The United Nations urges global efforts on carbon disclosure to measure, disclose, manage, and share vital climate information. Nevertheless, the practices of carbon disclosure face challenges such as the lack of transparency, credibility issues, and fragmented data sources. Emerging blockchain technology can be a potential solution due to its decentralization, immutability, and transparency. This paper develops a blockchain-based carbon informatics platform for multiple stakeholders using the spatial-temporal analytics approach to enhance transparency and reveal the carbon emission patterns using United States transportation carbon emissions data. Firstly, the stakeholder analysis is conducted to identify the key stakeholders and requirements. Secondly, the architecture of blockchain-based carbon informatics is developed to create an immutable ledger based on Hyperledger Fabric 2.5.3. Thirdly, spatial-temporal analytics is applied to visualize emission hotspots, regional disparities, and temporal trends in county-level transportation data. Based on the data from the United States Environmental Protection Agency Motor Vehicle Emission Simulator (MOVES), the case study is conducted to validate the feasibility of the proposed platform. The results show that the blockchain-enabled platform can offer a transparent and credible environment for carbon disclosure, while spatial-temporal analytics provides an insightful tool for multiple stakeholders (e.g., policymakers, regulators, carbon entities, and investors) to understand emission patterns.