In the 70s, They said there’d be an Ice Age

Everyone has a favorite decade, and for Climate deniers, that decade has got to be, the 70s. Yes, the decade of disco, kung fu, and watergate. I shall resign the presidency effective at noon tomorrow… Because in the 70's, deniers will tell you, all climate scientists believed an ice age was coming. Those crazy climate scientists! Why can't they make up their minds? But is that really true? The first calculations relating CO2 emissions to climate change were done by Svante Arrhenius in the early 20th century. [Correction: The year was 1898] His ideas received some attention, but were largely ignored for many decades. With the advent of the cold war, the US military poured money into sophisticated research using new instruments and computers to investigate radiative transfer at high altitudes helping create a new generation of heat seeking missiles. By the early 1950s, the issues were well resolved, and Popular Mechanics noted that the essentials of the CO2 greenhouse warming were now understood. Gilbert Plass, of Johns Hopkins University, was a leader in this effort, having used newly available computers and technology to show that adding more CO2 to the atmosphere did indeed soak up and radiate more heat. In 1957, the international Geophysical year brought modern technology to bear world wide on issues of weather and climate.

By 1958, Americans learned about the greenhouse effect from the all knowing and avuncular character of Dr Frank Baxter, in this Bell Telephone Science hour, directed by Frank Capra. Even now man may be unwittingly changing the world's climate through the waste products of the civilisation. Due to our release through factories and automobiles every year of more than six billion tons of carbon dioxide which helps air absorb heat from the Sun. Our atmosphere seems to be getting warmer. This is bad? Well, it's been calculated that few degrees rise in Earth temperature would melt the polar ice caps. And if this happens an inland sea would fill a good portion of Missisippi walley. Tourists from glass bottom boats would be viewing the drowned towers of Miami through 150 feet of tropical water.

For in weather we're not only dealing with forces of a far greater variety, than even the atomic physicist encounters, but with life itself. By the 1960s, the importance of a presidential scientific advisory panel became clear. President Johnson's Science Advisory Committee in 1965 produced a groundbreaking study on natural beauty and the environment, which contained a clear warning about climate and CO2. “Man is unwittingly conducting a vast geophysical experiment….”, noting that emissions by the year 2000 could be enough to cause “measurable and perhaps marked” climate change. In a special message to congress of February 8, 1965, President Johnson wrote, "…this generation has altered the composition of the atmosphere on a global scale through radioactive materials and a steady increase in carbon dioxide from fossil fuels." But a few scientists were looking at global temperature data, and beginning to worry about another pollution problem. Global Temperatures had been flat or decreasing since the 1940s.

Could man's addition of smoke and particulate matter to the atmosphere be blocking out the sun and leading to a potentially catastrophic global cooling? One of them was climatologist Stephen Schneider, who contributed to a widely quoted paper on the issue. Well nobody likes to be wrong. But remember I never said "I predict that we are going to induce an ice age." What I said was under these assumptions this is what you get. Other scientist say that could trigger an ice age. Even though a discussion was going on between a few scientists, popular media still reflected awareness of impending global warming. When I was a kid, food was food. Before our scientific magicians poisoned the water, polluted the soil. Decimated plant and animal life. Why in my day you could buy meat anywhere.

Eggs they had. Real butter. Fresh lettuce in the stores. I know. Sol. You told me before. How can anything survive in a climate like this. A heat wave all year long. A green house effect. Everything is burning up. Ok wiseguy. News of the scientist's concerns made its way into the popular media, such as this 1975 Newsweek article. The article quoted a number of scientists, and in addition, a National Academy of Science study pointing out that a change in climate would have impacts on global food supply. The Academy was also quoted saying that, in regard to climate change, in many cases we do not yet know enough to pose the key questions. Since the National Academy is a good bellweather of where science was at that moment, I decided to read what the original study actually said.

This particular study is a model of ambiguity. "..we do not have a good quantitative understanding of our climate machine. Without the fundamental understanding, it does not seem possible to predict climate.." The report concludes by saying, "The onset of cooling could be several thousand years in the future, though there is a finite possibility that a serious worldwide cooling could befall the earth within the next 100 years." And a few paragraphs later, “A leading effect is the enrichment of the atmospheric CO2 and such effects may combine to offset a future natural cooling, or to enhance a natural warming.” It was an uncharacteristically muddled effort by the academy, and its conclusions were somewhat distorted in media accounts. In early 1977, the Global 2000 report to President Jimmy Carter, was clear and explicit about climate. “Rising CO2 concentrations are of concern because of their potential for causing a warming of the earth. Agriculture and other human endeavors would have a great difficulty in adapting to such large, rapid changes in climate.

” In 1979, the Academy took another crack at the issue, surveying the balance of all the scientific literature of the 70s, and reported: "If Carbon dioxide continues to increase, there is no reason to doubt that climate changes will result, and no reason to believe that these changes will be negligible…. Ominously they warned, A “wait and see policy may mean waiting until it is too late..” By the mid seventies, a couple of things had happened to clarify our situation. Number one, global temperatures began a sustained rise that matched the predictions of CO2 effects. Number two, the publication of a seminal study marked the beginning of the contemporary view of climate change, and the cycle of ice age glaciations. The study confirmed a decades old theory, and gave us an understanding as to how the long slow changes in earth's rotation and orbit have been the timing clock of the glaciers. These cycles has been discussed in some other additions of this series. But with this study, the stage was set for our current generation of scientists to gain a whole new understanding of where we are in climatic cycles, and what to expect in the future. But, climate deniers still point to the popular media as evidence of what climate scientists were thinking at the time.

But of course, the gold standard in science is not pop culture, but the peer reviewed study published in a reputable journal. Most climate Deniers, bless their hearts, don't know the difference. But real scientists do. If there was still any question of what the majority of climate scientists thought in the 1970s, in 2008, a study published in the Bulletin of the American Meteorological Society finally put that question to rest. In a survey of 71 peer reviewed studies from 1965 to 1979, 7 predicted cooling, 20 were neutral, and 44 predicted Global Warming. The study concluded that global cooling was never more than a minor aspect of the scientific" literature of the era, let alone a consensus" comparable to the agreement of every established scientific organization on the planet that exists today, that climate change is real, we're doing it, the consequences are dire, and we need to stop. Thanks again for helping make this series a success. I hope you keep coming back for more on climate issues and solutions. Here on Climate Denial Crock of the Week..

Earth in 1000 Years

Ice in its varied forms covers as much as 16% of Earth’s surface, including 33% of land areas at the height of the northern winter. Glaciers, sea ice, permafrost, ice sheets and snow play an important role in Earth’s climate. They reflect energy back to space, shape ocean currents, and spawn weather patterns. But there are signs that Earth’s great stores of ice are beginning to melt. To find out where Earth might be headed, scientists are drilling down into the ice, and scouring ancient sea beds, for evidence of past climate change. What are they learning about the fate of our planet, a thousand years into the future and even beyond? 30,000 years ago, Earth began a relentless descent into winter, Glaciers pushed into what were temperate zones. Ice spread beyond polar seas. New layers of ice accumulated on the vast frozen plateau of Greenland.

At three kilometers thick, Greenland’s ice sheet is a monumental formation built over successive ice ages and millions of years. It’s so heavy that it has pushed much of the island down below sea level. And yet, today, scientists have begun to wonder how resilient this ice sheet really is. Average global temperatures have risen about one degree Celsius since the industrial revolution. They could go up another degree by the end of this century. If Greenland’s ice sheet were to melt, sea levels would rise by over seven meters. That would destroy or threaten the homes and livelihoods of up to a quarter of the world’s population. These elevation maps show some of the areas at risk. Black and red are less than 10 meters above current sea level. The Southeastern United States, including Florida, And Louisiana.

Bangladesh. The Persian Gulf. Parts of Southeast Asia and China. That’s just the beginning. With so much at stake, scientists are monitoring Earth’s frozen zones, with satellites, radar flights, and expeditions to drill deep into ice sheets. And they are reconstructing past climates, looking for clues to where Earth might now be headed, not just centuries, but thousands of years in the future. Periods of melting and freezing, it turns out, are central events in our planet’s history. That’s been born out by evidence ranging from geological traces of past sea levels, the distribution of fossils, chemical traces that correspond to ocean temperatures, and more. Going back over two billion years, earth has experienced five major glacial or ice ages. The first, called the Huronian, has been linked to the rise of photosynthesis in primitive organisms. They began to take in carbon dioxide, an important greenhouse gas. That decreased the amount of solar energy trapped by the atmosphere, sending Earth into a deep freeze.

The second major ice age began 580 million years ago. It was so severe, it’s often referred to as “snowball earth.” The Andean-Saharan and the Karoo ice ages began 460 and 360 million years ago. Finally, there’s the Quaternary, from 2.6 million years ago to the present. Periods of cooling and warming have been spurred by a range of interlocking factors: volcanic events, the evolution of plants and animals, patterns of ocean circulation, the movement of continents. The world as we know it was beginning to take shape in the period from 90 to 50 million years ago. The continents were moving toward their present positions. The Americas separated from Europe and Africa. India headed toward a merger with Asia. The world was getting warmer.

Temperatures spiked roughly 55 million years ago, going up about 5 degrees Celsius in just a few thousand years. CO2 levels rose to about 1000 parts per million, compared to 280 in pre-industrial times, and 390 today. But the stage was set for a major cool down. The configuration of landmasses had cut the Arctic off from the wider oceans. That allowed a layer of fresh water to settle over it, and a sea plant called Azolla to spread widely. In a year, it can soak up as much as 6 tons of CO2 per acre. Plowing into Asia, the Indian subcontinent caused the mighty Himalayan Mountains to rise up. In a process called weathering, rainfall interacting with exposed rock began to draw more CO2 from the atmosphere, washing it into the sea. Temperatures steadily dropped.

By around 33 million years ago, South America had separated from Antarctica. Currents swirling around the continent isolated it from warm waters to the north. An ice sheet formed. In time, with temperatures and CO2 levels continuing to fall, the door was open for a more subtle climate driver. It was first described by the 19th century Serbian scientist, Milutin Milankovic. He saw that periodic variations in Earth’s rotational motion altered the amount of solar radiation striking the poles. In combination, every 100,000 years or so, these variations have sent earth into a period of cool temperatures and spreading ice. Each glacial period was followed by an interglacial period in which temperatures rose and the ice retreated. The Milankovic cycles are not strong enough by themselves to cause the shift.

What they do is get the ball rolling. A decrease in solar energy hitting the Arctic allows sea ice to form in winter and remain over summer, then to expand its reach the following year. The ice reflects more solar energy back to space. A colder ocean stores more CO2, which further dampens the greenhouse effect. Conversely, when ocean temperatures rise, more CO2 escapes into the atmosphere, where it traps more solar energy. With so many factors at play, each swing of the climate pendulum has produced its own unique conditions. Take, for example, the last interglacial, known as the Eemian, from 130 to 115,000 years ago. This happened at a time when CO2 was at preindustrial levels, and global temperatures had risen only modestly. But with higher solar energy striking the north, temperatures rose dramatically in the Arctic. The effect was amplified by the lower reflectivity of ice-free seas and spreading northern forests.

There is still uncertainty about how much these changes affected sea levels. Estimates range from a 5 to 9 meters, levels that would be catastrophic today. That’s one reason scientists today are intensively monitoring Earth’s frozen zones, including the ice sheet that covers Greenland. Satellite radar shows the flow of ice from the interior of the island and into glaciers. In the eastern part of the island, glaciers push slowly through complex coastal terrain. In areas of higher snowfall in the northwest and west, the ice speeds up by a factor 10. The landscape channels the ice into many small glaciers that flow straight down to the sea. In the distant past, the center of the island may have been drained by a giant canyon, recently discovered. Scientists found that it’s 550 kilometers long and up to 800 meters deep.

It leads from Greenland’s interior to one of today’s most volatile glaciers. This is the Petermann Glacier in Northwest Greenland. Amid unusually warm summer temperatures in 2012, satellites tracked a giant iceberg as it broke off and moved down the glacier’s outlet channel. At about 31 square kilometers, this island of ice stayed together as it floated along. After two months, it finally began to fragment. The Jakobshavn glacier on Greenland’s west coast flows toward the sea at a rapid rate of 20 to 40 meters per day. At the ice front, where the glacier meets the sea, Jakobshavn has been retreating as it dumps more and more ice into the ocean. You can see it in this map. In 1851, the front was down here. Now it’s 50 kilometers up. One reason, scientists say, is that water seeping down into its base is acting like a lubricant.

Another is that as the glacier thins, it’s more likely to break off, or calve, when it interacts with warmer ocean waters. Scientists are tracking the overall rate of ice loss with the Grace Satellite. They found that from 2003 to 2009, Greenland lost about a trillion tons, mostly along its coastlines. This number mirrors ice loss in the Arctic as a whole. By 2012, summer sea ice coverage had fallen to a little more than half of what it was in the year 1980. While the ice rebounded in 2013, the coverage was still well below the average of the last three decades. Analyzing global data from Grace, one study reports that Earth lost about 4,000 cubic kilometers of ice in the decade leading up to 2012. Sea levels around the world are now expected to rise about a meter by the end of the century. What will happen beyond that? To gauge the resilience of Greenland’s great ice sheet, scientists mounted one of the most intensive glacial drilling projects to date, the North Greenland Eemian Ice Drilling Project, or NEEM. The ice samples they obtained from the height of Eemian warming told a surprising story.

If you were a visitor to Northern Greenland in those times, you would have stood on ice over two kilometers thick. Temperatures were warmer than today by about 8 degrees Celsius. And yet, the ice had receded by only about 25%, a relatively modest amount. That has shifted the focus to Earth’s other, much larger ice sheet, on the continent of Antarctica. Antarctica contains 90% of all the ice, and 70% of all the fresh water on the Earth. Scientists are asking: how dynamic are its ice sheets? How sensitive are they to melting? Data from Grace and other satellites shows that this frozen continent overall has lately been losing as much ice as it gains. The vast plateau of Antarctic ice is one of the driest deserts on Earth. What little snow falls, remains, adding to the continent’s mass. You can see evidence of this in the snow and ice that piles up at the South Pole research station. This geodesic dome was built in the 1970s.

By the time it was decommissioned in 2009, the entrance was nearly buried. With a thickness of up to 4 kilometers, the ice on which this outpost sits will not melt easily. That’s true in part because of the landmass below it, captured in an extraordinary radar image. The eastern part of the continent, the far side of the image, is a stable foundation of continental crust. In contrast, the western side dips as much as 2500 meters below present day sea level. Along the Amundsen Sea Coast, the ice is disappearing at an accelerating rate. Inland ice streams are moving toward the ocean at at least 100 meters per year. They end up in floating ice shelves that extend hundreds of miles into the ocean. This region is the greatest source of uncertainty about global sea level projections. When ice shelves like this grow, they become prone to fracturing. A giant crack, for example, recently appeared in the Pine Island Glacier. Within two years, a 720 square kilometer iceberg had broken off.

But the scientists are more concerned about what’s happening below the surface. In recent times, the Southern ocean that swirls around the continent has been getting warmer, at the rate of .2 degrees Celsius per decade. That has affected ice shelves like Pine Island by melting them from below. In a comprehensive survey of the continent, scientists concluded that this process was responsible for 55 percent of the mass lost from ice shelves between 2003 and 2008. It’s also been blamed for one of the more puzzling twists in the story of climate change, the spread of sea ice all around Antarctica. One possibility is that ramped up winds, circling the pole, are pushing the ice into thicker, more resilient formations. Another is that the melting of ice shelves has spread a layer of cold, fresh water over coastal seas, which readily freezes.

A team of researchers has come to the Pine Island Glacier to try to monitor the melting in real time. After five years of preparation, they drilled through 500 meters of ice to begin measuring ice volume, temperature, salinity, and flow. In some places, they found melt rates of about 6 centimeters per day, or about 22 meters in a year. Because ice shelves hold back inland glaciers, the melting could trigger larger changes. That’s likely what happened to the Larsen ice shelf on the Antarctic Peninsula in the year 2002. It’s thought to have been stable since the last interglacial. Warmer ocean waters had been eating away at Larsen’s underside. By early February of 2002, the shelf began to splinter into countless small icebergs. By March 7th, when this picture was taken, it had completely collapsed, forming a vast slush that drifted out to sea. Without the shelf’s buttressing effect, a series of nearby glaciers picked up speed, dumping an additional 27 cubic kilometers of ice into the ocean per year.

Evidence from the last interglacial, the Eemian, brings an ominous warning of what could lie ahead. It’s based on the height of ancient coral reefs, which grow to a depth relative to the sea level above them. Based on reefs along the Australian coast, a recent study published in the journal Nature showed that sea levels remained stable for most of the Eemian, at 3-4 meters above those of today. But the authors found that in the last few thousand years of the period, starting around 118,000 years ago, sea levels suddenly shot up to 9 meters above today. The authors concluded, in their words, that “a critical ice sheet stability threshold was crossed, resulting in the catastrophic collapse of polar ice sheets.” Looking ahead, uncertainties about the future of our climate abound. According to one study, the long cool down to the next glacial period is due to start in the next 1500 years or so, based on the timing of Milankovic cycles. But for this actually to happen, the study says, enough new ice would have to form to get the ball rolling. CO2 would have to retreat to below pre-industrial levels.

Instead, it appears that a warming climate is becoming a fact of life. The danger is that if the melting gains a momentum of its own, even reducing CO2 emissions may not be enough to stop it. The still unfolding story of Earth’s past tells us about the mechanisms that can shape our climate. But it’s the unique conditions of our time that will determine sea levels, ice coverage, and temperatures. What’s at stake in the coming centuries is the world we know, the one that has nurtured and sustained us. The Earth itself will go on, ever changing on short and long time scales, a dynamic living planet 1.