WE’RE PLAYING ROULETTE WITH CLIMATE RISKS, BROECKER WARNS

Stephanie Novak/MEDILL Wallace Broecker, 81, at the annual Comer Conference on abrupt climate change. Comer became one of the leading funders of climate change research and enlisted Broecker to help mentor the effort. They traveled together on research expeditions.
Stephanie Novak/MEDILL
Wallace Broecker, 81, at the annual Comer Conference on abrupt climate change. Comer became one of the leading funders of climate change research and enlisted Broecker to help mentor the effort. They traveled together on research expeditions.

by Stephanie Novak
Oct 23, 2012

Many know climate scientist Wallace Broecker, 81, as the “father of global warming”—but he says he isn’t very fond of the title.

“They say I’m the first one to use those words in print,” Broecker explained during a break at this year’s Comer Conference on abrupt climate change, held in southern Wisconsin. 

According to Broecker, the accolade comes from a paper he published in 1975, questioning if the planet was on the brink of global warming. 

Still, he said, Charles David Keeling deserves the title often bestowed upon him. Keeling, a geochemist with the Scripps Institution of Oceanography, was the first to measure carbon dioxide in the atmosphere, and later perfected the technique. The Keeling Curve brought awareness and solid science to rapidly increasing levels of CO2 and raised the alert that the buildup was linked to human activities. 

And CO2 levels, which continue to rise as people increase fossil fuel emissions, are a thermostat for a warming planet. 

“I don’t want to be remembered as the father of global warming. I want to be remembered for all the good science I’ve done” Broecker said. 

With or without the title, the man at the forefront of climate research since the 1970s has contributed innovative science to the field. He’s best known for his discovery of the ocean “conveyor belts” that play an important role in regulating the earth’s temperature. His 450 published journal articles and 10 books have also contributed to a greater understanding of the carbon cycle and the role of glaciers in regulating the earth’s temperature.

Broecker was born in Oak Park, Ill. After three years as an undergraduate at Wheaton College just a few miles west of his hometown, he transferred to Columbia University in New York and never left. He is currently the Newberry Professor of Geology in the Department of Earth and Environmental Sciences and a scientist at Columbia’s Lamont-Doherty Earth Observatory. He joined the university’s faculty in 1959.

And it was at Columbia that the late Gary Comer, the founder of outdoor apparel company Lands’ End, sought out Broecker and became one of his biggest champions. After selling his highly successful company to Sears, Comer funneled millions of dollars into climate change research across the globe and enlisted Broecker to help pull together top scientists and cutting-edge funding prospects. Stephanie and Guy Comer carry on their father’s legacy through the Comer Science and Education Foundation in Chicago.

Broecker brings straightforward explanations to the complexities of climate cycles and the role human activities are playing in global warming. He relies on the science behind greenhouse gases.

“Our best knowledge of the physics of greenhouse gases tells us that it should warm the planet, it’s an amplifier,” he said.  “Physics says it should warm, and it is warming. You can argue ‘til kingdom come whether what we’ve seen in the last 50 years is due to CO2 or not. I mean it makes sense that it is, but we can’t prove” that CO2 has led to extreme weather changes such as drought and flooding, he added.

This year’s hot summer makes a convincing case for the fact that greenhouse gases are indeed contributing to overall warming. One thing that Broecker’s science can predict is that when the planet warms overall, dry areas will become warmer and dryer and tropical, rainy areas will get wetter. The Midwest can expect more heat and damaging swings between flooding and drought.

Broecker equates taking climate change seriously to getting a regular check-up with your doctor. In medicine, people understand the value of preventative care—eating well to prevent obesity and diabetes, for example. 

The way Broecker sees it, he and his fellow climate scientists are just like doctors, offering preventative care medicine for the earth’s climate.  

“Nobody wants our medicine,” he said. “So I think, you know, we’re playing Russian roulette.”

And Broecker also understands that completely stopping all CO2 emissions isn’t a practical, near-term solution in a world that depends daily on things from heaters and air conditioning units to automobiles and airplanes.

“The time between now and when we’re on another energy source entirely is at least 50 years from now. We’re moving, but we’ve gotta replace everything,” he said. A complete switch to alternative energy sources such as wind and solar power or a solution such as fusion could even be a century away.

So Broecker, along with his colleague Klaus Lackner at Columbia is backing another solution.

“I think what we should be doing is pulling the CO2 out of the air and burying it,” he said, noting that  Lackner is working on carbon capture system to do just that.

“I think it ultimately has to be that way,” Broecker said, explaining that the biggest backlash has come from oil companies, but also from some environmentalists. 

“Environmentalists can be their own worst enemy,” he said. Some climate scientists oppose the idea of taking CO2 out of the atmosphere and burying it—in a nutshell, Lackner’s plan—because they say it encourages people to stop investing in other forms of energy and keep relying on fossil fuels. Broecker acknowledges this argument, but circles back to his point about massive alternative forms of energy being 50 years away.

Removing CO2 from the atmosphere can be a temporary solution until we can completely stop using fossil fuels, Broecker said.

Broecker said governments and not individuals will have to think global warming is a critical issue—funding plans like Lackner’s—in order for real change to happen.

“People always ask me ‘What can I do?,’” Broecker said. “In small ways you can help…turn off your lights, drive a Prius, but the problem is at the government level. At this point we really need a world government that has teeth—at least in regard to climate.”

LESS IS MORE: WHAT IT MEANS TO WARM THE PLANET ONE DEGREE

by Stephanie Novak
Oct 23, 2012

In the midst of Chicago’s scorcher of a summer, one degree warmer didn’t mean very much. One hundred degrees compared to 101?  The plain and simple answer: it was hot out.

But for climate scientists such as Aaron Putnam and Sean Birkel, one degree means a lot more.

They talk in the standard scientific unit of temperature – degrees centigrade – and use this measurement to calculate the earth’s overall temperature. 

NASA Droughts and floods linked to global warming threaten every continent, according to U.N.'s climate envoy.
NASA

In degrees centigrade, the planet has gotten approximately 1 degree warmer since the 1950’s, according to climate scientists. That’s about 1.8 degrees Fahrenheit. In passing, this may sound as insignificant as small changes in this summer’s rising temperatures. But when put in perspective, it adds up to a lot. 

“You can see huge dynamical changes in what appear to be pretty small changes in global temperature,” said Putnam, who is a postdoctoral research scientist at Columbia University’s Lamont-Doherty Earth Observatory in New York. During the last global ice age, the planet was only 6 degrees centigrade cooler than it is today, he said.

“One degree is one-sixth of the ice age,” Putnam said. “I think it just shows how little cooling you need to cause big changes across the planet,” he added.

It took 2,000 years for the earth’s temperature to warm 6 degrees centigrade, finally pulling it out of the last ice age, Putnam explained. With this in mind, 1 degree centigrade over the last century is one-sixth of a drastic change in global temperature.

And in the Arctic, where ice caps that play a large role in regulating temperature are found, warming has been even more significant.

“If we look at the Arctic in just the last 10 years, much of the Arctic has warmed probably on average 4 degrees centigrade, maybe even 5 degrees centigrade as a response to a loss of Arctic sea ice cover,” said Birkel, a postdoctoral research fellow at the University of Maine. That’s a whopping 7-9 degrees Fahrenheit in the place that’s warming fastest on the globe.

The Arctic is a key player in climate change, because melting there impacts all of the earth’s intertwined climate systems. 

“Winters are changing quite dramatically because of this Arctic melt,” Birkel said. In mid-September, when the annual ice melt comes to an end, the ice loss in the Arctic hit a new record high, he said. “So 2012 is uncharted territory. There’s a new minimum in Arctic sea ice. The Arctic today is not what it was 10 years ago. It’s much different. There’s no doubt that winters are warming in response to this.”

With changes in Arctic sea ice, the planet’s global hydrology—the way water is naturally distributed throughout the planet—will be amplified. Dryer places will receive less rain and wetter climates will receive more, exacerbating each region’s natural affinity for drought or flooding.

And there are other practical implications of one degree of climate change as well, such as the spread of infectious disease.

“Ten to 15 years ago, it wasn’t a big deal,” Birkel said, referring to infections such as Lyme disease, which have migrated north as winters have become shorter and warmer. “Now it is – people in New England know about it.”

Frozen ground and subzero temperatures kill the insects that carry diseases such as Lyme and West Nile. If they can survive the winter, they have a greater ability to move farther north, carrying disease. The spread of malaria, a mosquito-borne disease that kills millions of people every year, is among the worst threats of climate change.

Birkel and Putnam said they cannot predict what the future holds, partly because climate is so complex.

“It’s really a web of nonlinear systems,” Birkel explained. “Climate scientists understand them for the most part, but slight changes can make a big difference.”

LORD OF THE RINGS: OLD TREES PROVIDE NEW INSIGHT INTO CLIMATE CHANGE

Courtesy of Ancient Kauri Kingdom The largest Kauri log found whole in New Zealand, measuring 72 feet long and weighing 120 tons. Trees like these store troves of climate data in their annual rings.
Courtesy of Ancient Kauri Kingdom
The largest Kauri log found whole in New Zealand, measuring 72 feet long and weighing 120 tons. Trees like these store troves of climate data in their annual rings.

by Rachel E. Gross
Oct 21, 2012

The trees were quite dead.

But Jonathan Palmer, one of the world’s leading experts on tree rings, had expected them to be deader. Palmer has a strange calling. He chases the corpses of ancient trees throughout New Zealand bogs, and probes their annual growth rings for clues of climates past.

These trees were his specialty: New Zealand Kauri, a native plant that towers at more than 160 feet and lives up to two millennia. More than 25,000 years ago, Kauri would die and topple into peat bogs, where chemicals conspired to keep their bodies near-perfectly preserved. Today, people have been digging up the pickled time machines buried beneath the ground’s surface to make specialty furniture.

Whenever they do, Palmer gets a call. In 2006, he got one from a saw-miller he knew on the northern end of North Island. Cranes were lifting the trunks of four partially fossilized Kauri from a nearby swamp, and he’d better come quick if he wanted a sample. The New Zealander rushed to get a cookie—a cross-section up to 13 feet in diameter sliced through the trunk of the tree—to study. It wasn’t until lab results came back that Palmer and his colleague Chris Turney, a professor of climate change at the University of New South Wales, realized what they had on their hands.

These trees were 13,000 years old. Compared to the rest, positively youthful. More than that, the Kauri had occupied a pivotal chapter in earth’s climate history.

“It was unique and unusual,” Palmer says of the finding.

“Just brilliant,” is how Turney puts it.

As a dendrochronologist, Palmer reads the patterns in tree rings—layers of girth the tree lays down annually—to figure out what the earth was like at the time they formed. Looking at these rings, he could tell the Kauri had lived during a mysterious cold spell in the earth’s past known as the Younger Dryas.

Rachel Gross/MEDILL John Southon of the University of California at Irvine dates ancient trees to pinpoint key moments in the earth's past. He shared his findings at the recent Comer Conference on climate change.
Rachel Gross/MEDILL
John Southon of the University of California at Irvine dates ancient trees to pinpoint key moments in the earth’s past. He shared his findings at the recent Comer Conference on climate change.

Climate scientists regard the Younger Dryas as one of the most fascinating yet poorly understood periods in the earth’s past. A bout of cooling in the midst of an overall warming trend, it was a time when glaciers spread throughout Canada, encompassed the Great Lakes, and crept across the British Isles. The abrupt freeze is typically thought to have begun around 12,900 years ago and thawed 11,500 years ago.

But since the Younger Dryas happened mainly in the Northern Hemisphere, the Kauri down under had escaped the frost. To Palmer and Turney’s delight, the oldest Kauri tree in this grove had lived a ripe 1,350 years—covering most of the abrupt climate switch into this mystifying freeze. That made its rings a treasure trove. 

As any climate scientist or historian will tell you, we need to understand the past to predict the future. Climate modelers rely on what we know about the world’s transition into and out of the Younger Dryas to see what’s in store for the planet today—a goal made more urgent by disappearing species, a melting Greenland ice sheet, and an upward-creeping global thermostat.

As Turney writes on his website, quoting the poet T.S. Eliot:

Time present and time past
Are both perhaps present in time future,
And time future contained in time past.

To understand this critical moment in earth’s past, we need to know “what happened when,” as Turney says. In other words, we need a good dating system. Palmer and Turney rely on a system researchers have developed using a powerful combination of old and new(ish) dating techniques: traditional tree ring-counting and radiocarbon dating.

Here’s how it works.

Courtesy of Jonathan Palmer Kauri logs like this one, found in northern New Zealand, are more than 11,000 years old—yet their bark is remarkably well-preserved. “I’ve been there and leaves have come out green and turned brown in front of my eyes," says climate scientist Chris Turney.
Courtesy of Jonathan Palmer
Kauri logs like this one, found in northern New Zealand, are more than 11,000 years old—yet their bark is remarkably well-preserved. “I’ve been there and leaves have come out green and turned brown in front of my eyes,” says climate scientist Chris Turney.

First, radiocarbon dating. We used it on the pyramids of Egypt. We used it on the Dead Sea Scrolls. Radiocarbon dating measures the amount of decay of a radioactive isotope of carbon stored in an organic material, which means we can use it on anything that was once alive. 

But there’s a problem. If we go back far enough, radiocarbon years don’t match up to calendar years. That’s because radiocarbon levels in the atmosphere fluctuate based on the earth’s magnetic field, how much sunlight reached the planet, and how much radiocarbon got exchanged between the air and the sea.

So we also need a good calibration curve for radiocarbon, to translate radiocarbon years into calendar years.

That’s where tree rings come in. Their growth rings paint a clear picture of climate change year-by-year. Narrow rings mean years the tree survived harsh drought or frost, while fat rings reveal years of plenty. We can pair the calendar dates with the amount of radiocarbon the tree stored in its flesh during those years. “A two-pronged attack,” Turney calls it.

Researchers have cobbled together a tree calibration curve relying mostly on oaks and pines from central Europe. The project started in the 1960s, when researchers at the University of Arizona arranged a calibration sequence using the gnarled bodies of the Methuselian bristlecone pine going back 8,700 years. But the curve gets sketchy right around the start of the Younger Dryas. 

At that time, most of the trees in the Northern Hemisphere were “runty little pines struggling to survive,” says John Southon, a radiocarbon dating researcher at the University of California at Irvine who ran the dates for the recent Kauri project. Their tree rings might as well have been written in chicken scratch. That’s why Southern Hemisphere Kauri are so prized: nowhere on earth but in the swamps of New Zealand can we find tree rings going back 45,000 years—or more. 

Courtesy of Jonathan Palmer After a drought, brown "scorch marks" on a field in northern New Zealand reveal long-dead Kauri below the surface. See a video of Kauri extraction by Chris Turney here.
Courtesy of Jonathan Palmer
After a drought, brown “scorch marks” on a field in northern New Zealand reveal long-dead Kauri below the surface. See a video of Kauri extraction by Chris Turney here.

Back in 2006, Palmer and Turney sent off one ancient Kauri sample for dating at the University of Waikato in New Zealand by one Alan Hogg. But they had to make sure what they were seeing was true. So they also shipped some billets to Southon, in Irvine.

“This was a big deal,” recalls Southon, a Kiwi himself. At the time, he was dating stalagmites from Hulu Cave in China spanning a stretch of 16,000 years. When the wood came in 2008—two years of funding challenges delayed its arrival—he took out his microscope and peered at it through thick black spectacles. Then he did a double-take.

“It was just like reading pages out of a book,” he says. “I’ve never seen anything that looked that great.”

The researcher took tiny chunks comprising ten rings each, burned them to form graphite, and measured the ratio of the different isotopes of carbon with a mass spectrometer in his California lab. His results matched Hogg’s. The new Kauri sequence would firm up 1,300 years of the shaky calibration curve, decisively bridging the transition into and out of the Younger Dryas.

In September, Southon presented his findings to a roomful of climate scientists at the annual Comer Conference on abrupt climate change in Wisconsin—but cautioned that the sequence was a work in progress.

There is still work to be done before researchers can say exactly what the new Kauri sequence means for the Younger Dryas and climate change today. Before they publish later this year, they have to make sure the sequence is matched correctly with the rest of the calibration curve. Then, Turney hopes to input the new data into climate models at the University of New South Wales.

Plus, they’d like to get more trees in on the action, a goal that has depended so far largely on luck.

In 2009, Palmer and Turney returned to New Zealand’s North Island on a hunch they might find more wood. The country was in the midst of a devastating drought, which have grown more common as the planet’s thermostat rises. But this drought was also fortuitous: it had squeezed moisture from peat bogs and desiccated the top layer of grass, so that brown scorch marks now outlined ancient Kauri just below the surface.

“It was like somebody had come along and stenciled on the surface a tree,” Turney says.

He and Palmer watched as tractors extracted from the earth first one, then a dozen, and finally 25 trees. For climate research, it was a windfall. Yet without global warming, it’s possible the trees may never have been found.

“Isn’t that deliciously perverse?” Turney says. 

Palmer will soon join Turney at the University of New South Wales to continue probing the data. He spent this past year as a visiting scientist at The Kauri Museum in Northland, compiling an archive of Kauri samples for future researchers—as he has neither the time nor funds to analyze them all himself.
Palmer describes with reverence the first time he watched ancient Kauri being extracted: he says he was “in awe at the earth releasing such enormous logs from the ground.” Yet even after 30 years of searching, the tree ring expert still finds the Younger Dryas Kauri particularly exciting.

“Leaves you wondering what else might be still there,” he says.

ARTIFICIAL TREES: CAP YOUR CO2 AND SPEW IT TOO

Courtesy of Klaus Lackner One of Lackner's potential designs for a carbon-scrubber that would suck the molecule from the atmosphere.
Courtesy of Klaus Lackner
One of Lackner’s potential designs for a carbon-scrubber that would suck the molecule from the atmosphere.

by Rachel E. Gross
Oct 20, 2012

For those of us torn between concern for a warming globe and a lifestyle that relies on spewing tons of the greenhouse gases responsible for warming it, Klaus Lackner has a solution. 

Suck it up. 

That isn’t just tough love. The Columbia University geophysicist has spent nearly two decades developing a portable carbon scrubber to suck some of the carbon dioxide we emit back out of the atmosphere. 

His contraption is inspired by the mechanics of the tree: plastic “leaves” filter the diffuse greenhouse gas and store it to prevent some of the nastier effects our fossil fuel addiction is having on the planet. If we can extract enough carbon dioxide, Lackner says, we’ll be able to offset our oil-driven lifestyles without setting the earth’s dial to self-destruct. 

Biofuels and electric cars are promising, and the hydrogen fuel economy is always just around the corner. But, as the Greenland ice sheet melts, droughts and heat waves become more common, and carbon dioxide levels creep toward the earth’s tipping point, creative solutions to global warming grow more urgent. Lackner estimates that one-third to one-half of world carbon emissions come from billions of small sources—motorcycles, planes, cars. Those are the kinds of sources his scrubber would target. 

Now, technological advances and a government grant are bringing his prototype scrubber closer to commercial reality, he told a gathering of top scientists at an annual climate conference held in Wisconsin recently. The Comer Conference on abrupt climate change is organized by the family of the late Gary Comer, founder of clothing company Lands’ End. 

A single scrubber, which currently measures ten by five feet with a carousel-like cylinder on top, would remove one ton of CO2 per day—equivalent to the emissions produced by burning about 100 gallons of gasoline. The extracted CO2 would then be stored underground or used to make synthetic fuels. Because CO2 spreads throughout the world’s atmosphere, it can be extracted from anywhere; scrubbers might be placed en masse in deserts or in cooler regions such as Iceland, Lackner said at the conference. 

Courtesy of Klaus Lackner A previous "branch" design was based on a thicker plastic that was less efficient for carbon capture.
Courtesy of Klaus Lackner
A previous “branch” design was based on a thicker plastic that was less efficient for carbon capture.

Lackner’s goals for carbon capture are far-ranging. He said he hopes humanity will one day be able to set its own atmospheric carbon levels, effectively controlling the earth’s thermostat. But the scrubber has limits. It doesn’t target other greenhouse gases, such as methane. And it won’t fix the increasing acidification of the oceans, which is killing coral reefs and fish populations. 

“It’s part of a solution,” Lackner says. “Like anything else, it’s an option.” 

Lackner is on the defensive after facing challenges to his invention. In 2011, the American Physical Society deemed large-scale carbon scrubbing a “formidable” task that could not be deployed fast enough to deal with rapid climate change. The organization wrote that the prospect of chemical carbon capture was no excuse to delay lowering the world’s carbon footprint by alternative means, and that pursuing those means—”including low-carbon electric power production and transportation”—are higher priority. 

Lackner disagrees. With carbon levels already dangerously high, he says, we need all the options we can get. 

“I’m not advocating procrastination,” says the physicist, who published a paper defending carbon scrubbing this July in response to APS’s position. “Far from it. I’m telling you, we already overshot. And we need a solution that allows us to come back.” 

While acknowledging a high level of uncertainty, the APS estimated the cost of direct air capture at $600 to extract a ton of CO2. Lackner believes he could get it down to $30. But to achieve that kind of efficiency, first he needs “to get into the doing business,” he says. “It gets cheaper as you do.” 

Before tackling the world’s carbon problems, he’s banking on some “not horribly green options” to help his scrubbing business get off the ground: he hopes to sell the gas to greenhouses in Europe, or oil companies who use it for enhanced oil recovery. 

Rachel Gross/MEDILL Lackner presented his first vial of sequestered carbon dioxide to Gary Comer in 2006, months before the philanthropist's death. It sits in the library of the Comer family's estate.
Rachel Gross/MEDILL
Lackner presented his first vial of sequestered carbon dioxide to Gary Comer in 2006, months before the philanthropist’s death. It sits in the library of the Comer family’s estate.

In 2004, Lackner co-founded a company for direct air capture with seed money from the late Gary Comer. He presented his first vial of sequestered carbon dioxide to Comer in 2006, months before the philanthropist’s death.

The company, Kilimanjaro Energy in San Francisco, recently improved the plastic the scrubber will use to fix carbon. The material is now just a fraction of a millimeter thick—compared to a millimeter in his original model—and works six times as fast, according to Lackner. He will continue developing the technology with a six-month grant from the U.S. Office of Naval Research, which he and colleague Allen Wright secured in July. 

Making direct air capture work will be necessary if we are to stabilize world carbon levels in the future, says Wallace Broecker, one of the first climate scientists to predict global warming in the 1970s. The pioneer climate researcher of Columbia University foresees an international agreement—such as the 1987 Montreal Protocol, a worldwide treaty that phased out chlorofluorocarbons from aerosol cans that were boring a hole in the ozone layer. 

Broecker believes companies that remove carbon from the ground in the form of fossil fuels—oil, natural gas and coal—should be taxed. The tax would go toward a global fund to sequester that carbon or turn it back into fuel using Lackner’s technology, effectively closing the carbon cycle. 

“This will be done, not before I die,” says Broecker, who is 81 years old. “But I would say in 30 or 40 years, it will be not only talked about but being done.”

SCIENTISTS EXPRESS FRUSTRATION WITH THE POLITICS OF CLIMATE

by Matt Rhodesand Eric Eckstrom
Oct 18, 2012

Each year scientists at the cutting edge of climate research undertaken all across the world gather at the Comer Conference in Wisconsin to exchange their latest findings and data. Physics, chemistry,

Medill Photo Parched earth took a heavy toll on the Midwest's corn crop by mid-July. Weather extremes such as drought and flooding are linked to global warming.
Medill Photo
Parched earth took a heavy toll on the Midwest’s corn crop by mid-July. Weather extremes such as drought and flooding are linked to global warming.

geology, oceanography, biology and dozens of other disciplines are documenting the serious impact of global warming. It’s science – not politics, scientists emphasize. With climate change becoming an increasingly urgent problem, many experts express concern with the lack of policy based on the science, especially in the United States, and with the way the media has covered climate change.

 

Before they head back to their research, the conference closes with a hilltop picnic at the tent where the scientists join together for meals and to continue sharing research during the conference.

BHUTAN’S MELTING GLACIERS HOLD A MIRROR TO EARTH’S FUTURE CLIMATE

Photo by Douglas J. McLaughlin/Creative Commons The small mountain country of Bhutan is home to 700,000 people, many of whom rely on hydroelectric power that could be interrupted by the loss of the glaciers.
Photo by Douglas J. McLaughlin/Creative Commons
The small mountain country of Bhutan is home to 700,000 people, many of whom rely on hydroelectric power that could be interrupted by the loss of the glaciers.

 

by Matt Rhodes
Oct 15, 2012

Hiking up to 16,000 feet in the Himalayas, climate scientists plan to pin down how fast glaciers are melting near the top of the world. 

Bhutan, located at the center of the highlands of the Himalayas, is hosting a team of geoscientists as they research the small mountain country’s glaciers and forests. The area offers a snapshot of how changing temperatures are affecting glacial regions and global climate. 

The one-month expedition is a joint, three-pronged operation combining proxies from glaciology, glacier geology and dendrochronology dating climate changes by studying growth rings in tree trunks). 

Part of the job of glimpsing climate impacts requires removing cores – or “cookies” from trees to read the tree rings. That job that calls for Edward R. Cook, dendrochronologist at the Columbia University’s Tree Ring Research Laboratory the Lamont-Doherty Earth Observatory. Cook will take the cores as a member of the research team trekking up to their field area located at 16,000 feet.  

“We’ll be going through some of the deepest, oldest forests that you can find in the Himalayas,” says Aaron Putnam, postdoctoral research scientist at Lamont-Doherty. “The Bhutanese have been very conscious about not eliminating their forests.” 

geology.com
geology.com

Working at such a high altitude doesn’t come without risks. “Not everyone’s worked up that high and sometimes it doesn’t even matter,” says Putnam. “If the altitude hits you, it hits you.” 

Other challenges include getting a 2,000-watt, 50-pound portable generator from Wisconsin to the Himalayas. The generator never got beyond Minneapolis but one of the team’s hosts in Bhutan located a replacement, Putnam reports. 

The team hopes to get a record of several centuries from the sampled cores of the trees. “Maybe even 1,000 years of tree ring variability, which they think reflects changes in atmospheric temperature,” reported Putnam at the annual Comer Conference on abrupt climate change held this fall in Wisconsin. 

The annual climate conference brings reports of climate change from around the globe as leading scientists gather to share data. 

Once the team reaches their field area, they will begin drilling ablation stakes directly into a select series of glaciers. Summer Rouper, a glaciologist from Brigham Young University, leads this side of the triad. 

Drilling the stakes into the glaciers initiates a long-term monitoring program enabling the team to get melt rates of the glaciers. Members of the team will periodically check on the stakes and tick off how much of the glacier has melted, since the last checkpoint. Think of how a child stands next to a doorframe and marks their height as they grow up. It’s the same principle at work with the ablation stakes, but in the case of the glaciers, they are experiencing a shrink spurt rather than a growth spurt. 

Matt Rhodes/MEDILL Aaron Putnam (left) and colleague George Denton, professor of geological sciences at the University of the Maine (right) at the Comer Conference.
Matt Rhodes/MEDILL
Aaron Putnam (left) and colleague George Denton, professor of geological sciences at the University of the Maine (right) at the Comer Conference.

The stakes work in tandem with the automatic weather stations the team is building in their field area, which will monitor what the weather over the glaciers is doing. This allows the scientists to monitor how the climate is changing in real time. 

“It’s a means of calibration,” says Putnam. “We know the glaciers respond to temperature there, but we don’t know exactly how sensitive they are and that sensitivity is key.” 

In addition to studying the state of glaciers at present, the team is also collecting data to reconstruct glaciers of the past. Led by principal investigator, Joerg Schaefer, professor at Columbia’s Department of Earth and Environmental Sciences, the group is mapping the ridges and moraines demarcated by past glaciers. 

“If we can reconstruct the geometry of glaciers by using these mapped moraines we can actually quantify how much the climate has changed,” says Putnam. “Then the big question is when was it that much colder to produce a moraine outside, so then we use beryllium-10 to get the age of the moraine. And then we have the x-axis, which is time and the y-axis, which is temperature, and we can actually plot the temperature evolution over time.” 

The beryllium-10 isotope only appears in rocks when they are exposed to the air – in other words, when glaciers have retreated. The levels of the isotope offer a paleo calendar of when glaciers advanced and retreated. 

The team will then match this temperature evolution with other records of paleoclimate around the planet, revealing a better understanding of the mechanisms that drive climate change. 

Matt Rhodes/MEDILL Scott Travis is the facility manager of the Comer family estate and is assisting climate scientists in their research in Bhutan.
Matt Rhodes/MEDILL
Scott Travis is the facility manager of the Comer family estate and is assisting climate scientists in their research in Bhutan.

*** 

The team’s research will not only add clarity to the dynamics of climate change at large, but will also directly benefit Bhutan and its neighboring countries. 

“We’ll be helping Bhutan’s Ministry of Agriculture better understand the formation of glacial lakes – run-off water from the glaciers that causes problems flooding these steep Himalayan valleys,” says Facility Manager of the Comer Estate, Steve Travis, who will also be assisting Putnam and the rest of the team in Bhutan. 

Travis describes his role as a “go-for” (pronounced gopher). Whatever the team needs, Travis will go-for it and get it, he says. 

Travis worked with Putnam before in New Zealand and Patagonia. 

“After five seasons in the field doing exposure dating, I can be real specific and helpful,” says Travis. 

As the climate warms, many of the larger glaciers that historically produced giant meltwater streams withdraw from the moraines and form proglacial lakes instead, explains Putnam. These lakes lead to flooding because not enough water is making it out of the moraine downstream. 

The glacier lake outburst of Lugge Tsho in northern Bhutan killed 21 people in 1994. 

The decreasing water flow is also adversely affecting the biggest driver of Bhutan’s economy – the hydropower sector. 

Bhutan exports much of its energy to India through a system of hydroelectricity power plants that entirely depend on the downstream water discharge from melting glaciers and snow packs. Thus far, Bhutan has managed to sustain their hydropower industry while remaining a net carbon sink – a place that absorbs more carbon that it emits. The secret is in Bhutan’s preservation of forests that blanket some 70 percent of the country and absorb enough carbon to more than offset emissions from the nation’s agriculture and industry, with room to grow. 

Bhutan’s potential output of hydropower had previously been estimated at 30,000 megawatts (mW). But currently, the country has an output of about 1,500 mW from four plants and needs more plants to generate more power. 

India has agreed to assist Bhutan in developing the hydropower sector by funding construction of six more plants and plans to purchase at least 10,000 mW of power from the partnership by 2020. 

But a variant climate may change such ambitions. 

“No more glaciers, no more power,” says Travis. 

“You’ll find the same thing in New Zealand. They built a series of canals that trap the water and have hydropower associated with all the glacial run-off around Lake Pukaki,” he adds. For India, which faced massive power outages this summer. The climate stakes are very high. 

The team hopes their research will aid Bhutan in its plans for future development in its hydropower sector, while continuing to absorb more carbon than it’s emitting. 

“They’re smart and want to do it right from the beginning,” says Travis. “I wish them all the best with what they’re trying to do and if we can go help them understand climate change that’s even better.”

HOW LONG CAN GREENLAND ICE HOLD OUT? SCIENTISTS TRACK CLIMATE SWITCHES

by Stephanie Novak and Rachel E. Gross
Oct 23, 2012

As news of record sea ice loss in the Arctic made headlines this fall, some of the world’s top climate scientists met in Wisconsin to talk about the latest in climate change research and the accelerating pace of melting glaciers and global warming.

Helicopters whirred onto the private runway of a rural estate, bringing scientists working in New York, New Zealand, Antarctica and around the globe back to the heartland. From September 16-19, the family of the late Gary Comer—the founder of Lands’ End and a philanthropist who invested a fortune funding environmental research—opened the estate to the annual Comer Conference on abrupt climate change.

Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory NASA calls it "unprecedented Greenland ice sheet surface melt." According to NASA: "Extent of surface melt over Greenland’s ice sheet on July 8 [top] and July 12 [bottom]. Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting."
Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory
NASA calls it “unprecedented Greenland ice sheet surface melt.” According to NASA: “Extent of surface melt over Greenland’s ice sheet on July 8 [top] and July 12 [bottom]. Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting.”
The researchers looked at abrupt climate switches and retreats of glaciers from the past to shed light on Greenland’s dwindling ice today and what it means for the planet. Yet they remain hopeful that it will be “centuries, not decades,” before the ice cap melts. But no one knows for sure as the melting accelerates.  

To make solid predictions, the scientists rely on surface dating techniques, reconstruct snowlines and analyze the composition of polar ice and sediment cores. But no matter how nuanced the method, their guiding goal remains the same: to understand the planet’s past and—in doing so—better predict the future.

“We’ve got to understand enough so that we know what is, what was, and what will be,” said Richard Alley, one of the world’s premiere climate change researchers who worked extensively on the mile-long ice cores from Greenland, time machines trapping a record of hundreds of thousands of years of climate.

More than 30 climate scientists shared their findings and discussed the evolving role of key planetary markers that reveal changes in the earth’s climate. Here are some of the different markers scientists depend on to understand past climatic upheavals, and what they mean for the planet going forward.

Sediment Cores

At 4 meters, or 13 feet long, a clear cylindrical tube was the most striking way for climate scientists to display how they know when the earth’s surface was covered with glaciers and when it wasn’t.

Blue-grey layers of clay filled half the tube, showing periods of glaciation. The other half, layers full of sandy brown dust and dirt, was where scientists plucked out bits of vegetation—a small flower or scrap of moss—to show that the glaciers had retreated.

Sediment cores are physical geological records documenting where sediments accumulated over time, explained Gordon Bromley, a paleoclimateologist at the University of Maine. These sediments act as proxies of climate and environmental change because – as the earth’s climate shifts from hot to cold –  vegetation changes as well.

“It’s geology in your hand, you pull them out and you have like a little time machine in your hand,” Bromley said.

Scientists at Bromley’s lab recently used these sediment cores to challenge a longstanding hypothesis. For decades, climate scientists have postulated that the Younger Dryas, the ice age that occurred between 12,900 and 11,500 years ago, was an anomaly of Northern Hemisphere cooling during an overall period of warming, especially in the Southern Hemisphere.

But Bromley’s research with sediment cores from Scotland questioned this idea, using bits of newly vegetated landscape to show that, during the Younger Dryas, Scotland warmed too.

“Our ages came back earlier than the end of the Younger Dryas, which made us say that Scotland had become deglaciated by then,” Bromley said. “The vegetation can only grow when the ice is gone and so radiocarbon dating is a solid example of when the ice was gone,” he added.

But despite the fact that some climate scientists found Bromley’s results surprising, he said that his work adds to a growing body of research rather than being a completely new finding. 

“We can see this theory of the Younger Dryas cooling being eroded all over the place,” with cooling in some areas and warming in others.  

Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory
Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory

Sediment coring, however, is both an extremely accurate and imperfect method of dating the earth’s past, according to Bromley. In cores, the brown dirt clearly indicates when rock was exposed to air and vegetation grew. But since vegetation can be sparse – a bit of moss at one location and more a mile away – samples from all over the same rock formations do not always yield the same information.

“It’s like you’re drilling down into this unknown world which you can’t see and trying to find the bottom, trying to find the treasure,” Bromley said.

Ice Cores

Like sediment cores, ice cores from Greenland and Antarctica record time in their clearly-defined stripes. Winter snow is tightly packed, while summer snow falls more loosely, with pockets of air bubbles trapped within.

Looking at a core drilled from one of the earth’s two ice caps, it’s easy to determine what happened when, said Alley, a prominent geoscientist at Pennsylvania State University. 

“If you want to know what the temperature in Greenland or the temperature in Antarctica was, there are a number of indicators in an ice core that, taken together, give you a clearer picture of the the history of temperature than anywhere else,” said Alley. He served as the conference’s unofficial emcee, kinetic with an unflappable enthusiasm for the science and casual, wearing silver-rimmed glasses and a polar-blue polo shirt.

Alley, who authored the book “The Two Mile Time Machine” about the ice cores, explained how they continue to be one of the most versatile markers of past climate switches. The Greenland cores show scientists that the world’s climate has always been in flux, alternating between deep freezes, melts and mild spells. 

Rachel Gross/MEDILL Rachel Gross/MEDILL At the conference, Pennsylvania State geoscientist Richard Alley demonstrates the effect of glacial melt on sea level.
Rachel Gross/MEDILL
Rachel Gross/MEDILL
At the conference, Pennsylvania State geoscientist Richard Alley demonstrates the effect of glacial melt on sea level.

Ancient air pockets in ice cores track carbon dioxide levels back as much as 800,000 years, for instance. But nowhere in this 800,000-year history do they show CO2 levels in the atmosphere as high as they are now. 

Today carbon dioxide in the atmosphere hovers at a global average of 394 parts per million. Nearly 40 percent of that has accumulated in the past century and a half, from a relatively stable 280 parts per million after the last ice age and prior to the Industrial Revolution. The ice cores tell a sobering story – before humans started burning fossil fuels for energy and creating greenhose gas emissions, levels hadn’t topped 300 parts per million in 800,000 years. And CO2 is a thermostat for global warming.

Ice cores are sliced into sections and stored at the National Ice Core Laboratory in Colorado, some 800,000 years of climate history stored in its layers. But those layers reveal more than just time. 

Trapped in the ice is dust showing periods of dryness in Asia; ash from fires that came downwind from Canada; and lead deposited during the First Industrial Revolution. The air bubbles in the ice capture earth’s atmospheric past, revealing changes in greenhouse gases like carbon dioxide and methane across years and poles.

“The ice core is sampling all different places and it’s putting it in the same record. It’s the same ledger, the same memory box, at the same time,” said Alley. “So you can go ask the ice core, did a lot of the world’s climate change at the same time? And it says, yes it did.”

Researchers are looking forward to results from cores drilled through the West Antarctic Ice Sheet, a relatively unstable part of Antarctica that NASA experts estimate could hike up sea levels by 16-20 feet if it were to melt completely. 

Thanks to new techniques and ideal snowfall conditions this year, the new cores will be the first clear record in the region going back 68,000 years, said Joseph McConnell, who helped analyze the new cores at his laboratory at the Desert Research Institute in Nevada. McConnell attended the conference, but could not report publicly on his results because they aren’t published as yet.

“We got very lucky with the timing,” he said via email. He added that the data revealed by the new cores “will be much broader in scope than other deep Antarctic ice cores and measured at ultra-high depth resolution so the climate record will be very detailed.”

The results will also strengthen climate scientists’ understanding of large switches in the earth’s past and allow them to better match up past climates in the Northern and Southern hemispheres, said Alley, who helped work on the forthcoming core.

“They are recording this coupled oscillation of the whole earth system, and it really does all work together,” he said.

Tree Rings and Radiocarbon

Researchers at the conference are making strides using a powerful combination of older and newer dating techniques: radiocarbon dating and counting tree rings. 

John Southon, a radiocarbon dating researcher at the University of California at Irvine, reported on work with a windfall of fossilized trees from Northern New Zealand that will help climate researchers more accurately date a crucial but poorly understood transition in the earth’s past—the rapid switch into the Younger Dryas, the Earth’s most recent ice age that covered the Great Lakes in glaciers.

“The Younger Dryas epitomizes abrupt climate change,” said Bromley, the paleoclimatologist studying sediment cores in Scotland. “Understanding it means understanding fully the implications of climate change.”

Along with New Zealand researchers, Southon is working to improve radiocarbon dating techniques for the Younger Dryas interval. He has dated the growth rings from trees going back nearly 13,000 years to better calibrate the accuracy of radiocarbon dating during that time. The tree rings — fatter in warm and wet periods and stringy during cold and dry years — offer a remarkably accurate climate almanac.

The partially fossilized New Zealand Kauri trees are especially important, because few trees in the Northern Hemisphere survived the frigid weather conditions of the Younger Dryas. Finding a batch from that had lived during this time period “was a big deal,” Southon said. “It was a way of filling in that gap.” 

The radiocarbon-tree ring dating combination has also been a boon for Aaron Putnam, a glacial geologist and paleoclimateologist at Columbia University’s Lamont-Doherty Earth Observatory in New York.  At the conference, he presented work on a “graveyard” of 42 long-dead poplar trees that have been left standing in the Taklamakan desert of Southern China.

Poplar can’t survive in the desert heat. That tells Putnam the Taklamakan must have once been a thriving river ecosystem, until the change to desert conditions dried these trees out. But he needed evidence of the specific timing to test his hypothesis.

So he sent samples of the 600-year-old wood—with growth rings intact—to Southon for radiocarbon dating. Southon ran the dates. 

The trees had lived from 1389 to 1411 AD, he reported back to Putnam—precisely.

Beryllium-10

In order to gain a greater understanding of climate changes across the planet, climate scientists are increasingly using an isotope called beryllium-10, which allows them to date rocks left behind by glaciers from all over the Earth.

“Beryllium-10 has special cosmogenic nuclei that’s created in a rocks surface when the surface is exposed to the sky,” said Putnam. 

When glaciers retreat, the surfaces of of rocks they leave behind is exposed to the air. Once this exposure happens, cosmic rays hurling across the galaxy strike the rock, blasting atoms apart creating beryllium-10. This particle builds up on the rock’s surface the longer it is exposed but not when it is covered by a glacier. This means that scientists can measure the amount of beryllium-10 on a rock’s surface and the concentrations tell them when the surface was covered in ice and when the ice retreated.  

Beneath the science of cosmic rays and atoms blasted apart, Putnam said that charting when glaciers waxed and waned is critical to climate science.

“Glaciers are the earth’s best thermometers because they’re physical geologic formations that respond to temperature,” he said. “What it allows us to do is reconstruct, on a global basis, anywhere there have been glaciers on the planet and how climate has changed in the past.”

Understanding how climate changed in the past, said Putnam, allows climate scientist to study the way the climate changed during the 20th century and put modern global warming into a larger, historical context. This perspective lets them analyze the impact that humans have on climate today.

Putnam said that Beryllium-10’s greatest value is that it allows climate scientist to test the hypothesis that current global warming is not human produced, but rather a natural expression of climate variation. 

“That’s a completely valid hypothesis, because it can be tested,” Putnam said. “The requirement for that hypothesis to be correct is that you have to go on opposite sides of the planet and see if there was warming on both,” he added. 

By charting past climate change on the planet—wherever glaciers left rocks behind—scientists can paint a more accurate picture of the climate footprint that humans are leaving here now.


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