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Geology major Laura Bochner ’10 (Bethlehem, Pa.) explored climate change as an EXCEL Scholar with Kira Lawrence, assistant professor of geology and environmental geosciences.
As an underclassman, I was attracted to Professor Kira Lawrence’s courses because they offered a more in-depth look at climate change, an issue that I had been reading about in the popular news media but barely understood. Collaborating with Professor Lawrence on her paleoclimate research has provided me with an even deeper understanding of climate change.
Recently, the Intergovernmental Panel on Climate Change (IPCC), a body of scientists established by the United Nations and the World Meteorological Organization, concluded that, due to anthropogenic activity, global temperature could rise between about 1 and 6 degrees C (2 and 11 degrees F) during the 21st century; the IPCC’s best estimate for global mean annual temperature rise by 2100 is 3 degrees C (5.4 degrees F). In light of this prediction, warm times of the past are notable. The last time the Earth was 3 degrees C warmer was during the Pliocene epoch, a span of geologic time between about 5.3 and 1.8 million years ago. In fact, the Pliocene is considered one of our best analogues for what the future may be like.
Professor Lawrence and I are interested in the evolution of climate from the Pliocene to the present. This span of time saw the last major climate transition: a world with ice at the South Pole only became a world with ice at both poles. Because instrumental climate records extend back just a few hundred years, we have to turn to the geologic record for information about past climates millions of years ago. Specifically, we use the alkenone organic proxy to estimate past temperatures in the surface ocean.
Alkenones are lipids (fats) produced by algae that dwell in the surface ocean. These algae manufacture their alkenones differently depending on the temperature of the water in which they live. Alkenones can be found in ocean sediment because some of the organisms that produced them died and sank to the ocean floor, accumulating over time. In our research, we isolate alkenones from ocean sediment samples provided by the Ocean Drilling Program and analyze them using gas chromatography. The relative abundance of different alkenones in the samples we analyze tells us what the temperature of the sea surface was at the time the alkenones were produced. Essentially, these fats are our thermometers.
Recently, we have been focusing on generating a high-resolution temperature record for a site in the equatorial Atlantic, off the west coast of Africa. With our data, as well as previously generated records from other sites, we can assess temperature change over space as well as time; we can characterize the evolution of ocean temperature gradients across both latitudes and longitudes by comparing our data with data from a site in the North Atlantic and one in the equatorial Pacific. Ultimately, we are interested in the mechanism responsible for the climate changes we have observed. Knowledge about how the climate system changed in the past will inform our understanding of how it may respond in the future.
Assisting Professor Lawrence with her research in paleoclimatology has been an eye-opening, rewarding lesson in the scientific method. I am grateful for the opportunity to become involved in scientific research at the undergraduate level, and the experience has brought to life material that was first presented in textbooks. Furthermore, it has been thrilling to learn how scientists “do science.” Prior to doing EXCEL, I had no concept of the importance of research. Professor Lawrence is an enthusiastic, engaging teacher. Her passion for climatology/paleoclimatology and interest in student learning are equally apparent in the lab and the classroom.