Soils & Climate: from Hidden Depths to Centre Stage?

Soils offer a major share of the world’s actual and potential carbon storage. Globally, the top 30 cm of soil hold about double the carbon in the atmosphere, and more than that in all the forests and sunlit ocean layer combined. Increasing carbon in soils is potentially an effective means of reducing levels of carbon dioxide in the atmosphere and in oceans, while providing positive co-benefits, particularly for food security.

Management practices that increase soil organic carbon are largely very low in cost compared to alternative greenhouse-gas abatement options. Scientists and policymakers broadly agree that soil organic carbon can deliver climate-change abatement while helping meet various goals in food security, sustainable development, economic growth and equity. Soils have a carbon-sequestration potential as high as six billion tonnes a year globally, though a more conservative estimate is in the order of a billion tonnes a year, which is about a tenth of total annual emissions of greenhouse gases from all sources. On the back of optimism about them, there is growing visibility for soil organic carbon solutions.

Pioneering initiatives around the world provide evidence of economic viability and rapid results (see carousel). A mix of regulatory and voluntary initiatives at national and sub-national levels provide timely lessons for global upscaling of action on soil organic carbon. Early adopters of market-based approaches to increasing soil organic carbon include Australia and California. While only eight UNFCCC Nationally Determined Contributions (NDCs) present targets for soil organic carbon within their intended mitigation options (Armenia, Burkina Faso, China, Japan, Malawi, Namibia, Uruguay and Zambia), many countries have policies that support stronger action. They range from Canada, which recognizes the potential of soil organic carbon under conserved forests and wetlands, to Bhutan with its sustainable soil policy, and France, which has soil health through agro-ecological principles at the heart of its 2014 Law on the Future of Agriculture, Food and Forestry.

A more compelling value proposition for farmers and land managers would provide the incentives to incorporate building soil organic carbon within their day-to-day management activities. An attractive business case would not need to deliver near-term cash necessarily, but would have to be profitable within a farm’s planning horizon. Farmers speak the language of sustained and stable returns, valuing on-farm resilience and productivity over any duty to provide public goods such as climate-change mitigation. Thus they are likely to be more interested in soil health than soil organic carbon per se. A strong value proposition would be likely to include elements of enhanced productivity, risk management and market access alongside any financial returns to carbon assets. Important topics for policy attention to support farmers’ management of soil organic carbon include: secure carbon tenure that allows farmers and investors to protect their carbon assets from counter-claims (including by the state); improving equitable access to market-based carbon schemes, particularly among small-scale farmers in developing countries; and consistency in supply-chain contracts and in public policy to enable the long-term management changes expected of farmers. Looking ahead, better practices could be rewarded by better competitiveness; for example, through higher land values or through lower interest rates on loans and lower insurance premiums. Incentives for connectivity and collective action among neighbouring, or like-minded, farmers are also likely to accelerate scaling up of action on soil organic carbon.

Some knowledge gaps hold back action at the political level. One is the perception that the soil organic carbon sink is much less permanent than other solutions such as carbon capture and storage. The potential for double-counting and double-selling of carbon is also a concern, drawing attention again to the need for more secure and transparent rules for carbon tenure. Financial mechanisms also deserve more regard in policy and research circles. Public policies to repurpose subsidies and taxes are working in several countries. For example, since 1998 Costa Rica has diverted a 3.5 per cent gasoline tax into payments for land-based environmental services, and Colombia introduced a similar tax in 2016. Green bonds in the form of ‘soil bonds’ for land restoration also hold promise as a financial mechanism. Rewarding performance on a farm-by-farm basis is expensive and inefficient, perhaps workable for pilots but not enough to reach scale; however, effective incentives above the farm level are not yet well developed.

More generally, soils remain mysterious and dirty to most people. Public awareness and engagement are paramount, but they are tough when neither the carbon nor the healthy soil is easy to see. In the words of John Naisbitt, our collective perspective on soils is ‘drowning in information but starved for knowledge.’ Yet World Soil Day, led by the FAO, has done well to capture the imagination of adults and children in recent years through farmers across the globe showing that buried underpants decompose faster in higher-carbon soils. More fun and engaging publicity campaigns that drive home a small number of strong messages could put soils onto the international political agenda, as has happened for marine plastic pollution recently.

Technology and innovation offer much untapped promise. While the agrifood sector is not a major spender on research, there has been increasing investment in recent years on sensors and data applications. With further development these could rapidly bring down the costs of monitoring soil organic carbon and soil health. The urban disconnect from food supply chains means a greater focus on the future potential of non-land food production. For example, agrifood start-ups in OECD countries are concentrated around soilless production systems (forthcoming Hoffmann Centre study), claiming positive environmental impacts through avoided use of land, but overlooking the tremendous potential that soils offer as carbon sinks. Many observers understand development of cost-effective monitoring and accounting tools and protocols to be the key step towards unlocking action on soil organic carbon.

Soil organic carbon needs to be packaged with other co-benefits of sustainable land management, but as a discrete building block, not as an amorphous bundle. A thread throughout the dialogue was the importance of valuing soil organic carbon within a wider set of private and public benefits from land management, not as a standalone asset. However, soils are in danger of being the ‘orphan asset’, forgotten when food security or forests are discussed. Soil can be better understood as a discrete building block in the assembly of sustainable land management. This means setting specific goals, targets and metrics for soils within any wider agenda on building natural capital, tackling climate change or raising agricultural productivity. Understanding soils as natural infrastructure – as the foundation for other services – might also change hearts and minds.

Momentum is building and partners are coordinating work on different parts of the global agenda. Following this dialogue, a coalition of research partners led by The Nature Conservancy and Cornell University through its Atkinson Center will conduct a scientific project in 2018 to fill key knowledge needs voiced by decision-makers in the public and private sectors. The 4 per 1000 Initiative will enter its first year of global action. The focus of UNCCD this year is on connecting consumers with the value of sustainable land use practices. Meanwhile, parties and observers to the UNFCCC are invited to submit views in March 2018 on what to include in the Koronivia joint work on agriculture. Members of the World Business Council on Sustainable Development are working on a business case for investing in soil health. The Global Alliance on the Future of Food will carry forward multiple strands of work, including the informal Chantilly Group of investors in soil and land-based carbon. The Gold Standard, in association with Danone, Mars and Livelihoods Venture, will develop, and in 2019 open out to engagement, a new approach for Scope 3 greenhouse gas emissions, including guidance on sequestration through soil organic carbon. Land-based solutions have also been announced as a key focus of the Global Climate Action Summit 2018, which will bring together non-state activists and practitioners from all over the world. Evidence-based advocacy on soils – both persistent and consistent – is laying the foundation for action at scale within an urgent timeframe.