Author Archives: Joseph Valencia

Krypton-ice : what the noble gases tell us about the ancient climate

Tree rings famously reflect the age of the tree, but they can also encode information about the environmental conditions throughout the organism’s life. A similar principle motivates the study of ice cores – traces of the ancient atmosphere are preserved in the massive ice caps covering Earth’s polar regions.

This Sunday’s guest is Olivia Williams, a graduate student here at Oregon State who is helping to uncover the wealth of climate information harbored by polar ice cores. Olivia is a member of the College of Earth, Ocean and Atmospheric Sciences (CEOAS), where she is advised by Christo Buizert. Their lab uses ice cores to study paleoclimatology and heads the Center for Oldest Ice Exploration (COLDEX), a multi-institution NSF collaboration.

Drilling an ice core in the Arctic or Antarctic is an expensive and labor-intensive process. As a result, once they have been studied by project leads, most American ice core samples are centrally managed by the National Ice Core Lab in Denver, CO and carefully allocated to labs throughout the country. Researchers analyze cross-sections of the larger ice core sample for many geochemical features, including dust records, stable isotopes, and evidence of volcanic eruptions. Determining the historical levels of carbon dioxide, methane, and other greenhouse gases is one application of ice core analysis that yields important insights into climate change.

Olivia’s project focuses on “melt layers”, which are formed by a large-scale melting and refreezing event. The frequency and intensity of melt layers help characterize polar summer temperatures, and specifically the number of days above freezing. Typically, researchers use visual examination or optical instruments to locate layers with relatively smooth and bubble-free ice. However, such methods can fail further down in ice cores, where clathrate ice formed by increased pressure excludes all bubbles. In response, the lab of Jeffrey Severinghaus at the Scripps Institution of Oceanography developed a chemical method to serve as a supplement. This technique extracts noble gases from the core and compares the ratio of the heavier (xenon and krypton) to argon, the lightest noble gas. Since the heavier noble gases are more water-soluble, spikes in the relative concentration of krypton and xenon suggest that a melting event occurred.

During a typical day in the lab, Williams takes samples from the ice core stored at -20 C in a large walk-in freezer and handles the samples in chilled ethanol baths. She particularly focuses on ice cores from Greenland and time periods such as the last interglacial period ~120 thousand years ago and the early Holocene ~12 thousand years ago. Since the OSU lab’s noble gas methodology is novel, Olivia’s work involves a lot of design and troubleshooting the extraction line, which extracts the trapped gases. One time, she even had to commission a scientific glassblower for custom cold traps in the extraction line.

Olivia presenting at the International Partnerships in Ice Core Science conference 
Handling ice quarter core samples in the Wilkinson freezer

Williams’ interest in geology was impressed upon her at an early age, in part by the influence of her grandfather, a longtime science writer for the Seattle Times. Her grandfather’s love for the geology of the Pacific Northwest inspired her to follow in his footsteps as a scientific journalist. At Boston University, Olivia initially planned to major in communications, until she took a seminar on interdisciplinary science communication offered by BU Antarctic Research Lab, together with education and earth sciences majors. This experience helped solidify her interest in geology, and she switcher her major to earth sciences. Her senior research project related to nutrient cycling in salt marshes, but she knew that she eventually wanted to work in polar science and paleoclimatology. Besides her research at OSU, Olivia has stayed active in science communication, serving as the outreach chair for the CEOS graduate student association. She has helped organize education tables at the Corvallis Farmer’s Market. In the future, Olivia hopes to pursue an academic career and continue research and teaching in the field she loves but is open to the full range of earth science career paths.

For more on Olivia’s exciting research and to hear what it is like to drill ice from a lava formation, tune in this Sunday, January 22nd at 7PM on KBVR 88.7 FM or look out for the podcast upload on Spotify!

Heat, Hatchlings, and Sea Turtle Survival

Heat, Hatchlings, and Sea Turtle Survival

A team of researchers makes its way across the beach on this dark night, lighting their way only with starlight and moonlight. It’s high tide on this small island off the coast of Brazil, and the kind of night when green sea turtles love to come ashore to nest. The turtles fall into a trance-like state after wandering around for hours and finally building their nests, and this is when the team approaches. They take a skin sample, place a temperature logger to measure the nest temperature, and tag the turtle with a nail polish marking for future identification. One member of the team is Vic Quennessen (she/they), the subject of our next episode. Vic is a PhD student in the Department of Fisheries, Wildlife, and Conservation Sciences. Quennessen is a computational researcher on the project but helping out on nights like these is part of the job. Vic’s team collaborates with Projeto TAMAR, a Brazilian nonprofit organization that works to preserve and conserve these endangered animals throughout Brazil since the 1980s.

Vic Quennessen releases their first hatchling!

Sea turtles have no sex chromosomes, and their sex is instead determined by the environmental temperature during incubation. Eggs subjected to higher temperatures are more likely to produce female hatchlings. The point at which the sex ratio of eggs approaches 50/50 is around 29 degrees Celsius, but at just one degree higher, some clutches of eggs produce as high as 90% female hatchlings. As temperatures rise due to climate change, this has resulted in a worrying oversupply of female hatchlings.

Sea turtles are difficult to study due to their long and mysterious life cycles. It is believed that they reach reproductive maturity after around twenty-five years, but only females are readily observed because they return to land to build their nests and lay eggs. In contrast, the males stay out at sea for their entire lives. This complicates any effort to ascertain the true population structure. Sea turtles also live a long time, so there is a lag between changes in the hatchling population and the overall population. Finally, hatchlings lack external reproductive organs or other visible sexual characteristics, so the sex ratios must be estimated using temperature as a surrogate.

Vic has always loved the ocean, and they came to OSU looking to help conserve resources that are threatened, such as fish stocks or sea turtles. While attending UMass Dartmouth for their undergraduate degree, they double majored in computational mathematics and marine biology. Initially these felt like separate interests, until a professor suggested that she apply to a NOAA workshop on marine resources and population dynamics. Here she learned that mathematical methods could be a part of rigorous modeling efforts in population biology. After a gap year dedicated to science education, Vic made her way to Oregon State for a Masters in Fisheries Science. Her advisor, Prof. Will White, persuaded her to stay on for a PhD with an opportunity to study her beloved sea turtles.

Sea turtles visit the beaches of more than eighty countries, but Vic’s fieldwork focuses on a population that nests on a small Brazilian island.

Quennessen’s research seeks to predict how the green sea turtle population will be affected by their looming sex imbalance. Vic uses data collected from over 3000 hatchlings per season, including nest temperature readings as well as the numbers of nesting females, hatchlings, and captured males. They build a mathematical model to explore possible scenarios for the “mating function”, the unknown relationship between the sex ratio and reproductive success. On the one hand it is easy to imagine that such a mismatch could reduce the number of mating pairs and lead to a rapid population decline. On the other, it is not well understood how many breeding males are required to sustain the population, and adaptations in mating behavior could slow the decline in population long enough for the more optimistic climate mitigation scenarios to take effect. In any case, it will take a lot of international cooperation to conserve these ancient marine creatures – green sea turtles nest on the shores of over 80 countries. Vic’s hope is that a mathematical exploration of this question could help reveal the chances of survival for the green sea turtles and possibly inform these conservation efforts.

To learn more about Vic’s research and their other interests, including science education and working with CGE, the graduate student union at OSU, tune in Sunday, Nov 6th at 7pm PST on KBVR 88.7 FM or online!

Missed the show? Don’t worry, you can download this episode via your podcast player of choice here.