Spraying diamond dust to cool Earth: What a new study proposes, despite ‘geoengineering’ concerns

Spraying diamond dust to cool Earth: What a new study proposes, despite ‘geoengineering’ concerns

Sub: Geo

Sec: Climatology

Context:

• A recent study suggests spraying millions of tonnes of diamond dust in the Earth’s upper atmosphere annually to cool the planet and combat global warming.
• Other compounds—sulphur, calcium, aluminium, and silicon—have also been proposed to reflect solar radiation and reduce Earth’s temperature.
• Alternative proposal: Installing space-based mirrors to reflect sunlight.

What is Geoengineering?

• It refers to large-scale efforts to alter Earth’s climate to mitigate global warming.
• Two main types:
  • Solar Radiation Management (SRM): Reflects sunlight away from Earth.
  • Carbon Dioxide Removal (CDR): Removes CO₂ from the atmosphere.

Current Geoengineering Efforts:

• Solar Radiation Management (SRM): Inspired by volcanic eruptions (e.g., 1991 Mount Pinatubo) that release sulphur dioxide, forming particles that reflect sunlight.
  • The study found diamond dust could be more effective than other materials in SRM.
  • To lower temperatures by 1.6°C, approximately 5 million tonnes of diamonds would need to be dispersed annually.
• Carbon Capture and Storage (CCS): Captures CO₂ at the source and stores it underground, currently the most-used method.
• Carbon Capture, Utilisation, and Storage (CCUS): Uses some captured CO₂ in industries and stores the rest.
• Direct Air Capture (DAC): “Artificial trees” extract CO₂ from ambient air, then store or utilize it.
• Ocean fertilization or ocean nourishment:
  • Ocean fertilization is a type of climate engineering based on the purposeful introduction of nutrients to the upper ocean to increase marine food production and to remove carbon dioxide from the atmosphere.
  • A number of techniques, including fertilization by iron, urea and phosphorus have been proposed.
• Soil carbon sequestration (SCS)
  • Soils can serve as a sink for carbon dioxide since atmospheric concentrations of carbon dioxide have crossed 410 parts per million and oceans are already turning acidic.
  • Carbon sequestration in soils has the potential to offset GHG emissions from fossil fuels by up to 15% annually.
  • Soil organic carbon (SOC) comes from plants, animals, microbes, leaves and wood, mostly found in the first metre or so.
  • There are many conditions and processes that determine changes to SOC content including temperature, rainfall, vegetation, soil management and land-use change.
• Stratospheric aerosol injection (SAI)
  • SAI is the main type of solar radiation management (SRM) .
  • In the case of SAI, gases are pumped into the stratosphere to reflect some of the sun’s heat, mimicking an effect that happens naturally in a strong volcanic eruption.
  • Scale of SAI makes its governance difficult — implementing it in one country can trigger rain and extreme weather across borders. Lack of public support might be the biggest hurdle.
• Marine cloud brightening (MCB)
  • MCB involves reflecting sunlight away from the earth in some way. In this case, sea salt or other particles are sprayed into marine clouds to make them thicker and more reflective.
• Cirrus cloud thinning (CCT)
  • CCT is almost the opposite of marine cloud brightening. High-altitude Cirrus clouds are thin and whispy, so they don’t reflect much solar radiation back into space, and instead trap long-wave radiation on earth.
  • CCT proposes thinning them further through cloud seeding, letting more long-wave radiation escape.

Challenges and Concerns:

• Technical and Financial Challenges:
  • SRM has high technological and financial demands.
  • Using CCS extensively could cost around US$ 30 trillion more by 2050 than prioritizing renewables and energy efficiency.
• Potential Risks:
  • SRM could unintentionally disrupt weather patterns, affect rainfall, and impact agriculture and biodiversity.
  • Heavy reliance on CCS alone may be unsustainable without an adequate number of safe underground storage sites.

Urgency and Emission Goals:

• Rising Global Temperatures: Despite efforts, temperatures are 1.2°C above pre-industrial levels, with 2023 around 1.45°C warmer.
• Paris Agreement Target: Aims to limit warming below 1.5°C but achieving this requires a 43% cut in emissions by 2030, while current actions may only achieve a 2% reduction.
• Role of CCS/CDR: These technologies are now viewed as essential to any scenario aiming to meet the 1.5°C or 2°C targets.