In the presence of climate change and biodiversity loss, soils have become one of the most vulnerable resources in the world.

Soils host the largest terrestrial carbon pool and play a crucial role in the global carbon balance by regulating dynamic biochemical processes and the exchange of greenhouse gases (GHG) with the atmosphere. Soil organic carbon (SOC) stocks amount to an estimated 1,500 ±230 GtC in the first meter of soil, but until now soils have been a global net source of GHGs. These losses are strongly affected by land use, land use change, vegetation cover and soil management. SOC stocks in the upper soil layers (first 40 cm) are especially sensitive and responsive to such changes in land use and management, which provides an opportunity to influence the amount of CO2 in the atmosphere. This can be achieved by maintaining existing soil carbon stocks (of particular importance in soils with high SOC content), or by soil carbon sequestration.  

With about 33% of the world’s soils being degraded, large losses of soil organic matter (SOM) (and hence SOC) have occurred in soils from various global agroecosystems (i.e. croplands, grazing lands, rangelands, peatlands, etc.) where losses ranged between 25–75% of their original SOC pool. These losses provide an opportunity: the recoverable carbon reserve capacity of the world’s agricultural and degraded soils is estimated to be between 21 to 51 Gt of carbon. As such, SOC is included in the monitoring of SDG indicator 15.3.1, under which carbon stocks above and below ground is one of three sub-indicators to determine the proportion of land that is degraded over total land area.

The role of soils and SOC in the climate system and in the context of climate change adaptation and mitigation has been widely recognized and validated in various studies, both experimentally and through modelling. However, large-scale baseline and trend assessments are still inaccurate and many of the factors determining SOC quality and quantity in different parts of the world, as affected by climate change and measures to enhance SOC, are insufficiently investigated.

During the 5th Working Session of the Intergovernmental Technical Panel on Soils (ITPS) of the Global Soil Partnership (GSP), ITPS and the Acting Secretary of the IPCC agreed that it would be desirable to incorporate the topic of SOC in the IPCC Assessment Report (ARs), from AR6 onwards. As a result, the ITPS and IPCC, supported by FAO, jointly organized the Global Symposium on Soil Organic Carbon (GSOC17) to discuss and elaborate the latest information on the role of soil and SOC in the climate change agenda. The UNCCD and its Science-Policy Interface (SPI) and the World Meteorological Organization (WMO) agreed to co-sponsor GSOC17 in light of the important contribution that maintaining and enhancing SOC can make to meeting the objectives of land degradation neutrality, reducing GHG emissions, and enhancing climate change adaptation.

The Symposium was a scientific meeting, held over three days at FAO Headquarters in Rome, Italy from 21-23 March 2017 with over 400 participants representing all regions of the world.

The three main themes were:

1. Measuring, mapping, monitoring and reporting SOC
2. Maintaining and/or increasing SOC stocks (fostering SOC sequestration) for climate change mitigation and adaptation, and Land Degradation Neutrality
3. Managing SOC in soils with a) high SOC - peatlands, permafrost, and black soils b) grasslands, and livestock  production systems and c) in dryland soils

Abstracts and papers for key topics were invited to support the above themes and incorporate case studies from different countries. Guidelines for the preparation of abstracts and papers were provided.

Participants included representatives from FAO member states, UNCCD country Parties, organizing institutions, relevant panels, presenters whose abstracts were accepted and scientists working in related fields.