The research, led by scientists at the USC Dornsife College of Letters, Arts and Sciences and published in the journal Paleoceanography and Paleoclimatology, reconstructs nearly 240,000 years of lake history from a sediment core drilled from the lakebed. The team found that the enormous lakes of the past were brief departures from the basin’s usual hypersaline state, an extremely salty condition that has dominated the record for the vast majority of the time. Both giant lakes appear to have followed the same pattern: as the regional climate warmed and dried, the water receded, salinity climbed and salt deposits formed on the lakebed. The scientists note that the timing of the older of the two transitions is less precise than the younger one, but the overall trajectory of shrinkage and salinification is consistent across both events.

Corresponding author Rachel So, a recent PhD graduate in Earth sciences at USC Dornsife, compares the long-term record to watching a puddle that remains nearly the same size for an hour, briefly swells into a pond and then shrinks again. Scaled up to the size of the present Great Salt Lake, she explains, that is essentially what the basin looked like across nearly a quarter of a million years. For most of the past 240,000 years the lake stayed roughly the same size, but on two separate occasions it briefly grew to ten times its modern extent. The comparison captures the central finding of the study: the freshwater phases that produced the region’s most spectacular lakes were geologically fleeting interruptions in an otherwise salty story.

Scientists have long known that Lake Bonneville once covered much of western Utah during the last ice age, and its ancient shorelines remain etched into the landscape today, visible as terraces on hillsides far above the modern waterline. But those shorelines provide snapshots rather than a continuous account of how the lake’s size and salinity changed through time. To build a continuous record, the researchers turned to a nearly 400-foot sediment core drilled from the bed of Great Salt Lake in 2000. Its layered sediments preserve an archive stretching back about 236,000 years, spanning multiple glacial cycles and capturing both of the great freshwater episodes in a single, uninterrupted sequence.

The team dated the sediment layers by measuring radioactive decay in minerals, a technique that functions as a kind of geological clock and anchors the record in time. They also analyzed molecules left behind by microorganisms that once lived in the lake. Because the relative abundance of those molecules changes with salinity, their signatures allowed the researchers to broadly gauge whether the water at any given moment was fresh, brackish or extremely salty. Together, the dating and the biomarker analysis turned the core into a chronicle of the lake’s alternating states, revealing two major interruptions in its long hypersaline history.

The first and most recent interruption came between roughly 30,000 and 16,000 years ago, when the lake expanded into Lake Bonneville. The second, an earlier deep lake known from the Little Valley interval, existed roughly 140,000 to 135,000 years ago. Shoreline evidence suggests both lakes approached 1,000 feet in depth, but they were not identical twins. The Little Valley lake may have remained somewhat brackish rather than truly fresh, and it lasted less than half as long as Lake Bonneville. The most recent freshwater phase was therefore both longer and fresher than its older counterpart, a difference that offers clues about how variable the region’s wet episodes can be.

Senior author Sarah Feakins, professor of Earth sciences at USC Dornsife, emphasizes that the core’s span of two and a half glacial cycles is what makes the comparison possible. Because the record captures two complete fresh-to-salty transitions, the researchers can compare the two freshwater events directly, evaluating their durations and their degrees of freshness, and seeing how fragile and fleeting those moments were in the basin’s history. The record also aligns with evidence from elsewhere in the American West: various records from Nevada, California and Arizona show similar wet-to-dry shifts during the same periods, suggesting that Great Salt Lake was responding to climate changes felt across the entire region rather than to purely local conditions.

The mechanism behind the lake’s dramatic swings comes down to a balance between water arriving and water leaving. Feakins explains that during the cooler periods, lower temperatures slowed evaporation while more frequent storms delivered additional water into the basin, allowing Lake Bonneville to fill, as she puts it, one storm at a time. As temperatures rose, the balance reversed: evaporation increased, storms became less frequent, and the lakes dwindled. Their remaining water grew progressively saltier until minerals began to form crystals and settle onto the lakebed, leaving salt deposits that the core still preserves today. Great Salt Lake’s lack of an outlet makes it especially sensitive to this balance, since water leaves the basin mainly through evaporation, so any shift in temperature, precipitation or river flow is registered directly in the lake’s level and salinity.

Modern Great Salt Lake faces pressures its ancient predecessors never encountered. Human water use, mostly for agriculture, reduces the amount of water reaching the lake, while human-caused climate change increases evaporation across the region. Feakins notes that today the climate is warming at an unprecedented rate, and that warming makes the atmosphere thirstier, accelerating evaporative drying from soils and lakes throughout the West. Both researchers caution against misreading the ancient record as reassurance. So warns that people should not use the argument that climate changed naturally in the past, and so the lake shrank, to justify treating shrinking lakes today as normal or purely natural phenomena. The geological record shows what a warming and drying climate can do to a closed basin; it does not excuse the additional human pressures now compounding that vulnerability.

The study is not without limitations, and the researchers are candid about them. Dating precision decreases in the core’s older layers, where margins of error span several thousand years, and dating some of the ancient salt deposits proved especially difficult. Attempts to reconstruct past temperatures were also hampered, because the lake’s high salinity made those results unreliable. Despite these challenges, the sediment core delivers a nearly continuous account of a lake responding to major shifts in the West’s water balance, and it demonstrates with unusual clarity how a vast freshwater lake covering thousands of square miles can give way to salt when the climate warms and dries. As the modern West grapples with a shrinking Great Salt Lake, the basin’s own sediments provide a 240,000-year perspective on just how quickly fresh water can disappear.

Subject of Research: Reconstruction of 240,000 years of salinity and lake-level change at Great Salt Lake, Utah, from sediment core evidence

Article Title: Great Salt Lake’s ancient past reveals how quickly fresh water can disappear

Article References: Great Salt Lake’s ancient past reveals how quickly fresh water can disappear. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Great Salt Lake, Lake Bonneville, paleoclimatology, sediment core, salinity, climate change, USC Dornsife, hypersaline lakes, American West, evaporation, glacial cycles, water resources

Peters will not arrive alone in name only. He will be appointed to the Carmen H. and Louis Warschaw Endowed Chair in Practical Politics, a position currently held by Robert Shrum, the center’s founding director, who is retiring after years at the helm. Shrum, a veteran Democratic strategist whose career included some of the most consequential campaign battles of the late twentieth century, built the center around the idea that students learn politics best from the people who actually practice it. Peters will share leadership of the center with Republican strategist Mike Murphy, who remains co-director. That arrangement is believed to make the Center for the Political Future the only university political center in the country jointly led by a Democrat and a Republican, a structural commitment to bipartisanship that distinguishes it from the many university institutes that study politics from a single ideological vantage point.

The center, founded in 2018, has grown into one of the most visible civic institutions at USC. Its programming brings political leaders, campaign strategists, journalists and policymakers from across the ideological spectrum to campus, where they engage directly with undergraduates in public forums, classroom settings and smaller working sessions. Through its fellows program, its calendar of public events and its affiliation with the Jesse M. Unruh Institute of Politics, the center gives students firsthand exposure to the mechanics of campaigns, governance and public policy. It also provides internships, scholarships and professional development opportunities designed to move students from the audience to the arena. The underlying theory is straightforward: if the next generation of political professionals is trained in an environment where disagreement is civil and compromise is treated as craft rather than betrayal, some of that culture may follow them into Washington.

Peters brings to that mission a legislative record that is unusually well documented. Now in his second Senate term after three terms in the U.S. House of Representatives, he has been recognized by the nonpartisan Center for Effective Lawmaking as the most effective U.S. senator in each of the last three Congresses. The ranking is not an honorific; it is a statistical assessment of how often a lawmaker’s bills advance, attract cosponsors from both parties and ultimately become law. Notably, Peters first earned the top ranking while his party held the minority, a feat no senator had accomplished in more than fifty years. During the 117th Congress, he authored nineteen bipartisan stand-alone bills that were signed into law, the most by any senator in a single Congress in more than four decades. Those numbers matter for a center whose core message is that cross-party work still produces results.

His own description of the move frames it as a culmination rather than a departure. “I see this as a capstone to my years in public service and an opportunity to help prepare the next generation to take the reins,” Peters said in the announcement. “CPF has done a terrific job bringing people with different perspectives together. I’m excited to build on Bob Shrum’s accomplishments and work with Mike Murphy to encourage more young people to get involved in our democracy and show that people who disagree can still find common ground and get things done.” The statement echoes the center’s founding logic, but it also reflects the practical style that defined Peters’ Senate career, which leaned toward infrastructure, cybersecurity, government efficiency and Great Lakes restoration, issues where coalition-building across the aisle was a requirement rather than an option.

The appointment also carries a geographic dimension. Peters plans to expand the center’s presence in Washington, D.C., using USC’s Capital Campus as a base for courses and programs that connect students more directly with policymakers and the institutions of government. He will divide his time between Washington and Los Angeles, teaching at both campuses, while working to bring USC faculty and their research closer to the people who make federal policy. For a university with growing ambitions in the capital, the arrangement effectively converts a retiring senator’s institutional knowledge into a permanent curricular asset. Students in Los Angeles will encounter him in the classroom; students in Washington will encounter the machinery of government with a former insider as their guide, an experience few undergraduate programs can replicate.

USC Dornsife Dean James Bullock framed the hire in terms of what it models for students. “Gary Peters brings an extraordinary combination of public service, bipartisan leadership and real experience getting things done in Washington,” Bullock said. “He has spent his career showing that you can hold strong political convictions and still work productively with people who see the world differently. I’m especially excited about what his leadership will make possible for our students, both in Los Angeles and in Washington.” The dean’s emphasis on conviction alongside cooperation reflects a deliberate distinction: the center does not ask students to moderate their beliefs, but to hold them in a way that leaves room for negotiation, evidence and the ordinary friction of democratic lawmaking.

Endorsements from across the aisle accompanied the announcement, and they carry particular weight given the source. Republican Sen. Rick Scott of Florida, who served alongside Peters on the Senate Homeland Security and Governmental Affairs Committee, described him as “a consistent, bipartisan partner who was always willing to work across the aisle and deliver real results for the American people.” Scott added, “I know he will carry that same thoughtful, collaborative spirit with him to USC, and I look forward to seeing what this new partnership produces.” For Murphy, the co-director who will now share the stage with a former committee colleague from the opposing party, the fit is professional as much as philosophical. “Gary Peters is that rare thing: a principled politician who also knows how to get things done,” Murphy said. “I very much look forward to working with him as we grow the center’s mission to teach and inspire USC students to embrace the idea that civility and reasoned compromise are far from the enemy of politics; they’re essential to turning political disagreement into practical results.”

For Peters personally, the move represents a return to higher education rather than an experiment in it. Before his congressional career, he taught strategic management and finance at Oakland University and Wayne State University, and he later held the Robert and Marjorie Griffin Endowed Chair in American Government at Central Michigan University. That teaching history, combined with nearly two decades in Congress spanning both chambers, gives him an unusual dual fluency in academic and legislative cultures. “I’ve learned a lot over the years about what it takes to get things done at all levels of government, and I look forward to sharing my experience with students,” Peters said. “But I also expect to learn from them.” As universities nationwide grapple with how to sustain open political dialogue on polarized campuses, USC’s bet is that the most persuasive lesson in democratic possibility comes not from a syllabus but from a practitioner who spent six Congresses proving that the system, worked carefully, still functions.

Subject of Research: Appointment of U.S. Senator Gary Peters as director of USC's bipartisan Center for the Political Future

Article Title: US Sen. Gary Peters to lead USC Dornsife’s Center for the Political Future

Article References: US Sen. Gary Peters to lead USC Dornsife’s Center for the Political Future. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Gary Peters, USC Dornsife, Center for the Political Future, bipartisanship, Mike Murphy, Robert Shrum, political leadership, civic education, U.S. Senate, higher education, civil dialogue, practical politics