The Great Climate Mitigation Potential of Cropland Ecosystem Management in China

Abstract

Limiting climate warming to below 2°C requires more intense mitigation efforts. Alongside the steep reductions in fossil fuel emissions needed, natural climate solutions (NCS) act as an additional first step toward achieving China's emission reduction goals. We first quantified the historical contribution of NCS as 0.34 PgCO2 equivalent (PgCO2e) yr−1 through the implemented national ecological restoration projects as well as positive management measures. Based on successful practices, we then designed 21 pathways to quantify the potential of NCS in increasing terrestrial carbon sinks or reducing greenhouse gas (GHG) emissions in forest, grassland, cropland, and wetland ecosystems. We show that the maximum mitigation potential of NCS between 2020 and 2060 under guaranteed food and fiber security is 1.95 (1.54–2.38) PgCO2e yr−1 (95% CI), which can offset nearly 20% of the annual net emissions. Historically, forest ecosystems have contributed the most to carbon sequestration; however, future projections show cropland ecosystems will account for the largest proportion (47.6%), followed by forest ecosystems. Approximately 47% (0.91 PgCO2e yr−1) of the maximum represents cost-effective mitigation potential that can be realized at ≤100 USD/MgCO2e. Conservation tillage is the most cost-effective option in China, achieving a maximum contribution of 181.60 TgCO2e yr−1. In addition, a series of cropland management measures have contributed 1.14 PgCO2e in the past two decades. Our study highlights the high effectiveness of cropland pathways in reducing carbon emissions and emphasizes the key role of cropland ecosystems in mitigating climate change.