The year 2024 has been the warmest on record; temperatures surpassed 1.55°C above the pre-industrial level due to infrared radiation trapped by greenhouse gases. Carbon dioxide (CO2), primarily from burning fossil fuels and wood, nitrous oxide (N2O) from fertilisers in agricultural fields, and methane (CH4) largely from agriculture are the primary culprits.
It is becoming increasingly clear that the Earth’s average temperature will soon exceed 1.5°C. While we have temporarily crossed 1.55°C, it remains to be seen if the long-term average increase will reach 1.5°C. The calculation is done on a 10-year average—the past five years’ temperatures combined with projections for the next five years.
For a detailed explanation of these calculations, refer to this article: One-point-five degrees: Has global warming exceeded the much-feared tipping point?.
A rise of 1.5°C to 2°C is considered a tipping point, signifying irreversible changes to permafrost, glaciers, and other natural systems. This threatens the survival of numerous species, including humans. Habitat loss and disruptions to the food chain could lead to widespread extinctions.
Despite global efforts, the rate of greenhouse gas emissions has not significantly declined. Consequently, geoengineering—the deliberate large-scale manipulation of the planetary environment to counteract human-induced climate change—has emerged as a topic of intense discussion. Many influential voices, especially from the fossil fuel lobby, advocate for geoengineering as a solution. But is it truly the answer?
Geoengineering can be broadly categorized into two types: Carbon Dioxide Removal (CDR) and Solar Radiation Management (SRM).
Carbon Dioxide Removal (CDR)
Afforestation is a primary CDR method. However, its potential is limited by the availability of land and the challenges of deforestation. Moreover, indiscriminate tree planting can harm water resources.
Other proposed CDR methods include:
Ocean Iron Fertilization (OIF): This involves spraying iron trace elements into the ocean to increase phytoplankton populations, thereby trapping more CO2 through photosynthesis. However, OIF may end up creating nutritional imbalances in the ocean, potentially harming marine ecosystems.
Biochar: Produced by heating wood, leaves, or manure in a low-oxygen environment to create a form of charcoal, biochar sequesters more carbon than traditional methods. However, its contribution is limited due to low efficiency and the eventual decay of its carbon content. Further, biochar delays emissions rather than permanently removing them.
Mineral Sequestration: This method captures CO2 in silicate rocks. However, the process is currently too slow, and faster reactants are needed for efficient CO2 capture. However, disposing of solid carbonates will remain a challenge.
Solar Radiation Management (SRM)
SRM involves reflecting solar radiation back into space. There are various technologies suggested for this.
Sulphate Aerosols: Russian climatologist Mikhail Budyko suggested burning sulphur in the atmosphere to produce aerosols that reflect sunlight. The 1991 eruption of Mt. Pinatubo, which released 10 million tons of sulphur, cooled the Earth by 0.5°C for a year or two. However, artificial aerosol spraying could significantly reduce rainfall, as evaporation is more sensitive to sunlight than temperature. Studies also warn of potential ozone depletion.
Marine Cloud Brightening: This involves spraying seawater rich in salt (NaCl) over low-level marine clouds to enhance their reflectivity. However, this technology is not yet viable due to the lack of large-scale spray generators. Some studies suggest it could degrade clouds’ ability to reflect sunlight.
Space-Based Reflectors: Suggestions include placing reflectors at the L1 Lagrange point between the Earth and the Sun. However, this remains beyond current technological capabilities.
The Need for Lifestyle Changes
As outlined above, most geoengineering methods have harmful consequences or are limited in scope. They cannot offset the current rate of greenhouse gas emissions.
The most viable solution remains a fundamental change in how we live. Emission reductions must occur at a rate that stabilises global temperatures. High-emission countries must significantly alter their lifestyles, but developing nations following similar consumption patterns must also adapt.
Adivasis in India and other Indigenous communities across the world, who live in harmony with nature, could serve as role models for sustainable living. Their practices demonstrate how humans can coexist with the environment without depleting its resources.
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With Professional Assistance for Development Action (PRADAN)
With Professional Assistance for Development Action (PRADAN)
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