SOIL CARBON UNDERESTIMATED BY >2 TRILLION TONNES

PALE CARBONATES UNDER DARK SOILS

Since agriculture & pastoralism began, human activity has altered   half the land area of the Earth. Besides visible landform and albedo changes, this disturbance has increased rates of soil alteration.  A report in Science reassesses how much inorganic carbon is vulnerable to such changes and how this impacts the global carbon cycle. 

Size, distribution, and vulnerability of the global soil inorganic carbon

YUANYUAN HUANG , XIAODONG SONG, YING-PING WANG, JOSEP G. CANADELL, YIQI LUO, PHILIPPE CIAIS, ANPING CHEN, SONGBAI HONG, YUGANG WANG, [...], AND GAN-LIN ZHANG +17 authorsAuthors Info & Affiliations

SCISCIENCE

11 Apr 2024

Vol 384, Issue 6692

pp. 233-239

DOI: 10.1126/science.adi7918

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Abstract

Global estimates of the size, distribution, and vulnerability of soil inorganic carbon (SIC) remain largely unquantified. By compiling 223,593 field-based measurements and developing machine-learning models, we report that global soils store 2305 ± 636 (±1 SD) billion tonnes of carbon as SIC over the top 2-meter depth. Under future scenarios, soil acidification associated with nitrogen additions to terrestrial ecosystems will reduce global SIC (0.3 meters) up to 23 billion tonnes of carbon over the next 30 years, with India and China being the most affected. Our synthesis of present-day land-water carbon inventories and inland-water carbonate chemistry reveals that at least 1.13 ± 0.33 billion tonnes of inorganic carbon is lost to inland-waters through soils annually, resulting in large but overlooked impacts on atmospheric and hydrospheric carbon dynamics.