Recent studies have suggested that millions of tonnes of diamond powder should be sprinkled into the Earth’s upper atmosphere each year to reduce global temperatures and combat global warming. Other compounds such as sulfur, calcium, aluminum and silicon have also been proposed to reflect solar radiation. An alternative proposal is to install mirrors in space to reflect sunlight.
Definition of Geoengineering: Geoengineering means making large-scale changes to the Earth’s climate to reduce global temperature rise. There are two main types of it:
- Solar radiation management (SRM): It reflects sunlight away from the Earth.
- Carbon dioxide removal (CDR): It is the process of removing CO₂ from the atmosphere.
Current geoengineering efforts
- Solar radiation management (SRM): These efforts are inspired by volcanic eruptions, such as the 1991 eruption of Mount Pinatubo, to mimic the effects of sulfur dioxide.
- Studies have found that diamond dust may be more effective than other materials in SRM.
- About 5 million tons of diamond dust would need to be sprayed annually to reduce temperatures by 1.6°C.
Other geoengineering technologies
- Carbon capture and storage (CCS): This technology captures CO₂ at the source and stores it underground.
- Direct air storage (DAC): This is an “artificial tree” technology that extracts CO₂ from ambient air and stores or uses it.
- Ocean fertilization: The act of injecting nutrients into the oceans to increase ocean food production and remove CO₂ from the atmosphere.
- Stratospheric aerosol injection (SAI): This technique pumps gases into the stratosphere to reflect the sun’s heat.
- Marine cloud brightening (MCB): Spraying sea salt or other particles into marine clouds to make them more reflective.
Challenges and concerns
Technical and financial challenges
- High cost: The technical and financial demands of solar radiation management (SRM) are enormous.
- It is estimated that widespread use of carbon capture and storage (CCS) could cost about US$30 trillion more by 2050 than prioritising renewable energy and energy efficiency.
- Structural infrastructure: CCS requires a secure and adequate number of underground storage sites to be successful. If these sites are scarce, heavy reliance on CCS alone may not be sustainable.
Potential risks
Climate change impacts: The use of SRM technologies may inadvertently alter weather patterns, leading to:
- Changes in rainfall distribution.
- Negative impacts on agricultural productivity.
- Loss of biodiversity, which can lead to ecosystem imbalance.
- Instability in science and technology: Adoption of new technological solutions may involve high R&D costs and time, which may delay the delivery of immediately effective solutions.
Urgency and emission targets
Global temperature rise
- Despite efforts, global temperatures are 1.2°C above pre-industrial levels.
- By 2023, this increase is likely to reach around 1.45°C.
Paris Agreement target
- According to the Paris Agreement, it is necessary to limit the temperature rise to below 1.5°C.
- To achieve this, emissions must be reduced by 43% by 2030, while current action is only achieving a 2% reduction.
Role of CCS/CDR
- Technologies such as carbon capture and direct air capture (CDR) are considered essential to achieving the 1.5°C or 2°C targets.
- Without them, controlling global temperatures and tackling climate change will be extremely difficult.