Professor Tierney's research concentrates on molecular paleoclimatology, where she investigates past environmental change from fossil molecules (called 'biomarkers') preserved in sediments. With this approach, she focuses on placing present and future changes in Earth's environment within the perspective of past changes. Her major region of focus has been the tropics, where she has conducted research over large portions of Africa, the Indian Ocean, and the Indo-Pacific Warm Pool, in addition to leading global syntheses of ocean changes over the Common Era (the last 2,000 years). Professor Tierney is a Packard Fellow, a recipient of the American Geophysical Union's James B. Macelwane Medal for significant scientific contributions by an early career scientist, and is a Fellow of the American Geophysical Union.