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Abstract Sea level rise (SLR) is a global concern in the era of climate change, prompting the exploration of interventions such as solar radiation modification through stratospheric aerosol injection (SAI). This intervention could affect the physical system in various ways. The present study analyzes the global and regional impacts of SAI using ARISE-SAI-1.5 (SAI-1.5) simulations with the Community Earth System Model 2. We calculated the regional thermosteric sea level under different scenarios. After validating our methodology for sea level components over the period 1995–2014, we determined changes in sea level variables under both SAI-1.5 and the underlying Shared Socioeconomic Pathway 2–4.5 (SSP2-4.5) relative to the reference period (1995–2014). In contrast to sea surface temperature, which under this SAI strategy should be maintained near 1.5 °C above preindustrial values, global SLR would continue increasing under SAI-1.5. However, SAI would significantly impact thermal expansion in SSP2-4.5 simulations, reducing the global long-term sea level trend from 3.7 ± 0.03 mm yr⁻¹for SSP2-4.5–1.9 ± 0.04 mm yr⁻¹for SAI-1.5, a 49% reduction. The associated ocean heat content is reduced from (2.0 ± 0.3) × 10²²J yr⁻¹under SSP2-4.5 to (1.17 ± 0.30) × 10²²J yr⁻¹under SAI, a 42% reduction. Additionally, SAI would impact the regional and global ocean by reducing the SLR rate. These findings underscore the potential of SAI as a climate intervention strategy with significant implications for sea level change. 

Abstract In this study, the potential changes in tropical cyclone (TC) lifetime in the western North Pacific basin are examined for different future climates. Using homogeneous 9-km-resolution dynamical downscaling with the Weather Research and Forecasting (WRF) Model, we show that TC-averaged lifetime displays insignificant change under both low and high greenhouse gas concentration scenarios. However, more noticeable changes in the tails of TC lifetime statistics are captured in our downscaling simulations, with more frequent long-lived TCs (lifetime of 8–11 days) and less short-lived TCs (lifetime of 3–5 days). Unlike present-day simulations, it is found that the correlation between TC lifetime and the Niño index is relatively weak and insignificant in all future downscaling simulations, thus offering little explanation for these changes in TC lifetime statistics based on El Niño–Southern Oscillation. More detailed analyses of TC track distribution in the western North Pacific basin reveal, nevertheless, a noticeable shift of TC track patterns toward the end of the twenty-first century. Such a change in TC track climatology results in an overall longer duration of TCs over the open ocean, which is consistent across future scenarios and periods examined in this study. This shift in the TC track pattern is ultimately linked to changes in the western North Pacific subtropical high, which retreats to the south during July and to the east during August–September. The results obtained in this study provide new insights into how large-scale circulations can affect TC lifetime in the western North Pacific basin in warmer climates. Significance StatementUsing high-resolution dynamical downscaling with the Weather Research and Forecasting (WRF) Model under low- and high-emission scenarios, this study shows that the basin-averaged tropical cyclone (TC) lifetime in the western North Pacific (WNP) basin has no noticeable change under both warmer climate scenarios, despite an overall increase in TC maximum intensity. However, the tails of the TC lifetime distribution display significant changes, with more long-lived (6–20 days) TCs but less short-lived (3–5 days) TCs in the future. These changes in TC lifetime statistics are caused by the shift of the North Pacific subtropical high, which alters large-scale steering flows and TC track patterns. These results help explain why previous studies on TC lifetime projections have been inconclusive in the WNP basin and provide new insights into how large-scale circulations can modulate TC lifetime in a warmer climate. 

Abstract Stratospheric aerosol injection (SAI) would involve the addition of sulfate aerosols in the stratosphere to reflect part of the incoming solar radiation, thereby cooling the climate. Studies trying to explore the impacts of SAI have often focused on idealized scenarios without explicitly introducing what we call ‘inconsistencies’ in a deployment. A concern often discussed is what would happen to the climate system after an abrupt termination of its deployment, whether inadvertent or deliberate. However, there is a much wider range of plausible inconsistencies in deployment than termination that should be evaluated to better understand associated risks. In this work, we simulate a few representative inconsistencies in a pre-existing SAI scenario: an abrupt termination, a decade-long gradual phase-out, and 1 year and 2 year temporary interruptions of deployment. After examining their climate impacts, we use these simulations to train an emulator, and use this to project global mean temperature response for a broader set of inconsistencies in deployment. Our work highlights the capacity of a finite set of explicitly simulated scenarios that include inconsistencies to inform an emulator that is capable of expanding the space of scenarios that one might want to explore far more quickly and efficiently. 

Climate change represents a significant existential challenge in modern times, with widespread anxiety over its impacts. There's a growing desire among students to explore climate solutions and identify actions they can personally undertake to address climate change. Despite mitigation efforts, current greenhouse gas emission reduction measures are insufficient, and the development of negative emission technologies is both slow and costly. Consequently, the past two decades have witnessed an escalating interest in alternative strategies to temporarily and intentionally cool the planet. These strategies include injecting reflective particles into the stratosphere or increasing the reflectivity of low-lying ocean clouds. Collectively known as climate engineering, also called geoengineering, these approaches could serve as a temporary shield against the most severe outcomes of climate change, buying time while efforts to mitigate emissions and enhance carbon sequestration reach the required scale.In line with the Indiana state science standards (HS-ESS3-4), this article presents the Climate Engineering Teaching Module (CETM) and recounts firsthand experiences from its application in high school settings. Launched over three years ago, the CETM has been effectively integrated into fifteen Indiana classrooms. As the future citizens and leaders of Indiana, it is crucial that students are well-informed on climate engineering. Educating them about the scientific, ethical, political, and economic facets of climate engineering is imperative for fostering responsible decision-making. By examining the trade-offs associated with climate engineering and encouraging students to conceptualize ways to implement these technologies beneficially while minimizing risks, the CETM offers an innovative and practical approach to teaching climate change and engineering design. This method not only prepares students for active engagement in future discussions on climate engineering but also equips them with a comprehensive understanding of its complexities. 

Abstract Atmospheric rivers (ARs), intrusions of warm and moist air, can effectively drive weather extremes over the Arctic and trigger subsequent impact on sea ice and climate. What controls the observed multi-decadal Arctic AR trends remains unclear. Here, using multiple sources of observations and model experiments, we find that, contrary to the uniform positive trend in climate simulations, the observed Arctic AR frequency increases by twice as much over the Atlantic sector compared to the Pacific sector in 1981-2021. This discrepancy can be reconciled by the observed positive-to-negative phase shift of Interdecadal Pacific Oscillation (IPO) and the negative-to-positive phase shift of Atlantic Multidecadal Oscillation (AMO), which increase and reduce Arctic ARs over the Atlantic and Pacific sectors, respectively. Removing the influence of the IPO and AMO can reduce the projection uncertainties in near-future Arctic AR trends by about 24%, which is important for constraining projection of Arctic warming and the timing of an ice-free Arctic. 

Abstract Climate change is a prevalent threat, and it is unlikely that current mitigation efforts will be enough to avoid unwanted impacts. One potential option to reduce climate change impacts is the use of stratospheric aerosol injection (SAI). Even if SAI is ultimately deployed, it might be initiated only after some temperature target is exceeded. The consequences of such a delay are assessed herein. This study compares two cases, with the same target global mean temperature of ∼1.5° C above preindustrial, but start dates of 2035 or a ‘delayed’ start in 2045. We make use of simulations in the Community Earth System Model version 2 with the Whole Atmosphere Coupled Chemistry Model version 6 (CESM2-WACCM6), using SAI under the SSP2-4.5 emissions pathway. We find that delaying the start of deployment (relative to the target temperature) necessitates lower net radiative forcing (−30%) and thus larger sulfur dioxide injection rates (+20%), even after surface temperatures converge, to compensate for the extra energy absorbed by the Earth system. Southern hemisphere ozone is higher from 2035 to 2050 in the delayed start scenario, but converges to the same value later in the century. However, many of the surface climate differences between the 2035 and 2045 start simulations appear to be small during the 10–25 years following the delayed SAI start, although longer simulations would be needed to assess any longer-term impacts in this model. In addition, irreversibilities and tipping points that might be triggered during the period of increased warming may not be adequately represented in the model but could change this conclusion in the real world. 

Climate solutions related to mitigation and adaptation vary across the United States and India, given their unique current socio-political–technological abilities and their histories. Here, we discuss results from online face-to-face interviews undertaken with 33 U.S.-based climate experts and 30 India-based climate experts. Using qualitative grounded theory, we explore open-ended responses to questions related to mitigation and adaptation and find the following: (1) there is broad agreement among experts in both countries on the main mitigation solutions focused on the decarbonization of energy systems, but (2) there are a diversity of views between experts on what to prioritize and how to achieve it. Similarly, there is substantial agreement that adaptation solutions are needed to address agriculture, water management, and infrastructure, but there is a wide variety of perspectives on other priorities and how best to proceed. Experts across both countries generally perceived mitigation as needing national policies to succeed, while adaptation is perceived as more local and challenging given the larger number of stakeholders involved in planning and implementation. Our findings indicate that experts agree on the goals of decarbonization, but there was no consensus on how best to accomplish implementation. 

Abstract The impacts of Stratospheric Aerosol Injection (SAI) on the atmosphere and surface climate depend on when and where the sulfate aerosol precursors are injected, as well as on how much surface cooling is to be achieved. We use a set of CESM2(WACCM6) SAI simulations achieving three different levels of global mean surface cooling and demonstrate that unlike some direct surface climate impacts driven by the reflection of solar radiation by sulfate aerosols, the SAI‐induced changes in the high latitude circulation and ozone are more complex and could be non‐linear. This manifests in our simulations by disproportionally larger Antarctic springtime ozone loss, significantly larger intra‐ensemble spread of the Arctic stratospheric jet and ozone responses, and non‐linear impacts on the extratropical modes of surface climate variability under the strongest‐cooling SAI scenario compared to the weakest one. These potential non‐linearities may add to uncertainties in projections of regional surface impacts under SAI. 

Solar geoengineering, or deliberate climate modification, has been receiving increased attention in recent years. Given the far-reaching consequences of any potential solar geoengineering deployments, it is prudent to identify inherent biases, blind spots, and other potential issues at all stages of the research process. Here we articulate a feminist science-based framework to concretely describe how solar geoengineering researchers can be more inclusive of different perspectives and potentially contradictory conclusions, in the process illuminating potential implicit bias and enhancing the conclusions that can be gained from their studies. Importantly, this framework is an adoptable method of practice that can be refined, with the aim of conducting better research in solar geoengineering. As an illustration, we retrospectively apply this framework to a well-read solar geoengineering study (also led by the first author of this study), improving transparency by revealing its implicit values, conclusions made from its evidence base, and the methodologies that study pursues. We conclude with a set of recommendations for the geoengineering research community whereby more inclusive research can become a regular part of practice. Throughout this process, we illustrate how feminist science scholars can use this approach to study climate modeling.