Solar Radiation Management Research Articles

Avoiding atmospheric anarchy: Geoengineering as a source of interstate tension

Idealized climate modeling of geoengineering, notably including stratospheric aerosol injection, routinely frames the practice as the provision of a global public good in the absence of geopolitical context. This study argues that the situation of geoengineering governance within individual state governments combined with the technology’s substantial, unforeseeable consequences present a potential security dilemma that heightens tensions between states and risks conflict, including potential environmental catastrophe. Initially, there is a brief overview of geoengineering technology and the associated concerns before highlighting four elements of the technology that potentially generate interstate tension: the potential for independent action, low costs, ambiguity surrounding deployment, and the possibility of counter-geoengineering. This is followed by a discussion of four speculative geoengineering scenarios intended to illustrate the complexity of potential geoengineering impacts on states’ strategic thinking and risks associated with solar geoengineering. The article outlines four scenarios derived by isolating the availability of counter-geoengineering and the controllability of geoengineering as drivers for contesting strategic climate outcomes. The scenarios emphasize possible geopolitical tensions that could emerge under geoengineering, encouraging further study of potential geoengineering efforts within international security.

Simulated responses and feedbacks of permafrost carbon under future emissions pathways and idealized solar geoengineering scenarios

The carbon-rich northern high-latitude permafrost is a potential climate tipping point. Once triggered, its thawing and release of carbon dioxide and methane might unleash irreversible changes in the Earth’s climate system. We investigate the response of permafrost under three Shared Socioeconomic Pathways (SSPs) with no mitigation (SSP5-8.5), moderate mitigation (SSP2-4.5) and delayed mitigation (SSP5-3.4-OS), and three solar geoengineering scenarios applied to each experiment to prevent global warming from exceeding 2 °C above pre-industrial. The long-term negative emissions in SSP5-3.4-OS preserves much more frozen soil than SSP5-8.5, but shows nearly as much permafrost carbon loss this century as SSP2-4.5 due to its mid-century temperature overshoot. Solar geoengineering to meet the 2 °C target above pre-industrial effectively suppresses permafrost thawing and reduces subsequent carbon release from the soil. However, the carbon emission from permafrost still continues after the temperature is stabilized, due to the decomposition of thawed permafrost carbon. More solar insolation reduction is required to compensate the positive permafrost carbon feedback, which exerts greater impacts on the efficiency of solar geoengineering under a scenario with strong climate policy and lower carbon emissions.

Uncertainties and confidence in stratospheric aerosol injection modelling: a systematic literature review

Abstract Model projections performed to evaluate the efficacy and impacts of solar geoengineering interventions, such as Stratospheric Aerosol Injection (SAI), include multiple sources of uncertainty, namely scenario, model, and natural variability uncertainty. It is well accepted that a quantitative uncertainty assessment related to SAI modelling is required to provide robust and policy-relevant information on SAI. This study investigates how and to what extent articles using a climate modelling approach on SAI quantify and communicate uncertainty sources. We conducted a systematic literature review of a sample of 60 peer-reviewed articles in order to (i) analyse whether uncertainties were addressed, and if yes, which methods were used to characterize uncertainties, and (ii) study how the articles communicated assumptions and limits that contribute to the estimation of confidence in the used models and the resulting projections. We present statistics on the uncertainty quantification methods used in the articles and we discuss the vocabulary employed for conveying these uncertainties and model confidence. In the studied article sample, the attention paid to uncertainty estimations in the SAI literature increased with time, and overall, uncertainties were treated using a variety of methods. Model confidence was not always explicitly communicated as the models used are already tested in the literature and their strengths and weaknesses are known to the community although this is often implicit. Our results show that it is currently difficult to perform global, quantitative assessments of uncertainty related to SAI research, in line with recent review reports on solar geoengineering.

Solar Geoengineering, Learning, and Experimentation

Solar Geoengineering, Learning, and Experimentation

Like diamonds in the sky? Public perceptions, governance, and information framing of solar geoengineering activities in Mexico, the United Kingdom, and the United States

ABSTRACT Solar geoengineering (also known as solar radiation modification) is garnering more attention (and controversy) among media and policymakers in response to the impacts of climate change. Such debates have become more prominent following the first-ever field trials of stratospheric aerosol injection (SAI) in 2022. How the lay public perceives solar geoengineering remains unclear, however. We use nationally representative samples (N = 3013) in Mexico, United States, and United Kingdom to examine public perceptions of risks and benefits, support, and policy preferences. We also employ an information-framing design that presented individuals with media-style reports on SAI activities differing along three dimensions: location, actor, and scale and purpose. Support for SAI is found to be generally higher in Mexico; perceptions of risks and benefits do not differ between countries. Information about SAI activities has a limited effect. There is evidence that activities conducted by universities receive more support than those by start-up companies.

An investigation of the relationship between tropical monsoon precipitation changes and stratospheric sulfate aerosol optical depth

Abstract Stratospheric aerosol geoengineering (SAG) is one of the several solar geoengineering options that have been proposed to counteract climate change. In the case of SAG, reflective aerosols injected into the stratosphere would reflect more sunlight and cool the planet. When assessing the potential efficacy and risks of SAG, the sensitivity of tropical monsoon precipitation changes should be also considered. Using a climate model, we perform several stylized simulations with different meridional distributions and amounts of volcanic sulfate aerosols in the stratosphere. Because tropical monsoon precipitation responds to global mean and interhemispheric difference in radiative forcing or temperature, we quantify the sensitivity of tropical monsoon precipitation to SAG in terms of two parameters: global mean aerosol optical depth (GMAOD) and interhemispheric AOD difference (IHAODD). For instance, we find that the simulated northern hemisphere monsoon precipitation has a sensitivity of −1.33 ± 0.95% per 0.1 increase in GMAOD and −7.62 ± 0.27% per 0.1 increase in IHAODD. Our estimated precipitation changes in terms of the two sensitivity parameters for the global mean precipitation and for the indices of tropical, northern hemisphere, southern hemisphere and Indian summer monsoon precipitation are in good agreement with the model simulated precipitation changes. Similar sensitivity estimates are also made for unit changes in global mean and interhemispheric differences in effective radiative forcing and surface temperature. Our study based on planetary energetics provides a simpler framework for understanding the tropical monsoon precipitation response to external forcing agents.

The laureate as public intellectual: Paul Crutzen and the politics of the environment

This article argues that Nobel Prize-winning chemist Paul Crutzen (1933–2021) spoke in the name of science over several decades as a public intellectual who shaped research fields, environmental policy, and public understanding of the environment. It analyses the atmospheric chemist as a case study to explain the formation and influence of the scientist as a public intellectual, tracing the trajectory of his public career, focusing on his critical contributions to four significant episodes in modern environmental politics: his warnings in the 1970s of damage to the ozone layer, his catalysing impact on the nuclear winter debates of the 1980s, his turn-of-the-century conceptualization of the Anthropocene, and his late-career advocacy of solar geoengineering. It undertakes a textual analysis of four agenda-setting articles to demonstrate how Crutzen performed the public intellectual functions of testing the assumptions of scientific and policy elites, and framing new ways of understanding environmental problems. It argues that he was a technocratic public intellectual who viewed scientists as guides for society to understand and respond to human-caused environmental threats. As climate change becomes a defining issue of the twenty-second century, Crutzen’s career illuminates the potential and limitations of the technocratic public intellectual to shape global environmental politics.

Harnessing the characteristic of compound parabolic concentrators for directional concentration of emitted thermal radiation and solar shielding in building-integrated radiative cooling

Radiative sky cooling (RC) is a promising solution for meeting the growing cooling demands by passively dissipating waste heat into frigid outer space. However, current RC systems suffer from low cooling power density and limited installation flexibility, impeding their effective application as building cooling strategies. To overcome these challenges, a novel concentrated RC system coupled with a compound parabolic concentrator (CPC) is proposed and experimentally studied. The objective is to investigate the effectiveness of the CPC in enhancing the cooling capability of the RC system and the feasibility of achieving all-day RC in unfavorable working conditions when integrated with building roofs. During nighttime experiments in the humid Nottingham region, the CPC-RC system exhibited an average emitter temperature that was 5.83 °C lower than the ambient temperature, representing a 30 % and 13.6 % improvement in RC performance compared to the flat-RC system and trapezoidal-concentrated RC system, respectively. The Photopia optical software simulation indicates that when the modules are tilted to the north, the CPC functions as a solar shield, effectively limiting solar radiation reaching the emitter surface, which is advantageous for conducting daytime RC experiments. In the daytime experiment, the emitter temperature of the CPC-RC module in anti-sunward group was still 1.59 °C lower than the ambient temperature and 5.49 °C lower than that of flat-RC module. At night, the CPC-RC module of the three placement groups all showed the highest RC effect in the same group. The average emitter temperature of the CPC-RC module in the horizontal placement group is 0.6 °C lower than that of the flat RC module. This novel CPC-RC scheme presents a new energy-saving strategy for buildings and showcases its potential for achieving 24-hour RC when integrated into anti-sunward roofs.

The Indonesian Throughflow circulation under solar geoengineering

Abstract. The Indonesia Throughflow (ITF) is the only low-latitude channel between the Pacific and Indian oceans, and its variability has important effects on global climate and biogeochemical cycles. Climate models consistently predict a decline in ITF transport under global warming, but it has not yet been examined under solar geoengineering scenarios. We use standard parameterized methods for estimating the ITF – the Amended Island Rule and buoyancy forcing – to investigate the ITF under the SSP2-4.5 and SSP5-8.5 greenhouse gas scenarios and the geoengineering experiments G6solar and G6sulfur, which reduce net global mean radiative forcing from SSP5-8.5 levels to SSP2-4.5 levels using solar dimming and sulfate aerosol injection strategies, respectively. Six-model ensemble-mean projections for 2080–2100 show reductions of 19 % under the G6solar scenario and 28 % under the G6sulfur scenario relative to the historical (1980–2014) ITF, which should be compared with reductions of 23 % and 27 % under SSP2-4.5 and SSP5-8.5. Despite standard deviations amounting to 5 %–8 % for each scenario, all scenarios are significantly different from each other (p<0.05) when the whole 2020–2100 simulation period is considered. Thus, significant weakening of the ITF occurs under all scenarios, but G6solar more closely approximates SSP2-4.5 than G6sulfur does. In contrast with the other three scenarios, which show only reductions in forcing due to ocean upwelling, the G6sulfur experiment shows a large reduction in ocean surface wind stress forcing accounting for 47 % (38 %–65 % across the model range) of the decline in wind + upwelling-driven ITF transport. There are also reductions in deep-sea upwelling in extratropical western boundary currents.

Correcting for artificial heat in coupled sea ice perturbation experiments

A common approach to assessing how polar amplification affects lower latitude climate is to perform coupled ocean-atmosphere experiments in which sea ice is perturbed to a future state. Recent work with a simple 1-dimensional energy balance model (EBM) shows that sea ice perturbation experiments impose an artificial heat flux on the climate system. We explore this effect in a broader range of models and suggest a technique to correct for the artificial heat post-hoc. Our technique successfully corrects for artificial heat in the EBM, and a possible generalization of this approach is developed to correct for artificial heat in an albedo modification experiment in a comprehensive earth system model. Generalizing this technique to sea ice perturbation methodologies that employ a ‘ghost flux’ seen only by the sea ice model would require a better understanding of the effect of ghost fluxes on the surface energy budget. Applying the correction to the comprehensive albedo modification experiment, we find stronger artificial warming than in the EBM. Failing to account for the artificial heat also leads to overestimation of the climate response to sea ice loss (SIL), and can suggest false or artificially strong ‘tugs-of-war’ between low latitude warming and SIL over some fields, for example Arctic surface temperature and zonal wind.

Development of LoRaWAN-based IoT system for water quality monitoring in rural areas

This article delineates the design and deployment of an innovative real-time water quality monitoring system tailored for rural regions, focusing on monitoring the water resource quality parameters. We propose a solar-powered, waterproof, portable, and Internet of Things (IoT)-enabled solution that leverages Long Range Wide Area Network (LoRaWAN) technology. Central to this system is a sophisticated LoRa node outfitted with an array of sensors for capturing key water parameters, such as pH, total dissolved solids, turbidity and temperature. A conjunction of an Arduino microcontroller-based board and a LoRa shield facilitates real-time data capture and transmission to a LoRaWAN gateway. The acquired data is transmitted to The Things Network server, which is seamlessly integrated with a ThingSpeak web-based IoT server and ThingView mobile applications. We incorporate a solar cell with a solar shield to ensure sustainable energy provision for powering the entire system through a rechargeable battery. This allows users to access vital water quality information online simultaneously and continuously in real-time. As a testament to its robustness, the system was empirically tested at Gambang Lake to demonstrate its effectiveness, functionality, buoyancy, and waterproof capabilities. We further validated the results by comparing them with laboratory sample analysis findings. Experimental evaluations confirmed the system's reliability, as evidenced by the strong agreement between the water conditions measured using our solution and those obtained from laboratory instruments. Moreover, our system efficiently and remotely updated data across multiple IoT platforms using the LoRa radio interface over the LoRaWAN gateway.

Climate Changes through Data Science: Understanding and Mitigating Environmental Crisis

Climate change represents an urgent environmental crisis with far-reaching risks to ecosystems and human communities worldwide. Rapid development of mitigation strategies and solutions is imperative but relies profoundly on advancements in detection, attribution, and prediction derived from climate data analytics. This paper examines the growing role of data science in not only quantifying anthropogenic climate change but also informing impact assessment and targeted intervention across climate-sensitive sectors. First, we survey established and emerging techniques for climate characterization, including machine learning applications on Earth systems data. Next, we discuss how sophisticated climate models alongside statistical analysis of multi-domain datasets—from migration patterns to crop yields—deepens scientific comprehension of climate change repercussions. Building on these insights, we spotlight data-enabled solution paradigms enabling smart climate action, ranging from high-resolution climate risk mapping, emissions reductions via optimized renewable energy infrastructure, to global warming suppression via solar radiation management. However, we also carefully examine the practical limitations hindering deployment and the ethical concerns posed by certain climate intervention proposals. Ultimately, while data science delivers powerful tools for climate change detection, attribution, and response, this paper underscores how continued climate data gathering alongside cross-disciplinary collaboration is vital to overcome analytical uncertainties, implementation barriers, and moral objections as we work to avert profound environmental breakdown.

Systemic risks and solar climate engineering research. Integrating technology ethics into the governance of systemic risks

The paper explores how the framework of systemic risks can help govern the risks imposed through solar climate engineering research. The central argument is that a systemic perspective of risk is a useful tool for analysing and assessing the risks imposed through Stratospheric Aerosol Injection (SAI) research. SAI is a form of climate engineering that could cool the planet by enhancing its albedo through the injection of aerosols into the stratosphere. Researching such a technology creates systemic risks with a strong sociotechnical component. This component consists of the potential societal harm that a developing or new technology might cause to existing norms, values, institutions, and politics. The systemic risk framework is a valuable heuristic for this case, given the complex interdependencies of societal systems, infrastructures, markets, etc. At the same time, the systemic risk framework can be enhanced through the inclusion of a more robust and reflected ethical considerations on technological risks. Consequently, this article seeks to supplement the systemic risk governance framework with insights from technology ethics. Specifically, the paper offers an ethically reflective conception of societal value dynamism and stakeholder engagement and participation, tying it to existing systemic risk governance approaches.

How may solar geoengineering impact global prospects for climate change mitigation?

Abstract As disruptions from climate change increase, so will the urgency to find shorter-term approaches to ameliorating its harms. This may include calls to implement solar geoengineering, an approach to cooling the planet by reflecting incoming sunlight back to space. While the exact effects of solar geoengineering are still highly uncertain, physical science to date suggests that it may be effective at reducing many aspects of climate change in the short term. One of the biggest concerns about solar geoengineering is the extent to which it may interfere with crucial emissions reductions policies, i.e. mitigation. There are multiple channels by which geoengineering could alter mitigation pathways, both financial and behavioural. Here we define three such linkages and present the evidence available to constrain their potential magnitudes. Because solar geoengineering is not a substitute for mitigation, policies to develop or implement technologies that could be used to carry it out should be designed to accentuate its complementary nature to mitigation and deter the possibility it is used to delay decarbonizing the economy.

Exposure to climate change information predicts public support for solar geoengineering in Singapore and the United States

Solar geoengineering is a controversial climate policy measure that could lower global temperature by increasing the amount of light reflected by the Earth. As scientists and policymakers increasingly consider this idea, an understanding of the level and drivers of public support for its research and potential deployment will be key. This study focuses on the role of climate change information in public support for research and deployment of stratospheric aerosol injection (SAI) in Singapore (n = 503) and the United States (n = 505). Findings were consistent with the idea that exposure to information underlies support for research and deployment. That finding was stronger in the United States, where climate change is a more contentious issue, than in Singapore. Cost concern was negatively related to support for funding and perceived risk was negatively related to support for deployment. Perceived government efficacy was a more positive predictor of support for funding in Singapore than in the United States. Additionally, relatively low support for local deployment was consistent with a NIMBY mindset. This was the first study to quantify the role of climate change information in SAI policy support, which has practical implications for using the media and interpersonal channels to communicate about SAI policy measures.

Uncovering the Drivers and Regional Variability of Cotton Yield in China

Cotton (Gossypium hirsutum L.) is an economically important crop in China, and responses of cotton yield in different regions to separate and joint changes in natural and anthropogenic factors are the foundation for sustainable development under climate change; however, these remain uncertain. Here, we analyzed the spatiotemporal evolution and heterogeneity of cotton cultivation in China from 1949 to 2020 and quantified the response of cotton yield variations in air temperature, precipitation, solar radiation, disaster, and crop management factors between 1980 and 2020 by the Pettitt mutation test and GeoDetector. Multi-site meteorological data were obtained from different cotton-growing regions and corresponding cotton yield and phenology data were obtained from provinces. Our findings showed that all 17 Chinese provinces experienced advancements in cotton yield. Relative to 1949–1967, China’s cotton production in 2007–2020 increased by 400% while cotton yield increased by 420%. Increases in factors such as minimum temperature (TES), average temperature (ADT), effective accumulated temperature (EAT), precipitation (PP), daily solar radiation (SSD), non-farm employment opportunities (O), disaster area (D), geographic region (GEO) and agricultural technologies like fertilizer usage (F), genetically modified varieties (Bt), and mechanized farming (M) have contributed to the enhanced cotton yield. The importance of single factors influencing cotton yield of China in descending order was as follows: F > Bt > M > GEO > EAT > O > PP > TES > ADT > SSD > D. However, the effects of different climatic and agriculture technological elements on cotton yield are spatially heterogeneous by region, and the combined effects of those elements are higher than those of single elements. The effects of driving factors vary across regional scales. The most significant interaction effects were observed between chemical fertilizer use and other driving factors. Specifically, the interaction between F and TES has the greatest explanatory influence in Northwest China. Our findings provide a reference for the development of more accurate adaptation strategies and management measures in different regions. We recommend that policymakers prioritize measures such as improving climate-resilient cotton varieties, encouraging technological advancements, and implementing policies that support equitable distribution of cultivation.

Natural Disasters are Not All Natural

For a half century, the military has been developing technologies to turn climate and extreme environmental phenomena into weapons.
 This study is a literature review, which was conducted with the following objectives: 1/ to expose the known powerful military technologies of climate and environmental modification; 2/ to emphasize that many extreme environmental events observed in recent years coincide with the effects that these military technologies are able to generate; 3/ to analyze the conclusions of the Intergovernmental Panel on Climate Change (IPCC) on the origins of the increase in natural disasters.
 The literature used comes from official sources: peer-reviewed scientific articles (except one); patents; intergovernmental organizations; military documents; policy documents; university documents; national newspapers; news agencies; writings by respected scientists in their fields.
 Results of the literature review reveal that HAARP (High-frequency Active Auroral Research Program), the most powerful ionospheric heater in operation, is able to influence climate. High-power electromagnetic pulses in the earth's crust, produced by a mobile magneto-hydrodynamic generator, is a technique developed since the 1970s to trigger earthquakes. Directed energy weapons, a real technology, can ignite destructive fires at range. For several years, official documents report effects on health and the environment similar in all aspects to those that would be detected if solar geoengineering by stratospheric aerosol injection, a climate-altering technique, was used. Due to numerous biases and a lack of objectivity, the IPCC's arguments on the causes of the growth in extreme environmental phenomena (heat and cold waves, storms, hurricanes, tornadoes, droughts, floods, wildfires, air pollution, etc.) are flawed. The solar hypothesis isn't appropriate either, given its low activity for several years.
 In conclusion, the use of military climatic and environmental modification technologies appears to be the most relevant explanation to understand the increase in natural disasters over the last 20 years.

Attention, sentiments and emotions towards emerging climate technologies on Twitter

Public perception of emerging climate technologies, such as greenhouse gas removal (GGR) and solar radiation management (SRM), will strongly influence their future development and deployment. Studying perceptions of these technologies with traditional survey methods is challenging, because they are largely unknown to the public. Social media data provides a complementary line of evidence by allowing for retrospective analysis of how individuals share their unsolicited opinions. Our large-scale, comparative study of 1.5 million tweets covers 16 GGR and SRM technologies and uses state-of-the-art deep learning models to show how attention, and expressions of sentiment and emotion developed between 2006 and 2021. We find that in recent years, attention has shifted from general geoengineering themes to specific GGR methods. On the other hand, there is little attention to specific SRM technologies and they often coincide with conspiracy narratives. Sentiments and emotions in GGR tweets tend to be more positive, particularly for methods perceived to be natural, but are more negative when framed in the geoengineering context.

Photosynethics: a groundwork for being with the light

ABSTRACT It has been suggested that we turn to solar geoengineering to counter global warming, which would consequently transform the relationship of terrestrial plant-life to the sun. This is an article not about geoengineering as such, but instead what is called photosynethics, or, thinking about our moral relationship to the light – in particular, as it is mediated by plants. Working from within but then extending the idea of responsibility found in the work of Emmanuel Levinas, it is argued here that, since the plant cultivates the conditions of life on earth by photosynthesis, its relationship to the sun is then a relation of giving to others that is properly moral. The plant’s existence is an exposure so out of kilter with human ways of understanding existence that it interrupts our own and brings us into a relation of responsibility. It is concluded that rather than redirecting the sun’s radiation, we should turn to plants to reconsider how we live with the light on a heating planet. This first means separating moral responsibility from human vision so that we might encounter light on its own terms, and not simply as an element of rationality or sentiment or discipline.

International Climate Agreements under the Threat of Solar Geoengineering

International Climate Agreements under the Threat of Solar Geoengineering