Researchers used fossil foraminifera species in sediment cores as indicators of past ocean temperatures, since some species prefer warm water while others favor cooler conditions.
Notes on verification
Well-established paleoceanographic method, corroborated by multiple independent scientific and educational sources beyond the original article.
Sources
- Ocean Current That Keeps Europe Warm Is Weakening (smithsonianmag.com)
- https://australian.museum/learn/science/human-evolution/how-do-we-know-what-their-environments-were-like/ (australian.museum)
- https://www.sciencedirect.com/science/article/abs/pii/S0031018215000905 (sciencedirect.com)