Though he’s no fortuneteller, doctoral student Elliot Jagniecki can predict the future of climate change by analyzing rock samples.

Jagniecki studies two related minerals. Nahcolite, which is essentially baking soda, is found in deposits from ancient salty lakes in the western United States and eastern China. Trona, nahcolite’s chalky chemical cousin, is often found nearby.

Nahcolite and trona form under such similar conditions that, in nature, only one or the other forms at a given time and place. Which one forms is determined by carbon dioxide (CO2) levels in the Earth’s atmosphere: Trona forms when CO2 is low, nahcolite when CO2 is high. The catch? Trona can also form under high CO2 if temperatures are very high.

Comparing these minerals’ abundance provides a way to determine past levels of CO2 and link them to hotter or colder climates.

“It’s a more clear-cut approach than has been used in the past,” Jagniecki says. “The minerals can give you a better connection between CO2 and temperature because they’re either going to form or not, depending on conditions.”

Jagniecki grows nahcolite and trona in the lab under varying CO2 concentrations to clarify the conditions under which each mineral forms.

Tim Lowenstein, professor of geology at Binghamton, works with Jagniecki. “Elliot is applying modern geochemical techniques to an old problem,” he says. “It’s a really good experimental approach.”

Understanding how greenhouse gases affect the global climate may allow scientists to predict what to expect as the Earth’s temperature climbs. “We’re making this environment that has a lot of CO2, and it’s probably going to get warmer, ” Jagniecki says. “Now we can start asking,  ‘What else is going to happen? What do we really need to start focusing on?’”