National Science Review最新文献

A synthesis of global barite sulfate isotope data from approximately 635 million years ago, at the end of a global glaciation, undermines the hypothesis that river sulfate was the primary carrier of the distinctive 17O-depleted atmospheric O2 signature of the time. Instead, an aqueous H2S oxidation model on the shelf emerges as a compelling alternative, though it demands extensive validation across multiple fronts by the scientific community.

Ozone pollution is a major environmental threat to human health. Timely assessment of ozone trends is crucial for informing environmental policy. Here we show that for the most recent decade (2013-2022) in the northern hemisphere, warm-season (April-September) mean daily 8-h average maximum ozone increases much faster in urban regions with top ozone levels (mainly in the North China Plain, 1.2 ± 1.3 ppbv year^-1) than in other, low-ozone regions (0.2 ± 0.9 ppbv year^-1). These trends widen the ozone differences across urban regions, and increase extreme pollution levels and health threats from a global perspective. Comparison of historical trends in different urban regions reveals that ozone increases in China during 2013-2022 differ in magnitude and mechanisms to historical periods in other regions since 1980. This reflects a unique chemical environment characterized by exceptionally high nitrogen oxides and aerosol concentrations, where reducing ozone precursor emissions leads to substantial ozone increase. Ozone increase in China has slowed down in 2018-2022 compared to 2013-2017, driven by ongoing emission reductions, but with ozone-favorable weather conditions. Historical ozone evolution in Japan and South Korea indicates that ozone increases should be suppressed with continuous emission reduction. Increasing temperature and associated wildfires have also reversed ozone decreases in the USA and Europe, with anthropogenic ozone control slowing down in recent decades.

The final frontiers on our planet challenge humans' survival as much as our ambition. The Arctic and Antarctic areas together exert enormous influence on the climate of the whole planet, as they contain 87% of its fresh water, 90% of its ice and snow, 90% of its permafrost and 69% of its glaciers. However, our lack of understanding of changes in the polar regions, such as melting ice sheets, results in major uncertainties in our estimates and predictions with regard to rising sea levels and other effects of climate change. For example, as the Arctic region is warming up two to four times faster than the global average, Eurasia now experiences colder winters. As its mechanism is yet to be elucidated, forecasts of extreme weather events in China, which aim to avert severe damages, remain inadequate. In order to raise awareness of polar science, National Science Review invited Dr. Dake Chen of the Second Institute of Oceanography, Ministry of Natural Resources (MNR) to organize a forum discussion with five Chinese experts to explore these crucial topics. Jianfang Chen () Professor, Second Institute of Oceanography, MNR Ruibo Lei () Professor, Polar Research Institute of China, MNR Jiping Liu () Professor, School of Atmospheric Science, Sun Yat-sen University Qinghua Yang () Professor, Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) Meng Zhou () Professor, School of Oceanography, Shanghai Jiao Tong University Dake Chen () (Chair) Professor, The Second Institute of Oceanography, MNR and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai).

Candidate bacterial phylum CSP1-3 has not been cultivated and is poorly understood. Here, we analyzed 112 CSP1-3 metagenome-assembled genomes and showed they are likely facultative anaerobes, with 3 of 5 families encoding autotrophy through the reductive glycine pathway (RGP), Wood-Ljungdahl pathway (WLP) or Calvin-Benson-Bassham (CBB), with hydrogen or sulfide as electron donors. Chemoautotrophic enrichments from hot spring sediments and fluorescence in situ hybridization revealed enrichment of six CSP1-3 genera, and both transcribed genes and DNA-stable isotope probing were consistent with proposed chemoautotrophic metabolisms. Ancestral state reconstructions showed that the ancestors of phylum CSP1-3 may have been acetogens that were autotrophic via the RGP, whereas the WLP and CBB were acquired by horizontal gene transfer. Our results reveal that CSP1-3 is a widely distributed phylum with the potential to contribute to the cycling of carbon, sulfur and nitrogen. The name Sysuimicrobiota phy. nov. is proposed.

This study offers new insights into the heterogeneity behind the widely accepted notion that irrigated crops contribute 40% to global food production. It also highlights the potential of irrigation to mitigate the negative effects of climate change on crop yields.

In 2023, the CO₂ growth rate was 3.37 ± 0.11 ppm at Mauna Loa, which was 86% above that of the previous year and hit a record high since observations began in 1958, while global fossil fuel CO₂ emissions only increased by 0.6% ± 0.5%. This implies an unprecedented weakening of land and ocean sinks, and raises the question of where and why this reduction happened. Here, we show a global net land CO₂ sink of 0.44 ± 0.21 GtC yr^-1, which is the weakest since 2003. We used dynamic global vegetation models, satellite fire emissions, an atmospheric inversion based on OCO-2 measurements and emulators of ocean biogeochemical and data-driven models to deliver a fast-track carbon budget in 2023. Those models ensured consistency with previous carbon budgets. Regional flux anomalies from 2015 to 2022 are consistent between top-down and bottom-up approaches, with the largest abnormal carbon loss in the Amazon during the drought in the second half of 2023 (0.31 ± 0.19 GtC yr^-1), extreme fire emissions of 0.58 ± 0.10 GtC yr^-1 in Canada and a loss in Southeast Asia (0.13 ± 0.12 GtC yr^-1). Since 2015, land CO₂ uptake north of 20°N had declined by half to 1.13 ± 0.24 GtC yr^-1 in 2023. Meanwhile, the tropics recovered from the 2015-2016 El Niño carbon loss, gained carbon during the La Niña years (2020-2023), then switched to a carbon loss during the 2023 El Niño (0.56 ± 0.23 GtC yr^-1). The ocean sink was stronger than normal in the equatorial eastern Pacific due to reduced upwelling from La Niña's retreat in early 2023 and the development of El Niño later. Land regions exposed to extreme heat in 2023 contributed a gross carbon loss of 1.73 GtC yr^-1, indicating that record warming in 2023 had a strong negative impact on the capacity of terrestrial ecosystems to mitigate climate change.

The weakening and poleward expansion of the Hadley circulation (HC) are considered robust responses of atmospheric meridional circulation to anthropogenic warming. Climate impacts arising from these changes enhance drought conditions and reduce food production in the affected regions. Therefore, understanding the mechanisms of HC changes is critical to anticipating the resultant climate risks. First, we demonstrate that robust future HC changes in boreal winter, and the uncertainty in their future projections, are both largely related to sea surface temperature (SST) warming. Next, we investigate the impact of anthropogenic regional ocean warming on the future HC. Accordingly, we conduct a large ensemble of individual ocean basin perturbation experiments at 1.5°C, 2°C, and 3°C warming thresholds (as in the Paris Agreement). These experiments highlight (i) the leading role of tropical Indian Ocean warming in HC changes and (ii) inter-model differences in tropical Pacific warming as a source of uncertainty in HC projections.

Atmospheric CO₂ growth rate (CGR), reflecting the carbon balance between anthropogenic emissions and net uptake from land and ocean, largely determines the magnitude and speed of global warming. The CGR at Mauna Loa Baseline Observatory reached a record high in 2023. We quantified major components of the global carbon balance for 2023, by developing a framework that integrated fossil fuel CO₂ emissions data and an atmospheric inversion from the Global ObservatioN-based system for monitoring Greenhouse GAses (GONGGA) with two artificial intelligence (AI) models derived from dynamic global vegetation models. We attributed the record high CGR increase in 2023 compared to 2022 primarily to the large decline in land carbon sink (1803 ± 197 TgC year^-1), with minor contributions from a small reduction in ocean carbon sink (184 TgC year^-1) and a slight increase in fossil fuel emissions (24 TgC year^-1). At least 78% of the global decline in land carbon sink was contributed by the decline in tropical sink, with GONGGA inversion (1354 TgC year^-1) and AI simulations (1578 ± 666 TgC year^-1) showing similar declines in the tropics. We further linked this tropical decline to the detrimental impact of El Niño-induced anomalous warming and drying on vegetation productivity in water-limited Sahel and southern Africa. Our successful attribution of CGR increase within a framework combining atmospheric inversion and AI simulations enabled near-real-time tracking of the global carbon budget, which had a one-year reporting lag.

We present the proposed strategic study, 'Integrated elements for Martian life signature exploration', to support the sampling and identification of any potential biosignatures in compliance with the engineering constraints of the Tianwen-3 mission.