Medill Reports, Oct. 31, 2018 –
An alpine forest turns into a desert within a mere 16,000 years – the geologic equivalent of a blink of an eye. The transformation is just one climate mystery waiting to be solved.
Wondering what drives local rainfall? Curious about tipping points for the entire global weather system? To find answers, you’ll have to go through the “lake mafia,” a disparate collection of scientists who study closed lake basins.
They admit they don’t have definitive explanations. But with the clues they collectively gather and assess, they’re are coming ever closer.
That’s why such a “mafia” even exists, or was jocularly referenced by Douglas Boyle, a climatologist at the University of Nevada, Reno, who identified his colleagues with that specific moniker during a presentation at the 2018 Comer Climate Conference this fall on climate in the Mono Lake basin.
The mafia members gathered at the annual conference to present their latest research findings. Yonaton Goldsmith, a geochemistry postdoc at the California Institute of Technology, studies lakes in China. Geochemist Sidney Hemming and her sixth-year Ph.D. student Guleed Ali with Columbia University’s Lamont-Doherty Earth Observatory, pursue fieldwork at Mono Lake in California. Adam Hudson, a geologist with the U.S. Geological Survey, studies the now nearly empty basin of ancient Lake Chewaucan in Oregon.
Lakes that don’t have an outlet are called closed basin lakes. These provide vital clues to understanding and developing theories of climate, Goldsmith said. “There are abrupt events where lakes rose rapidly and we would like to know the relationship of these events to climate changes,” Goldsmith says. “Why does this happen? How does it happen? This is still an enigma but we do really see these rapid changes in lake size and ultimately rainfall.” The big picture goal, Goldsmith says, is understanding the mechanisms of climate and how rainfall water availability respond to climate changes.
In the United States, the Great Basin watershed, an arid area that extends from California to Utah, is a hotbed of study for paleoclimatology – the study of climate past stretching back hundreds of thousands and even millions of years. These scientists are telling the story of how lake changes that occurred naturally inform our most pressing concerns about the pace and magnitude of climate change as human use of fossil fuels are pushing it now. But the history of these lake scientists, their relationships to each other, and their work tells a story as well about how science is conducted and how powerful hypotheses are developed over time.
“The lake scientists at this conference come from different institutions and we work in different places around the globe,” Goldsmith says. “Before this conference we weren’t really connected, it wasn’t an organic connection … and I think that for us this whole becoming a gang has happened here [at the Comer Conference]. Oh, we’re all doing the same thing! We’re all working on really similar questions! We should be talking to each other.”
Columbia University geochemist Wallace Broecker is the common thread among these lake researchers. They are his former students, students of his former students, or of past and present colleagues. His decades of research span oceanography and climate science. He is credited with discovering the global circulatory system of the Earth’s ocean and was a pioneer in radiocarbon dating. Broecker began investigating the geology of Pyramid Lake in Nevada over 60 years ago, when he was pulled aside by Phil Orr, a pipe-smoking scientist in cowboy boots who told him, “Look kid, I can tell you know a lot about math and science. But you don’t know a goldarn thing about the Earth. You come with me for three weeks and I’ll change your life.”
Pyramid Lake is where Broecker collected his first sample of lake limestone, towers of rock called tufas that jut out from the shoreline. “It was a tufa from the highest shore line of [ancient] Lake Lahontan,” Broecker explains. “So I got interested in those lakes. And dated quite a few samples and then had students that worked on it, and then more recently these other people appeared who, you know, are eager to work on it, so they created the ‘mafia’ … they were following in my footsteps in a way.”
Broecker’s work analyzing tufas and recording the history of Pyramid Lake and others as they expanded or receded helped develop current theories of how temperature, rainfall and evaporation are connected, and how quickly they respond to changes. If lakes can dry up in a matter of centuries, than our current pace of global warming can have a profound impact on local climates, threatening future water availability.
“Most precipitation that comes to the Great Basin falls as snow in the winter,” Hudson explains. “And it comes from the Pacific Ocean, and where it comes into the coast and how often it gets there is controlled by a variety of things.”
At the Comer Conference, the mafia presented new research on lake regions. Ali demonstrated Mono Lake’s historic fluctuations with new research. Hudson used ancient fossilized fish remains to map a more precise history of Lake Chewaucan’s past volume. And Goldsmith linked lakes in East Asia to water availability. “With geology, what’s going on today informs how we think about what see from the past record,” Hemming says. “I feel like I’ve done a second Ph.D. working on Mono Basin.”
Another equally important reason that scientists are drawn to these lakes and to the flowing ice of glaciers is because of their intrinsic and captivating beauty. Hudson Tufas in Mono Lakedescribes a section of mountain, a fault between two lava flows in Southeast Oregon, as “the walls of Mordor”; Hemming has been coming to Lake Mono for years.
“It’s really the only lake I ever studied,” Hemming says. “Every day is a discovery it is so beautiful and enigmatic and I’ve never not spent a single day that I went out in the field that I didn’t come back thinking: I really learned or discovered something that I hadn’t known before. It’s just that … field work in general just brings that level of discovery to your life. It’s way better than the lab.”
Photo at top: Geo-chemist Yonaton Goldsmith digs through lake sediments in Mongolia. (Courtesy of Yonaton Goldsmith/Caltech)