ClimateSense at ClimateCheck 2026

This paper describes our submission to the ClimateCheck 2026 shared task on scientific fact-checking of climate-related claims (Task 1) and disinformation narrative classification (Task 2). For Task 1, we use a three-stage pipeline combining BM25 retrieval over 394,269 scientific abstracts, ensemble re-ranking with five fine-tuned BGE cross-encoders aggregated via Reciprocal Rank Fusion, and zero-shot claim verification using the gpt-oss-120b model. For Task 2, we use a zero-shot approach with a custom prompt based on the CARDS taxonomy and the gpt 5.2 model. Our system outperforms the organizers’ baseline across all subtasks. Furthermore, we achieve the best

result for the Task 1.1 (retrieval score of 0.466), and Task 1.2 (verification score of 1.183 - F1 + Recall@5), and the third best result for Task 2 (Macro F1 of 0.583).