What is Geo engineering?

A new study has argued that spraying millions of tonnes of diamond dust in the Earth’s upper atmosphere every year could help cool down the Earth and combat global warming. It might appear to be a rather outlandish claim, but this is not the first time such a solution has been proposed.

• Several other compounds, such as sulphur, calcium, aluminium, and silicon, have been suggested previously for doing the same job. The central idea here is to scatter material that can reflect solar radiation into Space and prevent it from reaching Earth, thereby cooling down the planet. The installation of space-based mirrors has also been proposed.
• Such solutions, called geo-engineering(more specifically solar radiation management), have been under study for quite some time, though they have never been tried. The new study published in Geophysical Research Letters found that diamonds would be more effective in doing the job than any other material previously considered.

Context for geoengineering: The problem of rising temperatures:

• The measures employed so far to halt global warming have proved inadequate. Global temperatures have continued to rise and emissions of greenhouse gases, the main reason for the warming, have not been curbed, maintaining an upward trend in 2022.
• Scientists estimate that even if global emissions magically dropped to zero now, it would be decades before temperatures stabilise and come down.

Global temperatures are already about 1.2 degrees Celsius higher than pre-industrial times (between 1850-1900), with 2023 being around 1.45 degrees Celsius warmer. The world cannot restrict this rise below 1.5 degrees Celsius, one of the targets mentioned in the 2015 Paris Agreement, though some theoretical scenarios still allow for the possibility.

• The bare minimum for achieving the target requires the world to cut its emissions by at least 43 per cent from the 2019 levels, by 2030. Ongoing and promised actions, however, will likely result in a reduction of just two per cent by 2030. As a result, scientists have been looking for radical technology solutions that achieve dramatic results within a short period, even if only temporarily. Geoengineering offers such options.

What is Geoengineering?

Geoengineering refers to any large-scale attempt to alter the Earth’s natural climate system to counter the adverse impacts of global warming. Solar Radiation Management (SRM), in which materials are proposed to be deployed in Space to reflect incoming solar rays and prevent them from reaching Earth, is one of the two broad geoengineering options being explored.

• Then there are Carbon Dioxide Removal (CDR) technologies, which include Carbon Capture and Sequestration (CCS). While they offer quick-fix solutions for reducing emissions or temperatures, they are not particularly viable.
• The only method being tried out in practice is CCS. Carbon dioxide emitted, from industry or power plants, is “captured” at source and deposited deep below the Earth’s surface in suitable geological formations for long-term storage. Since carbon dioxide is not released into the atmosphere, overall emissions are reduced.

Another option involves the captured carbon being used as an input for other industrial processes (known as Carbon Capture and Utilisation or CCU). In Carbon Capture, Utilisation and Storage (CCUS), some carbon dioxide is utilised and the rest is stored underground.

Under Direct Air Capture (DAC) methods, carbon dioxide is sucked out through large “artificial trees” from ambient air and directed towards storage sites or utilisation. Since these methods can potentially eliminate carbon dioxide accumulated over the years, the benefits are larger compared to CCS. But the challenges are bigger too. Some experimental projects are currently trying out these technologies.

Potential for Solar Radiation Management:

• The most ambitious and potentially rewarding form of geoengineering is SRM, which is still at the conceptual stage. It draws inspiration from the natural process of volcanic eruptions, in which large amounts of sulphur dioxide are released. These combine with water vapour to form sulphate particles that reflect sunlight into space, reducing the amount reaching Earth.
• The Mount Pinatubo eruptions in the Philippines in 1991, one of the largest in the 20th century, are believed to have reduced the Earth’s temperature by 0.5 degrees Celsius that year. Scientists are trying to artificially emulate the process and have explored the capabilities of several materials, including sulphur dioxide, calcium carbonate, and sodium chloride or common salt.
• Diamonds have been discussed, too. The new study compared seven compounds and found diamonds the most effective in producing the desired results. But to achieve a temperature reduction of 1.6 degrees Celsius, about five million tonnes of diamonds would need to be sprayed into the upper atmosphere every year.

Challenges and concerns:

• Though theoretically possible, SRM options face huge technology and cost challenges in implementation. Besides, manipulating natural processes on a large scale can have unintended and unforeseen consequences. It can affect global and regional weather patterns and rainfall distribution. There are ethical concerns as well. Altering natural sunlight can affect agriculture, vegetation, and biodiversity, and might be detrimental to some life forms.
• Even CCS technologies have flaws, as one study by researchers from Oxford University and Imperial College in London showed last year. Though it might be technically possible or desirable to deploy these technologies in some cases, heavy reliance on them to achieve climate objectives might not be feasible or practical, it said.
• It further pointed out that mainly employing CCS to meet climate goals by 2050 would cost the world at least US$ 30 trillion more than a route primarily focused on renewable energy and maintaining energy efficiency. Besides, an adequate number of safe underground sites for storing huge amounts of carbon dioxide might not be available.

Still, CCS options are considered almost inevitable now, given the already visible effects of global warming. There are no scenarios for the world to achieve the 1.5 degree or 2 degree Celsius targets that do not require contribution from CCS and CDR technologies