Dr. Kristine DeLong: Using New Innovations to Examine the Past

Walking into Dr. Kristine DeLong’s laboratory on Louisiana State University’s campus is like walking back in time. Bleached coral skeletons sit proudly atop filing cabinets, the giant trunk of a once-stately oak tree takes up an entire table of workspace, and petrified wood lies preserved for eternity in small plastic boxes. A soft whirling can be heard in the next room, the result of a grinding machine at work. One of her undergraduate researchers is drilling out a small section of coral skeleton. The calcium carbonate dust falls into an awaiting metal pan where it will remain until it is needed for further analysis.

Sectioning off coral grains for isotope analysis Photo Credit: Victoria Barker

Sectioning off coral grains for isotope analysis Photo Credit: Victoria Barker

From the wide variety of items in her lab, it might be difficult to figure out exactly what it is Dr. DeLong studies. As we walk around the collection of old objects, she states that her research focuses on “anything that has rings that can be counted,” including trees, stalactites, oyster shells, and coral skeletons. Her field of expertise is paleoclimatology: the study of reconstructing past climate patterns. A subspecialty of this field, and one that is becoming popular in southern Louisiana, is paleotempestology: the study of reconstructing hurricane patterns through tree ring analysis.

Dr. DeLong is a woman who loves to be on the cutting edge, which means her careers are a varied and charismatic as she is. After graduating with a degree in mechanical engineering, she worked as a lighting engineer for Warner-Brothers, running the light and sound technology behind “Bugs Bunny on Broadway.” At a time when color printers were rarities in the business world, she worked as a digital color systems regional manager for Ricoh, the first woman ever to do so. Today, she is a professor in Louisiana State University’s Department of Geography and Anthropology, with research focusing on paleoclimatology.

It’s ironic that a woman who is so focused on being at the forefront of scientific discovery bases her research thousands of years into the past. Yet she assures me that, while her work focuses on understanding past climate trends, the methods behind that work are “on the edge of new technology.” As it is impossible to know first-hand what the climate was like thousands of years ago, proxies are substituted for key environmental conditions such as sea surface temperature, sea level, etc. Her graduate students combine physical observations of tree rings and coral growth bands with highly sophisticated mass spectrometry and stable isotope data in order to recreate the past.

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This intense desire to pioneer new scientific methods is currently being practiced by one of her Ph.D. students, who is devising a new proxy for determining the historical intensity of the equatorial trade winds. Throughout history, the intensity of these winds has changed in response to prevailing climate patterns. The winds carry Saharan Desert dust across the Atlantic, where it is deposited in the Caribbean Sea and taken up by corals. This dust has a unique elemental composition, making it easy to differentiate from local sources of dust. Therefore, chemical analysis of coral skeletons can show elemental disparities. The stronger the disparity, the stronger the trade winds during that growth period. Each layer of the coral skeleton can be aged with radiocarbon dating, giving an accurate timeline of the intensity of the trade winds going back hundreds of years.

Another discovery literally fell into the lab’s lap when Hurricane Ivan unearthed ancient, petrified cypress stumps 10 miles off the coast of Orange Beach, Alabama. The find is extraordinary not only because the trees are so well preserved but also because they are too ancient to accurately carbon date, which means they’re more than 50,000 years old. In fact, sea level hasn’t been low enough to support bald cypress swamps at that location since the last glacial period: 20,000 to 100,000 years ago! Additionally, their location disagrees with the established paleoclimate record of the area, which previously suggested that the region was too cold and dry for subtropical plants. As bald cypress trees only grow in wetland regions, these stumps could redefine our understanding of the Gulf coast’s paleoclimatological timeline. One of her students is working to age this wood by examining the levels of uranium contained within the wood itself, a technique that has never before been used for aging.

In addition to inventing innovative new proxies, Dr. DeLong has a thirst for combining just about every scientific field out there in truly unique ways. Her background in engineering, biology, chemistry and geology are all evident in the projects she undertakes and the classes she teaches. I sat in on one of her lectures for a class entitled Environmental Change in Ice Ages. Over the course of an hour, she seamlessly incorporated topics ranging from oxygen isotopes in precipitation, sedimentation rates, Earth’s rotational cycles, tectonic movement, the melting of Arctic ice sheets, and speleothems (aka stalactites and stalagmites). And that was only one class!

Dr. Kristine DeLong teaches her class about the Asian Monsoon season Photo credit: Victoria Barker

Dr. Kristine DeLong teaches her class about the Asian Monsoon season Photo credit: Victoria Barker

It’s not all fun and games though, she assures me. Being a professor at a major university means that she “do[es] a lot of talking to students” and “a lot of admin work.” “It’s a necessary evil,” she said, “it’s not the fun part.” Additionally, she writes proposals for grants and composes manuscripts for submission to scientific journals.

“The fun part” is fieldwork. Despite difficult conditions, fieldwork is the bread and butter of any scientist. Her team works around the world, from New Caledonia and Tahiti in the Pacific to the Gulf of Mexico. They SCUBA dive at the site off the coast of Alabama, bringing ancient wooden planks out of the muck and into the sunlight. These cruises are “hard work” with scientists “working…. and sleeping in shifts.” But she assures me that while these trips aren’t vacations they are the part that makes it all worthwhile.

Dr. DeLong is an innovator whose passion for paleoclimatology is unrivaled. She motivates and inspires her students from the first day of class to the final exam. Her novel research techniques are creative, thought provoking, and are revolutionizing the field.

For more information follow the links below:

PAST Lab Homepage: http://ga.lsu.edu/blog/pastlab/

Selected publications:

A reconstruction of sea surface temperature variability in the southeastern Gulf of Mexico from 1734 to 2008 CE using cross‐dated Sr/Ca records from the coral Siderastrea siderea

Recent 121‐year variability of western boundary upwelling in the northern South China Sea

Sea surface temperature variability in the southwest tropical Pacific since AD 1649

A snapshot of climate variability at Tahiti at 9.5 ka using a fossil coral from IODP Expedition 310

Editorial Note: Edited by Paige Jarreau

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