NASA has published a time lapse video that recounts the history of Ice Age glaciers starting from 122,000 years ago. The animation is based on a new model of glacier movements and the response of the Earth’s land masses. The animation was created by scientists at the University of Toronto and NASA’s Jet Propulsion Laboratory.
According to an accompanying article, the model is helping scientists understand postglacial rebound, also known as glacial isostatic adjustment, which refers to the way land masses rebound when heavy glaciers melt and disappear from the surface. This factor is crucial in predicting the rise of sea level over time.
From Science: “About 1 million years ago, one of Earth’s most important metronomes mysteriously shifted: Ice ages went from occurring every 40,000 years to every 100,000 years. At the same time, the ‘conveyor belt’ of warming currents in the North Atlantic Ocean slowed sharply. Last week, scientists at the Goldschmidt Conference presented a clue to these twin mysteries: evidence that glaciers in the Northern Hemisphere suddenly began to stick to their beds. Growing thicker, they might have triggered a cooling that disrupted the conveyor belt and allowed the 100,000-year cycle that we see today to take root.”
Glacier Recession and Summer Streamflow in the Cascades
From Water Resources Research: “The Pacific Northwest (PNW) is the most highly glacierized region in the conterminous United States (858 glaciers; 466 km2)… We applied a high‐resolution glacio‐hydrological model to predict glacier mass balance, glacier area, and river discharge for the period 1960‐2099…Results show that the rate of regional glacier recession will increase, but the runoff from glacier melt and its relative contribution to streamflow display both positive and negative trends.”
From New York Times: “After an emergency landing on a Swiss glacier, the group of 12 Americans drank melted snow and survived on rations of one chocolate bar a person until daring pilots shuttled them to safety after five days marooned on the ice. Relics of that harrowing adventure and the successful rescue of all those onboard…resurfaced after more than 70 years this month when scorching summer temperatures in Europe caused the glacial ice to recede.”
The movie “The Day After Tomorrow” depicts a catastrophic climate shift to global cooling, which is referred to as the new ice age. In the movie, melting of polar ice caused by global warming disrupts the North Atlantic current, rapidly dropping the ocean temperature, ultimately leading to the freezing of the ocean on a global scale. Although this over-the-top effect portrayed by this fictional film contains little scientific truth, many scientists are coming up with hypotheses about a global ice age during the Cryogenian, a geologic period that lasted from 720 to 635 million years ago.
Nearly 15 years later, research on glacial refugia has been heating up the debate about this ice age: a contention over the extent to which the glaciation covered the Earth. Two main hypotheses are on the table: “Snowball Earth” theory, which argues that ice covered the entire Earth, and “Slushball Earth” hypothesis, where the band of the sea near the equator stayed open, allowing the hydrologic cycle— evaporation and precipitation of water— to persist.
The term Snowball Earth was first coined by Joe Kirschvink, a geobiologist at CalTech in the late 1980s. The theory was based on the early observation that glacial deposits from this time were widely distributed on nearly every continent, some geologic evidence even suggesting glaciation at tropical latitudes. The abrupt change in the climate is rooted in the positive feedback loop, commonly referred to as the albedo (“whiteness” in Latin) effect. Simply put, as Earth cools and ice forms from the pole down to lower latitudes, the albedo, or the whiteness of the Earth increases, reflecting more solar radiation—just like a black t-shirt under strong sunlight gets hotter as black absorbs more heat, while a white t-shirt reflects all wavelengths of light.
Shortly after the concept of plate tectonics was developed, scientists noticed that, along with the albedo effect, the long-term carbon cycle kicked into high gear, making a double positive feedback. As the ancient supercontinent, Rodinia, broke apart, the newly created coastline in the low latitude intensified the weathering, as there was a more active water cycle assisting the chemical weathering of the rock. Silicate rock, which is a type of rock constituting the majority of the Earth’s crust, goes through a chemical weathering reaction that removes CO2 from the atmosphere. As the atmospheric CO2 was reduced, Earth became colder, as CO2, along with greenhouse gases, worked as blocking shields against the re-emitted heat from escaping the Earth. Moreover, because these broken up continents were in the low latitudes, they could not have prevented the advance of ice that formed in the poles, the coldest region on Earth, which would have created a completely frozen planet.
The critics of the Snowball Earth theory— professor Richard Peltier and his fellow colleagues at the University of Toronto and Texas A&M—published a paper refuting the hypothesis, in which they run a series of simulations that resulted in an equatorial belt of open water that may explain the survival of the organisms during the ice age, as well as the subsequent revival of numerous species.
The argument stems from the fact that the process of glaciation not only entailed positive feedback, but also one important negative feedback. As the climate got colder, the atmospheric oxygen would have sunk deeper into the ocean. As atmospheric oxygen spread deep into the sea, it bonded with the layer of old organic matter. This organic matter formed in shallow oceans and later drifted down to deeper waters, where it combined with oxygen, forming CO2. Carbon dioxide, released back into the atmosphere, would have warmed the Earth by the greenhouse effect, which would have defrosted Earth, stopping the ice sheets and glaciers from further advancing. Therefore, such negative feedback would have prevented ice from completely covering the Earth surface.
Peltier provides another key evidence against Snowball Earth theory, the geographic region that allowed the survival of multicellular fauna and flora referred to as the “glacial refugia.” Had the Earth completely frosted itself, its harsh climate would have killed off many organisms. Moreover, complete reflection of solar radiation would have decimated photosynthetic organisms. Yet, there is no such geological indication that a mass extinction event occurred.
The debate of hard versus slushy Snowball Earth becomes more enigmatic at the end of the Cryogenic period and start of Cambrian, when the so-called “Cambrian explosion” of animal life occurs. The Cambrian explosion refers to a short interval during which many multicellular animals in diverse forms appeared on the surface of the Earth. Critics of Snowball Earth argue that such a dramatic increase in biodiversity within a short period of time would not have been able to happen in a hard Snowball Earth scenario, as many organisms prior to the explosion would have gone extinct. The supporters of Snowball Earth, on the other hand, argue that the biodiversity is simply the result of the robust micro-organisms that survived the Snowball Earth, evolving in size as well as anatomical complexity through time.
Neither of these hypotheses is set in stone, but rather are part of an ongoing debate that requires much clarification. To better understand what happened during the Cryogenian period, developing different climate models with many parameters is necessary, giving flexibility to the ever-unknown complexity of past climate conditions. Moreover, careful study of the organisms that survived Snowball Earth could further assist our understanding of this enigmatic period.
Magnificent, beautiful and mysterious, glaciers are a critical part of nature. For thousands years, humans have responded to glaciers through art, incorporating them in paintings, poems, folk songs, and more recently, movies. With the development of modern arts, specifically the film industry, glaciers have popped up in a range of creative endeavors from documentaries to animated pictures.
Explore some popular films featuring glaciers with GlacierHub.
Chasing Ice (2012) is the story of one man’s quest to gather evidence of climate change. A documentary film about environmental photographer James Balog, it tells the story of his trip to the Arctic to capture images to help tell the story of Earth’s changing climate.
The film included scenes from a glacier calving event lasting 75 minutes at Jakobshavn Glacier in Greenland, the longest calving event ever captured on film.
“Battling untested technology in subzero conditions, he comes face to face with his own mortality,” the film introduction states. “It takes years for Balog to see the fruits of his labor. His hauntingly beautiful videos compress years into seconds and capture ancient mountains of ice in motion as they disappear at a breathtaking rate.”
Ice Age (2002) is one of the most popular animations in the world and its sequels have continued to delight thousands of children and adults. First directed by Chris Wedge and produced by Blue Sky Studios, the film is set during the ice age. The characters in the film must migrate due to the coming winters. These animals, including a mammoth family, a sloth Sid, and a saber-tooth tiger Diego, live on glaciers. They find a human baby and set out to return the baby.
The animation won positive reviews and awards, making it a successful film about glaciers.
Jökulsárlón, an unearthly glacial lagoon in Iceland, makes its appearance in several James Bonds films, including A View to Kill (1985) and Die Another Day (2002).
A View to Kill, starring Roger Moore, Christopher Walken and Tanya Roberts, was also filmed on location at other glaciers in Iceland, including Vatnajökull Glacier in Vatnajökull, Austurland, Iceland.
China: Between Clouds and Dreams
The documentary China: Beyond Clouds and Dreams (2016) is an award-winning new series by Director Phil Agland. The five-part series tells intimate human stories of China’s relationship with nature and the environment as the country grapples with the reality of global warming and ecological collapse. See the trailer here.
Commissioned by China Central Television and filmed over three years, the film includes a scene of glaciers on the Tibetan Plateau, where the impacts of climate change are most obvious.
A new study in Nature says the Earth, previously headed for an Ice Age before the Industrial Revolution, is likely to maintain its current warm phase in the glacial cycle for an unprecedented amount of time.
The researchers―Andrey Ganopolski, Ricarda Winkelmann, and Hans Joachim Schellnhuber of the Potsdam Institute for Climate Impact Research―first examined the effect of the Earth’s orbital characteristics on the glacial cycle, but found that increased carbon dioxide (CO2)played a more important role. Additionally, they found a critical relationship between CO2 and solar radiation that could aid in predicting the beginning of the next glacial period.
“This illustrates very clearly that we have long entered a new era, and that in the Anthropocene humanity itself has become a geological force. In fact, an epoch could be ushered in which might be dubbed the Deglacial,”co-author Hans Joachim Schellnhuber said in a press release for the study.
Interglacial periods are the phases in Earth’s history with generally low amounts of global ice, and glacial periods have the most ice. The study uses the commonly accepted theory that glacial periods occur when Northern Hemisphere summer solar radiation (the amount of solar energy reaching the Earth’s surface) is at its lowest.
If summer solar radiation is low in the Northern Hemisphere, where there is more land, snow does not melt as readily. This build up of snow leads to more reflectivity―albedo―at the surface. As global albedo increases, even less snow melts and this process continues enhancing itself; this positive feedback loop could potentially trigger a glacial period.
This concept was used to support the study’s claim that our planet was headed for a glacial period prior to the Industrial Revolution since the solar exposure was, and still is, close to its minimum. The authors argue that the level of CO2 and low amount of solar radiation seen prior to industrialization should have led to a rapid buildup of ice sheets.
The team also considered the effect that the Earth’s orbital shape might have on climate. The eccentricity of the Earth is currently in a low phase―the Earth’s orbit fluctuates over thousands of years between having a more pronounced elliptical shape in its high phase and a more circular one in its low phase. In its current orbital pattern, the Earth does not get far enough from the sun during the Northern Hemisphere summer to achieve the solar radiation minima that typically spur the buildup of ice. They believed that the current near-circular orbital pattern may have countered the effects of the cooling that would be expected from the lower solar radiation.
In other words, the team thought the shape of the Earth’s orbit could explain why we have not entered an ice age.
In order to test this theory, the researchers used paleoclimate data (data derived from studying natural indicators of the conditions found in previous geologic times) from two similar glacial periods to see if there are any important similarities to the period we are in today, known as the Holocene.
The theory that the orbit had caused the delayed ice age was challenged by the fact that similar orbital patterns have led to glacial periods in the past. It was found that neither period matched the Holocene’s characteristics well enough, again showing the unprecedented behavior of the glacial cycle.
Though not a providing a perfect replication of current circumstances, this paleo data provided the closest geological approximation of similar global conditions and was incorporated into their simulations to try to get the most accurate representation of when the next glacial period should begin. The team used a highly sensitive model which had accurately modeled the last eight glacial cycles to examine the effect CO2 and orbit patterns had on this cycle.
Ultimately, they concluded that carbon dioxide, not the Earth’s orbital shape, was the more important factor.
The team surmised that even accounting for the planet’s current near circular orbit “…the Earth system would already be well on the way towards a new glacial state if the pre-industrial CO2 level had been merely 40 ppm [parts per million] lower than it was during the late Holocene…” This clearly shows the importance of the increased CO2 levels.
Using their data, a more accurate threshold of CO2 levels was determined in order to predict the onset of the next glacial period; with this threshold the team was able to find the “glacial inception” point for various levels of solar radiation.
The researchers argue that even without further human influence, the system would still have an exceedingly long time between glacial periods.
“[O]ur study also shows that relatively moderate additional anthropogenic CO2-emissions from burning oil, coal, and gas are already sufficient to postpone the next ice age for another 50.000 years,” the lead author said in a press release for the study.
“The bottom line is that we are basically skipping a whole glacial cycle, which is unprecedented. It is mind-boggling that humankind is able to interfere with a mechanism that shaped the world as we know it.”
“Iceberg calving is ultimately related to the mechanical failure of ice. However, predicting mass loss from calving events remains challenging because calving takes on diferent forms under different conditions. For example, large tabular icebergs sporadically detach from freely foating ice tongues with many years of quiescence between major calving events”
Read more on ESRI’s Story Maps and Time-lapse here.
Linking Earth’s Ice Ages to Ocean Floor topography
“The evidence comes from seafloor spreading centers: sites throughout the ocean where plates of ocean crust move apart and magma erupts in between, building new crust onto the plates’ trailing edges. Parallel to these spreading centers are “abyssal hills”: long, 100-meter-high ridges on the diverging plates, separated by valleys. On bathymetric maps of seafloor topography, they look like grooves on a record. These grooves, it now turns out, play the tune of Earth’s ice ages.”