  Understanding causality is a core aspect of intelligence. The Event Causality
Identification with Causal News Corpus Shared Task addresses two aspects of
this challenge: Subtask 1 aims at detecting causal relationships in texts, and
Subtask 2 requires identifying signal words and the spans that refer to the
cause or effect, respectively. Our system, which is based on pre-trained
transformers, stacked sequence tagging, and synthetic data augmentation, ranks
third in Subtask 1 and wins Subtask 2 with an F1 score of 72.8, corresponding
to a margin of 13 pp. to the second-best system.
