Study published on the rocks
A study written by a UH professor and her colleagues has been published in the most recent edition of the scientific journal, Proceedings of the National Academy of Sciences. It concerns the history of the Antarctic peninsula’s ice sheets.
Julia Wellner, research assistant professor of UH’s Department of Earth and Atmospheric Sciences and UH Biology student Reham Rafe Al Hussien investigated the history of the Antarctic peninsula’s icesheets.
“Temperatures in the Antarctic peninsula are rising faster than anywhere else on the planet right now,” Wellner said. “Ice shelves, like the Larsen, are collapsing and glaciers are retreating at what may be an unprecedented rate compared to the last several thousand years.
“The amount of ice in the peninsula is relatively small and, even though it is melting, it will not cause global sea levels to rise significantly. The Antarctic peninsula, however, provides a natural laboratory to examine how ice responds to warming conditions and thus can help us understand how the larger Antarctic ice sheets will respond as warming progresses farther south.”
The Antarctic peninsula was the last portion of the area to develop ice layers. Over the past 35 million years, ancient plants have disappeared under the ice, leaving fossilized pollen in glaciers that can help provide answers to questions about climate change.
“The PNAS paper that came out last week is part of a large project called SHALDRIL addressing the history of the Antarctic Ice Sheet and how it has waxed and waned over time,” Wellner said.
“SHALDRIL was to bring a drill rig to the Antarctic to sample rocks that are not otherwise accessible. Because the Antarctic continent is almost entirely covered by ice, it is hard to study the geology and past environmental conditions of the continent. In order to study certain time periods, the only way to get the right samples is to drill on the sea floor.”
SHALDRIL, which stands for Shallow Drilling, is a project funded by the National Science Foundation and includes Rice University marine geologist John Anderson, Louisiana State geologist Sophie Warny and University of Southampton micropaleontologist Steven Bohaty.
More than a dozen other researchers helped out with analysis and collecting data.
“As a sedimentologist, I look at sand, mud, and pebbles as a way to determine where and how rocks were formed,” Wellner said. “Pebbles are a key way to understand the relative role of ice in forming sedimentary rocks as rivers and the like don’t usually carry large pebbles or gravel — only ice can do that.
“We X-rayed the sediment cores collected during SHALDRIL and then used the X-rays to count the pebbles contained in each part of the core. My student, Reham Rafe Al Hussien, made most of these counts.
“Her work formed the basis for our interpretation of when the ice sheet first started to grow, about 35 million years ago.”
In addition to this study, Wellner will start Project LARISSA in 2012, an intiative aimed at understanding the region from the perspective of a different time period.
“LARISSA is a project studying the collapse of the Larsen Ice Shelf in 2002 and the ongoing changes of the ice. This project is focused on a completely different time scale than SHALDRIL. It’s decades rather than millions of years, but uses the same principles of studying the sediments to determine how ice has behaved. LARISSA includes two cruises to the Weddell Sea,” Wellner said.
“The first was in 2010 and a UH undergrad, Yuribia Muñoz, was able to participate. Next year, I will be taking a graduate student to help with the research.”