Focus on Research
Penn State Intercom......March 23, 2003

Dinosaurs experienced climate
changes before K-T collision  

By A'ndrea Elyse Messer
Public Information

Climate change had little to do with the demise of the dinosaurs, but the last million years before their extinction had a complex pattern of warming and cooling events that are important to our understanding of the end of their reign, according to geologists.

An extraterrestrial object that impacted the Earth near the Yucatan in Mexico 65.51 million years ago doomed the dinosaurs and 70 percent of the Earth's other species, vaporizing itself and the surrounding rocks and throwing enough ash, soot and debris into the atmosphere to effectively stop photosynthesis worldwide. This impact radically altered the natural progression of evolution. The time of the impact is called the K-T boundary and marked the end of Cretaceous Period and the beginning of the Tertiary Period.

"The terrestrial paleoclimate record near the K-T is historically contradictory and poorly resolved," said Peter Wilf, assistant professor of geosciences at Penn State. "In contrast, the resolution of K-T marine climates that has emerged over the last 10 years is excellent. Our work brings the terrestrial record up to speed so that we can look for global climate events that occurred for both land and sea."

Wilf worked with Kirk R. Johnson, curator of paleontology, Denver Museum of Nature and Science, who provided the data on land plant fossils and Brian T. Huber, curator of Foraminifera, National Museum of Natural History, Smithsonian Institution, who provided the marine data.

"It could be argued that we are still recovering from that impact and the mass extinctions of dinosaurs, mammals, insects, plants and sea life that it caused," said Wilf, who worked on this project at the University of Michigan before coming to Penn State. "For example, not only the dinosaurs, but also 80 to 90 percent of the Cretaceous plant species, including all the dominant species, disappeared."

According to Wilf, there is a lingering minority argument that the K-T extinction was caused by climate change, but the research team's results both document the climate changes and show that they were not the principal cause. Wilf, Johnson and Huber first worked to create a finely resolved terrestrial temperature record, based on plant fossils, and then correlated that record with the existing marine records. Plant fossils from the 1 million-year period before the extinction that are abundant and well preserved in a fine time sequence are found only in New Mexico and North Dakota. Of the two, the North Dakota sites are comparably much more intensively collected and studied and enabled Johnson to collect 22,000 plant fossils of more than 300 fossil plant species.

"Only in the last year, with the publication of an entire volume filled with new research results on the Hell Creek Formation in North Dakota, can we do this work and tie the plant fossil record there to actual dates in millions of years rather than relative dates," said Wilf. Johnson is a co-editor and contributor for the Hell Creek volume.

Fossils can be dated relatively by their position in the stratigraphy or layers of sediment using a simple rule. In undisturbed layers, the oldest fossils are in the lowest layers and the most recent fossils are in higher levels. Tying relative dates to real dates is not easy, especially keeping within the 100,000 year sensitivity available in the marine record, which comes from the scientific results of the ocean drilling program. Luckily, the K-T extinction occurred during a short interval in the Earth's magnetic pole reversals. Periodically, the Earth's poles switch polarity making North negative and South positive. Eventually, another switch occurs making North positive and South negative. A record of the Earth's paleomagnetism is recorded in the rocks as they are laid down.

"Three hundred and thirty-three thousand years before the extinction, a pole reversal occurred," said Wilf. "Two hundred and seventy thousand years after the extinction, another reversal occurred."

Because the researchers have three datable points -- the two reversals and the K-T impact -- they could attach ages to the layers and the fossils within and correlate the terrestrial and marine data at much finer resolution than ever before.

"The K-T impact affected the Earth's living things severely and dramatically, but the climate changes right before the impact, by comparison, did not," Wilf said. "Understanding the climate and vegetation before the impact gives us insight into what kind of world the meteorite struck and shows us that it was warming, cooling, lushly forested and otherwise functioning the way it always has done. The dinosaurs were well adapted to global warming and cooling, but not to giant speeding rocks from space."

A'ndrea Elyse Messer can be reached at aem1@psu.edu.

Atmospheric pattern leads
to cold European winters,
plenty of Mediterranean rain

By A'ndrea Elyse Messer
Public Information

An especially cold winter in Europe, lots of snow in Scandinavia or lots of rain in the Mediterranean all are symptoms of what meteorologists call the North Atlantic Oscillation, but a group of Penn State researchers has gone beyond the symptoms to try to decipher the dynamics of this atmospheric pattern.

"Some scientists argue that the impact of the NAO on global climate is comparable to El Nino," said Sukyoung Lee, associate professor of meteorology. "However, most of the scientific community's analyses to date have been of monthly or seasonal averages which fail to reveal the intrinsic nature of the NAO."

The fundamental dynamic process of the North Atlantic Oscillation is on a two-week scale, said Christian Franzke, postdoctoral fellow in meteorology, referencing an earlier work by Steven Feldstein, senior research associate, Penn State's Environmental Institute. Looking at seasonal data does not really say anything about the causes or mechanisms of the phenomenon.

The NAO is best known as a pressure difference between the air over Iceland and the air over the Azores -- located in the middle of the Atlantic on a latitude with Lisbon, Portugal. If pressure is higher than usual over Iceland, it is colder in Europe during the winter and there is more rain in the Mediterranean. If pressure is anomalously low over Iceland, there are more storms and precipitation in Europe, a milder winter and there is less rain in the Mediterranean.

"The NAO has a strong influence on European weather and is an economic issue as well for fish production and agriculture," Franzke said.

The NAO occurs in the tropopause, the areas of the atmosphere between the troposphere and the stratosphere at between seven to 10 miles above the Earth's surface. A stream of air called the Polar Front Jet Stream moves from the Pacific, across North America and over the Atlantic Ocean.

During the typical winter season, there are about two or three separate NAO incidents, some positive and some negative.

Franzke, Lee and Feldstein looked at 40 years of daily weather data gathered by the National Center for Atmospheric Research. This data includes measures of temperature, pressure, wind speed and direction and surface pressure. They used existing climate models to recreate the patterns associated with the NAO and compared those to observational data.

In the Atlantic, they found that the stream sometimes moves in a breaking wave pattern and is oriented either from the northwest to the southeast or from the southwest to the northeast. Each breaking wave takes about six days to form and then disappear and is usually followed by a second wave, completing the two-week pattern. The wave crest can actually collapse and become flat just as ocean waves do, initiating a period of no NAO. When the wave breaks with an orientation from the southwest to northeast, the pattern is considered positive and produces low pressure over Iceland making European winters warmer. When the wave breaks in the opposite direction -- southeast to northwest -- higher than usual pressure forms over Iceland and European winter is cold. This is a negative incident.

"The recent trend toward global warming shows more bias toward positive phase NAOs," Franzke said. "There are more positive than negative events occurring during a winter."

This would tip the winter weather pattern toward one of milder winters in Europe.

The researchers also found that episodes of NAO are linked to storms in the Pacific Ocean. A storm in the Pacific will create one breaking wave pattern. If the storm is in the northern Pacific, than there will likely be a negative NAO. If the storm starts farther south, the NAO probably will be positive. If a series of storms follows each other, then an NAO episode will last longer. If there are no storms entering the North Atlantic, the NAO dies out.

"Because of this connection to Pacific storms, it might be possible to pr edict the changes in European weather four or five days in advance," Franzke said.

With so much interest in global warming, we definitely need to understand the mechanism of NAO before we begin to make any predictions, Feldstein noted.

The researchers have not yet looked at the effects of the NAO on North American weather, but Franzke states that there is an influence on Eastern Seaboard weather. With Pacific storms implicated in NAO formation, and the Pacific the controlling factor for El Nino, there might be a strong link between the two phenomena. However, to fully understand the global links, the North Atlantic Oscillation must be fully understood.

The National Science Foundation funded this research.

A'ndrea Elyse Messer can be reached at aem1@psu.edu.

NEWS IN BRIEF

Don't like math?
Better study it anyway

Completing just one algebra II course makes a high-school student more than twice as likely to ultimately earn a college degree, according to a new Penn State study. One trigonometry course raises the likelihood more than threefold.

Despite these findings, significant numbers of high-school and middle-school math teachers have little training and no certification to teach intensive math courses. While school counselors and parents are encouraging students to attend college, administrators should do more to prepare the pupils in mathematics.

"Previous studies from the 1980s and 1990s show that teachers, parents and school counselors are increasingly advising students to attend college," said Jerry Trusty, coordinator of the Secondary School Counseling Program in Counselor Education and co-investigator of the study. "These adults should concurrently advise students toward being well-prepared in mathematics."

Trusty teamed with Spencer Niles, professor in charge for Counselor Education, to conduct the research using data from the National Center for Education Statistics. The high-school variables that had the most potent influence on bachelor's degree completion were units in intensive high-school mathematics courses, namely, algebra II, trigonometry, pre-calculus, and calculus.

Expendable mikes may help
locate tragedy survivors

Data gathered by Penn State engineers in a volunteer effort at the World Trade Center tragedy, suggests that simple, inexpensive microphones dropped into the rubble of a collapsed building may aid search and rescue teams despite ground level noise.

Thomas B. Gabrielson, associate professor of acoustics and senior research associate at the Applied Research Laboratory, said, "In conventional survivor searches, noise generating activities at the surface must be stopped while listening for survivors." However, the Penn State team found that the noise level in the interior voids of the rubble was about the same as that of a quiet residential neighborhood even though the noise level at the surface was much higher due to constant operation of three heavy lift cranes, air hammers and dozens of rescuers workers.

"Our results suggest that if expendable microphones were dropped or thrown into the voids in a building collapse, the sounds from trapped survivors would be louder and the surrounding noise quieter so that acoustic search could be continued without interfering with other operations," Gabrielson said. Since the Penn State team made their measurements, they have developed small wireless microphones in hardened packages that can be thrown into areas too dangerous for people to enter.

PENN STATE'S RESEARCH HERITAGE

The heart-assist pump was developed by faculty in the colleges of Medicine and Engineering in 1976 to prolong the lives of cardiovascular patients. It pioneered applications of fluid mechanics and was the first surgically implantable, seam-free, pulsatile bloom pump to receive widespread clinical use. It led to the Penn State Heart, first successfully implanted in 1985.

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