One-of-a-Kind Research Study May Provide Clues to Climate Change Impacts | Nebraska today


As the famous American astronomer Carl Sagan once said, “You have to know the past to understand the present.”

This principle may become particularly relevant as the world enters uncharted territory with climate change. One way to better understand what the future holds and how society can cope is to look at previous episodes of global warming.

With a grant of nearly $ 350,000 from the National Science Foundation, Ross Secord of Nebraska will participate in a one-of-a-kind study that explores trends in community ecology during the Early Eocene climatic optimum, or EECO, which took place about 52 million years ago and marks the hottest interval in the past 70 million years. Secord and his collaborators from Hunter College, City University of New York, CUNY Brooklyn College and Brown University are analyzing fossil records from this era to shed light on how climate change affected the environment, ecosystems, and organisms.

Their findings may provide clues to scientists trying to predict future conditions if carbon dioxide levels and temperatures continue on their current tracks.

“Right now a lot of people are building climate models,” said Secord, associate professor of earth and atmospheric sciences. “They need to know what the parameters might be: what is the range of possible results you might get from an increase in temperature? During past episodes of climate change, has an increase of 9 degrees Fahrenheit caused a loss of forest cover, or has it had a particular effect on animals, or have certain types of species? faded away ? Realistically, you can’t expect the same to happen in the future, but studying the intervals in the geological record where the global warming experience has already occurred gives you a way to determine what may be the possible outcomes of climate change.

The EECO was characterized by high levels of carbon dioxide, estimated between 1,000 and 2,000 parts per million, a level that is expected to return by 2100 and beyond if CO2 emissions remain on their current trajectory. For comparison, today’s levels are around 415 ppm. Temperatures during the EECO were about 9 to 14 degrees Fahrenheit higher than today, with higher sea levels and increased precipitation. This time interval is considered one of the best analogues available for our future world.

To better understand what happened during this period, the Secord team is focusing on the Bighorn and Wind River basins in Wyoming, selected for their rich collections of fossils from before and throughout the EECO. Researchers are particularly interested in identifying the types of three-dimensional plant structures – such as open savannah-like habitats or closed-canopy tropical rainforests – that have prevailed over the years. EECO. The structure of vegetation impacts the reflectivity of the earth’s surface, the water cycle, atmospheric circulation near the earth’s surface, and carbon storage, which influence all biogeochemical cycles and the global climate.

By tracing the evolution of vegetation structures during this period, the Secord team will fill a gap in the ecological record. The most recent research on changes in mammals during the EECO indicated that the early part of the period had the greatest diversity of species from the early Cenozoic era, which spans 66 million years ago until today. It also showed a significant turnover of species in certain biozones.

But by linking climate change directly to mammalian ecology, these findings missed a crucial intermediary: plants. Climate change affects plants, which in turn impact the evolution of mammals. The Secord team plans to paint a more complete picture of this interrelation.

“The climate affects plants, and as plants change, that’s what affects mammals,” Secord said. “Mammals are not particularly sensitive to changes in temperature. You have to understand one to understand the other.

One way to deduce the structure of vegetation is to use a technique that is Secord’s expertise: the geochemistry of stable isotopes. Most elements, such as carbon and oxygen, have two or more forms, each called an isotope and having a different mass. The environment dictates the relative abundance of one isotope over another, producing a signature isotope ratio for a given type of environment.

Secord is particularly interested in the carbon isotopic ratios of leaves, which vary according to the type of photosynthetic pathways used by the plant. In areas of dense canopy, carbon isotope ratios are low. The reverse is true in open areas like grasslands and brush.

Because Secord cannot directly analyze the sheets of the EECO, he will use the fossil teeth of herbivorous mammals from this period to discern the isotopic ratios of carbon.

“Tooth enamel is very dense and hard, and does a great job of preserving these ratios,” he said. “By doing this for a number of different species, you can get a good idea of ​​the average value of the area and make interpretations about what type of environment they were in. Carbon isotopes show a nice gradation between tropical forests and open areas. and dry areas.

In addition to Secord’s isotope analyzes, collaborators Stephen Chester and Christopher Gilbert of CUNY use fossil collections to glean information about EECO animal feed, modes of locomotion and body mass. Their analyzes will provide additional clues as to how vegetation structure influences ecological change and how some species in the region have responded to warming.

The project includes an innovative broader impacts plan led by Judy Diamond, Husker’s science education expert. Through partnerships with 50 rural and tribal libraries in Nebraska and across the country, the initiative will provide the public with up-to-date information on climate change, water resources, mammal evolution and other related topics, with the aim of presenting the work of Indigenous Authors.

Diamond and his advisers are developing a master list of publications, ranging from baby books to adult books, from which partner libraries can select for $ 500 of material that best suits their audience. His advisers include Judi gaiashkibos, executive director of the Nebraska Commission on Indian Affairs, and Vicki Wood, director of youth services at Bennet Martin Library in Lincoln.

“We want to give small rural and tribal libraries the chance to get the best and the latest books on these subjects, because a lot of the highest quality work has just been published,” said Diamond, professor of university and museum libraries. . “This grant offers these libraries the opportunity to acquire high quality books.

Diamond hopes this work will stimulate a trend to use community libraries and other locally integrated entities as a focal point for scientific outreach. Historically, NSF has funded outreach programs that capitalize on the resources of museums and other established actors. Diamond said the agency’s funding for this project may reflect an increased awareness of the need to support small, community-based institutions.

“This is part of a new recognition of how to work with very local communities and the central role of libraries and their potential for scientific outreach,” said Diamond. “They are the route to a literate public that uses science to their advantage. Thanks to libraries, people can begin to understand that our world is changing, and they can ask for more information and begin to understand what is going on.


Paul N. Strickland