higher levels of uncertainty. In this study, consumer-level, low-altitude microdrones were used to conduct repeated photogrammetry at the lower part of LHG12, and a digital orthophoto map (DOM) and a digital surface model (DSM) with a resolution at the centimeter scale were generated, from 2017 to 2021. The dynamic parameters of the glacier were detected by artificial and automatic extraction methods. Using a combination of GNSS and drone-based data, the dynamic process of LHG12 was analyzed. The results show that the terminus of LHG12 has retreated by 194.35 m in total and by 19.44 m a−1 on average during 2008–2021. The differential ablation leading to terminus retreat distance markedly increased during the study period. In 2019–2021, the maximum annual surface velocity was 6.50 cm day−1, and during ablation season, the maximum surface velocity was 13.59 cm day−1, 52.17% higher than it is annually. The surface parameters, motion, and mass balance characteristics of the glacier had significant differences between the west and east branches. The movement in the west branch is faster than it is in the east branch. Because of the extrusion of the two ice flows, there is a region with a faster surface velocity at the ablation area. The ice thickness of LHG12 is decreasing due to intensified ablation, leading to a deceleration in the surface velocity. In large glaciers, this phenomenon is more obvious than it is in small glaciers in the Qilian mountains.

Antarctica is considered as an important component of the glo-bal climate system,not only because of its ability to drive global sea-level rise through ice melting[1],but also because of its stabi-lizing effect on global atmospheric energy balance/circulation[2].In recent years,Antarctica has experienced rapid climatic changes and frequent climate extremes,such as a rapid decrease in summer sea ice extent since 2016[3]and the highest air temperature recorded at Esperanza station in the Antarctic Peninsula on 9 February 2020[4].In this context,climate extremes in Antarctica have received increasing attention recently[4-7].

The paleo-cryosphere is the cryosphere of the earth in the past geological time. The history of the Earth covers about 4.6 billion years (Ga). However, there are only 542 million years (Ma) since the Cambrian. The long geological period before the Cambrian covers about 4 Ga and is called the Precambrian.