Global Carbon Sink Resources Analysis and Market Assessment: A Comprehensive Review

Carbon sinks—natural and artificial systems that absorb more carbon dioxide than they release—have become central to global climate mitigation strategies. This review provides a comprehensive analysis of global carbon sink resources and their associated market mechanisms. It examines three primary sink categories: forest (terrestrial) carbon sinks, blue carbon (coastal and marine) ecosystems, and emerging geological and technological sinks. The analysis integrates resource quantification, market structure assessment, and economic valuation frameworks, drawing on systematic reviews of peer-reviewed literature, carbon registry data, and market reports. Key findings include: global forest ecosystems sequester approximately 15.6 billion tonnes of CO₂ annually, with China alone contributing over 1.2 billion tonnes; blue carbon projects have grown to encompass 2.0 million hectares with annual emission reductions of 20.4 MtCO₂e; and voluntary carbon markets are undergoing significant structural transformation toward high-integrity removal credits. Mathematical frameworks for resource assessment, market equilibrium, and quality valuation are presented to support quantitative analysis.

1. Introduction

The global carbon cycle operates through a fundamental mass balance equation that governs atmospheric CO₂ concentrations-10:

$C_{\text{atm}}(t)=C_{\text{atm}}(t-1)+E(t)-S_{\text{land}}(t)-S_{\text{ocean}}(t)$

where $C_{\text{atm}}$ represents atmospheric CO₂ concentration, $E$ denotes anthropogenic emissions, and $S_{\text{land}}$ and $S_{\text{ocean}}$ represent terrestrial and oceanic sink uptake, respectively. This equation, formalized by the Global Carbon Project, captures the core dynamics of the global carbon budget-10. With atmospheric CO₂ concentrations reaching 421.20 ppm in July 2024—a 3.3 ppm increase from the previous year-8—the role of carbon sinks in climate mitigation has never been more critical.

Carbon markets have emerged as institutional mechanisms to finance sink enhancement and protection. These markets are divided into two categories: compliance markets, mandated by national/international regulations, and voluntary carbon markets (VCMs), driven by private sector participation to meet emission goals-2. The VCM has attracted significantly increased stakeholder interest, defying even the economic effects of COVID-19, and represents a major potential force for mitigation efforts-2.

This review addresses three key questions:

1. What is the current global distribution and magnitude of carbon sink resources?

2. How do carbon market mechanisms value and trade sink-based credits?

3. What are the key challenges and opportunities for scaling sink-based climate solutions?

2. Forest Carbon Sinks: The Terrestrial Foundation

2.1 Global Resource Assessment

Forests cover 31% of Earth's land surface and constitute the largest terrestrial carbon sink, sequestering an estimated 15.6 billion tonnes of CO₂ annually-5. The global distribution of forest resources reflects significant regional variation:

Source: FAO (2024), cited in -5

China's forest carbon sink resources are particularly noteworthy. The country's annual carbon sink exceeds 1.2 billion tonnes, ranking first globally-1. China's artificial forest area has reached 92.4087 million hectares, accounting for 37% of national forest area and 27% of global artificial forest area