El Nino Proxies (image) University of Hawaii ‑ SOEST Caption Corals, tree rings, and sediment cores serve as proxies for El Niño sea surface temperature. Credit Gisela Speidel Usage Restrictions For educational purposes only. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.