Green Bonds Drive USD555bn Surge as Development Banks Join USD1tn Issuer Club

Strong first half of 2025 volumes underline investor appetite and broaden issuer leadership in sustainable finance.

Key Highlights: 

1. By the end of H1 2025, Climate Bonds Initiative (Climate Bonds) had recorded an aligned cumulative volume of USD6.2tn green, social, sustainability, and sustainability-linked (GSS+) debt. 
2. Aligned green volume accounted for 61% of total aligned volume in H1 of 2025. 
3. Development banks join the ‘USD1tn Club’. 

Download the full version of the Sustainable Debt Global State of the Market H1 2025 here: Climate Bonds | Sustainable Debt Global State of the Market H1 2025 

London 11/09/2025 09:00 GMT: The sustainable debt market continues to expand at pace, with the Climate Bonds Initiative (Climate Bonds) reporting today that cumulative aligned issuance of green, social, sustainability, and sustainability-linked (GSS+) bonds reached USD6.2 trillion, with USD555.8bn issued by the close of the first half of 2025 (H1 2025).  

This marks an increase of 17% from the average semi-annual volume recorded since 2021 (USD474.9bn), reflecting a steady rise in market activity compared to recent averages and reinforcing investor appetite for climate and sustainability-focused financing. Similarly, Q2 2025 (USD286.1bn) saw the second highest quarterly output of aligned GSS+ volume across all quarters, behind Q1 2024’s record USD316.5bn. 

 Clodagh Muldoon, Head of Research, Climate Bonds Initiative: “The first half of 2025 marked a milestone, as Climate Bonds-aligned GSS+ debt volume recorded surpassed USD6tn. This achievement was accompanied by several other positive developments, including a continued rise in issuance from development banks and the second-highest quarter (Q2 2025) for the green theme. H1 2025 also saw strong volumes across both sustainability and social themes, alongside an uplift in SLB deals. All themes are thriving, setting an optimistic tone for the second half of the year.” 

Green Bonds Lead 

Aligned green bonds were the primary driver of growth. Q2 2025 aligned green volume reached USD193.6bn, the second-highest quarterly issuance after Q1 2024 (USD207.4bn). Green bonds accounted for 67% of aligned issuance in Q2 2025 and 61% in H1 2025, underscoring their central role in the sustainable debt market. 

Sustainability-linked bonds (SLBs), though smaller in volume, showed encouraging progress with one of their strongest halves ever (third-highest half, USD9.7bn), illustrating the increasing traction for innovative instruments. 

Development Banks Reach Historic Milestone 

Following a record Q1 2025, development banks crossed the USD1tn milestone in cumulative aligned issuance, joining governments, financial institutions, and corporates as issuer groups each surpassing USD1tn in cumulative aligned GSS+ volumes. Climate Bonds have previously highlighted the crucial role of banks in the net-zero transition, with their potential to steer customers towards more climate-friendly investments. We are now seeing encouraging signs of this potential, with development banks now comprising 45% of the cumulative aligned sustainability-labelled debt market. 

Spotlight: Methane abatement 

While explicit references to methane abatement in green bonds are still at an early stage, Climate Bonds has recently begun to incorporate this theme into its market reports, highlighting how capital markets are starting to channel investment into methane abatement and related infrastructure. Recent examples include issuances from Fluvius in Belgium, Waga Energy in France, and U.S.-based Kinetik Holdings.  

This focus aligns with the ‘Mobilizing Sustainable Finance for Methane Abatement Programme’, a two-year initiative funded by the Global Methane Hub. The programme aims to scale up methane abatement finance and reduce emissions in line with 1.5-degree pathways. In its second year, the project will deliver an expanded set of reports, activities, and events from teams across the Climate Bonds Initiative. 

Gathering the numbers – Climate Bonds’ Database Methodology 

The findings of the Sustainable Debt Global State of the Market H1 2025 align with Climate Bonds’ Market Intelligence Methodologies, which set the benchmark for sustainable finance by combining scientific rigor with practical usability. These methodologies ensure that only assets meeting strict climate criteria are included in Climate Bonds’ data products, safeguarding market integrity while accelerating climate investment. As a result, in cases whereby data matching these criteria are picked up retrospectively, these may then be added to the existing dataset. If you have any queries about a particular deal, please feel free to visit our market data insights page on our website. 

The key discussion points from this report will be highlighted further at the Global Climate Bonds CONNECT conference in London 22/10/25. More information, including registration here: Climate Bonds | Global: Climate Bonds CONNECT 2025 

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Contact for Interviews and further information:  

Barney Lloyd-Wood 

Communications Specialist 

Barney.lloyd-wood@climatebonds.net 

About the Climate Bonds Initiative: Climate Bonds is the leading international non-governmental organisation mobilising global capital for climate action. We drive the growth of the green and sustainable debt market through science-aligned frameworks including our taxonomies and standards, our Certification, our data and insights, and our provision of expert policy and technical advice. More information on our website here. 

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