Why is it in the news?

• A new study proposes that spraying millions of tonnes of diamond dust into the Earth’s upper atmosphere annually could help combat global warming.
• While this idea may seem far-fetched, it’s not the first time such a solution has been suggested; previous alternatives included compounds like sulphur, calcium, aluminium, and silicon.
• The underlying concept is to scatter materials that reflect solar radiation back into space, thereby preventing it from reaching Earth. Additionally, proposals for space-based mirrors have emerged.
• These geoengineering approaches, particularly in solar radiation management (SRM), have been researched extensively but have yet to be implemented.

Context for Geoengineering: The Problem of Rising Temperatures

• Current measures to mitigate global warming have proven insufficient, with global temperatures continuing to rise and greenhouse gas emissions remaining high.
• In 2022, global temperatures were approximately 1.2 degrees Celsius above pre-industrial levels, with 2023 seeing an increase of around 1.45 degrees Celsius.
• Meeting the Paris Agreement’s target of limiting warming to below 1.5 degrees Celsius is becoming increasingly challenging. To achieve this goal, global emissions must be reduced by at least 43% from 2019 levels by 2030, but existing efforts are projected to yield only a 2% reduction.
• Consequently, scientists are exploring radical technological solutions that can deliver substantial results quickly, making geoengineering a potential option.

What is Geoengineering?

• Geoengineering refers to large-scale attempts to alter the Earth’s climate system to mitigate the impacts of global warming. One of the main strategies being explored is solar radiation management (SRM), which involves deploying materials in space to reflect incoming solar radiation.
• Another approach is carbon dioxide removal (CDR) technologies, which include carbon capture and sequestration (CCS). While CCS is currently the only method being implemented, it captures carbon dioxide from industrial sources and stores it underground to reduce emissions.
• There are also methods such as carbon capture and utilization (CCU), which repurpose captured carbon for industrial processes.

Potential for Solar Radiation Management

• SRM is considered the most ambitious form of geoengineering, drawing inspiration from natural volcanic eruptions that release sulphur dioxide, creating sulphate particles that reflect sunlight. For instance, the 1991 eruption of Mount Pinatubo significantly reduced global temperatures by about 0.5 degrees Celsius.
• Researchers are investigating various materials, including sulphur dioxide, calcium carbonate, and sodium chloride, to replicate this effect.
• The recent study evaluated seven compounds and concluded that diamonds are the most effective for this purpose. However, achieving a temperature reduction of 1.6 degrees Celsius would require approximately five million tonnes of diamonds to be sprayed into the atmosphere annually.

Challenges and Concerns

• Despite its theoretical feasibility, SRM faces significant technological and financial challenges for implementation. Manipulating natural processes on a large scale may result in unforeseen consequences, impacting global and regional weather patterns and rainfall distribution.
• Ethical concerns also arise, as altering sunlight could affect agriculture, ecosystems, and biodiversity, potentially harming various life forms.
• Additionally, while CCS technologies are deemed essential for meeting climate goals, a study by researchers from Oxford University and Imperial College highlighted the impracticality of relying solely on these methods.
• They estimate that primarily using CCS to meet climate objectives by 2050 could cost at least US$30 trillion more than focusing on renewable energy and energy efficiency. Furthermore, there may be insufficient safe underground sites for carbon storage.
• Given the visible impacts of global warming, the adoption of CCS options seems inevitable, as no feasible scenarios exist for achieving the 1.5-degree or 2-degree Celsius targets without incorporating CCS and CDR technologies.