Climate of Uncertainty
by Daniel Grossman and John Rudolph

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Introduction

Ira Flatow: From American RadioWorks this is Climate of Uncertainty. I'm Ira Flatow. According to some scientists, global warming could trigger an abrupt change in the earth's climate - bringing frigid winters, massive floods, and hundred year droughts.

Michael Oppenheimer: If the Greenland or West Antarctic Ice sheet were to crumble completely, if that happens my descendants may well be the proud owners of beach-front property in the center of Manhattan.

Flatow: When, or even if, an abrupt climate shift might happen is under debate - but scientists say the probable catalyst is something we can control: carbon dioxide emissions. The key question is, are we willing as a species ultimately to spend a couple percent of global economic productivity over the next century to avoid making major climatic changes throughout the global environment? In the coming hour, Climate of Uncertainty, from American RadioWorks. First, this news update.

Part 1

[Sound of thunderstorm]

Flatow: This is Climate of Uncertainty, an American RadioWorks documentary. I'm Ira Flatow

Most of us have woken up in the night to a deafening clap of thunder and a brilliant stroke of lightening. Though startling, from the comfort of a dry, warm home, these natural sound and light shows are fun to watch and a good dousing for a thirsty earth. But consider - these seemingly ordinary storms might also be a sign of troubling change. Some scientists say global warming is bringing extra rain and snow to northern areas, more or less above the parallel that passes through the middle of the United States. And they say this extra water could disrupt a delicate balance between fresh and salt water in the Atlantic Ocean. They say the change might cripple a massive ocean current known as the Great Conveyor. And if the Great Conveyer stopped, it could cause catastrophic climate changes like sudden cooling in some areas and devastating droughts in others. Today we try to shed some light on this "climate of uncertainty". Later in the hour, we'll hear about what might be done to reduce the chance of this kind of climate catastrophe. But first, Daniel Grossman explains why scientists are worried about the Great Conveyor.

[Thunderstorm continues. Walking down steps and street. Sound of running water going into sewer]

Dan Grossman: Rivulets of rainwater run off the roofs of this tidy neighborhood in the suburbs of Boston. The water flows down the driveways and across the street and disappears into a storm drain. And from there, it's flushed into the Atlantic Ocean. This rainwater, combined with water from melting glaciers far north of here may be diluting the Atlantic, making it less salty, or fresher. It seems far-fetched, but some scientists say the foundation of civilization itself could by influenced by these drops.

And scientists say all of us, including the producers of this show and all the listeners, are responsible. It all has to do with global warming, caused by the carbon dioxide produced when fossil fuels like oil or coal are burned, for instance, to make electricity. NASA climate expert James Hansen says Americans produce more of this gas than the people of any other country. And it's piling up.

James Hansen: Carbon dioxide has increased from about 280 parts per million that existed 150 years ago to about 370 right now.

Grossman: That's a 30 percent increase. One way to see how that gas and several others are warming things up is to hop into a car. The storm has passed now and the sun has come out.

[sound of car door opening, getting in car and closing door]

Grossman: Geez. It's hot in here. Why? Because sunlight is pouring in the windows and is beating down on the dark seats. These hot surfaces slowly release the energy they absorb, heating the air in here. But the heat can't escape through the windows, which act like an insulating blanket. The greenhouse effect works much the same way. Gasses like carbon dioxide in the atmosphere are like the car's windows, letting sunlight come in, but keeping heat from going out to space. In moderation, this insulation is good. It helps make Earth warm enough for life. The problem is humans are creating more and more insulation by using fuels like the gasoline in this car. Scientist James Hansen compares the warming caused by humans to the amount of heat produced by the tiny bulbs hung on Christmas trees.

Hansen: So it's equivalent to having two of the tiny Christmas tree bulbs over each square meter of the Earth's surface.

Grossman: Multiply that by the Earth's huge surface area, 150 trillion square meters, and that's the amount of energy produced by a million nuclear power plants. And ever so slowly, that has heated the planet.

Hansen: Temperature on the average is indeed rising. It's increased about 3/4 of a degree Celsius, which is more than one degree Fahrenheit over the last century.

Grossman: One degree Fahrenheit might not sound like much because we're used to daily temperature changes of 10 or more degrees between when we get up in the morning and lunch. But James Hansen says averaged over the entire globe, one degree is significant. Hansen shook up the world one hot summer day in 1988 when he told a congressional committee that humans were warming Earth. His was a minority opinion then. It's scientific consensus now. And over the years, evidence has accumulated that this warming is having an impact. The most obvious changes are taking place at Earth's poles, which have warmed the most. For instance, winter temperatures on the Antarctic Peninsula have climbed an alarming 10 degrees Fahrenheit in the last 50 years. One researcher says this warming will cause Adelie Penguins to disappear from that part of the southern continent within a decade.

[snowmobile passing by]

Grossman: And in the Arctic, the ice cap over the Arctic Ocean has lost 40 percent of its volume in 30 years.

[Distant sound of town and dogs. Louder dog sounds around Steger intro.]

Grossman: Twelve hundred miles below the North Pole, the town of Iglulik is among the northern-most inhabited lands on Earth. The tiny hamlet forms a crescent of pale-colored homes along one shore of a rocky island. Snow mobiles are parked in front of every house. There's plenty of snow and the sea is frozen solid - even in mid-May. Adventurer Will Steger just arrived here by dog sled. With three teams of huskies to pull his baggage, he walked and skied half way across Canada through more than two months of total Arctic darkness and months of temperatures of 30 degrees below zero or lower. Though a slight man with hunched shoulders, Steger is legendary for his polar exploits. He's walked across both the South and the North Poles and discovered first-hand the impact of global warming.

Will Steger: We traveled 12 years ago across the Larson Ice Shelf in Antarctica. It was 300 miles long at that time. That entire ice shelf now is in the ocean. We based an expedition in the Arctic on the Ward-Hunt Ice Shelf, when we went to the North Pole. That is the largest ice shelf in the Arctic. And that has slipped into the ocean.

Grossman: On his travels, Steger is collecting impressions of Inuit hunters and elders about climate change in the Arctic. He makes a stop at the home of hunter Theo Ikummag. Ikummag says the weather has become more variable and harder to predict. Snowfields that previously were permanent now completely melt by late summer. Their sweet melt-water is no longer available to quench the thirst of Inuit and caribou. The 50-year old hunter says he's also noticed changes in wildlife.

Theo Ikummag: Talking to my older brother. He was, like I said 21 years older. As a child he said, the closest ground squirrel that they could find as a child was 70, 75 miles south. Now they are all over the place. Even on the island itself.

Grossman: Ikummag tells Steger that, like the ground squirrel, foxes, wolverines, birds even lake trout are moving north.

Ikummag: So all these animals are migrating north. They're reaching further north every year, is what we're finding.

Steger: Would that a good thing for your culture?

Ikummag: It might be good for the culture but might be chaotic for the wildlife as well. They need a certain equilibrium in order to survive.

[Inuit Music]

Grossman: Changes like these won't notably alter the lives of these people at the top of the world. But they could be prelude to more serious problems. NASA scientist James Hansen says the two tiny light bulbs worth of heat that humans have added to each square meter of Earth's surface has brought the planet to the brink of a completely new chapter of climate history.

Hansen: We're becoming as warm as it has been in the last million years, and soon it will be warmer than it has been in the last million years. So we're really going into territory that hasn't been charted for a long time.

Grossman: For the last million years, the Earth has alternated between ice ages, which last about 80,000 years and warm periods, called interglacials, which are much shorter. We're currently about 11,000 years into an interglacial. We probably should be sliding toward the next ice age. Instead it's getting warmer.

[Sound of wind in Greenland]

Grossman: Heinz Miller is an expert on glaciers, a glaciologist. He says in order to figure out what happens next, scientists study what happened before.

Miller: And in order to understand this, we have to look at very many different stages of climate.

Grossman: Miller is a professor at Germany's Alfred Wegner Institute. At a base camp on Greenland's windswept ice sheet, he says researchers have only measured the climate systematically with precise scientific instruments like thermometers for about 150 years. Those measurements represent only a fleeting snapshot of Earth's past. However researchers have other ways to gauge climate further back in time.

Miller: And we find those, for instance, in sediments of the deep sea and we find them in tree rings or we find them lake sediments.

Grossman: Tree rings, for instance, tend to be thicker in wetter years. Lake sediments store pollen that shows what plants were growing. Cave stalactites hold evidence of past temperatures in fine rock layers. Cylinders, or cores, of glacier-ice contain climate records trapped in frozen water molecules.

Miller: Ice cores are a very special climate archive, because they will tell us about past temperatures and at the same time they will tell us about atmospheric composition.

Grossman: Glacier cores give scientists some of the most detailed pictures of past changes in climate because researchers can distinguish annual layers of ice like tree rings and count tens of thousands of years back in time.

[Sound of exterior with plane taxiing]

Grossman: The absolute best place in the world to get a detailed record of what the climate has been doing for at least the last 140,000 years is the middle of Greenland on a massive glacier nearly two miles thick and about the size of the United States east of the Mississippi river.

Grossman: A team of European scientists, flown in by military transport planes, has set up a base here. Blindingly white ice and snow stretch for hundreds of miles in all directions.

[Sound of winch lowering cable. The whole Greenland section has a sound bed of sounds in the drilling area]

The researchers hope to drill a core containing ice tens-of-thousands of years older than any previous ice core sampled in the northern hemisphere. They're at work in a cavern they dug just below the surface.

Jensen: Thorsteinn, how deep are we now?

Thorsteinsen: 3,083 meters - 83.5.meters.

Grossman: Chief scientist Dorthe Dahl Jensen and driller Thorsteinn Thorsteinsen are lowering the core drill by a slender cable of steel wound on a spool the size of a trash can.

Jensen: We're getting there. It can't be more than two days of drilling left.

Grossman: Imagine the ice sheet is a two-mile thick chocolate layer cake. The drill, a motorized cookie cutter. The scientists cut out core samples about one meter, or one yard, long at a time Then the device is hoisted to the surface and the sample is removed.

[Sounds of removing core and Dahl Jensen talking]

Grossman: And the drill returned to the hole. It's taken seven years for the European teams to get a taste of the very bottom layers.

Jensen: Ice from the last 100 meters is ice that is 130 to 115 thousand years old. It is ice from a climate period when the climate was slightly warmer than our present climate. We call it the Eemian period.

Grossman: These are the only good samples from the Eemian period ever collected in the northern hemisphere. Danish glaciologist Sigfus Johnsen says the chunks of frozen water contain critical clues to our future. Johnsen is a professor at the University of Copenhagen.

Johnsen: Our aim here was to look at the last warm period. How did it end? If we are disturbing our climate - and we're doing that, with pollution, with CO₂ - we need to understand how a warm period is actually ending without that disturbance in order to better predict how our own warm period is going to end.

Grossman: It will take some time before researchers can use the new Greenland core to make better predictions about how our own warm period will end. But previous cores drilled in Greenland contain ominous hints that the closing act might have a surprise ending. Scientists have discovered that in the past, climate has at times, responded with alarming abruptness to gradual changes in natural factors like fluctuations in the sun. Some researchers say the gradual heating caused by increased carbon dioxide could have a similar sudden impact.

Flatow: I'm Ira Flatow. You are listening to Climate of Uncertainty from American RadioWorks. Coming up in a moment, surprises in the ice cores.

Alley: So you would see this pretty green line on his computer display going weo weo weo. And he's been doing this for a mile. Going weo weo weo. And he came to ice that was completely different. It was almost as if he had gone over a cliff. He's going weo weo weo. BOOM.

Flatow: Our program continues in just a moment from American Public Media.

Part 2

Flatow: This is Climate of Uncertainty, a documentary from American RadioWorks. I'm Ira Flatow. We've just seen how scientists drill ice cores to learn about Earth's past. Now - what they've learned from earlier ice cores and why that makes some scientists worried that the climate may undergo sudden abrupt changes. Daniel Grossman continues his report.

[Under host we hear door opening and fade up freezer.]

Mayewski: There are ice cores in here from all over the world. Greenland, Devon Island, all over Antarctica, New Zealand.

Grossman: In a one-story building at the University of Maine in Orono, there's a walk-in freezer for keeping ice cores like those just drilled in Greenland. They're stored in cardboard mailing tubes stacked neatly on shiny steel shelves. There's nearly a mile of ice here, most of it collected by Glaciologist Paul Mayewski. Gingerly taking one of the plastic-wrapped cylinders off the shelf, the researcher says scientists need samples from all over the world for the same reason that meteorologists need lots of thermometers: because climate is complicated and varies greatly over time and space.

Grossman: Mayewski

Grossman: So somewhere in these records there's the piece of ice that was formed when the constitution was signed, when Jesus was born

Mayewski: Absolutely. When the Spanish Armada tried to invade Britain.

Grossman: In the late 1980s and early 1990s, Mayewski led a U.S. coring team in Greenland. Scientists studying that core made a discovery that changed the way they look at Earth's climate.

Mayewski: And what we discovered in that record was what had been hinted to, but that we were able to demonstrate unequivocally. And that is that there are response to climate change that can be extremely abrupt.

Grossman: The ice cores showed that more than a dozen times during and just after the last ice age, temperatures in Greenland changed suddenly by up to 18 degrees Fahrenheit. That's like jumping between Florida and Boston. Scientists have since dubbed events like these that occur in about a decade or less abrupt climate changes. Penn State University professor Richard Alley was on the ice sheet with colleague Ken Taylor when the team got the first definitive evidence of these dramatic incidents.

Alley: And he had been going very slowly measuring small changes that were related to the seasons. So you would see this pretty green line on his computer display going weo weo weo. And he's been doing this for a mile. Going weo weo weo. And he came to ice that was completely different. It was almost as if he had gone over a cliff. He's going weo weo weo. BOOM.

Grossman: They realized they were staring at the science equivalent of a smoking gun, proving that huge and dramatic changes had taken place in the climate of Greenland. Later they learned that the event wasn't some local anomaly but a humungous climate earthquake with tremors that reverberated around the world.

Alley: So you find the events recorded in how much the wind was affecting the ocean off of Arabia. Or how much plants were growing in the surface waters off of Venezuela. And in fact many of these events show up in Antarctic ice cores as well. So it is very clear that this is not a Greenland story. This is a lot of the world story.

Grossman: And the story includes not only changes in temperature but also a complete overhaul of weather patterns. It's hard to predict how an abrupt change like this would affect us today. No society has ever experienced these extraordinary events. All the ones discovered so far occurred during the last ice age or soon after it ended 11,000 years ago, way before civilization began. It's probably just as well. Because some scientists say less dramatic incidents decimated some of the most sophisticated civilizations of the past.

[Fade up music]

Grossman: 4,300 years ago Mesopotamia was ruled by King Sargon - architect of the world's first great empire: Akkad. The kingdom stretched from what is now northeastern Syria and northern Iraq to the Persian Gulf.

Weiss: This was a kingdom whose merchants traveled at will across the expanse of the Near East.

Grossman: Archeologist Harvey Weiss of Yale University has been excavating a northern outpost of the once-great empire for 25 years.

Weiss: In one of the famous descriptions of the empire, it is said that ships from far away across the Indus Valley brought their exotic materials to the harbor side of Akkad.

Grossman: The civilization blossomed for a century. Then something terrible happened.

Weiss: As astounding as its sophistication is its sudden demise.

Grossman: Approximately 4,200 years ago, the Akkadian empire vanished, an event known as the Akkadian collapse, leaving only a three-foot layer of dust and sand.

Reader: "The large fields produced no grain / the flooded fields produced no fish / the watered garden produced no honey and wine."

Grossman: The Curse of Akkad, an epic poem written down on cuneiform tablets about 100 years after the Akkadian collapse appears to describe drought-induced famine.

Reader: "He who slept in the house, had no burial / People were flailing at themselves from hunger."

Weiss: Most of the people who studied these documents considered this to be poetic metaphor.

Grossman: A maverick among archeologists, Weiss says the explanation is simpler.

Weiss: We in fact know that those were in fact the real world conditions out there.

Grossman: He knows because Columbia University professor Peter deMenocal has studied the climate of Mesopotamia. DeMenocal examined sea sediment in the Gulf of Oman.

deMenocal: All of the sudden at about 4,200 years, something we can date very precisely, there is a very large and short-lived spike in the abundance of mineral dust that is actually transported from Mesopotamia. It was about a 300-year period of intensely drier conditions. It occurred at the same time as the societal collapse.

Grossman: This was not just a dry spell. This was a 300-year drought. Societies all the way from present day Crete to India toppled. Even the Old Egyptian Kingdom, the society that built the great pyramids, crumbled. Peter deMenocal says big droughts at other times felled other societies, including the Yucatan's Mayan civilization about 1,200 years ago.

deMenocal: Each one of these is a very good lesson for us. A lesson in humility. We are not above this.

[Music ends]

Grossman: A similar drought today would be catastrophic, says the scientist. And he says although researchers aren't certain exactly how these past droughts were caused, there is some reason to believe humans might trigger one. Think back to the massive abrupt incidents noticed in Greenland. Before they were discovered, scientists believed that Earth's climate always changed gradually as if controlled by the dial of a global thermostat. Professor Richard Alley says the Greenland events made scientists realize that climate sometimes it behaves like its controlled instead by a switch.

Alley: And a switch you push on it a little and nothing happens. But if you push on it a little more and boom something's changed. And what the ice cores in Greenland forced us to believe is that the climate has switches as well as dials.

Grossman: If you want know how these switches work, you need to talk to Columbia University professor Wally Broecker. Broecker has come up with a theory that has gained widespread scientific acceptance.

[Wally Broecker's office. We hear squeak of white board being drawn on.]

Grossman: You got North America there?

Broecker: Uhuh. There's North America.

Grossman: Uhuh.

Broecker: There's good old South America. There's the Antarctic Peninsula.

Grossman: In a spacious office at Columbia's Lamont Doherety Earth Observatory north of New York City, Broecker leans over a white board. His thinning gray hair appears tussled by high winds. He's making a series of lines and arrows on a map he's drawn of the Earth.

Broecker: It starts out here in the South Atlantic. Goes through the Caribbean. Swings around Florida where it becomes the Gulf Stream that we know and love.

Grossman: Broecker is sketching the path of an ocean current that flows with the strength of 150 Amazon Rivers he's dubbed the Great Ocean Conveyor Belt. It includes the Gulf Stream along the east cost of the U.S.. At Cape Hatteras it veers toward the north Atlantic.

Broecker: And some of the water goes up into the Norwegian and Greenland sea, keeping that region of the ocean unusually warm because heat is being pumped up there all the time.

Grossman: Tropical heat from the Great Conveyor warms western Europe, which is in part why the English tend gardens at the same latitude Canadian Inuit build igloos. Two things happen as the conveyor approaches the north Atlantic, both of which cause its waters to become denser or less bouyant. First, as the conveyor gives off heat, its waters become cooler. And cooler water is denser. Second, the conveyor's water becomes saltier, because fresh water evaporates on the odyssey from the equator. Saltier water is also denser. Between Iceland and Norway, the now very dense conveyor sinks below surrounding lighter waters. Like the piston of a pump, this downward flow pushes the current on its circuitous path around the globe. The conveyor's water flows south along the ocean floor and into the Pacific where it warms up and returns to the surface. Then it begins the long trip back. Wally Broecker has proposed that changes in the Great Conveyor altered the North Atlantic's climate and caused Greenland's abrupt events.

Broecker: This conveyor was essentially turning on and off, so all that heat no longer came up there and we think during glacial time that allowed the surface ocean to freeze over.

Grossman: Broecker's theory is now the leading explanation for these abrupt changes. It explains, for example why Europe, which is warmed by the Conveyor, cooled dramatically about 8,000 years ago. However, scientists are still uncertain how the shutdown reverberated worldwide. How eastern China and India and Mesopotamia where the Akkadians lived became drier. How a rain belt near Venezuela moved. How wind patterns off California changed. Nevertheless Broecker says after years of research, scientists do know what caused the conveyor to shut off.

Broecker: One of the triggers that caused the conveyor to go off was the sudden release of a lot of fresh water.

Grossman: Remember that salt water is denser than fresh water. If a lot of fresh water was mixed into the north Atlantic, the current would be too buoyant to sink, jamming the conveyor's piston. Researchers have discovered that at least three times in the past, that's exactly what happened. These incidents appear to be related to minute fluctuations in sunlight. The last such event occurred 8,200 years ago, a couple of thousand years after the last ice age ended. Glaciologist Richard Alley has studied the incident.

Alley: The great ice sheet in Canada was really melting away. It was melting back toward Hudson Bay. And it had ponded around it an immense lake. And it is reasonably clear that that lake drained maybe in a summer. So you're taking maybe the biggest lake on Earth and putting it into the Atlantic in a summer.

Grossman: Today, there's no such water poised to flood the North Atlantic. But Broecker says global warming has created a new mechanism that might flip the conveyor's off switch.

Broecker: As climate warms due to the steady creeping warmth more water will evaporate in the warm parts of the planet. And hence more of that water will get to the high latitudes. And the extra rain and snow in the regions around the north Atlantic will add enough fresh water to kill the conveyor.

[Fade up ocean sounds at Woods Hole]

Grossman: There's some evidence that extra rain has already begun. Rainfall in mid- and high-northern latitudes increased by about 10 percent in the 20th century. Ruth Curry, a scientist at the Woods Hole Oceanographic Institute in Falmouth, Massachusetts, says she has evidence this and other recent climate changes are having an impact. Curry is sitting on a dock next to the research vessel Oceanus as workers ready it for sea.

Curry: The upper ocean salinities in the tropics and subtropics of the Atlantic have been getting saltier and the waters at the higher latitudes have been getting fresher.

Grossman: In the scientific journal Nature, Curry wrote that these changes have been going on for 40 years and began to speed up in the 1990s. They're exactly the sort of changes Broecker fears could cause the Conveyor, also called the thermohaline circulation, to shut off. Curry says there hasn't been any notable impact on the conveyor so far. But it is worrisome.

Curry: Preconditioning is taking place. All of the steps that are required to alter the thermohaline circulation are in fact taking place.

Grossman: Some scientists say global warming's extra precipitation is enough to complete the triggering process. Ruth Curry thinks it might take something more dramatic, like a big piece of Greenland's ice sheet breaking off - a process some experts say might happen within the next century.

[fade out dock and ocean sounds]

Grossman: Above professor Wally Broecker's desk is a large plush stuffed snake with a sign on it that says "Angry Beast." It refers to the researcher's view that climate sometimes responds ferociously to the slightest provocation.

Broecker: And I say that by adding CO₂ to the atmosphere we're poking it.

Grossman: And if poking the angry beast causes the Great Conveyor to shut down, Europe would almost certainly get cooler again. Wally Broecker says the most serious consequence could be long deep droughts, like the one that destroyed the Akkadian empire. He says he doesn't expect the beast to get angry in less than several decades. By then global warming will probably have made the north Atlantic too warm to freeze over as it did in the past. So the impact won't be the same as in previous incidents. Still,

Broecker: You don't want the conveyor to stop and then find out what its effects are. That's probably the only way we'll really find out is to do it. And if you do, it's sort of irreversible. You're not going to make it turn on artificially. It'll turn on when it's ready. That might be 50 years. It might be a couple hundred years.

Grossman: Scientists are united in agreement that huge, abrupt climate changes have occurred, and most likely will occur again. There's also widespread agreement that global warming could bring one on. However nobody can predict the likelihood. Which leads to differences about whether the threat is urgent. Thomas Stocker at the University of Bern in Switzerland is in the "urgency" camp. Based on a computer simulation he ran of the impact of global warming he says:

Stocker: A complete shutdown of the thermohaline circulation cannot be excluded if the warming persists long enough and strong enough.

Grossman: Stocker says a complete shutdown is unlikely until the next century. But he says a slowdown of the conveyor, which could also have big impacts, is possible much sooner. Climate scientist Andrew Weaver is one of the most vocal scientists in the "not urgent" camp. A professor at the University of Victoria in British Columbia, Weaver published a paper in the journal Science questioning whether changes in precipitation and evaporation, also called the hydrological cycle, could harm the Great Conveyor.

Weaver: I cannot see a mechanism that would bring the amount of fresh water required to actually cause it to collapse. Because increased hydrological cycle because of climate change and global warming doesn't cut it as far as I'm concerned.

Grossman: The huge floods that caused some of the past shutdowns were dozens of times bigger than the amount of water that global warming could add to the north Atlantic argues Weaver. He says Stocker's simulations and others like them are flawed. He accuses his colleagues of exaggeration.

Weaver: The one thing I cannot stand is fear mongering to try to get people to change and to take action.

Grossman: Columbia University's Wally Broecker agrees that computer simulations showing a shutdown are inadequate. And he agrees that global warming will not cause a repeat of the past. So is the threat urgent or not? Broecker says the stakes are too high to ignore the possibility, however slight, that humans might trigger an abrupt change.

Broecker: Unfortunately the world is going to have to make a very important decision on the basis of inadequate data. All we can say is that in the past the earth has done incredibly crazy things all on its own.

Grossman: Meanwhile, the amount of carbon dioxide in the air continues to grow. Last year it made the second biggest leap since systematic measurements began in the 1960s. So the gradual warming, and the risk of a dramatic, abrupt change, continues to grow. For American Radio Works, I'm Daniel Grossman.

Flatow: I'm Ira Flatow. You're listening to Climate of Uncertainty. Many climate researchers say the world should immediately begin to reduce the amount of carbon dioxide produced by burning fossil fuels and capture the rest before it goes into the air. Coming up next, combating global warming:

Lackner: Clearly it is possible today, with today's technology to take carbon dioxide and put it underground and make a reasonable claim that it will stay there for a very, very long time

Flatow: Major funding for American RadioWorks comes from the Corporation for Public Broadcasting. To see a slideshow of the ice core drilling process, and illustrations of the Great Ocean Conveyor, visit us online at AmericanRadioWorks.org. You'll also find information on ordering a CD of this program. That's all at AmericanRadioWorks.org. Our program continues in just a moment, from American RadioWorks, the documentary unit of American Public Media.

Part 3

Flatow: This is Climate of Uncertainty, an American RadioWorks special. I'm Ira Flatow.

As climatologist Wally Broeker points out, the science of abrupt climate change is evolving, and the information we have is incomplete. But while there are many things that scientists still don't know, there is a growing sense in the scientific community and among some policy makers that we need to begin taking steps now to avoid catastrophic changes that may occur in the future.

Scientists are already working on measures that would drastically reduce emissions of carbon dioxide and other greenhouse gasses. And as John Rudolph reports, the public is just starting to consider the cost of those solutions and the potential consequences of doing nothing.

[movie sound]

Rudolph: The Hollywood thriller The Day After Tomorrow has introduced movie audiences around the world to the idea of abrupt climate change. In the film, a sudden new ice age caused by global warming leads to massive destruction. Much of the film is set in New York City, which is hit by a tidal wave, and then becomes encased in a thick layer of ice.

[movie sound]

Rudolph: When the film opened, a group of climate scientists and political leaders, including former Vice President Al Gore, held a public forum in New York to warn about the potential consequences of abrupt climate change. They agreed that these changes would not happen anytime soon or as fast as the film suggests. But Princeton University's Dr. Michael Oppenheimer said even on a slower timetable the effects could be devastating.

Oppenheimer: I live in the middle of Greenwich Village in the middle of the lower part of the island. If the Greenland or West Antarctic Ice Sheet were to crumble completely, which is a plausible outcome for subsequent centuries, if that happens, my descendants may well be the proud owners of beach-front property in the center of Manhattan.

Rudolph: In some parts of the federal government, concern is growing over the possibility of sudden destructive changes to the world's climate. Peter Schwartz recently wrote a report for the Pentagon warning that abrupt climate change could lead to regional emergencies.

Schwartz: We will see a number of refugee crises and humanitarian crises around the world where the U.S. might be called in to intervene and help manage the crisis.

Rudolph: Schwartz's Pentagon report predicts rising international tensions over climate-related shortages of food, water and energy. Even if the Great Conveyor of the Atlantic current never shuts down, scientists believe the world may still have to contend with extreme climate change. The answer to this challenge, they say, is to make major reductions in greenhouse gas emissions.

In some places this is already starting to happen.

[car sounds]

Rudolph: We're driving across the plains of the Canadian Midwest to the Weyburn oil field. Our guide is Mike Monea, an oilman-turned environmentalist. He heads the Petroleum Technology Research Centre at the University of Regina in Saskatchewan.

Monea: They have a joke here that you can watch your dog run away here for three days, it's so flat. It's all beautiful wheat fields. We'll be coming up on our oil field very shortly, and there are literally tens of thousands of wells that'll be in the oil field.

Rudolph: Before he came to work at the university, Mike Monea ran his own oil company. In those days, he barely thought about global warming. But since entering academia less than two years ago, Monea has become a believer. Abrupt climate change, he says, is a threat.

Monea: Probably my turning point was seeing data on ice core samples in the last 100 years. When you start looking at the statistics on the melting of some of our arctic ice, and the impact that fresh water is going to have on, say, the circulation of oceans it's huge. That really got my attention.

Rudolph: Driving around Weyburn, you see hundreds of pump jacks slowly bobbing up and down as they suck black crude out of the ground. And as the oil comes out, carbon dioxide is being pumped in. At Weyburn, millions of tons of carbon dioxide have been liquefied and then injected into the oil wells. The CO₂ is literally being buried underground where it can't contribute to global warming.

[door shuts]

Craigen: Normally what we'll do is follow the flow of oil.

Rudolph: Dave Craigen works for Encana Corporation, the company that owns the sprawling 70-square-mile oil field. They've been producing oil here since 1954, which makes Weyburn a very old oil field. But you can extend the life of old oil wells by pumping them full of liquefied carbon dioxide. CO₂ increases the pressure in underground oil reservoirs. It also acts as a solvent, thinning the crude and making it easier to bring to the surface.

Craigen: The CO₂ project will extend the life of this field by 25 to 30 years.

Rudolph: This method's been used in West Texas for a couple of decades. In Texas any CO₂ that comes up with the oil is usually allowed to escape into the atmosphere.

But at Weyburn, carbon dioxide that rises to the surface is captured at the well-head. It's then reinjected to help extract more oil.

Unlike the U.S., Canada has a national policy to reduce greenhouse gas emissions, and Weyburn represents one small step toward meeting that goal.

Craigen: It's almost as if there are two projects. There's enhanced oil recovery, or EOR, and that's what the oil industry's interested in. And then there's the geological sequestering of a greenhouse gas, which is what the science community is interested in.

Rudolph: Scientists carefully monitor the Weyburn site. They are eager to prove that CO₂ can be safely and permanently stored beneath the earth's surface.

Research shows that about 80 percent of the carbon dioxide injected into oil reservoirs stays underground. Some of it clings to subterranean rocks, and some dissolves into the oil. Eventually, when the oil field is shut down, the wells will be sealed, providing storage for all the CO₂ used at Weyburn.

Encana purchases its CO₂ from an industrial plant in neighboring North Dakota. The U.S. government funded the plant after the 1970s energy crisis to convert coal into natural gas.

One of the main byproducts of coal gasification is carbon dioxide. Now, instead of venting the CO₂ into the atmosphere, a lot of that waste gas is captured and shipped to Weyburn through a special pipeline.

Craigen: This is what we call the inlet header. This is line from Beulah, North Dakota that comes up with the 95-million cubic feet of gas.

Rudolph: It seems odd that a method to avert the extreme effects of climate change would be found in an oil field. But many scientists believe carbon sequestration, which is also called carbon capture and storage, could be an important tool in this effort.

Physicist Klaus Lackner works in a beige, spartan office at Columbia University in New York City. Lackner has been trying to find environmentally acceptable ways to use carbon-based fuels, especially coal. He believes the potential for carbon sequestration is huge.

Lackner: Clearly it is possible today, with today's technology to take carbon dioxide and put it underground and make a reasonable claim that it will stay there for a very, very long time.

Rudolph: It's estimated that about 15 percent of U.S. carbon emissions could be captured and stored over the next few decades. That would be significant since the U.S. produces one quarter of the world's greenhouse gasses. Lackner likes to equate the world's output of CO₂ to a great body of water. And he points out, it's going to take a lot more than one oil field to store all of it.

Lackner: In terms of liquid, the total CO₂ we will put out in this century is on the order of one Lake Michigan. So that sets the scale and these are just starting points.

Rudolph: Lackner believes changes need to occur immediately in the way carbon dioxide is disposed of, and the way energy is used. Those changes may come from research being conducted at a facility in southern Saskatchewan.

[sound inside lab]

Wilson: This is the most complete laboratory of its kind anywhere in the world.

Rudolph: Malcolm Wilson runs the office of energy and environment at the University of Regina. Inside a building that looks like an airplane hanger, scientists conduct tests on a working model of a power plant smoke stack. Their goal is to develop an inexpensive method for removing carbon dioxide from power plant emissions. Economics and technology go hand-in-hand in the effort to cut emissions of greenhouse gasses.

Wilson: What we need to do is really figure out what the economic benefits of avoiding climate change really are, so that we can start to set a real value on CO₂ that we prevent from release to the atmosphere.

Rudolph: This idea of putting a price on carbon, so you know how much money you are saving by not releasing it into the atmosphere, may be just as important as technological advances like carbon capture and storage. There is broad agreement that if the right economic incentives are put in place the technology will quickly follow. But where to focus those incentives? There are several competing strategies for curbing emissions.

Hawkins: Efficiency, renewable energy, and carbon capture and storage.

Rudolph: David Hawkins directs the climate change program at the Natural Resources Defense Council in Washington DC. Energy efficiency is at the top of his list.

Hawkins: As the world grows, the smarter we are about using energy, the more economic well being we can support without having to either strip a lot of fossil fuels off the landscape or occupy a lot of the landscape with windmills or solar panels. And so there's always gonna be an advantage for efficiency.

Rudolph: Yes, efficiency is important, says David Keith, a climate researcher at the University of Calgary in Alberta, Canada. But Keith points out that even when efficient methods are available, people don't always use them. Gas-guzzling Hummers still sell when gas prices reach record levels. What excites Keith is new technology. A number of emission reduction technologies are already in use - solar energy, hydro-power, planting trees and crops to absorb carbon dioxide - and one of Keith's favorites: wind energy.

Keith: Wind power is just raring to go. The rate is going up like a rocket, and there are enormous amounts of companies who are eager to supply wind power.

Rudolph: Wind supplies 20 percent of Denmark's electricity, 6 percent of Germany's power and 4 percent of Spain's. In the U.S., less than one percent of the nation's electricity comes from wind power. But some states - including California, Texas and Minnesota - are aggressively developing their wind resources.

[sound of Buffalo Ridge windmill in background]

Rudolph: In a windy corner of Minnesota known as Buffalo Ridge, you can get an idea of the impact wind energy could have on reducing greenhouse gas emissions. More than 400 modern windmills have been built in this part of the state. The towering white structures look like huge dinosaurs looming over the landscape.

[ambiance of Steve and Jane talking in their barn]

Rudolph: Steve and Jane Tiedeman farm 1,000 acres of soybeans and corn in Woodstock, Minnesota. Recently they installed two high-tech windmills that can generate enough electricity to serve about 500 homes. They earn a third of their income from the sale of wind power.

Steve Tiedeman: We get some real windy days, and people are cussing about it, and I can't say nothin'. (laughs)

Rudolph: Minnesota hopes to get 10 percent of its power from wind and other alternative sources by the middle of the next decade. But meeting that target is not likely to eliminate the need for new conventional power plants. The pace of implementation of wind energy and other methods to reduce carbon dioxide emissions worries David Hawkins of the Natural Resources Defense Council.

Hawkins: If we put a billion dollars today into a new coal-fired power plant that is designed with old fashioned technology, that power plant is going to be around for 50, 60, 70 years, and it's going to be putting carbon dioxide - global warming pollution - into the atmosphere for its entire lifetime, and the carbon dioxide is going to stay up in the atmosphere for hundreds of years.

Rudolph: Some scientists argue that carbon dioxide in the atmosphere eventually needs to be reduced to levels that existed before the industrial revolution.

In the future, hydrogen fuel cells could help reach this goal. So could building new nuclear power plants or a breakthrough in solar energy technology. The answer will probably come from a variety of approaches. But the first step, according to Canadian climate researcher David Keith, is to reach a consensus on the threat posed by climate change, and what we are willing to spend to reduce that threat.

Keith: The key question is, are we willing as a species ultimately to spend a couple percent of global economic productivity over the next century to avoid making major climatic changes that lead to really quite substantial changes and extinctions and so on throughout the global environment? And I think when you put it to people in that terms, most people are willing to pay.

Rudolph: If we want to eventually halt human activities that cause harmful changes to the world's climate - we can do it. Much of the technology exists, and new methods are being developed. What's harder is deciding if the risk is worth the effort and the cost. Is the threat of climate change, either gradual or abrupt, serious enough to take action on a global scale?

For American RadioWorks, I'm John Rudolph.

Flatow: We know that greenhouse gasses from human activities are being released into the atmosphere and that the world is getting warmer. But no one can predict with certainty the impact this warming will have on different regions of the world. Some places may get wetter, others could experience prolonged droughts. We also don't know if warming will lead to an abrupt shut down of ocean currents, and a dramatic cooling in some parts of the world.

Many believe the most important thing is to improve our methods for predicting climate change so we have a better idea of how severe future changes may be. But there is also a growing consensus among scientists that we must examine the imperfect information available to us now and use it to make some tough decisions. Preparing for abrupt climate change would be like taking out an insurance policy, start paying today to plan for the worst, and hope it never happens.

Climate of Uncertainty was produced by Daniel Grossman and John Rudolph. It was edited by Loretta Williams with Deborah George. The executive editor is Stephen Smith. The executive producer is Bill Buzenberg. I'm Ira Flatow.

To see photographs from Climate of Uncertainty and learn more about climate change, visit our Web site at AmericanRadioWorks.org. You can also sign up for our email newsletter and find out how to order a CD of this program.

Major funding for American RadioWorks comes from the Corporation for Public Broadcasting.

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