# 774–775 carbon-14 spike

> observed increase of 1.2% in the concentration of carbon-14 isotope in tree rings dated to 774 or 775

**Wikidata**: [Q4643553](https://www.wikidata.org/wiki/Q4643553)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/774–775_carbon-14_spike)  
**Source**: https://4ort.xyz/entity/774-775-carbon-14-spike