Kliti Grice is an internationally renowned organic geochemist and world-leading authority on molecular fossil and stable isotope geochemistry. Deep insight and excellence in applying advanced analytical approaches has enabled Grice to answer fundamentally important Earth Science questions. Her research into modern and ancient environments has greatly enhanced the understanding of Earth’s early life, microbial ecosystems of the past, aspects of plant and algal physiology and food webs. Grice pinpointed sulfide toxicity as an underlying cause of rapid biological turnover, by identifying the frequent presence of green sulfur bacteria in mass extinction sedimentary records. She also established the role of microbial activity in exceptional preservation of fossils.