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| 2. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Yang, Kunpeng, et al.
(författare)
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North Atlantic Ocean–Originated Multicentennial Oscillation of the AMOC : A Coupled Model Study
- 2024
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Ingår i: Journal of Climate. - 0894-8755 .- 1520-0442. ; 37:9, s. 2789-2807
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Tidskriftsartikel (refereegranskat)abstract
- Using a CESM1 control simulation, we conduct a follow-up study to advance our earlier theoretical research on the multicentennial oscillation (MCO) of the Atlantic meridional overturning circulation (AMOC). The modeled AMOC MCO primarily arises from internal oceanic processes in the North Atlantic, potentially representing a North Atlantic Ocean–originated mode of AMOC multicentennial variability (MCV) in reality. Specifically, this AMOC MCO is mainly driven by salinity variation in the subpolar upper North Atlantic, which dominates local density variation. Salinity anomaly in the subpolar upper ocean is enhanced by the well-known positive salinity advection feedback that is realized through anomalous advection in the subtropical to subpolar upper ocean. Meanwhile, mean advection moves salinity anomaly in the subtropical intermediate ocean northward, weakening the subpolar upper salinity anomaly and leading to its phase change. The salinity anomalies have a clear three-dimensional life cycle around the North Atlantic. The mechanism and time scale of the modeled AMOC MCO are consistent with our earlier theoretical studies. In the theoretical model, artificially deactivating either the anomalous or mean advection in the AMOC upper branch prevents it from exhibiting AMOC MCO, underscoring the indispensability of both the anomalous and mean advections in this North Atlantic Ocean–originated AMOC MCO. In our coupled model simulation, the South Atlantic and Southern Oceans do not exhibit variabilities synchronous with the AMOC MCO; the Arctic Ocean’s contribution to the subpolar upper salinity anomaly is much weaker than the North Atlantic. Hence, this North Atlantic Ocean–originated AMOC MCO is distinct from the previously proposed Southern Ocean–originated and Arctic Ocean–originated AMOC MCOs.
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| 4. |
- Wang, Fang, et al.
(författare)
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Emerging contaminants: A One Health perspective
- 2024
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Ingår i: Innovation. - 2666-6758. ; 5
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Forskningsöversikt (refereegranskat)abstract
- Environmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary health. Despite global efforts to mitigate legacy pollutants, the continuous introduction of new substances remains a major threat to both people and the planet. In response, global initiatives are focusing on risk assessment and regulation of emerging contaminants, as demonstrated by the ongoing efforts to establish the UN's Intergovernmental Science-Policy Panel on Chemicals, Waste, and Pollution Prevention. This review identifies the sources and impacts of emerging contaminants on planetary health, emphasizing the importance of adopting a One Health approach. Strategies for monitoring and addressing these pollutants are discussed, underscoring the need for robust and socially equitable environmental policies at both regional and international levels. Urgent actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.
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| 5. |
- Yang, Haijun, et al.
(författare)
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多百年际气候变率 : 观测、理论与模拟研究 [Multi-centennial climate variability: Observational, theoretical and modeling studies]
- 2023
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Ingår i: Chinese Science Bulletin. - 0023-074X .- 2095-9419. ; 68:16, s. 2037-2045
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Tidskriftsartikel (refereegranskat)abstract
- Research using long-term proxy data suggests the existence of multi-centennial climate variability in the Earth’s climate system. Its origin and mechanism have been bewildering for climatologists and archaeologists for a long time. Considering that the variation of external forcing of the Earth’ climate was relatively small from the mid-Holocene to the pre-industrial time, it is important to investigate the role of internal natural oscillation of the climate system during this period. The Atlantic meridional overturning circulation (AMOC) is thought to be the first candidate for such multi-centennial timescale variability. It is thus critical to investigate systematically the connection between the AMOC and the Earth climate system at this timescale. From the mid-Holocene to the pre-industrial time, the human civilization experienced rapid development. Historical documents in China suggest that in the past 2000 years, the historical climate in China had a low-frequency variation with 200–300 year period, which might have affected the ancient Chinese civilization. The multi-centennial variability of the AMOC may have played a role in the vax and vane of the human civilization.Currently, there is a lack of in-depth studies on the multi-centennial variability of the AMOC. This is mainly due to the following factors. First, the time period of modern instrumental observations is less than 200 years, which is not long enough to confirm the existence of the multi-centennial climate variability. Second, there is a lack of a well-recognized theory that can account for the multi-centennial variability of the AMOC. Third, it is much easier for a researcher to study the Earth climate change due to external forcing than to study the internal variability of the Earth climate system under a stable external forcing, particularly at this long timescale.Several coupled Earth climate system models have simulated the multi-centennial variability of the AMOC. However, the results from both coupled models and proxy data include comprehensive factors. To fundamentally understand the multi-centennial climate variability, a simple theoretical model is needed. Unfortunately, there is a lack of theoretical studies on the internal multi-centennial variability under the background of stable climate.In this work, we systematically review the current studies on multi-centennial climate variability from observational, theoretical and coupled modeling aspects. We hope that by proposing innovative theory and creative climate modeling approach, we can identify the intrinsic mode of multi-centennial climate variability, picture its spatial pattern, decipher the origin of its timescale, and reveal its internal mechanism. The outcome of these studies will help us understand deeply the wax and wane of the human civilization during the past several thousand years. It will also be of great significance for a better prediction of the long-term trend of future climate change.
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| 6. |
- Cao, Ning, 1987-, et al.
(författare)
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The role of internal feedbacks in sustaining multi-centennial variability of the Atlantic Meridional Overturning Circulation revealed by EC-Earth3-LR simulations
- 2023
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Ingår i: Earth and Planetary Science Letters. - 0012-821X .- 1385-013X. ; 621
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Tidskriftsartikel (refereegranskat)abstract
- A significant multi-centennial climate variability with a distinct peak at approximately 200 years is observed in a pre-industrial (PI) control simulation using the EC-Earth3-LR climate model. This oscillation originates predominately from the North Atlantic and displays a strong association with the Atlantic Meridional Overturning Circulation (AMOC). Our study identifies the interplay between salinity advection feedback and vertical mixing in the subpolar North Atlantic as key roles in providing the continues internal energy source to maintain this multi-centennial oscillation. The perturbation flow of mean subtropical-subpolar salinity gradients serves as positive feedback to sustain the AMOC anomaly, while the mean advection of salinity anomalies and the vertical mixing or convection acts as negative feedback, constraining the AMOC anomaly. Notably, this low-frequency variability persists even in a warmer climate with weakened AMOC, emphasizing the robustness of the salinity advection feedback mechanism.
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| 7. |
- Chen, Wenju, et al.
(författare)
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Porous cellulose diacetate-SiO2 composite coating on polyethylene separator for high-performance lithium-ion battery
- 2016
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 147, s. 517-524
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Tidskriftsartikel (refereegranskat)abstract
- The developments of high-performance lithium ion battery are eager to the separators with high ionic conductivity and thermal stability. In this work, a new way to adjust the comprehensive properties of inorganic-organic composite separator was investigated. The cellulose diacetate (CDA)-SiO2 composite coating is beneficial for improving the electrolyte wettability and the thermal stability of separators. Interestingly, the pore structure of composite coating can be regulated by the weight ratio of SiO2 precursor tetraethoxysilane (TEOS) in the coating solution. The electronic performance of lithium ion batteries assembled with modified separators are improved compared with the pristine PE separator. When weight ratio of TEOS in the coating solution was 9.4%, the composite separator shows the best comprehensive performance. Compared with the pristine PE separator, its meltdown temperature and the break-elongation at elevated temperature increased. More importantly, the discharge capacity and the capacity retention improved significantly.
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| 8. |
- Gravgaard Askjær, Thomas, et al.
(författare)
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Multi-centennial Holocene climate variability in proxy records and transient model simulations
- 2022
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 296
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Tidskriftsartikel (refereegranskat)abstract
- Variability on centennial to multi-centennial timescales is mentioned as a feature in reconstructions of the Holocene climate. As more long transient model simulations with complex climate models become available and efforts have been made to compile large proxy databases, there is now a unique opportunity to study multi-centennial variability with greater detail and a large amount of data than earlier. This paper presents a spectral analysis of transient Holocene simulations from 9 models and 120 proxy records to find the common signals related to oscillation periods and geographic dependencies and discuss the implications for the potential driving mechanisms. Multi-centennial variability is significant in most proxy records, with the dominant oscillation periods around 120–130 years and an average of 240 years. Spectra of model-based global mean temperature (GMT) agree well with proxy evidence with significant multi-centennial variability in all simulations with the dominant oscillation periods around 120–150 years. It indicates a comparatively good agreement between model and proxy data. A lack of latitudinal dependencies in terms of oscillation period is found in both the model and proxy data. However, all model simulations have the highest spectral density distributed over the Northern hemisphere high latitudes, which could indicate a particular variability sensitivity or potential driving mechanisms in this region. Five models also have differentiated forcings simulations with various combinations of forcing agents. Significant multi-centennial variability with oscillation periods between 100 and 200 years is found in all forcing scenarios, including those with only orbital forcing. The different forcings induce some variability in the system. Yet, none appear to be the predominant driver based on the spectral analysis. Solar irradiance has long been hypothesized to be a primary driver of multi-centennial variability. However, all the simulations without this forcing have shown significant multi-centennial variability. The results then indicate that internal mechanisms operate on multi-centennial timescales, and the North Atlantic-Arctic is a region of interest for this aspect.
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| 9. |
- Lin, Yuze, et al.
(författare)
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Mapping Polymer Donors toward High-Efficiency Fullerene Free Organic Solar Cells
- 2017
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 29:3
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Tidskriftsartikel (refereegranskat)abstract
- Five polymer donors with distinct chemical structures and different electronic properties are surveyed in a planar and narrow-bandgap fused-ring electron acceptor (IDIC)-based organic solar cells, which exhibit power conversion efficiencies of up to 11%.
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| 10. |
- Wang, Huan, et al.
(författare)
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Thermodynamic effect dictates influence of the Atlantic Multidecadal Oscillation on Eurasia winter temperature
- 2024
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Ingår i: NPJ CLIMATE AND ATMOSPHERIC SCIENCE. - 2397-3722. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The Atlantic Multidecadal Oscillation (AMO) has garnered attention for its important role in shaping surface air temperature (SAT) patterns over Eurasia. While Eurasian winter SAT was traditionally attributed to changes in large-scale atmospheric circulations associated with the AMO, a careful examination of the latest unforced CMIP6 simulations in this study unveils a significant contribution of the AMO's thermodynamic effects. Specifically, the heat released from the North Atlantic Ocean and transported to northern Eurasia through westerlies takes precedence over the effect of dynamic Rossby waves, resulting in warm (cold) phases during positive (negative) AMO cycles, along with increased (decreased) warm extremes and reduced (enhanced) cold extremes. This study contributes to an improved understanding of the dominating mechanism of the AMO's impact on Eurasian SAT.
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| 11. |
- Wen, Qin, et al.
(författare)
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Decoding Hosing and Heating Effects on Global Temperature and Meridional Circulations in a Warming Climate
- 2018
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Ingår i: Journal of Climate. - 0894-8755 .- 1520-0442. ; 31:23, s. 9605-9623
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Tidskriftsartikel (refereegranskat)abstract
- The global temperature changes under global warming result from two effects: one is the pure radiative heating effect caused by a change in greenhouse gases, and the other is the freshwater effect related to changes in precipitation, evaporation, and sea ice. The two effects are separated in a coupled climate model through sensitivity experiments in this study. It is indicated that freshwater change has a significant cooling effect that can mitigate the global surface warming by as much as similar to 30%. Two significant regional cooling centers occur: one in the subpolar Atlantic and one in the Southern Ocean. The subpolar Atlantic cooling, also known as the warming hole, is triggered by sea ice melting and the southward cold-water advection from the Arctic Ocean, and is sustained by the weakened Atlantic meridional overturning circulation. The Southern Ocean surface cooling is triggered by sea ice melting along the Antarctic and is maintained by the enhanced northward Ekman flow. In these two regions, the effect of freshwater flux change dominates over that of radiation flux change, controlling the sea surface temperature change in the warming climate. The freshwater flux change also results in the Bjerknes compensation, with the atmosphere heat transport change compensating the ocean heat transport change by about 80% during the transient stage of global warming. In terms of global temperature and Earth's energy balance, the freshwater change plays a stabilizing role in a warming climate.
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| 12. |
- Wen, Qin, et al.
(författare)
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Investigating the role of the tibetan plateau in ENSO variability
- 2020
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Ingår i: Journal of Climate. - 0894-8755. ; 33:11, s. 4835-4852
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Tidskriftsartikel (refereegranskat)abstract
- The role of the Tibetan Plateau (TP) in El Niño-Southern Oscillation (ENSO) variability is investigated using coupled model experiments with different topography setups. Removing the TP results in weakened trade winds in the tropical Pacific, an eastward shift of atmospheric convection center, a shallower mixed layer in the equatorial Pacific, and a flattened equatorial thermocline, which leads to an El Niño-like sea surface temperature (SST) response. In association with these mean climate changes in the tropical atmosphere- ocean system, the ENSO variability exhibits a much stronger amplitude in the world without the TP. Detailed diagnoses reveal that in the absence of the TP, both thermocline feedback in the eastern equatorial Pacific and Ekman pumping feedback in the central-eastern equatorial Pacific are enhanced substantially, leading to stronger ENSO variability. The changes of these two feedbacks are caused by the eastward shift of the atmospheric convection center and enhanced ocean sensitivity; the latter is due to the shallower mixed layer and flattened thermocline. This study suggests that the presence of the TP may be of fundamental importance for modern-day tropical climate variability; namely, the TP may have played a role in suppressing ENSO variability.
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| 13. |
- Yang, Haijun, et al.
(författare)
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Anatomizing the Ocean´s role in ENSO changes under global warming
- 2008
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Ingår i: Journal of climate. - 1520-0442. ; 21:24, s. 6539-6555
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Tidskriftsartikel (refereegranskat)abstract
- A revisit on observations shows that the tropical El Niño–Southern Oscillation (ENSO) variability, after removing both the long-term trend and decadal variation of the background climate, has been enhanced by as much as 50% during the past 50 yr. This is inconsistent with the changes in the equatorial atmosphere, which shows a slowdown of the zonal Walker circulation and tends to stabilize the tropical coupling system. The ocean role is highlighted in this paper. The enhanced ENSO variability is attributed to the strengthened equatorial thermocline that acts as a destabilizing factor of the tropical coupling system. To quantify the dynamic effect of the ocean on the ENSO variability under the global warming, ensemble experiments are performed using a coupled climate model [Fast Ocean Atmosphere Model (FOAM)], following the “1pctto2x” scenario defined in the Intergovernmental Panel on Climate Change (IPCC) reports. Term balance analyses on the temperature variability equation show that the anomalous upwelling of the mean vertical temperature gradient (referred as the “local term”) in the eastern equatorial Pacific is the most important destabilizing factor to the temperature variabilities. The magnitude of local term and its change are controlled by its two components: the mean vertical temperature gradient Tz and the “virtual vertical heat flux” −w′T′. The former can be viewed as the background of the latter and these two components are positively correlated. A stronger Tz is usually associated with a bigger upward heat flux −w′T′, which implies a bigger impact of thermocline depth variations on SST. The Tz is first enhanced during the transient stage of the global warming with a 1% yr−1 increase of CO2, and then reduced during the equilibrium stage with a fixed doubled CO2. This turnaround in Tz determines the turnaround of ENSO variability in the entire global warming period.
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| 14. |
- Yang, Haijun, et al.
(författare)
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Heat Transport Compensation in Atmosphere and Ocean over the Past 22,000 Years
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- The Earth's climate has experienced dramatic changes over the past 22,000 years; however, the total meridional heat transport (MHT) of the climate system remains stable. A 22,000-year-long simulation using an ocean-atmosphere coupled model shows that the changes in atmosphere and ocean MHT are significant but tend to be out of phase in most regions, mitigating the total MHT change, which helps to maintain the stability of the Earth's overall climate. A simple conceptual model is used to understand the compensation mechanism. The simple model can reproduce qualitatively the evolution and compensation features of the MHT over the past 22,000 years. We find that the global energy conservation requires the compensation changes in the atmosphere and ocean heat transports. The degree of compensation is mainly determined by the local climate feedback between surface temperature and net radiation flux at the top of the atmosphere. This study suggests that an internal mechanism may exist in the climate system, which might have played a role in constraining the global climate change over the past 22,000 years.
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| 15. |
- Yang, Junhua, et al.
(författare)
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South Asian black carbon is threatening the water sustainability of the Asian Water Tower
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Long-range transport of black carbon from South Asia to the Tibetan plateau and its deposition on glaciers directly enhances glacier melt. Here we find South Asian black carbon also has an indirect effect on the plateau’s glaciers shrinkage by acting to reduce the water supply over the southern Tibetan plateau. Black carbon enhances vertical convection and cloud condensation, which results in water vapor depletion over the Indian subcontinent that is the main moisture flux source for the southern Tibetan plateau. Increasing concentrations of black carbon causes a decrease in summer precipitation over the southern Tibetan plateau, resulting in 11.0% glacier deficit mass balance on average from 2007 to 2016; this loss rises to 22.1% in the Himalayas. The direct (accelerated melt) and indirect (mass supply decrease) effects of black carbon are driving the glacial mass decline of the so-called “Asian Water Tower”.
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| 16. |
- Zeng, Jiangyuan, et al.
(författare)
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Innovations in science, technology, engineering, and policy (iSTEP) for addressing environmental issues towards sustainable development
- 2024
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Ingår i: The Innovation Geoscience. - : Innovation Press. - 2959-8753. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- Sustainable development depends on the integration of the economy, society, and environment. Yet, escalating environmental challenges pose threats to both society and the economy. Despite progress in addressing environmental issues to promote sustainability, knowledge gaps in scientific research, technological advancement, engineering practice, and policy development persist. In this review, we aim to narrow these gaps by proposing innovation-based solutions and refining existing paradigms. Reviewing past research and actions, we first elucidate the evolution of sustainability science and the essence of sustainable development and its assessment. Secondly, we summarize current major environmental issues, including global warming and climate change, biodiversity loss, land degradation and desertification, and environmental pollution, as well as their relationships with sustainability and the achievement of Sustainable Development Goals (SDGs). Subsequently, this review critically evaluates the role of innovations in science, technology, engineering, and policy (iSTEP) and their synergies in advancing sustainability and SDGs. While their sequential relationships may vary based on specific contexts or sustainability scenarios within the iSTEP framework, each component reinforces the others, fostering continuous improvement. Finally, this review offers recommendations and future perspectives for formulating sustainability roadmaps. Recommendations include fostering a vision of sustainability, promoting interdisciplinary collaboration, and encouraging transboundary cooperation among stakeholders for future sustainability endeavors.
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