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*This item and others will be in the monthly “Solar Geoengineering Updates Substack” newsletter:* https://solargeoengineeringupdates.substack.com/ ----------------------------------------------------------------- *By Matthias Honegger* *05 October 2023. * The tiny sliver of atmosphere shining light blue as it envelopes our only planet and home. As the Earth continues to warm, scientists are exploring ways to combat climate change. One of these — so far largely ignored as outlandish — is called Solar Radiation Modification (SRM). In basic terms, SRM would work by reflecting some of the Sun’s rays back into space to cool down our planet. It sounds simple, but it could prove powerful in its effects on climate — global and local. Let us break down what we presently expect to be key effects of SRM on the climate: 1. Soften the Heat: SRM could help reduce both global temperatures and extreme heat events. That means fewer dangerously hot days in cities and towns all over the world. 2. Balancing the Rain: By using SRM, we might see a decrease in the changes to rainfall patterns, including those intense rainfalls that lead to floods. 3. Preserving Ice and Cold Regions: Our polar ice caps and glaciers are in danger due to the warming planet. SRM could help in slowing down their melting. This is crucial, as melting ice can lead to rising sea levels and other environmental issues. 4. Protecting Natural Systems: Some natural processes, like the circulation of ocean currents and the frozen state of vast regions known as permafrost, are at risk due to climate change. SRM might help delay or even prevent these changes. Importantly, keeping the permafrost frozen is crucial, as its melting can release methane, a potent greenhouse gas. In summary, SRM could act as a protective shield, potentially offering a way to balance out some of the harms of a warming planet. As with all solutions, it is important to understand it fully and consider the wide range of its implications — we start here by going through the natural science understanding of it. 1. Soften the Heat In a world where heatwaves are becoming more frequent and prolonged, the need to regulate our planet’s temperature is more pressing than ever. SRM, as its name suggests, manages the sun’s rays, reflecting a portion of them back into space. This means fewer of those rays are warming our Earth, helping counteract the rise in global temperatures. How Does It Work? Imagine the Earth enveloped in a protective reflective shield. SRM functions in a similar way. By using techniques such as introducing reflective particles into the atmosphere or modifying cloud properties, SRM can effectively scatter sunlight, preventing a portion from reaching and heating our planet’s surface. Why It Matters The world is experiencing a rise in temperature-related events, from stifling urban heat islands to extensive droughts. As global temperatures increase, these extreme events are becoming more commonplace and are affecting both ecosystems and communities. SRM’s potential to lower global temperatures does not just mean more comfortable summer days. It signifies a chance to reduce the occurrence of heat-related illnesses and deaths, minimize stress on ecosystems sensitive to temperature changes, and help maintain agricultural yields that can be affected by excessive heat. Challenges and Considerations While the promise of SRM is alluring, it is crucial to understand that it does not address the root cause of global warming, which is the accumulation of greenhouse gases in our atmosphere. Additionally, there are potential side effects and uncertainties tied to its large-scale deployment, which researchers are actively investigating. However, there is clear evidence that SRM holds the potential to soften the heat on planet and people — against the relentless climb of global temperatures. 2. Balancing the Rain The gentle patter of rain on a rooftop can be comforting, but when that patter turns into a deluge, it spells trouble. With climate change, we are witnessing not just a rise in temperatures but also shifts in rainfall patterns. Heavy downpours, floods, and prolonged droughts are becoming more frequent. Enter SRM, which offers potential in not just cooling our planet but also moderating erratic precipitation. How Does It Work? SRM’s primary function is to reflect some of the Sun’s rays away from Earth. This action does not just lower temperatures but can also influence atmospheric conditions, which in turn affect precipitation. By regulating the amount of solar energy entering the atmosphere, evidence from modelling studies of SRM clearly suggest that partial counteracting of warming would bring about a more balanced and predictable rainfall patterns in all world regions. Why It Matters Rainfall, as any farmer will attest, is crucial. It affects crop yields, replenishes reservoirs, and impacts ecosystems. But with climate change, what was once predictable is now erratic. Some regions are experiencing torrential downpours leading to flash floods, while others face prolonged dry spells, depleting water sources and affecting agriculture. The potential of SRM to bring a semblance of balance to this unpredictability could be a game-changer. Challenges and Considerations However, as with any intervention, SRM comes with its own set of challenges. Precipitation is a complex process, affected by a myriad of factors. While SRM may help across continents on net, some harmful events will naturally still occur. When this occurs, it will be challenging to deal with such harm to ecosystems or human communities, as the rain, which previously seemed unaffected by human action now turns into something that humans are influencing. In summary, SRM’s overall potential in balancing the rain is another very promising effect. But should SRM be pursued, it is essential to tread carefully, while addressing the new sets of policy challenges that emerge. 3. Preserving Ice and Cold Regions The pristine white expanses of polar ice caps and glaciers have for centuries been a testament to Earth’s chilling beauty and climatic balance. However, these icy regions are now under threat, facing rapid degradation due to escalating global temperatures. SRM emerges on the horizon as a potential intervention to protect these frigid zones. How Does It Work? By reducing the amount of solar energy warming the Earth, SRM can have a pronounced effect on temperature-sensitive regions like the poles. Its use could slow down the melting rate of glaciers and ice caps, providing a buffer against the devastating impacts of their complete degradation. Why It Matters The stakes are incredibly high. Polar ice caps and glaciers play a pivotal role in regulating global sea levels and global weather patterns. As they melt, vast amounts of water flow into our oceans, contributing to rising sea levels that threaten coastal cities and habitats worldwide. The heating accelerates as the reflective nature of ice — its albedo effect — helps in naturally reflecting sunlight. As more ice melts, darker ocean waters are exposed, which absorb more heat, creating a feedback loop of accelerating melt. The heating of polar regions in return destabilizes global weather patterns, at times letting polar cold fronts leap much further and at other times causing prolonged heat and dry periods in lower latitudes. Polar regions are also home to unique wildlife. SRM could thus counteract global weather destabilization from polar ice melt, sea level rise, and slow (and in some cases perhaps even halt) the dramatic transformation of polar ecosystems. Challenges and Considerations Of course, while SRM provides hope, it is not without its complications. Implementing such a solution without understanding its full implications could be risky. For instance, while SRM might be very effective at reducing melting in one region, it might not have the same efficacy elsewhere and one should not simply rely on such effects without control. There is also the concern that once SRM is discontinued or if there is an over-reliance on it, rapid melting could ensue, leading to sudden and unpredictable impacts. In conclusion, SRM holds potential to saveguard our world’s cold regions, granting them a reprieve from the relentless heat and indirectly limiting the global destabilization of weather patterns. But this is a delicate dance, and ensuring the right steps are taken is crucial for the well-being of our planet. 4. Protecting Natural Systems Earth’s intricate web of natural processes, from the rhythmic ebb and flow of ocean currents to the frozen silence of vast permafrost regions, is at the heart of our planet’s health and balance. Disturbingly, these systems are becoming increasingly vulnerable due to the pressing issue of climate change. SRM presents a glimmer of hope, potentially offering protection to these delicate mechanisms. How Does It Work? The temperature regulation from SRM does not only provide relief to hotspots or rainy regions but also halts the destabilization of ecosystems and other natural systems such as ocean currents, permafrost, and the vast amounts of the powerful greenhouse gas methane these frozen soils are harbouring. In this manner, SRM can have a profound effect also on the root-cause of climate change: greenhouse gas concentrations in the atmosphere. Why It Matters The importance of safeguarding these natural systems can hardly be overstated. Consider the Atlantic Meridional Overturning Circulation (AMOC), a significant component of Earth’s climate system, responsible for redistributing heat across our planet. If disrupted, the consequences on climate patterns, agricultural production and other conditions of human life could be drastic. Similarly, permafrost regions hold vast amounts of methane. When thawed, they can release this methane, which would dwarf our current efforts in cutting our greenhouse gas emissions. This could amplify global warming significantly. SRM’s potential to keep these regions frozen thus could prove to be a crucial layer of protection against runaway climate change. Challenges and Considerations As promising as SRM appears, it is essential to proceed with caution. The Earth’s natural systems are complex and interconnected. While the beneficial effects from SRM returning temperature and precipitation patterns closer to our historical values appears evident, it could nonetheless also harbour undesired effects — especially in the realm of politics not considered here. There may also be ethical considerations associated with relying heavily on a technological solution as some fear this would distract from the global transformation to a climate-neutral way of life. In conclusion, while there is clear evidence that SRM can potentially offer protection to some of Earth’s most vital natural systems, its implementation requires a blend of scientific rigour, ethical deliberation, and global collaboration. As stewards of this planet, our choices today will shape the legacy we leave for generations to come. Conclusion: Navigating the Future with SRM In the face of escalating global temperatures and their multifaceted impacts, the world stands at a pivotal crossroads. SRM emerges — at least judging by the science — as a promising additional type of climate action, offering much-needed relief across a range of increasingly disconcerting climate-related challenges. From softening the blow from scorching heatwaves and limiting an increase in erratic rainfall to safeguarding the invaluable ice caps and protecting the planet’s intricate natural systems, the scope of SRM is vast and impactful. However, as with all significant interventions, SRM comes with its complexities. It must not be confused for a silver bullet as it can only be an additional tool in the broader climate action toolbox and presently with insufficient evidence. While it may provide temporary relief from some of the symptoms of global warming, the root causes, primarily the escalating levels of greenhouse gases, continuously require the full attention of the international community. The — uncertain — potential of SRM underscores the importance of balance in pursuing increasingly comprehensive research efforts, ethical considerations, and international collaboration toward a shared understanding and broadly supported decisions should its use be considered in the future. The Earth’s systems and global politics are deeply intertwined, and any action in one area can ripple across the planet. It is thus crucial to approach this topic with care and to strive toward a broad understanding and a holistic view of our human and planet’s needs. *Note: This simplified guide did away with convoluted explanations and literature references normally included in more technical texts. Should there be demand for it I would be happy to develop a more detailed version including key references to underlying scientific evidence.* *Source: Medium* -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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