By Ivy Rose Marajas Cover Image by: Bruno Braga/Unsplash

2023 was the warmest year recorded since global records began in 1850. Though El Niño Southern Oscillation plays an important factor in this, it was noted by NASA that the record temperatures happened before the peak of El Niño. This highlights the critical need for sustained effort in reducing greenhouse gas emissions. Urgent prioritization is therefore essential to achieve the goal of net zero carbon dioxide emissions by 2050.

There should be a high reduction in carbon emissions through transitioning from fossil fuels to renewable energy to reach net zero carbon emissions. However, this transition alone may not meet our emissions reduction targets. Soils are an intricate part of climate through carbon, nitrogen, and water cycles and can have a crucial role in climate change.

One strategy that can complement efforts is soil carbon sequestration. We can mitigate the impact of carbon dioxide by sequestering it from the atmosphere and storing it in soils for an extended period to prevent emissions. We will delve into the importance of soil and explore how soil carbon management can contribute to our fight against climate change.

Understanding Soil and its Role in Climate Change

Soils contain a vast reserve of carbon, about twice the carbon dioxide in the atmosphere. Carbon stored in soil organic matter is called soil organic carbon and is a part of the carbon cycle. The decomposition of animals and plants produces soil organic matter. This process can release some of the stored carbon dioxide back into the atmosphere while the organic carbon resistant to decomposition will be released into the soil. The resistant soil organic carbon is a significant carbon stock and regulates the carbon cycle.  

However, soil carbon has depleted over the years due to land use changes. Management practices also affect soil carbon. Agricultural practices such as tillage have accelerated soil carbon loss leading to poorer soil health and reduced agricultural productivity.

Impacts of climate change on soil carbon

Climate change poses a threat to soil carbon stocks and global carbon cycling. Changes in temperature, precipitation patterns, and extreme weather events can all influence soil carbon storage, turnover, and release into the atmosphere.

Complex physical and chemical interactions within the soil protect soil carbon from microbial attacks. Soil microorganisms regulate the formation of organic matter and the release of carbon. Microbial decomposition of soil organic matter causes carbon emissions and its release increases global warming. This phenomenon creates a positive feedback loop where increased carbon dioxide concentrations intensify global warming, leading to even higher temperatures and accelerated soil carbon loss.

Importance of Soil Carbon Management

The Kyoto Protocol agreement aims to mitigate climate change by reducing net greenhouse gas emissions. It focused on sources, reservoirs, and sinks of greenhouse gases. The role of soil in the global carbon cycle has been gaining traction since then. There is a considerable increase in research publications on soil carbon.

The French government launched the “4 per 1000” Initiative during the COP21 conference in 2015. This initiative aims to increase global soil organic matter stocks by 4 per 1000 or 0.4% per year to compensate for anthropogenic greenhouse gas emissions. It is a voluntary action plan to implement farming practices that maintain or increase soil carbon stock on agricultural soils. Increasing soil carbon stocks can improve soil fertility and increase agricultural productivity.

Challenges and Future Directions

However, soil carbon management has challenges. Soils that have high C content tend to have higher nitrous oxide emissions. Organic matter addition into the soil can also increase nitrous oxide emissions. This can offset the mitigating effect of soil carbon sequestration.

The quantity of carbon that can be stored is finite. Soil carbon stocks have an equilibrium level depending on carbon inputs and outputs. Soil carbon sequestration is a reversible process and time-limited. Management practices can cause rapid loss of sequestered carbon.

Monitoring and verifying soil carbon sequestration rates need to be transparent and cost-effective. FAO outlined the monitoring, reporting, and verification (MRV) protocol of soil carbon sequestration. However, it relies on costly field measurements and laboratory analyses and imposes challenges for widespread adoption.

Addressing these challenges requires collaborative efforts from policymakers, scientists, and practitioners. Investing in innovative research and implementing evidence-based policies can improve soil carbon management as a climate change mitigation strategy.