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Professor involved in climate change research project reported in Science journal

Dr. Timothy Fisher, shown here three years ago with a thrust rod of a corer, which he used to recover 1-meter segments of sediment cores from lake ice on Goshorn Lake, an inland lake next to Lake Michigan south of Holland, Mich., conducted similar research on small lakes around Lake Superior.

Dr. Timothy Fisher, shown here three years ago with a thrust rod of a corer, which he used to recover 1-meter segments of sediment cores from lake ice on Goshorn Lake, an inland lake next to Lake Michigan south of Holland, Mich., conducted similar research on small lakes around Lake Superior.

UT Professor of Environmental Sciences Dr. Timothy Fisher is part of a team of scientists who discovered that a flood of fresh water from Lake Superior into the Atlantic Ocean contributed to a cold event 9,300 years ago.

The discovery of what caused a widespread cold anomaly is detailed in the paper called “Freshwater Outburst From Lake Superior as a Trigger for the Cold Event 9,300 Years ago.” The paper is posted on the Science Express website, which previews articles that will be published in a future print edition of Science journal.

The scientists propose that a drift dam in the southeastern corner of Lake Superior broke, causing fresh water to surge through the upper Great Lakes and into the ocean via the St. Lawrence Seaway at the end of the last ice age. That rush of fresh water caused the cold event by disrupting the Gulf Stream that pulls warm water north.

The Gulf Stream current brings warm salty water to the North Atlantic, where after cooling, its increased density causes it to sink to the bottom and flow south. The process drives much of the world’s ocean circulation pattern.

But when fresh water covers the top of the salt water, that warm water doesn’t get the chance to cool and the process is essentially stalled. Without warm water coming from the north, the area cooled and stayed that way for a couple hundred years. While the cold event 9,300 years ago has been recognized, a mechanism that triggered it had not been put forward.

Fisher is a lead writer and one of eight researchers involved in the paper published in Science; Shi-Yong Yu, a postdoctoral fellow at Tulane University, led the group.

“As geologists, we study past events in Earth’s history in association with modern processes to develop a historical context, equipping us to make better decisions for the future,” Fisher said.

“While a flood of fresh water such as what happened with Lake Superior at the end of the ice age is a different mechanism than what we see now with global climate change, this information tells us that the North Atlantic Ocean was very sensitive to minor changes in freshwater input,” Fisher explained. “Such information is useful as currently the increase in glacier melting on Greenland and mountain glaciers is not only driving seal level rise, it is also increasing the flux of fresh water to the oceans.”

Fisher contributed to the research by collecting sediment core samples from small lakes around Lake Superior that showed they were once actually a part of a larger lake in the Lake Superior basin, before the dam broke and the lake fell 43 meters in about a year.

The flood also explains the previously unknown cause of the oxygen isotope changes in Lake Huron and Lake Michigan at that time, when water from Lake Superior rushed into the other lakes, Fisher said.

Researcher receives international attention for space discovery

An unexpected discovery found with Herschel Space Observatory data has received international attention, and a UT researcher is behind the buzz-worthy research.

Dr. Tom Megeath pointed to NGC 1999, the green cloud in this image taken by Herschel, the European Space Agency’s far-infrared telescope. The dark spot to the right was thought to be a cloud of dust and gas, but Megeath discovered it is a hole blown in the side of NGC 1999 by the narrow jets of gas from young stars.

Dr. Tom Megeath pointed to NGC 1999, the green cloud in this image taken by Herschel, the European Space Agency’s far-infrared telescope. The dark spot to the right was thought to be a cloud of dust and gas, but Megeath discovered it is a hole blown in the side of NGC 1999 by the narrow jets of gas from young stars.

Data from Herschel, the European Space Agency’s far-infrared telescope, located a surprising vast hole in a dense cloud of gas and dust where young stars form.

Astronomers had seen this black patch in a nursery of young stars before, but the Herschel data combined with that of telescopes confirmed there is really nothing there. This hole seems to be created when the narrow jets of gas from young stars nearby break through the dust and gas of the cloud.

“Part of the study of star formation is what stops star formation, and we just got a better glimpse of how that happens,” said Dr. Tom Megeath, UT associate professor of astronomy, who is the principal investigator on the “Herschel Orion Protostar Survey” research project. “This is just a teaser. We’re going to be up to our eyeballs in data from Herschel and there will be much more to come.”

The European Space Agency and NASA, which is a partner in the Herschel project, released news of this unexpected discovery last week and it was quickly picked up by National Geographic, national CBS and Fox news organizations, and a number of international news and blog websites.

Megeath said he “never would have predicted this level of interest” and is glad to be a part of such a worthwhile research project.

This piece of datum on the unexpected hole is just one part of Megeath’s research into star formation in the Orion constellation using the Herschel telescope to delve into the “cold universe” and get the best view yet of stars enshrouded in dust.

Information gained from Megeath’s project and his 200 hours with the Herschel telescope will give insight to the origin of our own sun and why our solar system formed the way it did. And as one of the key projects for Herschel, his findings is likely to create a foundation that will impact the future of astronomy.