How to survive an ice age: We've done it before, but can we do it again?

What is an ice age?

An ice age is a long period of reduced surface and atmospheric temperatures on Earth. This causes large continental and polar ice sheets and alpine glaciers to form and advance, hence the word 'ice' and why this period is also called 'glacial.'

The climate on Earth varies between ice ages when glaciers advance and warmer periods when much of the world is devoid of glaciers as the glaciers retreat and sea levels rise. And, in fact, we are still technically in an interglacial period.

This current period of alternating glacial and interglacial periods is called the "Quaternary glaciation." This began around 2.6 million years ago and continues today. During this time, ice sheets have advanced and retreated over the Earth's surface, resulting in significant changes to the Earth's geography and sea levels.

These events have significantly impacted the climate, ecosystems, and human (as well as plant and animal) evolution. The height of the most recent glacial period, known as the "Last Glacial Maximum," occurred from around 26,500 to around 19,000 years ago. At that time, the global sea level was more than 400 feet lower than it is today, and glaciers covered approximately 25% of the Earth’s land area.

Intermittent warm periods during an ice age are known as "interstadials" or interglacial cycles. Individual pulses of cold temperature within an ice age are known as glacials or stadials (and sometimes referred to as glaciations, glacial stages, or states).

In glaciology, the term "ice age" denotes a time when both the northern and southern hemispheres have substantial ice sheets over a long interval of time.

According to this definition, the Holocene is the present interglacial epoch on Earth. If things follow the history of the geological record, the next glacial epoch should be just about to begin. However, researchers now believe that human-induced global warming has delayed this by around 50,000 years.

What causes ice ages?

As you can see, ice ages are a natural part of life on our planet. But what usually triggers them?

According to geologists, their causes result from the convergence of a few major factors. These include variations in the ocean and atmospheric circulation patterns, the amount of carbon dioxide in the atmosphere, and events such as volcanic eruptions, which all affect climate.

Over the last 450,000 years, four rather regular glacial-interglacial cycles have occurred. This period has alternated between much longer (70,000 to 90,000 years) glacial periods significantly colder than the present, with shorter interglacial cycles (10,000 to 30,000 years) that were nearly as warm as the present.

In the chart below, take note of the slower abrupt temperature swings into the warmer interglacials that are followed by the longer duration of jagged cooling events down into the colder glacials.

The changing positions of Earth's constantly shifting continents, which impact the ocean and atmospheric circulation patterns, are crucial at the beginning of the ice ages. Ice sheets may form and trigger a new ice age when plate tectonic action rearranges continents so that warm water flowing from the equator to the poles is impeded or decreased.

The formation of the land bridge connecting North and South America (the isthmus of Panama), which stopped the flow of tropical water between the Atlantic and Pacific Oceans and dramatically changed ocean currents, is thought to be the trigger for the current ice age.

Interglacials and glacial periods occur in relatively predictable, recurring patterns. Predictable periodic fluctuations in the Earth's orbit, which impact how much sunlight reaches various sections of the planet's surface, may greatly influence the timing of these.

Called "Milankovitch Cycles," it is hypothesized that these types of Earth's orbital movements affect how much solar radiation reaches the top of Earth’s atmosphere. The orbital variations include:

• Shifts in the eccentricity of Earth's orbit around the Sun;
• Changes in the obliquity of Earth's axis (the angle Earth’s axis is tilted with respect to the orbital plane); and
• The wobbling motion of Earth's axis (the direction Earth’s axis of rotation is pointed, called precession).

The validity of Milankovitch's theory has been widely demonstrated through scientific research, although it has also been shown that the cycles cannot account for the current period of rapid 'global warming' Earth has experienced since the pre-Industrial period.

All very interesting, but how do geologists know this?

Well, they have pieced together information on ice ages by putting together data from examining ice cores, deep-sea sediments, fossils, and landforms.

Ice and sediment cores provide an extensive history of the world's climate. Long hollow tubes inserted up to two miles through glacial ice or sediments on the ocean floor are used to gather core samples. Along with the millions of years of climate records in ocean sediment cores, ice cores give annual and seasonal climate records for hundreds of thousands of years.

The most thorough climatic records have been found in ice cores taken from Earth's two remaining ice sheets, Greenland and Antarctica.

Thanks to this evidence, geologists also understand how quickly these periods come and go. According to historical evidence, ice eras often begin slowly and finish quickly. This pattern can be seen in glacial and interglacial periods within an ice age.

Global temperatures are subject to frequent and abrupt changes on a shorter time scale. Over the past 100,000 years, multiple significant, widespread, and abrupt climate changes have been documented in various sources.

The incredible speed at which these changes occur is one of the more exciting recent discoveries. Global temperatures have changed by as much as 15°F (8°C) or more over the incredibly brief period (by geologic standards) of only a few decades or even a few years.

For instance, a warming trend stopped 12,800 years ago when temperatures sharply plummeted in just a few decades while Earth emerged from the most recent glacial cycle.

Only 1,300 years later, local temperatures rose by as much as 20°F (11°C) in a matter of years. Over the past 100,000 years, there have been at least 24 instances of sudden changes like this.

We are experiencing exceptionally stable temperatures today, which has been thought to be one reason for the rise of our modern, sophisticated societies. But, it is anyone's guess how much longer this might last.

But, more on that later.

Can humans survive an ice age?

We have in the past, in fact, twice, so the odds are likely in favor of doing so again.

The people who survived these periods were very much like us, genetically speaking, but were culturally and technologically very different. Homo sapiens, the first members of our species, first appeared in Africa some 300,000 years ago. Some populations remained in Africa during the ice age and were spared the worst of the cold.

Others spread over the globe, including into Europe's frigid, glacial regions.

They weren't alone either. Other hominin species, including the Neanderthals in Europe and the enigmatic Denisovans in Asia, lived in Eurasia during the start of the ice age. Hominins are a group that includes our immediate ancestors and our closest relatives.

These populations appear to have vanished before the ice era, but our ancestors miraculously survived. This is a big deal, as life would have been challenging during an ice age.

Most people refer to the last glacial period, which started about 115,000 years ago and concluded with the beginning of the present interglacial period when they use the term "ice age."

The world was far cooler back then than it is today. The average global temperature during its height, when ice sheets engulfed most of North America, was about 46 degrees Fahrenheit (8 degrees Celsius). That is 11 degrees Fahrenheit (6 degrees Celsius) colder than the current worldwide annual average.

Even though that difference might not seem significant, it was enough to cause most of North America and Eurasia to be covered in ice sheets. Since the majority of the water on Earth was frozen in the ice sheets, it was also much drier, and the sea level was significantly lower. Steppes or dry, grassy plains covered large areas.

You are likely already familiar with many species that existed during the ice period, such as brown bears, caribou, and wolves. However, the so-called megafauna, including mammoths, mastodons, saber-toothed cats, and enormous ground sloths, all went extinct around the end of the last ice age.

Various theories exist about why these species vanished. One is that humans hunted the megafauna to extinction, although most emphasize the role of ecological and environmental changes as the climate grew warmer.

There are several theories about why our species endured the ice age, whereas our cousins, the hominins, did not. Some believe it has to do with how adaptive we are and our social and communication skills. Additionally, it seems that humans did not stay in one place throughout the ice age but moved around in search of better conditions, shifting to new, warmer locations.

It was long believed that humans did not arrive in North America until the ice sheets began to melt. However, fossilized footprints discovered in New Mexico's White Sands National Park demonstrate that people have been present in North America for at least 23,000 years, or just before the end of the last ice age.

So, it appears we are a pretty tough species to kill off. But will we survive a future ice age?

When will the next ice age happen?

There is an ongoing discussion on when the next ice age will start, with the most recent theories suggesting that human influence on the climate is already delaying it. While most conservative estimates state it should occur within the next 50,000 years, the next ice age may, in fact, not peak for roughly 80,000 years.

The Holocene (the period of geological time we are currently living in), which has lasted approximately 11,600 years so far, has been marked by favorable environmental circumstances that have promoted the development of agriculture, technology, mobility, and the following enormous population expansion that has elevated humans to a dominant species on the planet.

Any significant change in the climate is likely to present difficult obstacles, but they are probably solvable.

After a protracted period of global cooling, many climate scientists—including those who are now concerned about global warming—believe that a planet-wide cooling trend that began nearly 50 million years ago is actually reversing and could lead the planet to more closely resemble the mid-Pliocene epoch, which ended three million years ago. At that time, the Northern Hemisphere was largely free of ice, and sea levels were around 60 feet higher than today. 

The last warm period was estimated to have lasted around 10,000 years based on evidence from sea sediments and other sources. It was long assumed that this gave at least a rough idea of how long the present interglacial would last.

The theory that cooling was coming soon was contested a few years ago. More information regarding the preceding warm period, which occurred 130,000 years ago, has led some scientists to conclude that it lasted twice as long as initially thought — 20,000 years instead of 10,000.

Some have argued that the Holocene is best modeled after an earlier warm period that lasted even longer—30,000 years. However, many specialists continue to express their conviction that the current warming should stop due to orbital cycles, "any millennium now," as Dr. Richard A. Muller, a physicist at the University of California in Berkeley, told The New York Times.

But humans are now exerting a new influence on the Earth. According to many climate experts, as long-buried reserves of coal, oil, and other carbon-rich fossil fuels are burned, billions of tonnes of carbon dioxide and other heat-trapping greenhouse gases are released into the atmosphere, delaying the onset of the next ice age by a millennium or two, if not longer.

According to Dr. James A. Hansen, director of NASA's Goddard Institute for Space Studies, an insulating blanket has a more significant impact on climate than the minor flux in solar energy entering the atmosphere due to variations in Earth's orientation concerning the Sun.

''We have taken over control of the mechanisms that determine climate change,'' he said.

While some scientists concur with this idea in the short term, they assert that eventually, the Earth, the ocean, and the atmosphere's balancing functions will return most of the released carbon to long-term storage, allowing the orbital rhythm to once again predominate.

''Orbital changes are in a slow dance leading to a peak 80,000 years from now,'' said Dr. Eric J. Barron, the dean of the College of Earth and Mineral Sciences at Penn State. ''I can hardly imagine that human influences won't have run their course by that time.''

It may appear that although human-caused global warming may be a centuries-scale calamity if it delays the coming ice age for a while, it could ultimately be beneficial, at least to humans.

However, many climatologists point out that our understanding of the intricate interactions between greenhouse gases, orbital changes, and other climate-related factors is still lacking. In fact, according to some experts, there is a possibility that human-caused warming would prevent heat-transporting ocean currents from keeping northern latitudes warmer than they otherwise would be.

If this is the case, the outcome might be a quicker decline into glacial times instead of a long wait.

Could humans survive the next ice age?

Whether it occurs "on schedule" in a few thousand years or we've delayed it for another 100,00 years, it appears clear that another major ice age will occur at some point in the future. Of course, we cannot possibly know where humans will be, technologically, by then, but what if an ice age suddenly hit us today, a bit like the movie 2012?

Given the differences in human society today compared to tens of thousands of years ago, could we survive? What would we need?

Well, perhaps the past could give us some hints.

It is widely believed that our ancestors survived the ice age by adapting to the changing environment, developing new tools and technologies, and forming social structures to support survival. During this period, humans lived as hunter-gatherers, traveling in small groups to gather food and hunt animals.

They also developed strategies for conserving food and staying warm in cold weather, such as creating fires, building shelters, and wearing animal hides. Through their resilience and resourcefulness, humans could thrive in the challenging conditions of the ice age and lay the foundation for the civilizations that would come later.

We were also able to move around and inhabit different habitats around the world, some of which were less impacted by the worst that ice ages had to offer. We, as a species, effectively hedged our bets by diversifying our "position" on the planet.

Since we are the descendants of these hardy people and inhabit more areas of the planet than in the last ice age, our chances should be pretty good by default. But what kind of impact would an ice age have on modern society?

How catastrophic could it be for us?

A new ice age would significantly impact modern humans, as our current way of life is not well adapted to a cold, harsh environment. Some of the effects would likely include the following:

• Agricultural disruption: A new ice age would likely result in widespread crop failures and food shortages, as growing conditions would become much more challenging, and our food crops are much less diverse than previously. This would likely lead to mass starvation and famine around the world.
• Infrastructure damage: Extreme cold and snow could damage buildings and infrastructure, such as roads and bridges, making it more difficult for people to travel, even locally, and access essential services. Combined with a lack of food, these structures would likely never be repaired or maintained.
• Health problems: People would be more vulnerable to cold-related illnesses like hypothermia and respiratory and cardiovascular problems. A lack of good infrastructure would further compound this problem, and diseases long thought "beaten" would probably run rampant.
• Economic impact: The global economy would likely suffer severely, as industries such as tourism and agriculture would be impacted.
• Forced migration: Many people may be forced to leave their homes in search of more hospitable climates, leading to large-scale displacement and potential conflicts over resources. This is likely the most "dangerous" impact of a new ice age, especially in a world armed with nuclear weapons.

So, much like an all-out nuclear war, society as we know it, could well cease to exist. Cities would be abandoned quickly, and we might even return to a nomadic existence, effectively putting our civilization back several tens of thousands of years.

About one of the most vital resources, food, it cannot be understated how bad things would get in an ice age. Most of the world's food is produced in a few countries with the most fertile land, favorable climates, and abundant water resources.

The largest food-producing regions are in the world's temperate zones and include areas in Europe, North America, South America, and Asia. These regions are characterized by their rich soils, moderate temperatures, and ample rainfall, ideal for growing various crops. The world's largest food-producing countries include China, the United States and Canada, India, Brazil, Ukraine, and Russia. If most of these areas were to be covered with ice sheets or otherwise turned into tundra-like areas, we could not support the population of humans we have today.

For this reason, as we'll discuss later, adequate methods of accessing food would likely be the key to our survival.

But is there anything we could do to prepare for such a thing? Could our current level of technology offer us any options to prevent the worst from happening?

What would we need as a species to survive a new ice age?

To survive a new ice age as a species, modern humans would need to take a multi-faceted approach, addressing challenges related to food, shelter, energy, and overall infrastructure, as discussed above.

So let's try to address each major "issue" separately, shall we?

1. Food security would be a must

A large-scale negative impact on food production would be one of the worst impacts of a new ice age. This would prove disastrous to most populations worldwide, leading to mass starvation, famine, and huge loss of life. Death rates would likely spike among the poor, the old, and the very young, and the future would look very bleak, to put it lightly.

Finding ways to grow and store food in a cold, inhospitable environment would be critical. This could include developing new crop varieties and new sources of food, increasing food storage and distribution systems, and improving methods for producing protein without animals, such as lab-grown meat.

So, is there anything around that could potentially be used? One answer might be in using technology currently designed for an environment beyond our planet — on other planets. It would be almost poetic if our exploits in developing habitats on other worlds could be used to save us back on Earth.

Scientists have found that growing food on other planets would require overcoming significant technological and environmental challenges, as the conditions on other planets are often vastly different from those on Earth. But, in an ice age world, some of these could be modified to work on "back home," too.

Some promising solutions would likely include the following:

• Hydroponic systems: Hydroponic systems use nutrient-rich water instead of soil to grow plants, which could be a solution in environments where the soil is scarce or unsuitable for growing crops.
• Specialist greenhouses: Greenhouses could create a controlled environment for growing crops, including temperature regulation, lighting, and atmospheric control.
• Vertical farming: Vertical farming involves stacking layers of crops on top of each other in a controlled environment, which could efficiently produce food in a limited space.
• Genetic modification: Genetic modification could be used to develop crops that are better suited to the harsh conditions on a colder planet.
• Food recycling and waste management: In a closed system like an ice age shelter, food recycling, and waste management will be essential to ensure sustainable food production and minimize waste.

Beyond that, not all land on Earth would become unusable for farming, so we'd probably have to change our diets a bit for more hardy, cold-loving plants. As for protein, we'd still likely have access to seafood and could rear some cold-loving animals like reindeer, seals, whales, salmon, cod, caribou, etc. However, as there would be far less land for grazing or growing feed, it is likely we will end up relying on food like algae and lab-grown meat, which can both be grown indoors, to provide protein.

Who knows, we might even be able to bring back ice age megafauna like the woolly rhino or mammoth for food too? Though they may not taste very nice to modern palates, as some brave souls who have tried to eat preserved meat will tell you.

2. Adequate shelter would be vital, obviously

With our food supplies sorted, the next most important thing would be adequate shelter from the elements. This is as true today as it has always been.

Providing warm and safe shelter for all people would be essential, which may require developing new building materials and insulation technologies. But construction and energy efficiency developments in our current climate could be a good starting point.

The best shelter would be one that barely "leaks" any heat energy. This would require superb insulation, near-perfect air tightness, and highly sophisticated ventilation systems to keep the air inside clean while not losing heat outside. Large windows and other normally thermally inefficient building parts can probably also go, as you'd only really get a view of near-constant blankets of snow anyway.

We've got television and digital cameras if we need to see what's outside when not venturing out.

For this kind of thing, we have a few existing technologies to take inspiration from, including Passivhaus building techniques and, once again, space technology. We could, for example, build ground-based "spacecraft" inspired shelters to keep any surviving humans safe and warm.

Apart from radiation shielding and low gravity technologies, atmospheric controls, life support systems, etc., would be pretty handy. Other elements like psychological support (plenty of space, privacy, etc.), communications, reliability, and system redundancy would also be handy.

Or, of course, we could build large amounts of polar-toughened habitats all over the place like those used by polar research stations. However, these facilities, being so remote, rely heavily on regular supply and resupply of supplies.

3. Reliable energy, and lots of it, would be another important resource

Access to reliable heat and light sources would be essential, especially when temperatures drop to extremely low levels. This could include developing new energy sources, such as nuclear, solar, wind, and geothermal power.

Since large-scale industries and global transportation of essentials like fuel would likely become unreliable at best, alternative means would be essential.

So, what are our options? Let's use the polar research stations for some inspiration once again.

Polar research stations typically produce energy using a combination of renewable and non-renewable sources. Wind and solar are the most common renewable energy sources used at polar research stations. Wind turbines are used to generate electricity from the wind, while solar panels convert sunlight into electricity.

Non-renewable sources, such as diesel generators, may also be used to supplement renewable energy sources or as backup power during a period of low wind or sun. The choice of energy source, however, depends on the specific needs and conditions of the research station, as well as the availability and cost of different energy sources in the region.

Solar panels and wind turbines would probably be a good idea, but liquid fuels, like diesel, would probably become a very limited commodity during an ice age. For this reason, we would probably want to invest heavily in ground-source heat pumps (vertical or horizontal) and other energy sources that would not require much refueling over long periods.

If only such a thing existed... Oh wait, what about nuclear energy? Whether fission or fusion (if available in time) it could be a perfect choice for powering large collections of cold-proof shelters.

4. We'd probably need to upgrade our infrastructure in preparation too

As we've seen from recent news events in places like North America, very cold weather snaps can cause havoc with modern infrastructure. For prolonged cold periods, like an ice age, the impacts would be catastrophic if nothing was done to prepare.

Some of the most likely impacts on infrastructure from an ice age would be:

• Frost heaving: The freezing and expansion of soil can cause pavement and building foundations to shift, leading to damage.
• Ice Damming: Melting snow and ice that refreezes along the roof edge can form dams that prevent meltwater from draining, causing water damage to buildings.
• Snow Loads: Heavy snow accumulation can damage roofs, power lines, and other structures.
• Cold Weather: Extreme cold temperatures can cause pipes to freeze and burst, leading to water damage and interruption of essential services.
• Storms: Severe winter storms can cause widespread power outages, damage roads and bridges, and disrupt transportation networks.

Overall, the combined effects of an ice age on infrastructure would be significant, requiring large investments in repair and adaptation measures. For this reason, upgrading and maintaining infrastructure, such as roads, bridges, and communication systems, would be necessary to ensure that people can access essential services and support each other. For structures like power lines, these would likely need to be moved underground, or decentralized power generation would become the "norm."

5. Good collaboration and planning would also be necessary

While less of a "concrete" preparation, collaboration and planning between groups of people would be very beneficial. To this end, surviving a new ice age would require significant cooperation and coordination between nations, communities, and individuals.

Developing a comprehensive plan for adapting to a changing climate and ensuring that resources are distributed relatively would be critical. Some institutions are already in place that could help here, like the United Nations, etc., but quite how effective they'd be in the face of massive environmental change on this scale is anyone's guess.

While this might be a little "utopian" thinking, if it could be achieved, the transition into an ice age world would be much less violent and traumatic for all involved. However, human history into how we react during times of enormous environmental stress is not encouraging.

Overall, surviving a new ice age as a species requires technological innovation, social and political organization, and individual resilience and adaptability.

And that's your lot for today, dystopian future enthusiasts.

In conclusion, surviving an ice age can seem daunting, but it is possible with the proper preparations and mindset. By understanding the causes and effects of ice ages, we can better prepare ourselves and our communities to withstand the harsh conditions that come with them.

Whether it's through stockpiling essential supplies, strengthening infrastructure, or simply changing our habits, there are steps we can all take to help ensure a safe and sustainable future for ourselves and generations to come. So, let us embrace the challenge of surviving ice ages and strive towards a better, more resilient world.