<h4>Introduction to Geoengineering</h4><p><strong>Geoengineering</strong> refers to large-scale interventions designed to deliberately alter the Earth's climate system. Its primary goal is to counteract the adverse effects of <strong>global warming</strong>, offering a potential, albeit controversial, pathway to climate mitigation.</p><div class='key-point-box'><p>A recent study proposed spraying millions of tonnes of <strong>diamond dust</strong> annually into the Earth’s upper atmosphere. This novel approach aims to lower the planet’s temperature by an estimated <strong>1.6°C</strong>, potentially offering a more effective solution for <strong>Solar Radiation Management (SRM)</strong> than previously considered materials.</p></div><p>Achieving global climate targets requires a substantial <strong>43% reduction</strong> in emissions from 2019 levels by <strong>2030</strong>. Current global efforts, however, are projected to yield only a modest <strong>2% decrease</strong>, highlighting the urgency for innovative and impactful solutions.</p><h4>Classification of Geoengineering Approaches</h4><p>Geoengineering primarily involves two distinct approaches, each targeting a different aspect of climate change mitigation:</p><ul><li><strong>Solar Radiation Management (SRM)</strong>: Focuses on reflecting sunlight back into space.</li><li><strong>Carbon Dioxide Removal (CDR)</strong>: Aims to remove existing carbon dioxide from the atmosphere.</li></ul><h4>Solar Radiation Management (SRM)</h4><p><strong>SRM</strong> techniques involve deploying materials or modifying surfaces to reflect a portion of incoming solar rays away from the Earth. This method seeks to cool the planet by reducing the amount of solar energy absorbed by the Earth's surface.</p><div class='info-box'><p>While still largely conceptual, SRM draws inspiration from natural phenomena. For instance, the <strong>1991 eruption</strong> of <strong>Mount Pinatubo</strong> in the Philippines reportedly reduced Earth's average temperature by approximately <strong>0.5°C</strong> in that year, demonstrating the potential cooling effect of atmospheric aerosols.</p></div><h4>Carbon Dioxide Removal (CDR) Techniques</h4><p><strong>CDR</strong> techniques are focused on the long-term reduction of atmospheric <strong>Carbon Dioxide (CO₂)</strong> levels. These methods directly address the root cause of global warming by removing greenhouse gases from the air.</p><ul><li><strong>Carbon Capture and Sequestration (CCS)</strong>: This is the main CDR method currently in practice. It involves capturing <strong>CO₂ emissions</strong> from industrial sources and storing them underground in suitable geological formations, preventing their release into the atmosphere.</li><li><strong>Direct Air Capture (DAC)</strong>: This technique extracts <strong>CO₂</strong> directly from ambient air using large devices, often referred to as “artificial trees.” The captured CO₂ can then be stored or utilized for other purposes.</li></ul><div class='key-point-box'><p><strong>DAC</strong> holds significant potential benefits as it can address historical <strong>CO₂ emissions</strong> already present in the atmosphere, not just new emissions. However, it also faces substantial technological and economic challenges.</p></div><ul><li><strong>Carbon Capture, Utilization and Storage (CCUS)</strong>: This approach combines carbon capture with the utilization of some of the captured <strong>CO₂</strong> in various industrial processes. The remaining portion is then stored underground.</li></ul><h4>Related Challenges</h4><p>The provided source material mentions 'Related Challenges' but does not detail them. Geoengineering, in general, faces significant challenges including ethical considerations, governance issues, potential unintended environmental side effects, and high implementation costs.</p>