When the Earth warmed and the oceans turned toxic with hydrogen sulfide about 250 million years ago, up to 95% of marine life and 70% of terrestrial species were wiped out – the largest of five mass extinction events in Earth’s history. Much of what we know about these is thanks to research by John Curtin Distinguished Professor Kliti Grice – organic and isotope geochemist and founder of Curtin’s WA-Organic and Isotope Geochemistry Centre within the Institute for Geoscience Research and the John De Laeter Centre for Isotope Research. Grice studies the molecular signatures of chemicals that have been made by micro-organisms, plants and animals, and deposited in lakes and oceans, thousands or even hundreds of millions of years ago.
Her work requires a deep knowledge of biochemical pathways, geology, chemistry, ecology, stable isotopes within organic molecules, and cutting edge analytical techniques in order to interpret clues left behind in rocks and determine which organisms lived in certain aquatic regions and when.
“I look at everything from about 2.3 billion years ago, through to the present day, including recovery after the mass extinction events,” she says. “Most people know about the dinosaur mass extinction, which was unique because it was due to a meteorite impact,” she says. But the other mass extinctions were caused by changes in the atmosphere and oceans.
Grice is working on the Triassic-Jurassic extinction, which occurred about 200 million years ago when supercontinent Pangaea began to break up. “There was a lot of carbon dioxide and flood basalts from volcanic eruptions. We established that the same conditions existed in the oceans then as they did in the largest mass extinction event 50 million years earlier,” she says. These events were biochemically driven, with environmental events leading to high carbon dioxide and hydrogen sulfide in bodies of water.
Grice’s research is also relevant to petroleum and mineral exploration, as well as to modern day climate and environmental changes. “We work with people across disciplines including geologists, engineers, mathematicians, biologists and geographers,” she says.
Grice is passionate about working with PhD students and early and mid-career scientists and helping them develop. “I like sharing my enthusiasm and ideas – seeing young scientists grow, helping them with their research and providing opportunities, including visits to different parts of the globe.”
– Michelle Wheeler