No laughing matter: Nitrous oxide rose at end of last ice age

Researchers measured increases in atmospheric nitrous oxide concentrations about 16,000 to 10,000 years ago using ice from Taylor Glacier in Antarctica. -  Adrian Schilt
Researchers measured increases in atmospheric nitrous oxide concentrations about 16,000 to 10,000 years ago using ice from Taylor Glacier in Antarctica. – Adrian Schilt

Nitrous oxide (N2O) is an important greenhouse gas that doesn’t receive as much notoriety as carbon dioxide or methane, but a new study confirms that atmospheric levels of N2O rose significantly as the Earth came out of the last ice age and addresses the cause.

An international team of scientists analyzed air extracted from bubbles enclosed in ancient polar ice from Taylor Glacier in Antarctica, allowing for the reconstruction of the past atmospheric composition. The analysis documented a 30 percent increase in atmospheric nitrous oxide concentrations from 16,000 years ago to 10,000 years ago. This rise in N2O was caused by changes in environmental conditions in the ocean and on land, scientists say, and contributed to the warming at the end of the ice age and the melting of large ice sheets that then existed.

The findings add an important new element to studies of how Earth may respond to a warming climate in the future. Results of the study, which was funded by the U.S. National Science Foundation and the Swiss National Science Foundation, are being published this week in the journal Nature.

“We found that marine and terrestrial sources contributed about equally to the overall increase of nitrous oxide concentrations and generally evolved in parallel at the end of the last ice age,” said lead author Adrian Schilt, who did much of the work as a post-doctoral researcher at Oregon State University. Schilt then continued to work on the study at the Oeschger Centre for Climate Change Research at the University of Bern in Switzerland.

“The end of the last ice age represents a partial analog to modern warming and allows us to study the response of natural nitrous oxide emissions to changing environmental conditions,” Schilt added. “This will allow us to better understand what might happen in the future.”

Nitrous oxide is perhaps best known as laughing gas, but it is also produced by microbes on land and in the ocean in processes that occur naturally, but can be enhanced by human activity. Marine nitrous oxide production is linked closely to low oxygen conditions in the upper ocean and global warming is predicted to intensify the low-oxygen zones in many of the world’s ocean basins. N2O also destroys ozone in the stratosphere.

“Warming makes terrestrial microbes produce more nitrous oxide,” noted co-author Edward Brook, an Oregon State paleoclimatologist whose research team included Schilt. “Greenhouse gases go up and down over time, and we’d like to know more about why that happens and how it affects climate.”

Nitrous oxide is among the most difficult greenhouse gases to study in attempting to reconstruct the Earth’s climate history through ice core analysis. The specific technique that the Oregon State research team used requires large samples of pristine ice that date back to the desired time of study – in this case, between about 16,000 and 10,000 years ago.

The unusual way in which Taylor Glacier is configured allowed the scientists to extract ice samples from the surface of the glacier instead of drilling deep in the polar ice cap because older ice is transported upward near the glacier margins, said Brook, a professor in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences.

The scientists were able to discern the contributions of marine and terrestrial nitrous oxide through analysis of isotopic ratios, which fingerprint the different sources of N2O in the atmosphere.

“The scientific community knew roughly what the N2O concentration trends were prior to this study,” Brook said, “but these findings confirm that and provide more exact details about changes in sources. As nitrous oxide in the atmosphere continues to increase – along with carbon dioxide and methane – we now will be able to more accurately assess where those contributions are coming from and the rate of the increase.”

Atmospheric N2O was roughly 200 parts per billion at the peak of the ice age about 20,000 years ago then rose to 260 ppb by 10,000 years ago. As of 2014, atmospheric N2Owas measured at about 327 ppb, an increase attributed primarily to agricultural influences.

Although the N2O increase at the end of the last ice age was almost equally attributable to marine and terrestrial sources, the scientists say, there were some differences.

“Our data showed that terrestrial emissions changed faster than marine emissions, which was highlighted by a fast increase of emissions on land that preceded the increase in marine emissions,” Schilt pointed out. “It appears to be a direct response to a rapid temperature change between 15,000 and 14,000 years ago.”

That finding underscores the complexity of analyzing how Earth responds to changing conditions that have to account for marine and terrestrial influences; natural variability; the influence of different greenhouse gases; and a host of other factors, Brook said.

“Natural sources of N2O are predicted to increase in the future and this study will help up test predictions on how the Earth will respond,” Brook said.

No laughing matter: Nitrous oxide rose at end of last ice age

Researchers measured increases in atmospheric nitrous oxide concentrations about 16,000 to 10,000 years ago using ice from Taylor Glacier in Antarctica. -  Adrian Schilt
Researchers measured increases in atmospheric nitrous oxide concentrations about 16,000 to 10,000 years ago using ice from Taylor Glacier in Antarctica. – Adrian Schilt

Nitrous oxide (N2O) is an important greenhouse gas that doesn’t receive as much notoriety as carbon dioxide or methane, but a new study confirms that atmospheric levels of N2O rose significantly as the Earth came out of the last ice age and addresses the cause.

An international team of scientists analyzed air extracted from bubbles enclosed in ancient polar ice from Taylor Glacier in Antarctica, allowing for the reconstruction of the past atmospheric composition. The analysis documented a 30 percent increase in atmospheric nitrous oxide concentrations from 16,000 years ago to 10,000 years ago. This rise in N2O was caused by changes in environmental conditions in the ocean and on land, scientists say, and contributed to the warming at the end of the ice age and the melting of large ice sheets that then existed.

The findings add an important new element to studies of how Earth may respond to a warming climate in the future. Results of the study, which was funded by the U.S. National Science Foundation and the Swiss National Science Foundation, are being published this week in the journal Nature.

“We found that marine and terrestrial sources contributed about equally to the overall increase of nitrous oxide concentrations and generally evolved in parallel at the end of the last ice age,” said lead author Adrian Schilt, who did much of the work as a post-doctoral researcher at Oregon State University. Schilt then continued to work on the study at the Oeschger Centre for Climate Change Research at the University of Bern in Switzerland.

“The end of the last ice age represents a partial analog to modern warming and allows us to study the response of natural nitrous oxide emissions to changing environmental conditions,” Schilt added. “This will allow us to better understand what might happen in the future.”

Nitrous oxide is perhaps best known as laughing gas, but it is also produced by microbes on land and in the ocean in processes that occur naturally, but can be enhanced by human activity. Marine nitrous oxide production is linked closely to low oxygen conditions in the upper ocean and global warming is predicted to intensify the low-oxygen zones in many of the world’s ocean basins. N2O also destroys ozone in the stratosphere.

“Warming makes terrestrial microbes produce more nitrous oxide,” noted co-author Edward Brook, an Oregon State paleoclimatologist whose research team included Schilt. “Greenhouse gases go up and down over time, and we’d like to know more about why that happens and how it affects climate.”

Nitrous oxide is among the most difficult greenhouse gases to study in attempting to reconstruct the Earth’s climate history through ice core analysis. The specific technique that the Oregon State research team used requires large samples of pristine ice that date back to the desired time of study – in this case, between about 16,000 and 10,000 years ago.

The unusual way in which Taylor Glacier is configured allowed the scientists to extract ice samples from the surface of the glacier instead of drilling deep in the polar ice cap because older ice is transported upward near the glacier margins, said Brook, a professor in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences.

The scientists were able to discern the contributions of marine and terrestrial nitrous oxide through analysis of isotopic ratios, which fingerprint the different sources of N2O in the atmosphere.

“The scientific community knew roughly what the N2O concentration trends were prior to this study,” Brook said, “but these findings confirm that and provide more exact details about changes in sources. As nitrous oxide in the atmosphere continues to increase – along with carbon dioxide and methane – we now will be able to more accurately assess where those contributions are coming from and the rate of the increase.”

Atmospheric N2O was roughly 200 parts per billion at the peak of the ice age about 20,000 years ago then rose to 260 ppb by 10,000 years ago. As of 2014, atmospheric N2Owas measured at about 327 ppb, an increase attributed primarily to agricultural influences.

Although the N2O increase at the end of the last ice age was almost equally attributable to marine and terrestrial sources, the scientists say, there were some differences.

“Our data showed that terrestrial emissions changed faster than marine emissions, which was highlighted by a fast increase of emissions on land that preceded the increase in marine emissions,” Schilt pointed out. “It appears to be a direct response to a rapid temperature change between 15,000 and 14,000 years ago.”

That finding underscores the complexity of analyzing how Earth responds to changing conditions that have to account for marine and terrestrial influences; natural variability; the influence of different greenhouse gases; and a host of other factors, Brook said.

“Natural sources of N2O are predicted to increase in the future and this study will help up test predictions on how the Earth will respond,” Brook said.

Geologists dig into science around the globe, on land and at sea

University of Cincinnati geologists will be well represented among geoscientists from around the world at The Geological Society of America’s Annual Meeting and Exposition. The meeting takes place Oct. 19-22, in Vancouver, Canada, and will feature geoscientists representing more than 40 different disciplines. The meeting will feature highlights of UC’s geological research that is taking place globally, from Chile to Costa Rica, Belize, Bulgaria, Scotland, Trinidad and a new project under development in the Canary Islands.

UC faculty and graduate students are lead or supporting authors on more than two dozen Earth Sciences-related research papers and/or PowerPoint and poster exhibitions at the GSA meeting.

The presentations also cover UC’s longtime and extensive exploration and findings in the Cincinnati Arch of the Ohio Valley, world-renowned for its treasure trove of paleontology – plant and animal fossils that were preserved when a shallow sea covered the region 450 million years ago during the Paleozoic Era.

Furthermore, in an effort to diversify the field of researchers in the Earth Sciences, a UC assistant professor of science education and geology, Christopher Atchison, was awarded funding from the National Science Foundation and the Society of Exploration Geophysics to lead a research field trip in Vancouver for students with disabilities. Graduate and undergraduate student participants will conduct the research on Oct. 18 and then join events at the GSA meeting. They’ll be guided by geoscience researchers representing the United Kingdom, New Zealand, Canada and the U.S. Those guides include Atchison and Julie Hendricks, a UC special education major from Batavia, Ohio, who will be using her expertise in American Sign Language (ASL) to assist student researchers representing Deaf and Hard of Hearing communities.

The meeting will also formally introduce Arnold Miller, UC professor of geology, as the new president-elect of the national Paleontological Society Thomas Lowell, professor of geology, is a recently elected Fellow of the Geological Society of America – a recognition for producing a substantial body of research. Lowell joins colleagues Warren Huff, professor of geology, and Lewis Owen, professor and head of the Department of Geology, as GSA Fellows.

Here are highlights of the UC research to be presented at the GSA meeting Oct. 19-22:

Staying Put or Moving On? Researchers Develop Model to Identify Migrating Patterns of Different Species

Are plant and animal species what you might call lifelong residents – they never budge from the same place? That’s a relatively common belief in ecology and paleoecology – that classes of organisms tend to stay put over millions of years and either evolve or go extinct as the environment changes. UC researchers developed a series of numerical models simulating shifting habitats in fossil regions to compare whether species changed environments when factoring geological and other changes in the fossil record. They found that geologically driven changes in the quality of the fossil record did not distort the real ecological signal, and that most species maintained their particular habitat preferences through time. They did not evolve to adapt to changing environments, but rather, they migrated, following their preferred environments. That is to say, they did not stay in place geographically but by moving, they were able to track their favored habitats. Field research for the project was conducted in New York state as well as the paleontological-rich region of Cincinnati; Dayton, Ohio, Lexington, Ky.; and Indiana. Funding for the project was supported by The Paleontological Society; The Geological Society of America; The American Museum of Natural History and the UC Geology Department’s Kenneth E. Caster Memorial Fund.

Presenter: Andrew Zaffos, UC geology doctoral student

Co-authors: Arnold Miller, Carlton Brett

Pioneering Study Provides a Better Understanding of What Southern Ohio and Central Kentucky Looked Like Hundreds of Millions of Years Ago

The end of the Ordovician period resulted in one of the largest mass extinction events in the Earth’s history. T.J. Malgieri, a UC master’s student in geology, led this study examining the limestone and shales of the Upper Ordovician Period – the geologic Grant Lake Formation covering southern Ohio and central Kentucky – to recreate how the shoreline looked some 445 million years ago. In this pioneering study of mud cracks and deposits in the rocks, the researchers discovered that the shoreline existed to the south and that the water became deeper toward the north. By determining these ecological parameters, the ramp study provides a better understanding of environments during a time of significant ecological change. Malgieri says the approach can be applied to other basins throughout the world to create depth indicators in paeloenvironments.

Presenter: T.J. Malgieri, UC geology master’s student

Co-authors: Carlton Brett, Cameron Schalbach, Christopher Aucoin, UC; James Thomka (UC, University of Akron); Benjamin Dattilo, Indiana University Purdue University Ft. Wayne

UC Researchers Take a Unique Approach to Monitoring Groundwater Supplies Near Ohio Fracking Sites

A collaborative research project out of UC is examining effects of fracking on groundwater in the Utica Shale region of eastern Ohio. First launched in Carroll County in 2012, the team of researchers is examining methane levels and origins of methane in private wells and springs before, during and after the onset of fracking. The team travels to the region to take water samples four times a year.

Presenter: Claire Botner, a UC geology master’s student

Co-author: Amy Townsend-Small, UC assistant professor of geology

Sawing Through Seagrass to Reveal Clues to the Past

Kelsy Feser, a UC doctoral student in geology, is working at several sites around St. Croix in the Virgin Islands to see if human developments impact marine life. The research focuses on shells of snails and clams that have piled up on the sea floor for thousands of years. Digging through layers of thick seagrass beds on the ocean floor, Feser can examine deeper shells that were abundant thousands of years ago and compare them to shallower layers that include living clams and snails. Early analysis indicates a greater population of potentially pollution-tolerant mussels in an area near a landfill on the island, compared with shells from much earlier time periods. Feser is doing this sea grass analysis around additional sites including tourist resorts, an oil refinery, a power plant and a marina. Funding for the research is provided by the Paleontological Society, the GSA, the American Museum of Natural History and the UC Geology Department.

Presenter: Kelsy Feser, UC geology doctoral student

Co-authors: Arnold Miller

Turning to the Present to Understand the Past

In order to properly interpret changes in climate, vegetation, or animal populations over time, it is necessary to establish a comparative baseline. Stella Mosher, a UC geology master’s student, is studying stable carbon, nitrogen, sulfur and strontium isotopes in modern vegetation from the Canary Islands in order to quantify modern climatic and environmental patterns. Her findings will provide a crucial foundation for future UC research on regional paleoclimatic and paleoenvironmental shifts.

Presenter: Stella Mosher, graduate student in geology

Co-authors: Brooke Crowley, assistant professor of geology; Yurena Yanes, research assistant professor of geology

A Study on the Impact of Sea Spray

Sulfur is an element of interest in both geology and archaeology, because it can reveal information about the diets of ancient cultures. This study takes a novel approach to studying how sea spray can affect the sulfur isotope values in plants on a small island, focusing on the island of Trinidad. Researchers collected leaves from different plant species to get their sulfur isotope value, exploring whether wind direction played a role in how plants were influenced by the marine water from sea spray. Vegetation was collected from the edges of the island to the deeply forested areas. The study found that sulfur isotope values deeper inland and on the calmer west coast were dramatically lower in indicating marine water than vegetation along the edges and the east coast. The findings can help indicate the foraging activities of humans and animals. Funding for the study was supported by the Geological Society of America, the UC Graduate Student Association and the UC Department of Geology.

Presenter: Janine Sparks, UC geology doctoral student

Co-authors: Brooke Crowley, UC assistant professor, geology/anthropology; William Gilhooly III, assistant professor, Earth Sciences, Indiana University-Purdue University Indianapolis

Proxy Wars – The Paleobiology Data Debate

For the past several decades, paleobiologists have built large databases containing information on fossil plants and animals of all geological ages to investigate the timing and extent of major changes in biodiversity – changes such as mass extinctions that have taken place throughout the history of life. Biodiversity researcher Arnold Miller says that in building these databases, it can be a challenge to accurately identify species in the geological record, so it has been common for researchers to instead study biodiversity trends using data compiled at broader levels of biological classification, including the genus level, under the assumption that these patterns are effective proxies for what would be observed among species if the data were available. Miller has been involved in construction of The Paleobiology Database, an extensive public online resource that contains global genus- and species-level data, now permitting a direct, novel look at the similarities and differences between patterns at these two levels. Miller’s discussion aims to set the record straight as to when researchers can effectively use a genus as a proxy for a species and also when it’s inappropriate. This research is funded by the NASA Astrobiology Program.

Presenter: Arnold Miller, UC professor of geology

A Novel New Method for Examining the Distribution of Pores in Rocks

Oil and gas companies take an interest in the porosity of sedimentary rocks because those open spaces can be filled with fuel resources. Companies involved with hydraulic fracturing (“fracking”) are also interested in porosity because it could be a source for storing wastewater as a result of fracking. In this unique study, UC researchers made pore-size measurements similar to those used in crystal size distribution (CSD) theory to determine distribution of pores as a function of their sizes, using thin sections of rock. In addition to providing accurate porosity distribution at a given depth, their approach can be extended to evaluate variation of pore spaces as a function of depth in a drill core, percent of pores in each size range, and pore types and pore geometry. The Texas Bureau of Economic Geology provided the rock samples used in the study. Funding for the study was supported by the Turkish Petroleum Corporation.

Presenter: Ugurlu Ibrahim, master’s student in geology

Co-author: Attila Kilinc, professor of geology

Researchers Turn to 3-D Technology to Examine the Formation of Cliffband Landscapes

A blend of photos and technology takes a new twist on studying cliff landscapes and how they were formed. The method called Structure-From-Motion Photogrammetry – computational photo image processing techniques – is used to study the formation of cliff landscapes in Colorado and Utah and to understand how the layered rock formations in the cliffs are affected by erosion.

Presenter: Dylan Ward, UC assistant professor of geology

Testing the Links Between Climate and Sedimentation in the Atacama Desert, Northern Chile

The Atacama Desert is used as an analog for understanding the surface of Mars. In some localities, there has been no activity for millions of years. UC researchers have been working along the flank of the Andes Mountains in northern Chile, and this particular examination focuses on the large deposits of sediment that are transported down the plateau and gather at the base. The researchers are finding that their samples are not reflecting the million-year-old relics previously found on such expeditions, but may indicate more youthful activity possibly resulting from climatic events. The research is supported by a $273,634 grant from the National Science Foundation to explore glacio-geomorphic constraints on the climate history of subtropical northern Chile.

Presenter: Jason Cesta, UC geology master’s student

Co-author: Dylan Ward, UC assistant professor of geology

Uncovering the Explosive Mysteries Surrounding the Manganese of Northeast Bulgaria

UC’s geology collections hold minerals from field expeditions around the world, including manganese from the Obrochishte mines of northeastern Bulgaria. Found in the region’s sedimentary rock, manganese can be added to metals such as steel to improve strength. It’s widely believed that these manganese formations were the result of ocean water composition at the time the sediments were deposited in the ocean. In this presentation, UC researchers present new information on why they believe the manganese formations resulted from volcanic eruptions, perhaps during the Rupelian stage of the geologic time scale, when bentonite clay minerals were formed. The presentation evolved from an advance class project last spring under the direction of Warren Huff, a UC professor of geology.

Presenter: Jason Cesta, UC geology master’s student

Co-authors: Warren Huff, UC professor of geology; Christopher Aucoin; Michael Harrell; Thomas Malgieri; Barry Maynard; Cameron Schwalbach; Ibrahim Ugurlu; Antony Winrod

Two UC researchers will chair sessions at the GSA meeting: Doctoral student Gary Motz will chair the session, “Topics in Paleoecology: Modern Analogues and Ancient Systems,” on Oct. 19. Matt Vrazo, also a doctoral student in geology, is chairing “Paleontology: Trace Fossils, Taphonomy and Exceptional Preservation” on Oct. 21, and will present, “Taphonomic and Ecological Controls on Eurypterid Lagerstäten: A Model for Preservation in the Mid-Paleozoic.”

###

UC’s nationally ranked Department of Geology conducts field research around the world in areas spanning paleontology, quaternary geology, geomorphology, sedimentology, stratigraphy, tectonics, environmental geology and biogeochemistry.

The Geological Society of America, founded in 1888, is a scientific society with more than 26,500 members from academia, government, and industry in more than 100 countries. Through its meetings, publications, and programs, GSA enhances the professional growth of its members and promotes the geosciences in the service of humankind.

Geologists dig into science around the globe, on land and at sea

University of Cincinnati geologists will be well represented among geoscientists from around the world at The Geological Society of America’s Annual Meeting and Exposition. The meeting takes place Oct. 19-22, in Vancouver, Canada, and will feature geoscientists representing more than 40 different disciplines. The meeting will feature highlights of UC’s geological research that is taking place globally, from Chile to Costa Rica, Belize, Bulgaria, Scotland, Trinidad and a new project under development in the Canary Islands.

UC faculty and graduate students are lead or supporting authors on more than two dozen Earth Sciences-related research papers and/or PowerPoint and poster exhibitions at the GSA meeting.

The presentations also cover UC’s longtime and extensive exploration and findings in the Cincinnati Arch of the Ohio Valley, world-renowned for its treasure trove of paleontology – plant and animal fossils that were preserved when a shallow sea covered the region 450 million years ago during the Paleozoic Era.

Furthermore, in an effort to diversify the field of researchers in the Earth Sciences, a UC assistant professor of science education and geology, Christopher Atchison, was awarded funding from the National Science Foundation and the Society of Exploration Geophysics to lead a research field trip in Vancouver for students with disabilities. Graduate and undergraduate student participants will conduct the research on Oct. 18 and then join events at the GSA meeting. They’ll be guided by geoscience researchers representing the United Kingdom, New Zealand, Canada and the U.S. Those guides include Atchison and Julie Hendricks, a UC special education major from Batavia, Ohio, who will be using her expertise in American Sign Language (ASL) to assist student researchers representing Deaf and Hard of Hearing communities.

The meeting will also formally introduce Arnold Miller, UC professor of geology, as the new president-elect of the national Paleontological Society Thomas Lowell, professor of geology, is a recently elected Fellow of the Geological Society of America – a recognition for producing a substantial body of research. Lowell joins colleagues Warren Huff, professor of geology, and Lewis Owen, professor and head of the Department of Geology, as GSA Fellows.

Here are highlights of the UC research to be presented at the GSA meeting Oct. 19-22:

Staying Put or Moving On? Researchers Develop Model to Identify Migrating Patterns of Different Species

Are plant and animal species what you might call lifelong residents – they never budge from the same place? That’s a relatively common belief in ecology and paleoecology – that classes of organisms tend to stay put over millions of years and either evolve or go extinct as the environment changes. UC researchers developed a series of numerical models simulating shifting habitats in fossil regions to compare whether species changed environments when factoring geological and other changes in the fossil record. They found that geologically driven changes in the quality of the fossil record did not distort the real ecological signal, and that most species maintained their particular habitat preferences through time. They did not evolve to adapt to changing environments, but rather, they migrated, following their preferred environments. That is to say, they did not stay in place geographically but by moving, they were able to track their favored habitats. Field research for the project was conducted in New York state as well as the paleontological-rich region of Cincinnati; Dayton, Ohio, Lexington, Ky.; and Indiana. Funding for the project was supported by The Paleontological Society; The Geological Society of America; The American Museum of Natural History and the UC Geology Department’s Kenneth E. Caster Memorial Fund.

Presenter: Andrew Zaffos, UC geology doctoral student

Co-authors: Arnold Miller, Carlton Brett

Pioneering Study Provides a Better Understanding of What Southern Ohio and Central Kentucky Looked Like Hundreds of Millions of Years Ago

The end of the Ordovician period resulted in one of the largest mass extinction events in the Earth’s history. T.J. Malgieri, a UC master’s student in geology, led this study examining the limestone and shales of the Upper Ordovician Period – the geologic Grant Lake Formation covering southern Ohio and central Kentucky – to recreate how the shoreline looked some 445 million years ago. In this pioneering study of mud cracks and deposits in the rocks, the researchers discovered that the shoreline existed to the south and that the water became deeper toward the north. By determining these ecological parameters, the ramp study provides a better understanding of environments during a time of significant ecological change. Malgieri says the approach can be applied to other basins throughout the world to create depth indicators in paeloenvironments.

Presenter: T.J. Malgieri, UC geology master’s student

Co-authors: Carlton Brett, Cameron Schalbach, Christopher Aucoin, UC; James Thomka (UC, University of Akron); Benjamin Dattilo, Indiana University Purdue University Ft. Wayne

UC Researchers Take a Unique Approach to Monitoring Groundwater Supplies Near Ohio Fracking Sites

A collaborative research project out of UC is examining effects of fracking on groundwater in the Utica Shale region of eastern Ohio. First launched in Carroll County in 2012, the team of researchers is examining methane levels and origins of methane in private wells and springs before, during and after the onset of fracking. The team travels to the region to take water samples four times a year.

Presenter: Claire Botner, a UC geology master’s student

Co-author: Amy Townsend-Small, UC assistant professor of geology

Sawing Through Seagrass to Reveal Clues to the Past

Kelsy Feser, a UC doctoral student in geology, is working at several sites around St. Croix in the Virgin Islands to see if human developments impact marine life. The research focuses on shells of snails and clams that have piled up on the sea floor for thousands of years. Digging through layers of thick seagrass beds on the ocean floor, Feser can examine deeper shells that were abundant thousands of years ago and compare them to shallower layers that include living clams and snails. Early analysis indicates a greater population of potentially pollution-tolerant mussels in an area near a landfill on the island, compared with shells from much earlier time periods. Feser is doing this sea grass analysis around additional sites including tourist resorts, an oil refinery, a power plant and a marina. Funding for the research is provided by the Paleontological Society, the GSA, the American Museum of Natural History and the UC Geology Department.

Presenter: Kelsy Feser, UC geology doctoral student

Co-authors: Arnold Miller

Turning to the Present to Understand the Past

In order to properly interpret changes in climate, vegetation, or animal populations over time, it is necessary to establish a comparative baseline. Stella Mosher, a UC geology master’s student, is studying stable carbon, nitrogen, sulfur and strontium isotopes in modern vegetation from the Canary Islands in order to quantify modern climatic and environmental patterns. Her findings will provide a crucial foundation for future UC research on regional paleoclimatic and paleoenvironmental shifts.

Presenter: Stella Mosher, graduate student in geology

Co-authors: Brooke Crowley, assistant professor of geology; Yurena Yanes, research assistant professor of geology

A Study on the Impact of Sea Spray

Sulfur is an element of interest in both geology and archaeology, because it can reveal information about the diets of ancient cultures. This study takes a novel approach to studying how sea spray can affect the sulfur isotope values in plants on a small island, focusing on the island of Trinidad. Researchers collected leaves from different plant species to get their sulfur isotope value, exploring whether wind direction played a role in how plants were influenced by the marine water from sea spray. Vegetation was collected from the edges of the island to the deeply forested areas. The study found that sulfur isotope values deeper inland and on the calmer west coast were dramatically lower in indicating marine water than vegetation along the edges and the east coast. The findings can help indicate the foraging activities of humans and animals. Funding for the study was supported by the Geological Society of America, the UC Graduate Student Association and the UC Department of Geology.

Presenter: Janine Sparks, UC geology doctoral student

Co-authors: Brooke Crowley, UC assistant professor, geology/anthropology; William Gilhooly III, assistant professor, Earth Sciences, Indiana University-Purdue University Indianapolis

Proxy Wars – The Paleobiology Data Debate

For the past several decades, paleobiologists have built large databases containing information on fossil plants and animals of all geological ages to investigate the timing and extent of major changes in biodiversity – changes such as mass extinctions that have taken place throughout the history of life. Biodiversity researcher Arnold Miller says that in building these databases, it can be a challenge to accurately identify species in the geological record, so it has been common for researchers to instead study biodiversity trends using data compiled at broader levels of biological classification, including the genus level, under the assumption that these patterns are effective proxies for what would be observed among species if the data were available. Miller has been involved in construction of The Paleobiology Database, an extensive public online resource that contains global genus- and species-level data, now permitting a direct, novel look at the similarities and differences between patterns at these two levels. Miller’s discussion aims to set the record straight as to when researchers can effectively use a genus as a proxy for a species and also when it’s inappropriate. This research is funded by the NASA Astrobiology Program.

Presenter: Arnold Miller, UC professor of geology

A Novel New Method for Examining the Distribution of Pores in Rocks

Oil and gas companies take an interest in the porosity of sedimentary rocks because those open spaces can be filled with fuel resources. Companies involved with hydraulic fracturing (“fracking”) are also interested in porosity because it could be a source for storing wastewater as a result of fracking. In this unique study, UC researchers made pore-size measurements similar to those used in crystal size distribution (CSD) theory to determine distribution of pores as a function of their sizes, using thin sections of rock. In addition to providing accurate porosity distribution at a given depth, their approach can be extended to evaluate variation of pore spaces as a function of depth in a drill core, percent of pores in each size range, and pore types and pore geometry. The Texas Bureau of Economic Geology provided the rock samples used in the study. Funding for the study was supported by the Turkish Petroleum Corporation.

Presenter: Ugurlu Ibrahim, master’s student in geology

Co-author: Attila Kilinc, professor of geology

Researchers Turn to 3-D Technology to Examine the Formation of Cliffband Landscapes

A blend of photos and technology takes a new twist on studying cliff landscapes and how they were formed. The method called Structure-From-Motion Photogrammetry – computational photo image processing techniques – is used to study the formation of cliff landscapes in Colorado and Utah and to understand how the layered rock formations in the cliffs are affected by erosion.

Presenter: Dylan Ward, UC assistant professor of geology

Testing the Links Between Climate and Sedimentation in the Atacama Desert, Northern Chile

The Atacama Desert is used as an analog for understanding the surface of Mars. In some localities, there has been no activity for millions of years. UC researchers have been working along the flank of the Andes Mountains in northern Chile, and this particular examination focuses on the large deposits of sediment that are transported down the plateau and gather at the base. The researchers are finding that their samples are not reflecting the million-year-old relics previously found on such expeditions, but may indicate more youthful activity possibly resulting from climatic events. The research is supported by a $273,634 grant from the National Science Foundation to explore glacio-geomorphic constraints on the climate history of subtropical northern Chile.

Presenter: Jason Cesta, UC geology master’s student

Co-author: Dylan Ward, UC assistant professor of geology

Uncovering the Explosive Mysteries Surrounding the Manganese of Northeast Bulgaria

UC’s geology collections hold minerals from field expeditions around the world, including manganese from the Obrochishte mines of northeastern Bulgaria. Found in the region’s sedimentary rock, manganese can be added to metals such as steel to improve strength. It’s widely believed that these manganese formations were the result of ocean water composition at the time the sediments were deposited in the ocean. In this presentation, UC researchers present new information on why they believe the manganese formations resulted from volcanic eruptions, perhaps during the Rupelian stage of the geologic time scale, when bentonite clay minerals were formed. The presentation evolved from an advance class project last spring under the direction of Warren Huff, a UC professor of geology.

Presenter: Jason Cesta, UC geology master’s student

Co-authors: Warren Huff, UC professor of geology; Christopher Aucoin; Michael Harrell; Thomas Malgieri; Barry Maynard; Cameron Schwalbach; Ibrahim Ugurlu; Antony Winrod

Two UC researchers will chair sessions at the GSA meeting: Doctoral student Gary Motz will chair the session, “Topics in Paleoecology: Modern Analogues and Ancient Systems,” on Oct. 19. Matt Vrazo, also a doctoral student in geology, is chairing “Paleontology: Trace Fossils, Taphonomy and Exceptional Preservation” on Oct. 21, and will present, “Taphonomic and Ecological Controls on Eurypterid Lagerstäten: A Model for Preservation in the Mid-Paleozoic.”

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UC’s nationally ranked Department of Geology conducts field research around the world in areas spanning paleontology, quaternary geology, geomorphology, sedimentology, stratigraphy, tectonics, environmental geology and biogeochemistry.

The Geological Society of America, founded in 1888, is a scientific society with more than 26,500 members from academia, government, and industry in more than 100 countries. Through its meetings, publications, and programs, GSA enhances the professional growth of its members and promotes the geosciences in the service of humankind.

Ancient Indonesian climate shift linked to glacial cycle

Using sediments from a remote lake, researchers from Brown University have assembled a 60,000-year record of rainfall in central Indonesia. The analysis reveals important new details about the climate history of a region that wields a substantial influence on the global climate as a whole.

The Indonesian archipelago sits in the Indo-Pacific Warm Pool, an expanse of ocean that supplies a sizable fraction of the water vapor in Earth’s atmosphere and plays a role in propagating El Niño cycles. Despite the region’s importance in the global climate system, not much is known about its own climate history, says James Russell, associate professor of geological sciences at Brown.

“We wanted to assess long-term climate variation in the region,” Russell said, “not just to assess how global climate influences Indonesia, but to see how that feeds back into the global climate system.”

The data are published this week in the Proceedings of the National Academy of Sciences.

The study found that the region’s normally wet, tropical climate was interrupted by a severe dry period from around 33,000 years ago until about 16,000 years ago. That period coincides with peak of the last ice age, when glaciers covered vast swaths of the northern hemisphere. Climate models had suggested that glacial ice could shift the track of tropical monsoons, causing an Indonesian dry period. But this is the first hard data to show that was indeed the case.

It’s also likely, Russell and his colleagues say, that the drying in Indonesia created a feedback loop that amplified ice age cooling.

“A very large fraction of the Earth’s water vapor comes from evaporation of the ocean around Indonesia, and water vapor is the Earth’s most important greenhouse gas,” Russell said. “As you start varying the hydrological cycle of Indonesia, you almost have to vary the Earth’s water vapor concentration. If you reduce the water vapor content it should cool the climate globally. So the fact that we have this very strong drying in the tropics during glaciation would argue for a strong feedback of water vapor concentration to the global climate during glacial-interglacial cycles.”

Surprisingly absent from the data, Russell says, is the influence of other processes known to drive climate elsewhere in the tropics. In particular, there was no sign of climate change in Indonesia associated with Earth’s orbital precession, a wobble caused by Earth’s axis tilt that generates differences in sunlight in a 21,000-year cycle.

“There’s very little indication of the 21,000-year cycle that dominates much of the tropics,” he said. “Instead we see this very big set of changes that appear linked to the amount of ice on earth.”

To arrive at those conclusions, the researchers used sediment cores from Lake Towuti, an ancient lake on the island of Sulawesi in central Indonesia. By looking at how concentrations of chemical elements in the sediment change with depth, the researchers can develop a continuous record of how much surface runoff poured into the lake. The rate of runoff is directly related to the rate of rainfall.

In this case, Russell and his colleagues looked at titanium, an element commonly used to gauge surface runoff. They found a marked dip in titanium levels in sediments dated to between 33,000 and 16,000 years ago – a strong indicator that surface runoff slowed during that period.

That finding was buttressed by another proxy of rainfall: carbon isotopes from plant leaf wax. Leaves are covered with a carbon-based wax that protects them from losing too much water to evaporation. Different plants have different carbon isotopes in their leaf wax. Tropical grasses, which are adapted for dryer climates, tend to have the C-13 isotope. Trees, which thrive in wetter environs, use the C-12 isotope. The ratio of those two isotopes in the sediment cores is an indicator of the relative abundance of grass versus trees.

The cores showed an increase in abundance of grass in the same sediments that showed a decrease in surface runoff. Taken together, the results suggest a dry period strong enough to alter the region’s vegetation that was closely correlated with the peak glaciation in the northern hemisphere.

The next step for Russell and his colleagues is to see if this pattern is repeated in multiple glacial cycles. Glacial periods run on cycles of about 100,000 years. Core samples from deeper in the Lake Towuti sediment will show whether this drying evident during the last ice age also happened in previous ice ages. It’s estimated that Lake Tuwuti sediments record up to 800,000 years of climate data, and Russell recently received funding to take deeper cores.

Ultimately, Russell hopes his work will help to predict how the region might be influenced by human-forced global warming.

“This provides the kind of fundamental data we need to understand how the climate of this region operates on long timescales,” he said. “That can then anchor our understanding of how it might respond to global warming.”

Ancient Indonesian climate shift linked to glacial cycle

Using sediments from a remote lake, researchers from Brown University have assembled a 60,000-year record of rainfall in central Indonesia. The analysis reveals important new details about the climate history of a region that wields a substantial influence on the global climate as a whole.

The Indonesian archipelago sits in the Indo-Pacific Warm Pool, an expanse of ocean that supplies a sizable fraction of the water vapor in Earth’s atmosphere and plays a role in propagating El Niño cycles. Despite the region’s importance in the global climate system, not much is known about its own climate history, says James Russell, associate professor of geological sciences at Brown.

“We wanted to assess long-term climate variation in the region,” Russell said, “not just to assess how global climate influences Indonesia, but to see how that feeds back into the global climate system.”

The data are published this week in the Proceedings of the National Academy of Sciences.

The study found that the region’s normally wet, tropical climate was interrupted by a severe dry period from around 33,000 years ago until about 16,000 years ago. That period coincides with peak of the last ice age, when glaciers covered vast swaths of the northern hemisphere. Climate models had suggested that glacial ice could shift the track of tropical monsoons, causing an Indonesian dry period. But this is the first hard data to show that was indeed the case.

It’s also likely, Russell and his colleagues say, that the drying in Indonesia created a feedback loop that amplified ice age cooling.

“A very large fraction of the Earth’s water vapor comes from evaporation of the ocean around Indonesia, and water vapor is the Earth’s most important greenhouse gas,” Russell said. “As you start varying the hydrological cycle of Indonesia, you almost have to vary the Earth’s water vapor concentration. If you reduce the water vapor content it should cool the climate globally. So the fact that we have this very strong drying in the tropics during glaciation would argue for a strong feedback of water vapor concentration to the global climate during glacial-interglacial cycles.”

Surprisingly absent from the data, Russell says, is the influence of other processes known to drive climate elsewhere in the tropics. In particular, there was no sign of climate change in Indonesia associated with Earth’s orbital precession, a wobble caused by Earth’s axis tilt that generates differences in sunlight in a 21,000-year cycle.

“There’s very little indication of the 21,000-year cycle that dominates much of the tropics,” he said. “Instead we see this very big set of changes that appear linked to the amount of ice on earth.”

To arrive at those conclusions, the researchers used sediment cores from Lake Towuti, an ancient lake on the island of Sulawesi in central Indonesia. By looking at how concentrations of chemical elements in the sediment change with depth, the researchers can develop a continuous record of how much surface runoff poured into the lake. The rate of runoff is directly related to the rate of rainfall.

In this case, Russell and his colleagues looked at titanium, an element commonly used to gauge surface runoff. They found a marked dip in titanium levels in sediments dated to between 33,000 and 16,000 years ago – a strong indicator that surface runoff slowed during that period.

That finding was buttressed by another proxy of rainfall: carbon isotopes from plant leaf wax. Leaves are covered with a carbon-based wax that protects them from losing too much water to evaporation. Different plants have different carbon isotopes in their leaf wax. Tropical grasses, which are adapted for dryer climates, tend to have the C-13 isotope. Trees, which thrive in wetter environs, use the C-12 isotope. The ratio of those two isotopes in the sediment cores is an indicator of the relative abundance of grass versus trees.

The cores showed an increase in abundance of grass in the same sediments that showed a decrease in surface runoff. Taken together, the results suggest a dry period strong enough to alter the region’s vegetation that was closely correlated with the peak glaciation in the northern hemisphere.

The next step for Russell and his colleagues is to see if this pattern is repeated in multiple glacial cycles. Glacial periods run on cycles of about 100,000 years. Core samples from deeper in the Lake Towuti sediment will show whether this drying evident during the last ice age also happened in previous ice ages. It’s estimated that Lake Tuwuti sediments record up to 800,000 years of climate data, and Russell recently received funding to take deeper cores.

Ultimately, Russell hopes his work will help to predict how the region might be influenced by human-forced global warming.

“This provides the kind of fundamental data we need to understand how the climate of this region operates on long timescales,” he said. “That can then anchor our understanding of how it might respond to global warming.”

The oldest ice core

<IMG SRC="/Images/571096301.jpg" WIDTH="350" HEIGHT="278" BORDER="0" ALT="This shows Antarctic locations (in bright blue) where 1.5 million years old ice could exist. The figure is modified from Van Liefferinge and Pattyn (Climate of the Past, 2013). – Van Liefferinge and Pattyn”>
This shows Antarctic locations (in bright blue) where 1.5 million years old ice could exist. The figure is modified from Van Liefferinge and Pattyn (Climate of the Past, 2013). – Van Liefferinge and Pattyn

How far into the past can ice-core records go? Scientists have now identified regions in Antarctica they say could store information about Earth’s climate and greenhouse gases extending as far back as 1.5 million years, almost twice as old as the oldest ice core drilled to date. The results are published today in Climate of the Past, an open access journal of the European Geosciences Union (EGU).

By studying the past climate, scientists can understand better how temperature responds to changes in greenhouse-gas concentrations in the atmosphere. This, in turn, allows them to make better predictions about how climate will change in the future.

“Ice cores contain little air bubbles and, thus, represent the only direct archive of the composition of the past atmosphere,” says Hubertus Fischer, an experimental climate physics professor at the University of Bern in Switzerland and lead author of the study. A 3.2-km-long ice core drilled almost a decade ago at Dome Concordia (Dome C) in Antarctica revealed 800,000 years of climate history, showing that greenhouse gases and temperature have mostly moved in lockstep. Now, an international team of scientists wants to know what happened before that.

At the root of their quest is a climate transition that marine-sediment studies reveal happened some 1.2 million years to 900,000 years ago. “The Mid Pleistocene Transition is a most important and enigmatic time interval in the more recent climate history of our planet,” says Fischer. The Earth’s climate naturally varies between times of warming and periods of extreme cooling (ice ages) over thousands of years. Before the transition, the period of variation was about 41 thousand years while afterwards it became 100 thousand years. “The reason for this change is not known.”

Climate scientists suspect greenhouse gases played a role in forcing this transition, but they need to drill into the ice to confirm their suspicions. “The information on greenhouse-gas concentrations at that time can only be gained from an Antarctic ice core covering the last 1.5 million years. Such an ice core does not exist yet, but ice of that age should be in principle hidden in the Antarctic ice sheet.”

As snow falls and settles on the surface of an ice sheet, it is compacted by the weight of new snow falling on top of it and is transformed into solid glacier ice over thousands of years. The weight of the upper layers of the ice sheet causes the deep ice to spread, causing the annual ice layers to become thinner and thinner with depth. This produces very old ice at depths close to the bedrock.

However, drilling deeper to collect a longer ice core does not necessarily mean finding a core that extends further into the past. “If the ice thickness is too high the old ice at the bottom is getting so warm by geothermal heating that it is melted away,” Fischer explains. “This is what happens at Dome C and limits its age to 800,000 years.”

To complicate matters further, horizontal movements of the ice above the bedrock can disturb the bottommost ice, causing its annual layers to mix up.

“To constrain the possible locations where such 1.5 million-year old – and in terms of its layering undisturbed – ice could be found in Antarctica, we compiled the available data on climate and ice conditions in the Antarctic and used a simple ice and heat flow model to locate larger areas where such old ice may exist,” explains co-author Eric Wolff of the British Antarctic Survey, now at the University of Cambridge.

The team concluded that 1.5 million-year old ice should still exist at the bottom of East Antarctica in regions close to the major Domes, the highest points on the ice sheet, and near the South Pole, as described in the new Climate of the Past study. These results confirm those of another study, also recently published in Climate of the Past.

Crucially, they also found that an ice core extending that far into the past should be between 2.4 and 3-km long, shorter than the 800,000-year-old core drilled in the previous expedition.

The next step is to survey the identified drill sites to measure the ice thickness and temperature at the bottom of the ice sheet before selecting a final drill location.

“A deep drilling project in Antarctica could commence within the next 3-5 years,” Fischer states. “This time would also be needed to plan the drilling logistically and create the funding for such an exciting large-scale international research project, which would cost around 50 million Euros.”

The oldest ice core

<IMG SRC="/Images/571096301.jpg" WIDTH="350" HEIGHT="278" BORDER="0" ALT="This shows Antarctic locations (in bright blue) where 1.5 million years old ice could exist. The figure is modified from Van Liefferinge and Pattyn (Climate of the Past, 2013). – Van Liefferinge and Pattyn”>
This shows Antarctic locations (in bright blue) where 1.5 million years old ice could exist. The figure is modified from Van Liefferinge and Pattyn (Climate of the Past, 2013). – Van Liefferinge and Pattyn

How far into the past can ice-core records go? Scientists have now identified regions in Antarctica they say could store information about Earth’s climate and greenhouse gases extending as far back as 1.5 million years, almost twice as old as the oldest ice core drilled to date. The results are published today in Climate of the Past, an open access journal of the European Geosciences Union (EGU).

By studying the past climate, scientists can understand better how temperature responds to changes in greenhouse-gas concentrations in the atmosphere. This, in turn, allows them to make better predictions about how climate will change in the future.

“Ice cores contain little air bubbles and, thus, represent the only direct archive of the composition of the past atmosphere,” says Hubertus Fischer, an experimental climate physics professor at the University of Bern in Switzerland and lead author of the study. A 3.2-km-long ice core drilled almost a decade ago at Dome Concordia (Dome C) in Antarctica revealed 800,000 years of climate history, showing that greenhouse gases and temperature have mostly moved in lockstep. Now, an international team of scientists wants to know what happened before that.

At the root of their quest is a climate transition that marine-sediment studies reveal happened some 1.2 million years to 900,000 years ago. “The Mid Pleistocene Transition is a most important and enigmatic time interval in the more recent climate history of our planet,” says Fischer. The Earth’s climate naturally varies between times of warming and periods of extreme cooling (ice ages) over thousands of years. Before the transition, the period of variation was about 41 thousand years while afterwards it became 100 thousand years. “The reason for this change is not known.”

Climate scientists suspect greenhouse gases played a role in forcing this transition, but they need to drill into the ice to confirm their suspicions. “The information on greenhouse-gas concentrations at that time can only be gained from an Antarctic ice core covering the last 1.5 million years. Such an ice core does not exist yet, but ice of that age should be in principle hidden in the Antarctic ice sheet.”

As snow falls and settles on the surface of an ice sheet, it is compacted by the weight of new snow falling on top of it and is transformed into solid glacier ice over thousands of years. The weight of the upper layers of the ice sheet causes the deep ice to spread, causing the annual ice layers to become thinner and thinner with depth. This produces very old ice at depths close to the bedrock.

However, drilling deeper to collect a longer ice core does not necessarily mean finding a core that extends further into the past. “If the ice thickness is too high the old ice at the bottom is getting so warm by geothermal heating that it is melted away,” Fischer explains. “This is what happens at Dome C and limits its age to 800,000 years.”

To complicate matters further, horizontal movements of the ice above the bedrock can disturb the bottommost ice, causing its annual layers to mix up.

“To constrain the possible locations where such 1.5 million-year old – and in terms of its layering undisturbed – ice could be found in Antarctica, we compiled the available data on climate and ice conditions in the Antarctic and used a simple ice and heat flow model to locate larger areas where such old ice may exist,” explains co-author Eric Wolff of the British Antarctic Survey, now at the University of Cambridge.

The team concluded that 1.5 million-year old ice should still exist at the bottom of East Antarctica in regions close to the major Domes, the highest points on the ice sheet, and near the South Pole, as described in the new Climate of the Past study. These results confirm those of another study, also recently published in Climate of the Past.

Crucially, they also found that an ice core extending that far into the past should be between 2.4 and 3-km long, shorter than the 800,000-year-old core drilled in the previous expedition.

The next step is to survey the identified drill sites to measure the ice thickness and temperature at the bottom of the ice sheet before selecting a final drill location.

“A deep drilling project in Antarctica could commence within the next 3-5 years,” Fischer states. “This time would also be needed to plan the drilling logistically and create the funding for such an exciting large-scale international research project, which would cost around 50 million Euros.”

Irish chronicles reveal links between cold weather and volcanic eruptions

Medieval chronicles have given an international group of researchers a glimpse into the past to assess how historical volcanic eruptions affected the weather in Ireland up to 1500 years ago.

By critically assessing over 40,000 written entries in the Irish Annals and comparing them with measurements taken from ice cores, the researchers successfully linked the climatic aftermath of volcanic eruptions to extreme cold weather events in Ireland over a 1200-year period from 431 to 1649.

Their study, which has been published today, 6 June, in IOP Publishing’s journal Environmental Research Letters, showed that over this timescale up to 48 explosive volcanic eruptions could be identified in the Greenland Ice Sheet Project (GISP2) ice-core, which records the deposition of volcanic sulfate in annual layers of ice.

Of these 48 volcanic events, 38 were associated, closely in time, with 37 extreme cold events, which were identified by systematically examining written entries in the Irish Annals and picking out directly observed meteorological phenomena and conditions, such as heavy snowfall and frost, prolonged ice covering lakes and rivers, and contemporary descriptions of abnormally cold weather.

Lead author of the study, Dr Francis Ludlow, from the Harvard University Center for the Environment and Department of History, said: “It’s clear that the scribes of the Irish Annals were diligent reporters of severe cold weather, most probably because of the negative impacts this had on society and the biosphere.

“Our major result is that explosive volcanic eruptions are strongly, and persistently, implicated in the occurrence of cold weather events over this long timescale in Ireland. In their severity, these events are quite rare for the country’s mild maritime climate.”

Through the injection of sulphur dioxide gas into the stratosphere, volcanic eruptions can play a significant role in the regulation of the Earth’s climate. Sulphur dioxide gas is converted into sulphate aerosol particles after eruptions which reflect incoming sunlight and result in an overall temporary cooling of the Earth’s surface.

Whilst the global effects of recent eruptions are quite well-known, such as the Mount Pinatubo eruption almost 22 years ago (15 June 1991), less is known about their effects on climate before the beginning of instrumental weather recording, or their effects on regional scales; the Irish Annals provided an opportunity to explore both of these issues.

The Irish Annals contain over one million written words and around 40,000 distinct written entries, detailing major historical events on an annual basis, and providing both systematic and sustained reporting of meteorological extremes.

The dating and reliability of the Annals can be gauged by comparing reported events to those which are independently known, such as solar and lunar eclipses.

“With a few honourable exceptions, the Irish record of extreme events has only been used anecdotally, rather than systematically surveyed and exploited for the study of the climate history of Ireland and the North Atlantic, and so the richness of the record has been largely unrecognized,” continued Dr Ludlow.

Although the effect of big eruptions on the climate in summer is largely to cause cooling, during the winter, low-latitude eruptions in the tropics have instead been known to warm large parts of the northern hemisphere as they cause a strengthening of the westerly winds that brings, for example, warmer oceanic air to Europe; however, this study identified several instances when low-latitude eruptions appeared to correspond to extreme cold winters in Ireland.

One example is the 1600 eruption in Peru of Huaynaputina, which the researchers found, against expectations, to be associated with extreme cold winter weather in Ireland in the following years.

“The possibility that tropical eruptions may result in severe winter cooling for Ireland highlights the considerable complexity of the volcano-climate system in terms of the regional expression of the response of climate to volcanic disturbances.

“It is on the regional scale that we need to refine our understanding of this relationship as ultimately, it is on this scale that individuals and societies plan for extreme weather,” continued Dr Ludlow.

Irish chronicles reveal links between cold weather and volcanic eruptions

Medieval chronicles have given an international group of researchers a glimpse into the past to assess how historical volcanic eruptions affected the weather in Ireland up to 1500 years ago.

By critically assessing over 40,000 written entries in the Irish Annals and comparing them with measurements taken from ice cores, the researchers successfully linked the climatic aftermath of volcanic eruptions to extreme cold weather events in Ireland over a 1200-year period from 431 to 1649.

Their study, which has been published today, 6 June, in IOP Publishing’s journal Environmental Research Letters, showed that over this timescale up to 48 explosive volcanic eruptions could be identified in the Greenland Ice Sheet Project (GISP2) ice-core, which records the deposition of volcanic sulfate in annual layers of ice.

Of these 48 volcanic events, 38 were associated, closely in time, with 37 extreme cold events, which were identified by systematically examining written entries in the Irish Annals and picking out directly observed meteorological phenomena and conditions, such as heavy snowfall and frost, prolonged ice covering lakes and rivers, and contemporary descriptions of abnormally cold weather.

Lead author of the study, Dr Francis Ludlow, from the Harvard University Center for the Environment and Department of History, said: “It’s clear that the scribes of the Irish Annals were diligent reporters of severe cold weather, most probably because of the negative impacts this had on society and the biosphere.

“Our major result is that explosive volcanic eruptions are strongly, and persistently, implicated in the occurrence of cold weather events over this long timescale in Ireland. In their severity, these events are quite rare for the country’s mild maritime climate.”

Through the injection of sulphur dioxide gas into the stratosphere, volcanic eruptions can play a significant role in the regulation of the Earth’s climate. Sulphur dioxide gas is converted into sulphate aerosol particles after eruptions which reflect incoming sunlight and result in an overall temporary cooling of the Earth’s surface.

Whilst the global effects of recent eruptions are quite well-known, such as the Mount Pinatubo eruption almost 22 years ago (15 June 1991), less is known about their effects on climate before the beginning of instrumental weather recording, or their effects on regional scales; the Irish Annals provided an opportunity to explore both of these issues.

The Irish Annals contain over one million written words and around 40,000 distinct written entries, detailing major historical events on an annual basis, and providing both systematic and sustained reporting of meteorological extremes.

The dating and reliability of the Annals can be gauged by comparing reported events to those which are independently known, such as solar and lunar eclipses.

“With a few honourable exceptions, the Irish record of extreme events has only been used anecdotally, rather than systematically surveyed and exploited for the study of the climate history of Ireland and the North Atlantic, and so the richness of the record has been largely unrecognized,” continued Dr Ludlow.

Although the effect of big eruptions on the climate in summer is largely to cause cooling, during the winter, low-latitude eruptions in the tropics have instead been known to warm large parts of the northern hemisphere as they cause a strengthening of the westerly winds that brings, for example, warmer oceanic air to Europe; however, this study identified several instances when low-latitude eruptions appeared to correspond to extreme cold winters in Ireland.

One example is the 1600 eruption in Peru of Huaynaputina, which the researchers found, against expectations, to be associated with extreme cold winter weather in Ireland in the following years.

“The possibility that tropical eruptions may result in severe winter cooling for Ireland highlights the considerable complexity of the volcano-climate system in terms of the regional expression of the response of climate to volcanic disturbances.

“It is on the regional scale that we need to refine our understanding of this relationship as ultimately, it is on this scale that individuals and societies plan for extreme weather,” continued Dr Ludlow.