college of earth

Study finds sudden shift in “forcing” led to demise of Laurentide ice sheet

CORVALLIS, Ore. – A new study has found that the massive Laurentide ice sheet that covered Canada during the last ice age initially began shrinking through calving of icebergs, and then abruptly shifted into a new regime where melting on the continent took precedence, ultimately leading to the sheet’s demise.

Researchers say a shift in “radiative forcing” began prior to 9,000 years ago and kicked the deglaciation into overdrive. The results are important, scientists say, because they may provide a clue to how ice sheets on Greenland and Antarctica may respond to a warming climate.

Results of the study, which was funded by the National Science Foundation with support from the National Aeronautics and Space Administration (NASA), are being published this week in Nature Geoscience.

David Ullman, a postdoctoral researcher at Oregon State University and lead author on the study, said there are two mechanisms through which ice sheets diminish – dynamically, from the jettisoning of icebergs at the fringes, or by a negative “surface mass balance,” which compares the amount of snow accumulation relative to melting. When more snow accumulates than melts, the surface mass balance is positive.

When melting outpaces snow accumulation, as happened after the last glacial maximum, the surface mass balance is negative.

“What we found was that during most of the deglaciation, the surface mass balance of the Laurentide Ice Sheet was generally positive,” Ullman said. “We know that the ice sheet was disappearing, so the cause must have been dynamic. But there was a shift before 9,000 years ago and the deck became stacked, as sunlight levels were high because of the Earth’s orbit and CO2 increased.

“There was a switch to a new state, and the ice sheet began to melt away,” he added. “Coincidentally, when melting took off, the ice sheet began pulling back from the coast and the calving of icebergs diminished. The ice sheet got hammered by surface melt, and that’s what drove final deglaciation.”

Ullman said the level of CO2 that helped trigger the melting of the Laurentide ice sheet was near the top of pre-industrial measurements – though much less than it is today. The solar intensity then was higher than today, he added.

“What is most interesting is that there are big shifts in the surface mass balance that occur from only very small changes in radiative forcing,” said Ullman, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “It shows just how sensitive the system is to forcing, whether it might be solar radiation or greenhouse gases.”

Scientists have examined ice cores dating back some 800,000 years and have documented numerous times when increases in summer insolation took place, but not all of them resulted in deglaciation to present-day ice volumes. The reason, they say, is that there likely is a climatic threshold at which severe surface melting is triggered.

“It just might be that the ice sheet needed an added kick from something like elevated CO2 levels to get things going,” Ullman said.

Media Contact: 

David Ullman, 541-737-4915, dullman@coas.oregonstate.edu

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A study of the demise of the Laurentide Ice Sheet that once covered Canada may help scientists better understand shrinking ice fields today - like this melting ice margin in Greenland. Photo link: https://flic.kr/p/v38JUe

Researchers to complete final deployment of OOI instrumentation this week

NEWPORT, Ore. – Oregon State University scientists this week will deploy a sophisticated research buoy and two undersea gliders, all fitted with a suite of oceanographic instruments – a final piece of the “Endurance Array,” a major component of the National Science Foundation’s $386 million Ocean Observatories Initiative.

This major marine science infrastructure project was launched in 2009 to better monitor the world’s oceans and the impacts of climate change. It is the largest single investment in ocean monitoring in United States history.

The Endurance Array off the Pacific Northwest coast has become a focal point for scientists because of emerging issues including hypoxia and marine “dead zones,” climate change impacts, subduction zone earthquakes, tsunamis, harmful algal blooms, wave energy potential, ocean acidification and dramatic variations in some upwelling-fed fisheries.

“This observatory opens up a new type of window to the sea, with environmental data available in ‘real time’ to researchers, educators, policy makers and ocean users,” said Ed Dever, a professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences and project manager for the Endurance Array. “In the short term, it will be a laboratory for the study of processes in one of the great coastal upwelling systems on our planet.

“In the long term, the information it collects will allow us, our children, and our grandchildren to better understand the impacts of global climate change on the coastal ocean off Oregon and Washington.”

The deployment this week of an inshore surface buoy about a mile off Nye Beach in Newport – in waters about 25 meters deep – is the third and final platform location in the array’s “Newport Hydrographic Line.”  The line includes a shelf surface buoy in 80 meters of water, about 10 miles off the coast; and an off-shore surface buoy in 500 meters of water, about 35 miles out.

The in-shore surface buoy is designed to be battered by severe Pacific Ocean waves that hit the coast in winter, yet stay in place and continue making important measurements, noted Jack Barth, an OSU oceanographer who has been a lead scientist on the Ocean Observatories Initiative since the early planning stages more than a decade ago.

“For the first time, the science community will be able to monitor and assess all components of the ocean simultaneously, from the physics to the biology to the chemistry,” Barth said. “The OOI is not just about measuring the ocean in different ways – it is a way to understand how ocean processes affect things like plankton production and how that in turns fertilizes the marine food web, affects acidification, leads to harmful algal blooms, and affects oxygen in the water that may lead to dead zones.”

The researchers say the proximity of the buoy to the coast is critical to understanding ocean wave and coastal river responses to winter storms.

The buoy will have an impressive array of instruments – at the surface, on the seafloor where it is anchored, and attached to a cable running up and down the water column. Various sensors will measure water velocity, temperature, salinity, pH, light intensity, carbon dioxide, dissolved oxygen, nitrate, chlorophyll, backscatter (or the measure of particles in the water), light absorption – and even populations of zooplankton and fish.

“This will provide an absolutely incredible amount of data,” Barth said. “The biggest difference is that these instruments will be out there constantly monitoring the oceans. Before, we had to rely on shipboard data, which is very hit-and-miss. As we began to use undersea gliders, we picked up more information – but gliders are limited by their power supply, so you can only load so many instruments on them.

“These buoys are game-changers,” he added. “We will be able to better monitor emerging hypoxia threats, toxic plankton blooms and ocean acidification. Fishermen can match oceanographic data with catch records and look at how temperature, salinity and other factors may affect fishing. The possibilities are endless.”

The other two buoys in the Newport Hydrographic Line will have a similar array of instruments. They will be paired with seafloor instruments that will be plugged into an underwater cable operated by the University of Washington. The cable will provide additional power for the instrumentation and high-bandwidth, two-way communications.

Oregon State also deployed a similar transect of three buoys off Grays Harbor, Wash. Together, the two east-west lines of buoys will give scientists an idea of what is happening in the ocean north and south of the influential Columbia River.

“As conditions change, we will have the ability to add new sensors and address questions that we may not be considering right now,” Dever said.

Undersea gliders represent another critical component of the Ocean Observatories Initiative. Oregon State will operate 12 gliders as part of the program, with six in the water patrolling the Northwest coast, and six more to rotate in after maintenance and reprogramming. Three gliders are operating now; two additional gliders will be deployed off Oregon this week, and a sixth glider off Washington later this month.

“The Pacific Northwest coast is becoming one of the most closely monitored ocean regions in the world,” Barth said.

Media Contact: 

Ed Dever, 541-737-2749, edever@coas.oregonstate.edu 

Jack Barth, 541-737-1607, barth@coas.oregonstate.edu

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New study: Iceberg influx into Atlantic during ice age raised tropical methane emissions

CORVALLIS, Ore. – A new study shows how huge influxes of fresh water into the North Atlantic Ocean from icebergs calving off North America during the last ice age had an unexpected effect – they increased the production of methane in the tropical wetlands.

Usually increases in methane levels are linked to warming in the Northern Hemisphere, but scientists who are publishing their findings this week in the journal Science have identified rapid increases in methane during particularly cold intervals during the last ice age.

These findings are important, researchers say, because they identify a critical piece of evidence for how the Earth responds to changes in climate.

“Essentially what happened was that the cold water influx altered the rainfall patterns at the middle of the globe,” said Rachael Rhodes, a research associate in the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University and lead author on the study, which was funded by the National Science Foundation. “The band of tropical rainfall, which includes the monsoons, shifts to the north and south through the year.

“Our data suggest that when the icebergs entered the North Atlantic causing exceptional cooling, the rainfall belt was condensed into the Southern Hemisphere, causing tropical wetland expansion and abrupt spikes in atmospheric methane,” she added.

During the last ice age, much of North America was covered by a giant ice sheet that many scientists believe underwent several catastrophic collapses, causing huge icebergs to enter the North Atlantic – phenomena known as Heinrich events. And though they have known about them for some time, it hasn’t been clear just when they took place and how long they lasted.

Rhodes and her colleagues examined evidence from the highly detailed West Antarctic Ice Sheet Divide ice core (http://www.waisdivide.unh.edu). They used a new analytical method perfected in collaboration with Joe McConnell at the Desert Research Institute in Reno, Nevada, to make extremely detailed measurements of the air trapped in the ice.

“Using this new method, we were able to develop a nearly 60,000-year, ultra-high-resolution record of methane much more efficiently and inexpensively than in past ice core studies, while simultaneously measuring a broad range of other chemical parameters on the same small sample of ice,” McConnell noted.

Utilizing the high resolution of the measurements, the team was able to detect methane fingerprints from the Southern Hemisphere that don’t match temperature records from Greenland ice cores.

“The cooling caused by the iceberg influx was regional but the impact on climate was much broader,” said Edward Brook, an internationally recognized paleoclimatologist from Oregon State University and co-author on the study. “The iceberg surges push the rain belts, or the tropical climate system, to the south and the impact on climate can be rather significant.”

Concentrating monsoon seasons into a smaller geographic area “intensifies the rainfall and lengthens the wet season,” Rhodes said.

“It is a great example of how inter-connected things are when it comes to climate,” she pointed out. “This shows the link between polar areas and the tropics, and these changes can happen very rapidly. Climate models suggest only a decade passed between the iceberg intrusion and a resulting impact in the tropics.”

The study found that the climate effects from the Heinrich events lasted between 740 and 1,520 years.

Media Contact: 

Rachael Rhodes, 541-737-1209, rhodesra@geo.oregonstate.edu; Ed Brook, 541-737-8197, brooke@geo.oregonstate.edu

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Antarctic Ice Core

Core from the West Antarctic Ice Sheet

New program to train international specialists in water conflict resolution

CORVALLIS, Ore. – The increasing need for access to fresh water for drinking, agriculture, fisheries and other uses is at the root of a growing number of geopolitical conflicts around the world, yet there are few resource managers in charge who have training in both water science and diplomacy.

A new cooperative international education program aims to address that shortfall.

Oregon State University, the University for Peace in Costa Rica, and the UNESCO-IHE Water Education Center in The Netherlands are creating an international joint education program aimed at addressing water conflicts in a more professional manner. The program will launch this fall with about 10 students enrolled to earn master’s degrees, eventually growing to 30 students from around the world.

“There is a real need for people trained in the art of ‘hydro-diplomacy,’” said Aaron Wolf, an Oregon State University geographer and internationally recognized expert on water conflict. “The problem is really rather simple – there just isn’t enough water to go around for every need. So if you manage water, you have to know how to manage conflict and that’s where the training has been lacking.

“The good news is that water gives you the opportunity to get certain people into the room that wouldn’t ordinarily sit across from each other,” Wolf added. “And it gives them a common language.”

Students in the new program will study at each of the three sites, ending up at Oregon State where they will be required to conduct a collaborative, applied research project somewhere in the United States where water management issues are in play, according to Mary Santelmann, director of Oregon State’s Water Resources Graduate Program, which will coordinate the new degree in the U.S.

The venture builds on a certificate program OSU offers in water conflict management, and utilizes the expertise of each institution.

“Oregon State has some 90 faculty members who are involved in some aspect of water science and another 20 faculty members who focus on some aspect of public policy and conflict resolution,” Santelmann said. “That expertise, along with OSU’s work with a variety of federal agencies, made the university uniquely positioned to play a lead role in the new educational venture.”

The University for Peace in Costa Rica is a United Nations-mandated institution established in 1980 as a treaty organization by the UN General Assembly. Scholars there have a great deal of experience at high-level diplomacy, as well as conflict theory and geopolitical expertise with developing countries.

The United Nations Educational, Scientific and Cultural Organization (UNESCO) Institute for Water Education is the largest international graduate water education facility in the world, and has researchers with extensive experience in working on water resource issues in Europe and elsewhere.

“There is no single institution that could offer an entire curriculum and suite of experiences necessary to train a generation of students in hydro-diplomacy,” said Wolf, who is a 2015 recipient of the prestigious Heinz Award for public policy. “It had to be collaborative, international and experiential.”

The issues students will deal with are vast. In Oregon, for example, there has been a major conflict over water rights in the Klamath River basin, where agricultural interests compete with fisheries management and tribal rights.

These kinds of issues are not unusual in the United States, Wolf pointed out, and can become even more contentious when an international component is added.

“Ethiopia has been constructing a major dam and Egypt is so concerned about the impact on its water that it has discussed going to war over it,” Wolf said. “There are many countries in central and Southeast Asia where similar border tensions have arisen over water that flows across multiple jurisdictions.”

Water management is conflict management, Santelmann pointed out. The collaborative new program will focus on guiding students to gain skills in a variety of areas through field work, working with experts from different disciplines, and gaining a broad understanding of varying points of view, resolution processes, and water management science.

“Regardless of the scale, there is a demand for people who can ensure that the needs of the people and the ecosystem that rely on this critical resource will be met,” Santelmann said.

Santelmann and Wolf are in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences.

Media Contact: 

Mary Santelmann, 541-737-1215, santelmm@geo.oregonstate.edu;

Aaron Wolf, 541-737-2722; wolfa@geo.oregonstate.edu

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This tributary of the Nu River in China has all of its water diverted by dams and is dry – just one example of water use conflict around the world. A new collaborative program that includes Oregon State University aims to help train leaders in water conflict resolution. (Photo by Kelly Kibler, courtesy of Oregon State University)

Researchers measure giant “internal waves” that help regulate climate

CORVALLIS, Ore. – Once a day, a wave as tall as the Empire State Building and as much as a hundred miles wide forms in the waters between Taiwan and the Philippines and rolls across the South China Sea – but on the surface, it is hardly noticed.

These daily monstrosities are called “internal waves” because they are beneath the ocean surface and though scientists have known about them for years, they weren’t really sure how significant they were because they had never been fully tracked from cradle to grave.

But a new study, published this week in Nature Research Letter, documents what happens to internal waves at the end of their journey and outlines their critical role in global climate. The international research project was funded by the Office of Naval Research and the Taiwan National Science Council.

“Ultimately, they are what mixes heat throughout the ocean,” said Jonathan Nash, an Oregon State University oceanographer and co-author on the study. “Without them, the ocean would be a much different place. It would be significantly more stratified – the surface waters would be much warmer and the deep abyss colder.

“It’s like stirring cream into your coffee,” he added. “Internal waves are the ocean’s spoon.”

Internal waves help move a tremendous amount of energy from Luzon Strait across the South China Sea, but until this project, scientists didn’t know what became of that energy. As it turns out, it’s a rather complicated picture. A large fraction of energy dissipates when the wave gets steep and breaks on the deep slopes off China and Vietnam, much like breakers on the beach.

But part of the energy remains, with waves reflecting from the coast and rebounding back into the ocean in different directions.

The internal waves are caused by strong tides flowing over the topography, said Nash, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. The waves originating in Luzon Strait are the largest in the world, based on the region’s tidal flow and topography. A key factor is the depth at which the warm- and cold-water layers of the ocean meet – at about 1,000 meters.

The waves can get as high as 500 meters tall and 100-200 kilometers wide before steepening.

“You can actually see them from satellite images,” Nash said. “They will form little waves at the ocean surface, and you see the surface convergences piling up flotsam and jetsam as the internal wave sucks the water down. They move about 2-3 meters a second.”

The waves also have important global implications. In climate models, predictions of the sea level 50 years from now vary by more than a foot depending on whether the effects of these waves are included.

“These are not small effects,” Nash said.

This new study, which was part of a huge international collaboration involving OSU researchers Nash and James Moum – as well as 40 others from around the world – is the first to document the complete life cycle of these huge undersea waves.

Media Contact: 

Jonathan Nash, 541-737-4573, nash@coas.oregonstate.edu

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Large "internal waves" are generally not seen at the surface, but their signature is - visible slicks and changes in surface roughness and color.

Emeritus OSU geologist outlines earthquake “time bombs” in a forthcoming book

CORVALLIS, Ore. – An emeritus Oregon State University geologist, who was one of the first scientists to point to the possibility of a major earthquake in the Pacific Northwest, outlines some of the world’s seismic “time bombs” in a forthcoming book.

One of those time bombs listed, in a segment he wrote last year, was Nepal where on April 25, an earthquake estimated at magnitude 7.8 struck the region, killing more than 7,500 people and injuring another 14,500.

Robert Yeats’ prescience is eerily familiar.

Five years ago, Yeats was interviewed by Scientific American on earthquake hazards and outlined the dual threats to Port au Prince, Haiti, of poverty and proximity to a major fault line. One week later, that time bomb went off and more than 100,000 people died in a catastrophic earthquake.

When the Scientific American reporter called Yeats after that seismic disaster to ask if he had predicted the quake, he said no.

“I could say where the time bombs are located – large, rapidly growing cities next to a tectonic plate boundary with a past history of earthquakes, but I had no way of knowing that the bomb would go off a week after my interview,” he said.

Fast forward to 2015 – Yeats has completed a new book, “Earthquake Time Bombs,” which will be published later this year by Cambridge University Press. In that book, he identifies other time bombs around the world; one is a region he has visited frequently in the past 30 years – the Himalayas, including Kathmandu, Nepal, a city of more than a million people.

Yeats points to several areas around the worlds where large cities lie on or adjacent to a major plate boundary creating a ticking time bomb: Tehran, the capital of Iran; Kabul in Afghanistan; Jerusalem in the Middle East; Caracas in Venezuela; Guantanamo, Cuba; Los Angeles, California; and the Cascadia Subduction Zone off the northwestern United States and near British Columbia.

“These places should take lessons from the regions that already have experienced major earthquakes, including Nepal,” said Yeats, who is with OSU’s College of Earth, Ocean, and Atmospheric Sciences.

Like Port au Prince, Kathmandu lies on a tectonic plate boundary – the thrust fault between the high Himalayas and the continent of India to the south. The plate began its northward movement 50 million years ago, Yeats said, and is progressing at the rate of about two-thirds of an inch a year. As the plate is forcing its way beneath Tibet, it is triggering periodic earthquakes along the way.

“It takes time to build up a sufficient amount of stress in these systems, but eventually they will rupture,” Yeats said. “The 2015 Nepal quake was, unquestionably, a disaster with losses of life in the thousands. But it could have been worse.”

“With the assistance of an American non-profit seismology group, the city of Kathmandu created a disaster management unit and a National Society for Earthquake Technology that established committees of citizens to raise awareness and upgrade buildings, especially public schools,” Yeats pointed out. “Other ‘time bombs’ would be wise to do the same.”

Making buildings more earthquake-resistant is imperative for cities near a fault, yet economics often preclude such measures. Yeats said some of the greatest losses in the Nepal quake took place in United Nations World Heritage sites of Bhaktapur and Patan, where ancient buildings had not been strengthened.

“We are not able to predict an earthquake, but we can identify potential trouble,” Yeats said. A seismic gap in the Himalayas was identified years ago by the late Indian seismologist K.N. Khattri in between western Himalaya of India and Kathmandu, where a magnitude 8.1 quake hit in 1934, he pointed out. The earthquake on April 25 struck within Khattri’s seismic gap, Yeats noted.

The 1934 earthquake killed an estimated 20 percent of the population of Kathmandu Valle, some 30,000 people. The population there was much smaller than it is today.

“The 1934 epicenter apparently was east of the city, whereas the epicenter of April 25’s earthquake was to the west, meaning that the two earthquakes may have ruptured different parts of the plate-boundary fault,” Yeats said.

Earlier earthquakes that damaged Kathmandu struck in 1833 and 1255. The location and magnitude of those two quakes are uncertain.

“Videos of this year’s earthquake focused on damaged and destroyed buildings and many of these were old historical buildings that had not been upgraded,” Yeats said. “Photos also showed new buildings that did not appear to be damaged. There’s a lesson there.”

Media Contact: 

Robert “Bob” Yeats, yeatsr@science.oregonstate.edu

Researchers think Axial Seamount off Northwest coast is erupting – right on schedule

NEWPORT, Ore. – Axial Seamount, an active underwater volcano located about 300 miles off the coast of Oregon and Washington, appears to be erupting – after two scientists had forecast that such an event would take place there in 2015.

Geologists Bill Chadwick of Oregon State University and Scott Nooner of the University of North Carolina Wilmington made their forecast last September during a public lecture and followed it up with blog posts and a reiteration of their forecast just last week at a scientific workshop.

They based their forecast on some of their previous research – funded by the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA), which showed how the volcano inflates and deflates like a balloon in a repeatable pattern as it responds to magma being fed into the seamount.

Since last Friday, the region has experienced thousands of tiny earthquakes – a sign that magma is moving toward the surface – and the seafloor dropped by 2.4 meters, or nearly eight feet, also a sign of magma being withdrawn from a reservoir beneath the summit. Instrumentation recording the activity is part of the NSF-funded Ocean Observatories Initiative. William Wilcock of the University of Washington first observed the earthquakes.

“It isn’t clear yet whether the earthquakes and deflation at Axial are related to a full-blown eruption, or if it is only a large intrusion of magma that hasn’t quite reached the surface,” said Chadwick, who works out of OSU’s Hatfield Marine Science Center in Newport and also is affiliated with NOAA’s Pacific Marine Environmental Laboratory. “There are some hints that lava did erupt, but we may not know for sure until we can get out there with a ship.”

In any case, the researchers say, such an eruption is not a threat to coastal residents. The earthquakes at Axial Seamount are small and the seafloor movements gradual and thus cannot cause a tsunami. Nor is the possible eruption tied to a possible Cascadia Subduction Zone earthquake.

“I have to say, I was having doubts about the forecast even the night before the activity started,” Chadwick admitted. “We didn’t have any real certainty that it would take place – it was more of a way to test our hypothesis that the pattern we have seen was repeatable and predictable.”

Axial Seamount provides scientists with an ideal laboratory, not only because of its close proximity to the Northwest coast, but for its unique structure.

“Because Axial is on very thin ocean crust, its ‘plumbing system’ is simpler than at most volcanoes on land that are often complicated by other factors related to having a thicker crust,” said Chadwick, who is an adjunct professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “Thus Axial can give us insights into how volcano magma systems work – and how eruptions might be predicted.”

Axial Seamount last erupted in 2011 and that event was loosely forecast by Chadwick and Nooner, who had said in 2006 that the volcano would erupt before 2014. Since the 2011 eruption, additional research led to a refined forecast that the next eruption would be in 2015 based on the fact that the rate of inflation had increased by about 400 percent since the last eruption.

“We’ve learned that the supply rate of magma has a big influence on the time between eruptions,” Nooner said. “When the magma rate was lower, it took 13 years between eruptions. But now when the magma rate is high, it took only four years.”

Chadwick and Nooner are scheduled to go back to Axial in August to gather more data, but it may be possible for other researchers to visit the seamount on an expedition as early as May. They hope to confirm the eruption and, if so, measure the volume of lava involved.

Evidence that was key to the successful forecast came in the summer of 2014 via measurements taken by colleagues Dave Caress and Dave Clague of Monterey Bay Aquarium Research Institute and Mark Zumberge and Glenn Sasagawa of Scripps Oceanographic Institution. Those measurements showed the high rate of magma inflation was continuing.

Media Contact: 

Bill Chadwick, 541-867-0179, bill.chadwick@oregonstate.edu

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Boca vent

Axial Seamount vent taken in 2011


Researchers find 200-year lag between climate events in Greenland, Antarctica

CORVALLIS, Ore. – A new study using evidence from a highly detailed ice core from West Antarctica shows a consistent link between abrupt temperature changes on Greenland and Antarctica during the last ice age, giving scientists a clearer picture of the link between climate in the northern and southern hemispheres.

Greenland climate during the last ice age was very unstable, the researchers say, characterized by a number of large, abrupt changes in mean annual temperature that each occurred within several decades. These so-called “Dansgaard-Oeschger events” took place every few thousand years during the last ice age. Temperature changes in Antarctica showed an opposite pattern, with Antarctica cooling when Greenland was warm, and vice versa.

In this study funded by the National Science Foundation and published this week in the journal Nature, the researchers discovered that the abrupt climates changes show up first in Greenland, with the response to the Antarctic climate delayed by about 200 years. The researchers documented 18 abrupt climate events during the past 68,000 years.

“The fact that temperature changes are opposite at the two poles suggests that there is a redistribution of heat going on between the hemispheres,” said Christo Buizert, a post-doctoral research at Oregon State University and lead author on the study. “We still don’t know what caused these past shifts, but understanding their timing gives us important clues about the underlying mechanisms.

“The 200-year lag that we observe certainly hints at an oceanic mechanism,” Buizert added. “If the climatic changes were propagated by the atmosphere, the Antarctic response would have occurred in a matter of years or decades, not two centuries. The ocean is large and sluggish, thus the 200-year time lag is a pretty clear fingerprint of the ocean’s involvement.”

These past episodes of climate change differ in a major way from what is happening today, the researchers note. The abrupt events of the ice age were regional in scope – and likely tied to large-scale changes in ocean circulation. Warming today is global and primarily from human carbon dioxide emissions in the Earth’s atmosphere.

The key to the discovery was the analysis of a new ice core from West Antarctica, drilled to a depth of 3,405 meters in 2011 and spanning the last 68,000 years, according to Oregon State paleoclimatologist Edward Brook, a co-author on the Nature study and an internationally recognized ice core expert.

Because the area where the ice core was drilled gets high annual snowfall, Brook said, the new ice core provides one of the most detailed records of Antarctic temperatures at a very high resolution. Greenland temperatures were already well-established, the researchers say, because of high annual snowfall and more available ice core data.

“Past ice core studies did not reveal the temperature changes as clearly as this remarkable core,” said Eric Steig, a professor in the Department of Earth and Space Sciences at the University of Washington, who co-wrote the paper. Steig’s laboratory made one of the key measurements that provides past Antarctic temperatures.

“Previous work was not precise enough to determine the relative timing of abrupt climate change in Antarctica and Greenland, and so it was unclear which happened first,” Steig noted. “Our new results show unambiguously that the Antarctic changes happen after the rapid temperature changes in Greenland. It is a major advance to know that the Earth behaves in this particular way.”

Kendrick Taylor, chief scientist on the project, said the core enabled the research team to get the relative timing of Greenland and Antarctic temperatures down to several decades.

“We needed a climate record from the Southern Hemisphere that extended at least 60,000 years into the past and was able to resolve fast changes in climate,” said Taylor, from the Desert Research Institute in Nevada. “We considered sites all over Antarctica before selecting the site with the best combination of thick ice, simple ice flow and the right amount of annual snowfall.”

Taylor and colleagues formed a science and engineering team consisting of 28 laboratories from around the United States. “The resulting information provides unprecedented detail about many aspects of the Earth’s past climate,” Taylor said. “This will provide a generation of climate researchers a way to test and improve our understanding of how and why global climate changes.”

OSU’s Buizert said it is “very likely” that the Atlantic Meridional Overturning Circulation, or AMOC, is involved in these abrupt climate reversals.

“This ocean circulation brings warm surface waters from the tropics to the North Atlantic,” said Buizert, who is in OSU’s College of Earth, Ocean, and Atmospheric Sciences. “As these water masses cool, they sink to the bottom off the ocean. This happens right off the coast of Greenland, and therefore Greenland is located in a sweet spot where the climate is very sensitive to changes in the AMOC.”

Brook said the AMOC seems to be critical, but was probably part of a combination of factors that ultimately controlled these past abrupt changes.

“Although ocean circulation may be the key, there are probably other feedbacks involved, such as the rise and fall of sea ice and changes in ice and snow cover on land,” Brook said. “There is probably some kind of threshold in the system – say, in the salinity of the surface ocean – that triggers temperature reversals.

“It’s not a problem to find potential mechanisms; it’s just a question of figuring out which one is right. And the precise timing of these events, like we describe in this study, is an important part of the puzzle.”


Media Contact: 

Christo Buizert, 541-737-1209

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antarctica surface

OSU’s Aaron Wolf receives prestigious Heinz Award

CORVALLIS, Ore. – Oregon State University’s Aaron Wolf, an internationally recognized expert on water conflict resolution, has been named a 2015 recipient of the Heinz Award in the category of public policy.

Established to honor the memory of U.S. Sen. John Heinz, the awards recognize significant contributions in arts and humanities, environment, human condition, public policy, and technology, the economy and employment. Wolf’s award, given by the Heinz Family Foundation, includes an unrestricted cash award of $250,000.

Wolf was cited for “applying 21st-century insights and ingenuity, as well as ancient wisdoms, to problems that few are paying attention to for the security of the planet.”

“In a world where water is rapidly becoming the most precious of resources and most geopolitical of issues, Aaron Wolf has found practical solutions to protect our water resources and find common ground on water-centered conflicts,” said Teresa Heinz, chairman of the Heinz Family Foundation.

“Water issues cross state and national boundaries, and his advocacy has driven treaties and agreements that recognize our competing demands on water resources and the vital importance of protecting those resources from a modern-day ‘tragedy of the commons.’”

A professor of geography in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences, Wolf decided early in his career to find ways to ease the tension over water rights, developing a negotiation approach that emphasizes listening and finding shared values among competing users.

Wolf also was cited for working to prepare future generations of scholars and leaders in water conflict resolution. He and other leading academics founded a consortium of 10 universities on five continents that seeks to build a global water governance culture focused on peace, sustainability and human security.

He also helped develop a new partnership between Oregon State, the UNESCO-IHE Institute for Water Education in The Netherlands and the University for Peace in Costa Rica that will offer a joint master’s degree program on water cooperation and peace.

“One thing I’m struck by over and over is what people of goodwill and creativity can accomplish, even in situations where everybody feels like they’re going to lose something,” Wolf said. “As I’ve watched the discourse change from water wars to water cooperation and peace, I’ve learned firsthand that people will resolve seemingly intractable problems when they’re given the space and the opportunity.”

Other Heinz Award winners include:

  • Roz Chast of Ridgefield, Connecticut, best-selling illustrator and cartoonist, the arts and humanities category;
  • Frederica Perera of New York, and environmental health researcher at Columbia University, the environment category;
  • William McNulty and Jacob Wood, founders of Team Rubicon in Los Angeles – which engages returning veterans to help in global relief efforts – the human conditions category;
  • Sangeeta Bhatia, a bioengineer at the Massachusetts Institute of Technology, in the technology, economy and employment category for pioneering efforts to cultivate liver cells outside the human body.

Wolf and the other winners will be honored at a ceremony on May 13 in Pittsburgh.

Media Contact: 

Aaron Wolf, 541-737-2722; wolfa@geo.oregonstate.edu

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Natural Resources Leadership Academy 2012
OSU's Aaron Wolf

Study: Past warming increased snowfall on Antarctica, affecting global sea level

CORVALLIS, Ore. – A new study confirms that snowfall in Antarctica will increase significantly as the planet warms, offsetting future sea level rise from other sources – but the effect will not be nearly as strong as many scientists previously anticipated because of other, physical processes.

That means that many computer models may be underestimating the amount and rate of sea level rise if they had projected more significant impact from Antarctic snow.

Results of the study, which was funded by the National Science Foundation, were reported this week in the journal Nature Climate Change.

Scientists have long suspected that snowfall in Antarctica increases during planetary warming and the impact of so much snow tied up on land would have a negative effect on global sea levels. However, computer models on what should happen during warm periods have not matched observational data, according to Peter Clark, an Oregon State University paleoclimatologist and co-author on the study.

“Intuitively, it makes sense that as it warms and more moisture is in the atmosphere, that it will fall as snow in Antarctica,” Clark said. “The problem is that we’re not really seeing that through the last 50 years of observations – and documenting the relationship between changes in temperature and snow accumulation is difficult to do because of such strong natural variability.”

So Clark and his colleagues looked to the past to examine ice core data to see what they could learn about the future. They found that ice cores taken from the Antarctic Ice Sheet captured snow accumulation over time – and they could match that accumulation with established temperature data. They focused on a period from 21,000 years ago to 10,000 years ago – when the Earth gradually came out of the last ice age.

What they found was that Antarctica warmed an average of 5 to 10 degrees (Celsius) during that period – and for every degree of warming, there was a 5 percent increase in snowfall.

“The additional weight of the snow would have increased the ice flow into the ocean offsetting some of the limiting effect on sea level rise,” said Katja Frieler, a climatologist at the Potsdam Institute for Climate Impact Research in Germany and the lead author of the study. “It’s basic ice physics.”

The scientists found that the ice core results agreed with projections from three dozen computer models used to calculate future changes in snowfall. The end result, Clark said, is that projected increasing snowfall will still have a limiting effect on sea level rise, but that impact will be some 20 percent less than previously expected.

“Looking at the past gives us more confidence in anticipating what will happen in the future,” Clark noted. “The validation through ice core studies helps ground truth the computer models.”

Clark, a professor in Oregon State’s College of Earth, Ocean, and Atmospheric Sciences, was coordinating lead author on sea level change for the fifth Intergovernmental Panel on Climate Change report.

Other researchers involved in the study are from the Potsdam Institute for Climate Impact Research in Germany; the University of Wisconsin-Madison, Utrecht University in The Netherlands, and the University of Potsdam.

Media Contact: 

Peter Clark, 541-737-1247; clarkp@geo.oregonstate.edu