Summary
Chang et al. applied a spatially explicit land surface model to quantify the full greenhouse gas balance of grasslands globally over 262 years, distinguishing direct human management effects from indirect climate and atmospheric drivers. Direct management activities (livestock intensification, pasture conversion) shifted grasslands from a carbon sink to a source, whilst climate change and elevated CO₂ enhanced soil carbon accumulation. The authors conclude that net warming from managed grasslands currently cancels cooling effects from natural and sparsely grazed grasslands, underscoring the urgency of sustainable management to mitigate grassland emissions.
UK applicability
The findings are relevant to UK policy on grassland management and livestock emissions, particularly given the UK's climate commitments and reliance on pastoral systems. UK grazing management practices and pasture intensification decisions will influence whether grasslands function as net sinks or sources, making the study's emphasis on sustainable management directly applicable to national climate and agricultural strategy.
Key measures
Radiative forcing (W m⁻²), greenhouse gas fluxes (CO₂, CH₄, N₂O), soil organic matter carbon storage, temporal trends 1750–2012
Outcomes reported
The study quantified global trends and regional patterns of greenhouse gas fluxes (CO₂, CH₄, N₂O) from managed and natural grasslands from 1750 to 2012, separating direct effects of human management from indirect effects of climate change, CO₂ increase, and nitrogen deposition. It found that net radiative forcing from managed grasslands currently offsets the climate cooling benefit from carbon sinks in sparsely grazed and natural grasslands.
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