Enhanced Rock Weathering (ERW)
Why it Matters?
Enhanced Rock Weathering (ERW) is an emerging climate mitigation strategy being applied on farms worldwide, including in India, to accelerate natural processes that capture and store carbon dioxide using finely crushed volcanic rock like basalt.
What You Should Know?
Enhanced Rock Weathering (ERW) is a carbon dioxide removal (CDR) technique that accelerates natural weathering processes by spreading crushed quick-weathering rocks like basalt on farmland.
Natural weathering involves carbon dioxide in air or soil forming carbonic acid, which breaks down rocks and leads to the formation of bicarbonates and eventually limestone, thereby storing CO₂.
ERW increases the rate of weathering by grinding rocks finely, thus increasing their surface area and reaction rate.
Basalt is commonly used due to its high weathering potential. A study found that applying 50 tonnes per hectare annually could capture up to 10.5 tonnes of CO₂ per hectare over 4 years.
Its effectiveness varies based on factors such as the type and grain size of rock, soil type, temperature and rainfall, and land and crop management practices.
ERW may still be beneficial even without direct CO₂ capture, as it neutralises soil acids, preventing them from flowing into rivers/oceans where they release CO₂ into the atmosphere.
Its additional benefits include increased soil alkalinity, improved crop productivity, and enhanced nutrient availability
The risks associated with ERW are heavy metals in certain quick-weathering rocks and health hazards from inhaling fine rock dust during spreading.