Seeking clearer views of the planet, a BYU professor became an expert on its stores of ice, the sentinels of climate change.
The tale of how David G. Long (BS ’82) stumbled into the global warming debate begins with what sounds like a joke: How do you lose a piece of ice that’s 60 miles long, 25 miles wide, and 1,000 feet thick?
The riddle didn’t amuse the staff of the National Ice Center in 1999, for an iceberg of those ridiculously huge dimensions had eluded them for months under the cover of a dark Antarctic winter. Then an inbound call to the iceberg tip line brought alarming news: the massive iceberg, known as B10A, was lurking in the Drake Passage, a busy shipping lane between South America and Antarctica. The center issued an international alert with coordinates to help vessels steer clear.
Disaster averted, attention turned to the caller who had located B10A. Rather than a maritime pilot, the first-time caller was an engineer at an ocean-less university in Provo, Utah. Professor Long and a band of students spotted the fugitive iceberg thanks to a computer algorithm they wrote to make sense of data from a scatterometer, a satellite-borne device that uses radar to gather data about the earth. Their processing techniques—powered by BYU’s supercomputer—gave enough clarity to distinguish ice from water.
“Radar allows us to easily track icebergs through darkness and clouds,” says Long, a BYU professor of electrical and computer engineering. “This was a serendipitous application. This satellite was really designed to measure wind.”
The new capability to use the scatterometer to study ice changed the course of Long’s research career. In the pursuit of clearer views of the planet, David Long inadvertently became an authority on its stores of ice—and by extension, an umpire on climate change.
Views from Above
David Long’s list of scientific publications looks like a well-used passport with exotic entries: the Amazon Basin, 1994; the Canadian Boreal Forest, 1996; the Yukon, 1998; Greenland, 2001; the Sahara desert, 2005; Antarctica, 2006; the Canadian Arctic, 2008. Each entry’s masquerade as adventure travel is betrayed by accompanying technical jargon such as “digital Doppler processor,” “cloud removal algorithm,” and “pencil-beam scatterometer.”
For nearly two decades, the engineering professor has collaborated with NASA to give the scientific community rich and unobstructed views of the planet. As a young BYU grad, Long took a job with NASA’s Jet Propulsion Lab in Pasadena, Calif. He spent the 1980s designing radar-equipped satellites and earning a PhD from the University of Southern California. He returned to BYU as a faculty member in 1990, and his success in the classroom and the lab was acknowledged last year with BYU’s Karl G. Maeser Distinguished Faculty Lecturer Award.
To appreciate what Long and his students do, think of NASA’s scatterometer as something like an iPhone, a cool device with lots of potential. The BYU engineers are the enthusiasts who write all the cool applications—or “apps”—that help users tap that potential.
Meteorologists at the National Hurricane Center love the BYU app that pinpoints the eye of tropical storms. Logistics personnel from the U.S. Navy use another BYU app to reroute ships around rough waters, drastically cutting fuel costs. There’s a BYU app that spots how much the Sahara desert expands. Another pinpoints where the Amazon rain forest is contracting. Some BYU apps are unbelievably precise, such as the one that tracks the vertical movement of morning dew within a forest.
And then there’s the suite of ice-detection apps, which track icebergs, record short-lived sea ice, and monitor which part of a glacier is melting and which part is growing.
It was in developing these apps that Long and his crew found the wandering iceberg in 1999. But detecting B10A was just the tip of the iceberg for Long and his students. With the blessing of the National Ice Center, the group began building the world’s largest iceberg-tracking database.
Around the year 2000, analysis of temperatures around the world showed an average increase of 1.3 degrees Fahrenheit in the previous 100 years. It appeared to scientists that the climate was warming, but why? Blaming the warming trend on increasing levels of greenhouse gases, activists called for global curbs on emissions, while skeptics pointed at the many shortcomings of climate models.
But Long is neither an activist nor a skeptic. He has always been in the business of observation, and the engineer entered the debate strictly as a highly curious observer.
One noteworthy shortcoming of temperatures recorded by man-made instruments is that they aren’t evenly spread around the globe. Thermometers tend to be where the people are—more particularly near the people of industrialized regions.
So the scientific community looked for confirming evidence of climate change in Mother Nature’s own climate sentinel, glacial ice. At the time, the number of icebergs wandering about the southern ocean seemed to have spiked. Since icebergs are born of glaciers, some wondered if this was a sign of a warming climate.
Enter Long and the BYU iceberg database. Armed with the latest technology and full access to the National Ice Center archives, Long and his students began investigating the bumper crop of icebergs.
The BYU study found that the increase in icebergs could be explained by two factors. First, tracking technology had gotten better; fewer ’bergs were going unnoticed, pushing the count higher. Second, historical records kept by sailors showed that huge litters of Antarctic icebergs are born every 50 to 60 years. The new batch of floating ice had arrived right on schedule.
In a published paper, Long and his students concluded that the increased iceberg count was unrelated to climate change. But Long was quick to clarify: “This result does not mean global warming is not occurring, only that the iceberg count couldn’t be used as evidence.”
The world’s biggest island, Greenland is home to 10 percent of the planet’s ice, more than one mile thick in places. The mass is so heavy that the middle of the island buckled and sank—below sea level at some points—shaping the land like a saucer.
Long and a former NASA colleague decided to establish some baseline measurements of Greenland’s ice. In the summer of 1996 they charted the landscape as a scatterometer-equipped satellite passed overhead. They also found unused scatterometer readings collected in 1978.
Their goal was to introduce techniques for observing glaciers from space. That part was straightforward. But they couldn’t help but notice larger summer melt zones and melt occurring at higher elevations—a possible trend they noted in their published research.
“We weren’t exactly sure at first, so we presented it in very cautious language,” says Long.
When satellites again pinged their microwave signals against Greenland’s landscape in 2000 and 2008, their caution yielded to firm evidence. Long and his colleague documented major growth in the southern and western melt zones.
The increased melt they observed from space was verified on the ground by scientists like Konrad Steffen of the University of Colorado. Steffen found that the melt season has lasted longer each of the past 30 years, with the exception of 1992 when Mt. Pinatubo’s ash cooled things down temporarily.
Long has published 18 scientific papers detailing the changing dynamics of Greenland’s ice. His findings, combined with the work of other scientists looking at Greenland, have helped convince Long that the global climate is getting warmer. “Greenland is warming, and as it warms it is melting,” Long says. “The rise in sea level is small so far but could accelerate as the flow of glacial ice is lubricated by melting water.”
And what melts in Greenland does not stay in Greenland. The International Panel on Climate Change (IPCC) estimates the oceans will rise anywhere from 18 to 59 centimeters by the end of the century, depending in large part on what happens in Greenland. Though the high end of the IPCC estimate doesn’t sound like much—59 centimeters is about two feet—it could displace millions of people residing in low-lying areas, particularly in Asia.
In the summer of 2008, for the first time in recorded history, Arctic ice retreated enough to briefly open two fabled shipping routes: the Atlantic and Pacific Oceans were connected via the Northwest Passage on the Canadian side and the Northern Sea Route on the Russian side. The 2008 summer season closed with 1.74 million square miles of Arctic ice left intact. That’s about 35 percent less than what typically survived the summers in the 1980s and 1990s. In addition, Long’s satellite imaging of the Arctic reveals that the remaining ice is thinner than it used to be.
Open Arctic waters would be good for international shippers and bad for polar bears. And in a campus-wide forum last January, Long explained why it’s of interest to everyone else. The formation of polar ice serves as a pump in the global weather system, Long said. It starts when cold winter winds blow over the poles. As the ocean water freezes, salt gets squeezed out and sinks with cold water to the ocean floor.
“The sinking water is replaced by warmer water drawn from the equator, resulting in global circulation of warm and cool water,” Long said. “This circulation is what keeps the equator from being too hot and the poles from being too cold. It is the key to our current climate.”
Whether in the Arctic or Greenland or elsewhere on the planet, Long’s analyses of scatterometer data lead to the broad conclusions that there is less glacial ice worldwide now than when the scatterometer record started three decades ago—and the rate of melt is accelerating.
Granted, Long’s part of the scientific debate is strictly observational. It’s the job of thousands of other scientists to find the culprit for a changing climate. Yet from his work scanning the globe from the perspective of space, Long has developed the opinion that the planet’s ice is melting at a clip consistent with the theory of human-induced climate change. “It’s very unlikely that 20th century warming can be explained only by natural causes,” Long says.
While some skeptics see conspiracy in the growing scientific consensus regarding global warming, Long’s personal experience in the research world takes him the opposite direction. “People need to appreciate how scientists work,” Long explains. “We’re out to get each other’s throats. A good scientist would love to prove everyone else wrong.”
Long acknowledges that political advocacy related to climate change often gets carried away with worst-case scenarios. Ignoring scientific evidence is a two-way street. “It is truly unfortunate that climate concern has become so politicized over the last few years,” Long says. “This is an issue that should transcend politics. We’re all in this together.”
Joe Hadfield is a media relations manager for BYU’s University Communications.
Taking the Earth’s Temperature
What several BYU professors are learning about climate change.
Who Poked that Hole in the Ozone?
The ozone hole, a seasonal absence of ozone molecules above Antarctica, means fewer ultraviolet rays are absorbed by the ozone layer and more reach the earth’s surface. The 1995 Nobel Prize in chemistry went to three scientists for explaining the ozone depletion. Man-made CFCs, they said, break into chlorine atoms in the stratosphere over Antarctica and then destroy ozone.
But studying chemical reactions in the Antarctic stratosphere is difficult. So BYU chemistry assistant professor Jaron C. Hansen and others simulated those conditions in the lab to test the CFC/ozone theory. In 2007 Hansen and collaborators reported that the effect of CFCs seems to have been overstated. Chlorine atoms cannot completely explain the ozone that vanishes each year. But Hansen isn’t saying the ozone layer is fine. Rather, he says, “we’re saying this is not the only mechanism that describes the ozone hole.”
Problems of Glacial Proportions
In 1998 there was a record global loss of glacial mass. The record has since been broken three times. In the Journal of Climate in 2008, BYU geology assistant professor Summer Burton Rupper (BS ’00) outlined glaciers’ vulnerabilities according to climate zone. Except in the tropics, glaciers are highly sensitive to even small changes in air temperature.
Rupper spent summer 2009 studying Switzerland’s Gorner glacier, which is melting far more quickly than expected. Drilling 15-meter ice cores, Rupper examined the ice to try to understand the glacier’s sensitivity. What she learns may yield more accurate forecasts for glaciers and for the people who depend on them as sources of water.
Is the Sink Full?
If too much carbon dioxide causes global warming, and if plants absorb carbon dioxide, can plants solve the problem? Can plants and soil act like a sink to store extra carbon dioxide?
In Texas grasslands, Richard A. Gill (BS ’93) and others tested the scenario. As expected, plants initially thrived with higher carbon dioxide levels. But the increased plant growth sapped the soil of nutrients. In a study published in Nature in 2002, Gill and his collaborators noted that the sink was nearly full.
“The ability for soils to act as a sink for this extra carbon is limited,” says Gill, now a BYU associate professor of biology. This finding, of course, has bearing on climate predictions. “Forecasting models assume that plants will sequester more carbon,” Gill says. “If we don’t have a carbon sink, we end up with much warmer temperatures.”
A Greener Greenland
Through satellite images of Greenland’s ice, engineering professor David G. Long (BS ’82) has observed that the island’s summer melt zones have been getting larger and larger with time.
Long also detected more snowfall in the north of Greenland, a finding consistent with theories of global warming: a rise in temperatures leads to more ocean evaporation, which leads to more snowstorms. “So we have more melting and more snow accumulation,” Long says, pointing out an interesting question: Which is winning, the snow or the melt? “Careful analysis of the data shows that increased melting is winning.”
Climbing the Mountain
As he studied the ages of Rocky Mountain trees, Matthew F. Bekker (BS ’94) noted that the tree line in high elevations had risen rapidly in the 1900s. “The upper tree line, where trees grade into tundra, should be a temperature sensitive site,” says Bekker, now a BYU assistant professor of geography. “If the temperature goes up, the conditions are more favorable for trees to grow at higher elevations.”
Bekker’s PhD dissertation and subsequent journal articles describe the dynamics of the tree line in Glacier National Park. At the end of the Little Ice Age in the 1700s, trees began climbing higher at a slow, steady pace. Then things took off in the past century—about the same time other scientists suggest human activities began having an influence on a warming climate. “The abrupt change,” Bekker says, “suggests that a temperature threshold has been reached that is now allowing rapid advancement of the tree line.”
Will Warming Lead to Cooling?
For nearly 10,000 years, the amount of carbon dioxide in the lower atmosphere remained near 220 parts per million. Industrialization and large-scale burning of fossil fuels, however, nudged those levels upwards.
Today the carbon dioxide levels are 385 parts per million. Carbon dioxide and other greenhouse gases allow incoming sunlight to pass through but halt a portion of outbound heat because of its longer wavelength.
BYU chemistry assistant professor Jaron C. Hansen is investigating other—possibly helpful—aspects of pollution and warming.
Warmer temperatures mean more evaporation, which means more clouds. The uncertainty is whether those clouds will be thick or thin. Thick, overcast skies keep out sunlight and cool things down overall. High, thin clouds retain more heat than they keep out.
Hansen is also studying the effect of tiny particles of pollution suspended in the air. Though bad for your lungs, those particles could keep light and heat from entering the atmosphere, thus having a cooling effect.
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