Climate change started thousands of years ago

And ancient farmers may have adverted an Ice Age for the foreseeable future

First time here? Story Voyager is a climate fiction newsletter I email to subscribers. This is the second episode in a documentary series about the history of climate change in the Holocene. You can find the first episode here. Or you can start by reading There Is Hope, my climate fiction series.

A well-coordinated slaughter

The longer you can look back, the farther you can look forward. —Winston Churchill

The blazing fire sparkled in the eyes of the hunters gathered on the limestone escarpment, peaking down at the frenzied herds of migrating horses. Maddening terror ignited by the sky-high flames rushed through their bodies like wildfire, driving the horses toward the narrow path along the ridge as they screamed and squealed, eager to escape, only to be corralled into an even deadlier trap. A well-coordinated slaughter begins when the humans descend upon the terrified horses with their Swiss-army-knife-like hunting tools skilfully embellished with detachable and interchangeable microliths, spearheads, harpoons, needles and projectile points.

While a product of the imagination, this could well be a scene from the seasonal horse hunts that took place at Roche de Solutré, France, where researchers estimate that ancient hunters slaughtered some 30,000 to 100,000 horses over 20,000 years during the Upper Paleolithic (40,000 to 10,000 years ago). For thousands of years, our ancestors hunted deer and horses, mammoths, hyenas, wolves, hares and foxes seasonally. The meat was then dried and preserved for the summer and winter months, which is how they survived the last Ice Age.

Source

When wildlife biologists look at those paintings of reindeer and bison, they can tell you what time of year it was painted just from the appearance of the animals' hides and skins. The way these people knew their environment was absolutely incredible by our standards. —Brian Fagan

Their tools, survival skills and intimate knowledge of the environment were passed down from generation to generation via fluent speech and storytelling, drawing, song and dance, thus ensuring our survival through a 40,000-year-long glacial period.

Surviving an Ice Age

The clear blue sky met the vast mammoth tundra at the horizon. A gust of wind twirls dust in the air, enveloping the group of humans and dogs walking over the roiling grassland carrying packs of food, tools, clothing and fur tents waiting to be unpacked at the next seasonal settlement. Further away, herds of migratory mammoths, reindeer and wild horses spread across the grassy landscape, all in a perpetuum mobile steadily followed by the humans. As the wind eases off and the dust settles on the tundra, the humans uncover their faces and breathe in the dry, cool air. Summer is coming.

The mammoth or steppe-tundra was Earth’s most extensive biome during the last Ice Age, and it stretched east to west from the Iberian Peninsula to North America and north to south from the Arctic to China. At the height of the last Ice Age, the steppe tundra extended over the Bering land bridge, a 1,000 km wide area situated between the Lena River in Russia and the Mckenzie River in Canada that was uncovered by the low sea levels and connected Europe with today’s Alaska and Canada. The tundra ecosystem dominated Earth for 100,000 years, or the length of an Ice Age cycle. It started to diminish about 12,000 years ago at the beginning of the current interglacial era, the Holocene.

Homo sapiens have been around for 300,000 years, and they survived two Ice Ages. The last Ice Age started 30,000 years ago, and 27,000 years ago, it reached the Last Glacial Maximum (LGM), which lasted until 19,000 years ago. The vast ice sheet covered North America and Northern Eurasia during this time. This caused glaciation in mountain ranges in North America, Europe, Africa, South America, the Tibetan Plateau, Australia, New Zealand, and Tasmania, lowered the sea level by approximately 130 meters and reduced the air surface temperature by 8–15°C below present-day values.

About 36% of Europe's continent remained suitable for human survival. At the beginning of the last glacial period, there were about 500,000 inhabitants in Europe, but by the peak of the last Ice Age, around 23,000 years ago, only about 200,000 inhabitants were left. Europeans lived isolated from each other by ice sheets and roamed in bands of fewer than 30 people, well below the stable size of healthy reproduction of 500 people. During the last ice age, there was a population density of 4.3 to 8.0 people per 100 km2. Today, Europe’s population is 742,073,577, with a density of 3,400 people per 100 km2.

From hunters to farmers

The delicate flames of the oil lamps sprinkled around the heavy fur tent raised on mammoth bone pilar tremble in the dark. The inhabitants of the little village are gathered around the heart where a bright fire is burning. The children are warming themselves up watching the adults sewing boots and clothing from the fur of young foxes, flintknapping daggers and arrowheads, repairing their portable hunting tools, making necklaces from bones, teeth, shells and tusks, or carving voluptuous statues of the goddess of fertility that would fit in the palm of the hand and protect them from famine during the long and harsh winters.

The Ice Age people lived between 37,000 and 14,000 years ago. They descended from a single founder population and contributed to the gene pool of present-day Europeans. During this time, they developed the Gravettian cultural complex that spread around Europe mainly due to their high mobility. To survive, bands of hunter-gatherers needed to have deep knowledge of the flora and fauna of an area as large as 250,000 square kilometers. Food was scarce due to the cold, and the Ice Age people invented modular portable tools for hunting, a prehistoric Swiss army knife. To protect themselves from the cold, they initially draped themselves in hides that doubled as sleeping bags and made baby carriers and protection gloves for chiseling stones. Then, about 30,000 years ago, they made one of the most significant inventions in humanity: the needle.

If you saw a needle from 20,000 or 30,000 years ago, you'd know what it was in an instant, a very fine-pointed tool with a hole in one end to put thread through. —Brian Fagan

The invention of the needle helped them make tailored clothing to protect themselves from sub-freezing temperatures. Like contemporary mountaineering clothing, their dress was made from carefully selected animal skins and was sewn and worn in layers ‘from moisture-wicking underwear to waterproof pants and parkas’. The thread was made from vegetable fiber and died in turquoise and pink. During the ice age, people lived in natural rock shelters, which they weatherproofed by draping large hides and building internal tents with a fire heart. During the summer months, they migrated outdoors in search of food. During the cold summer nights, they slept in tents covered in animal hides and topped with sod which served as permanent shelters for several months.

However, 14,000 years ago, the climate changed abruptly, becoming warmer, leading to icebergs melting, more precipitation, and a change in the landscape. The tundra was flooded together with the food sources of animals, such as mammoths, on which humans had subsisted during the Ice Age, who couldn’t adapt fast enough and got extinguished. With the climate change at the end of the Ice Age and the arrival of ancient farmers from the Near East around 8,000 years ago, the hunter-gatherer lifestyle that helped humans weather an entire Ice Age would end forever. A new agricultural lifestyle begins that will profoundly and unexpectedly influence Earth’s climate.

Winter isn’t coming

The ice sheet cracks and lifts from its grounding seafloor and starts marching backward toward the land, bobbing up and down on the tide of an ever-growing ocean. Calling ice shelves flood the tundra landscape, melting glaciers send rivers crashing down from the mountain tops, and storms beat against the shores, eroding the land as the frozen arid world of the last Ice Age melts into water.

At the end of an Ice Age cycle, a sudden climate change leads to a new interglacial period. The surge in atmospheric temperatures is so sudden and drastic that the ice sheet covering Eurasia melted away at a speed of 600 meters per day for several months in the area of today’s Norways about 15,000 years ago. The temperatures continued to rise and peaked at the beginning of the interglacial era, about 10,500 years. At the peak of natural warming in our interglacial, the carbon dioxide concentration in the atmosphere didn’t exceed 268 ppm or parts per million. Afterward, it started to drop, reaching 261 ppm around 8,000 years ago, and it would have continued to drop to about 240 ppm by the end of the pre-industrial era. Except it didn’t. In 1860, we had 284 ppm. Today, we are at 422 ppm. The last time global dioxide levels were 400 ppm was around four million years ago. We must turn our sights toward the sky to understand what happened next.

While the Earth rotates around the sun on an orbit that changes its shape every 100,000 years, tilts its axis toward and away from the sun in 41,000 years cycles, and wobbles its axis in circles that bring each hemisphere closer or farther from the sun in 23,000 years cycles, Ice Ages come and go in a climatic dance that shaped the blue planet for the past 2.4 million years. Three orbital movements are responsible for Earth’s pacing of the glacial-interglacial or Ice Age cycles, also known as the Milankovitch orbital cycles: eccentricity, obliquity and precession. And they have a story to tell.

Eccentricity or running in circles (or ellipses)

Eccentricity refers to the shape of Earth’s orbit around the sun. The more elliptical, the higher the variability in insolation or the amount of solar radiation that reaches the Earth’s surface on a specified area over a set period. Insolation increases the differences in air surface temperature between the seasons. The more concentric Earth’s orbit around the sun is, the lower the variability in insolation is. Eccentricity has a periodicity of 100,000 years, meaning that it changes shape every 100,000 years, determining the start and end of a new Ice Ace and the length of an interglacial.

To calculate how long the Holocene or MIS 1—Marine Isotope Stage 1—our current interglacial period should last, scientists had to find the previous isotope stage with a similar eccentricity to ours. Today, Earth’s orbit around the sun is almost a circle—the eccentricity is anomalously small—and we have low variability in insolation. With the help of the Milankovitch cycle, scientists could calculate that MIS 19, an interglacial period that started around 790,000 years ago, had a similar eccentricity to ours. MIS 19 lasted about 12,500. The Holocene began 12,500 years ago. By analogy, it should end by now.

Obliquity or the roly-poly planet (in slow motion)

Obliquity is Earth’s axis tilt relative to its orbital plane and has a periodicity of 41,000 years. As the Earth rotates around the sun, its axis is not parallel to its orbit but tilted towards it. In the last one million years, Earth’s axis tilt has varied between 22.1 and 24.5 degrees relative to Earth’s orbital plane. At maximum tilt or 24.5 degrees, we have more extreme weather differences between the seasons, as each hemisphere receives more insolation or solar radiation during summer because the Earth is at a lower angle toward the sun, thus getting solar radiation on a larger surface area. As the Earth tilts more toward its orbital plane, summers are getting cooler and at minimum tilt, or 22.1 degrees, a new period of glaciation starts. Glaciation periods usually last around 40,000 years and coincide with Earth’s obliquity cycles.

Currently, Earth’s tilt stands at 23.5 degrees relative to its orbit around the sun. The Earth was at maximum tilt—24.5 degrees—about 10,000 years; this is when we reached peak natural temperature in our current interglacial era, and it will reach minimum tilt—22.1 degrees—in about 10,000 years when, theoretically, the next glaciation should start. The current summer solar radiation or best summer half-year insolation—the amount of solar radiation Earth receives during the summer months—is characteristic of a late interglacial period. A similar summer half-year insolation was registered at the end of MIS 9 or the Holstein Interglacial period from about 300,000 years ago. This is the second clue that the Holocene should end by now.

Precession or how to get an even tan (even in winter)

While obliquity determines glaciation periods, precession determines interglacial periods. Precessions have a periodicity of 23,000 years, and they determine in which season Earth is closest to the sun. When Earth is closest to the sun during the summer solstice—perihelion—we have precession minima. When Earth is closest to the sun during the winter solstice—aphelion—we have precession maxima. During precession minima, summers are hotter while winters are cooler, and during precession maxima, summers are cooler, and winters are hotter. Interglacial periods always start around orbital precession minima.

The last precession minima occurred about 11,000 to 10,500 years ago, causing the midsummer insolation that led to warming, ice melting, monsoon flooding in tropical and subtropical areas and the maximum increase in methane emissions, about 700 ppb or parts per billion, at the beginning of the Holocene. This phenomenon of fast global warming occurs at the beginning of every interglacial period. The temperatures then naturally decrease over several thousands of years until the glacial inception that marks the end of the interglacial period. We are now in a period of precession maxima, and in 2023, Earth was closest to the sun on January 4th, meaning that in July, we had aphelion. Once again, the orbital mechanics indicate that we should witness glacial inception. It’s worth noting that after the natural peak methane emissions that occurred 10,500 years ago, the CH4 levels went on a downward trend, and they were expected to reach 450 ppb at the end of the preindustrial era. However, in 1860, the CH4 level was 704 ppb.

Winter isn’t coming. Why?

Breaking the Ice Age cycle

Had it not been for early agriculture, Earth’s climate would be significantly cooler today. —Stephen Vavrus

After reaching peak at the beginning of an interglacial era, the CO2 and CH4 levels start lowering naturally until a new glacial inception that marks the end of the interglacial and the beginning of a new Ice Age. The same downward trend could be observed in our interglacial, with the CO2 and CH4 levels on a downward trend until 8,000 years ago when the trend started to go in the opposite direction. 10,000 years since the onset of the current interglacial era, we reached 284 ppm and 704 ppb. However, during stages 5, 7, and 9, at the time of the closest modern analog or timescale, the CO2 values were around 250 ppm, and the CH4 values were around 450 ppb. In the Holocene, there was an anomaly of about 30 to 34 ppm and 230 ppb. This shows that very little is needed to bring Earth’s climate out of balance. It is a scary but informative notion.

So what happened?

The Early Anthropogenic Hypothesis (EAH) published in 2003 proposed that the CO2 and CH4 levels in the Holocene climate would have naturally cooled substantially during recent millennia. However, the anthropogenic greenhouse gas emissions reduced the cooling. Greenhouse gas emissions from early farming are why the Holocene climate remained relatively stable, and new ice sheets failed to appear. It is well-known that post-industrial emissions are generally attributed to human activity in the post-industrial era. However, a theory that traces global warming back to ancient farming? That is a controversial idea!

In a study from 2007 called The early anthropogenic hypothesis: Challenges and responses, William F. Ruddiman takes an in-depth look at the science behind his own hypothesis and comes to a surprising conclusion.

We live in a world in which peak interglacial warmth has persisted only because of the inadvertent impact of early farming.

Now, let us have a look at the science that proves this.

Insane in the methane (or the CH4 anomaly)

About 5,000 years ago, there was an abrupt reversal of the natural downward trend of the CH4 levels in the atmosphere. By 1500, an atmospheric methane anomaly of 230 ppb temporarily lowered during the Little Ice Age, only to increase back to 230 ppb for a total of 704 ppb by 1860. From its onset 12,500 years ago, the Holocene, our current interglacial era, looked identical to previously studied interglacial periods. Until 8,000 years when something unexpected happened: Homo sapiens started farming.

Also, 5,000 years ago, China started to use irrigation to grow wet-adapted strains of rice in Southeast Asia. By 3000 years ago, irrigated rice was cultivated from China to the Ganges River in India. Rice was initially grown in valleys next to rivers because it was easier to bring water to irrigate them, but it also meant that weeds were very prominent in the rice fields. Early rice farmers used disproportionately large areas to grow rice, meaning their CH4 emissions were also disproportionately large. As much as 25% to 40% of the CH4 anomaly in the preindustrial era is attributed to rice irrigation. The remaining 60% to 75% of contributors are livestock and human waste emissions, biomass burning, irrigation and climate system feedback. By 1500 AD, an anthropogenic warming of 0.5 degrees increased the methane emissions from natural feedback by 9%.

Research shows that the optimal CH4 levels for the onset of glacial inception are around 450 ppb. In July 2023, the atmospheric methane concentration was 1904 ppb. It’s safe to say that we won’t reach the methane levels necessary to end the Holocene and start the transition to the next Ice Age any time soon.

Burning down the house (or the CO2 anomaly)

What’s in a footprint? A footprint is…

• …an impression of the foot on a surface.

• …the area on a surface covered by something.

• …a measure of a defined population's total CO2 and CH4 emissions.

• …a measure of how fast we consume resources and generate waste compared to how fast nature can absorb our waste and grow new resources.

• …a measure of the area of deforestation necessary to grow food for a person. Or a forest footprint.

Did you know that today, the forest or agricultural deforestation footprint is 0.2-0.3 ha per person? We are 8.1 billion people. I won’t do the math.

Instead, let’s look at the forest footprint of humans through history and what it means for climate change.

Agricultural deforestation

Here’s some historical data on the deforestation areas needed to feed humans at different stages since the agricultural era started 8,000 years ago.

• 6000 years ago, the forest footprint of a Central European in the late Neolithic was 3 ha.

• By the Roman Empire, 27 BD - 330 AD, up to 90% of the agricultural land in Greece, Italy and the Iberian Peninsula had been deforested.

• In 1086 England, the forest footprint per capita was 9 ha. A similar footprint was registered in the rest of Europe.

• By 1500 AD, the indigenous people in the Americas had repeatedly burned vegetation to maintain grassland, attract game, and promote the growth of berries and other foods to supplement their nutritional needs.

• By 1700 AD, much of China had already been deforested. Most of the deforestation occurred by 1200 AD when the population of China reached ∼115 million, almost as large as the 130 million in 1700 AD.

Resource deforestation

Besides agricultural deforestation, there was a second type called resource deforestation, where wood was cut mainly for building homes and ships, cooking and heating, and charcoal production for smelting. By 1300, access to commoners in the remaining forests was forbidden in England, and other kingdoms followed.

Forest footprint and climate change

As we’ve already seen, our interglacial reached a natural peak CO2 levels of 268 ppm 10,500 years ago, which naturally decreased until 8,000 years ago when the trend reversed. By 1860, we should have had a natural CO2 level of around 240 ppm, facilitating the onset of the glacial inception and the end of the interglacial era. Instead, we were up at 284 ppm. But we actually reached this peak preindustrial levels by 1200 AD. The CO2 levels fell by 7 to 8 ppm in the next 500 years due to the Little Ice Age.

This means that, by 1860 AD, we had an anomaly of 34 to 40 ppm.

Scientists calculated that a 40-ppm preindustrial CO2 anomaly would require at least ∼550 Gt C of anthropogenic emissions during the last 8,000 years. But was this really the case? We have an anomaly of about 35 ppm. Let’s do some math.

• Pervasive early deforestation of southern and western Europe and more limited deforestation of northeastern Europe could have released ∼33 Gt of carbon by 1500.

• Total carbon emissions from China by 1700 AD amounted to ∼33 Gt C.

• In the Americas, total deforestation by 1500 would have produced ∼14 Gt C.

• By the Sung dynasty in the 1200s, China had become the world’s first partly “industrialized” country, with greater iron production than would later occur in Europe, even during the early stages of the industrial era. The early burning of coal in China and the deep erosion of soils in degraded regions of Eurasia could have contributed to more than 14 Gt C of additional preindustrial emissions.

• Total preindustrial carbon emissions: 120–137 Gt C, amounting to a 9 ppm increase.

So, where did the rest come from?

Feedback (not by Kanye West)

The short answer is feedback enhancement.

In previous interglaciations, natural CO2 decreases of 35 to 55 ppm occurred soon after peak interglacial warmth. As we’ve seen, after the peak warmth in the Holocene, the CO2 decreased by 7 ppm over 1,500 years and would have continued to get naturally cooler. Instead, the CO2 trend in the Holocene is anomalous by ∼35 ppm.

Scientists noticed that the natural CO2 decrease in an interglaciation doesn’t happen only in the atmosphere but also in the ocean because tropical monsoons are decreasing, and the tundra and forests are gradually replaced by ice sheets. The displaced CO2 most probably ends up in the deep ocean, the only remaining carbon reservoir. In the Holocene, the oceans should have absorbed about 85% of the 120–137 Gt C from preindustrial anthropogenic emissions. But this was not the case. While the surface temperature of the Southern Ocean cooled off toward glacial maximum values early in the previous interglacial stages 5 and 7, in the past 5,000 years of the Holocene, it remained ∼3°C warmer.

CO2 solubility decreases with increasing water temperatures. A warmer surface and deep ocean resulted in an atmospheric CO2 increase of 20 to 24 ppm as a feedback of the climate system. Thus, ancient farming warmed the atmosphere by 9 ppm, thus maintaining the ocean surface temperature at 3°C warmer, which led to more climate warming. Isn’t it alarming how little it takes to ruin the climate balance of a whole planet?

Baby, it’s not cold outside

By running simulations and studying previous interglaciations, scientists confirmed that the overdue glaciation hypothesis, which claims that a new glaciation is overdue because of greenhouse gas emissions by early farmers during the last few thousand years, is probably true. In interglacial stages 5, 7, and 9, substantial volumes of new ice accumulated by the times most analogous to today. This means that a glaciation of some extent would have begun by now if greenhouse gas levels were now at the reduced levels specified in the hypothesis. Instead, our planet is getting warmer and warmer. Humans have adverted a new Ice Age for the foreseeable future.

There is pretty good agreement in the community of climate scientists that we have stopped the next glaciation for the long, foreseeable future, because even if we stopped putting carbon dioxide into the atmosphere, what we have now would linger. The phenomenal fact is, we have maybe stopped the major cycle of Earth’s climate and we are stuck in a warmer and warmer and warmer interglacial. —William F. Ruddiman

Drop it like it’s hot (or cold)

In the first episode of this documentary on the history of climate change in the Holocene, we looked at the Ice Age and the role humans played in climate change during this time. Indeed, research on well-dated ice from Dronning Maud Land and the South Pole site has confirmed a CO2 drop of ∼7 ppm from 1100 to 1700 AD, breaking the upward trend that had started 8,000 years ago. Solar forcing due to volcanic activity is unlikely to have caused such a significant decrease. Instead, scientists looked at other sources for climate change: pandemics and social unrest.

Three major pandemics occurred in preindustrial times.

1. Between 200 and 600 AD, the Roman Empire lost 40% of its population in southern and western Europe, 10 million people, due to a pandemic over several centuries. As a result, broad farmlands reverted to waste until the population recovered to pre-pandemic levels by 1000 AD. Research indicates that the atmosphere registered a CO2 decrease of ∼1 ppm CO2 decrease during the interval 600–650 interval because of reforestation.

2. During the Black Death pandemic of 1347–1353 in Europe, the Middle East, and North Africa, bubonic plague killed 25–33 million people (one-third of the population), and abandonment of farmland was common in north-central Europe. Between 1400 and 1450, there was an abrupt CO2 decrease of ∼2 ppm in response to reforestation during the Black Death pandemic. Populations recovered to pre-plague levels by 1500 AD.

3. The arrival of the Europeans in the Americas in 1492 introduced a host of diseases from which the indigenous people had no immunity. Between 1500 and 1750 AD, 80– 90% of the pre-Columbian population or 50 to 60 million people, died. This caused a drop of almost 2 ppm CO2 between 1600 and 1700.

China experienced massive mortality (an estimated 40 million deaths) between 1250 and 1400 because of civil strife and the near collapse of the economic order. Because many people in northern China at this time burned coal instead of wood, these deaths would have reduced releases of carbon to the atmosphere, a net reduction of atmospheric CO2 to just over 4 ppm by 1600–1700.

The combined anthropogenic factors can account for about 4 ppm of the 7-ppm CO2 decrease observed between ∼1200 and 1750. This estimate matches the amount that was not explained by the natural cooling.

During the COVID-19 pandemic, CO2 emissions fell by 5.4% in 2020, but the amount of CO2 in the atmosphere grew as in previous years. As NASA reported, this is because of natural feedback enhancement and the fact that our warm oceans cannot absorb as much CO2 from the atmosphere. At this stage of our climate change journey, we are deep in unknown waters, and it is increasingly difficult to predict what will happen next. Our survival and advancement as a species have been tied to our ability to predict and anticipate our planet's climate.

Conclusion

Do you associate Stone Age people with Ice Age people? The ability of our ancestors to survive such adverse climate conditions, their skills, technology, environmental knowledge, fashion acumen and complex cultural system cast in a new light a very misunderstood period in human history. The vast landscapes that our hunter-gatherer ancestors roamed for survival leave us in awe, as does their lifestyle and deep connection with nature, raising questions about their capabilities. Could these resilient hunter-gatherers have, in their own way, laid the foundations for a civilization akin to ours during the interglacial? What would their world look like today?

Conversely, one must marvel at the profound impact human action has had on our planet since the advent of the agricultural lifestyle 8,000 years ago. Ancient farmers could break the Ice Age cycles that dominated Earth’s climate for over 2 million years. What else can we achieve as a species if we collectively redirect our lifestyle and relationship with the natural world? Is it time again for a radical shift, a new chapter that offers hope for our shared future?

Did you enjoy this episode?

This is the second episode in a four-part documentary on the history of climate change in the Holocene. You can read the first episode here.

In the third episode, we will explore the impact of climate change on historical societies and how climate has shaped human progress in the past 8,000 years.

As I navigate the intricate terrain of climate change, I am not a scientist but a curious learner, much like you. Your insights and perspectives are invaluable in this shared exploration. Please share your thoughts in the comments section.

1. What resonated with you?

2. Do you see connections between ancient farming practices and our present climate challenges?

Your engagement fuels the ongoing exploration here at Story Voyager, turning this journey into a collective adventure. Let us unravel the threads of our past together, weaving a better understanding of our collective future.

Story Voyager is where we explore climate change through the lens of climate fiction or cli-fi. Under the motto ‘travel your imagination’, we embark on a journey of reading, researching, writing, and exchanging ideas with like-minded people. Let’s change the narrative about the future of humankind together. If you’d like to support this space even more, please consider becoming a paid subscriber. Your financial support will go toward commissioning illustrations for my first cli-fi series, There Is Hope.

Resources

• The early anthropogenic hypothesis: Challenges and responses by

• Human population dynamics in Europe over the Last Glacial Maximum by

• Ice-age Europeans roamed in small bands of fewer than 30, on brink of extinction by Francesca Jenner

• How early humans survived the ice age by Dave Roos

• Slaughtering Site by Musée Départemental de Préhistoire de Solutré

• Glacial Inception in Marine Isotope Stage 19: An Orbital Analog for a Natural Holocene Climate by

• Integrated summer insolation forcing and 40,000-year glacial cycles: The perspective from an ice-sheet/energy-balance model by Peter Huybers, Eli Tziperman

• Evidence of Fur and Leather Clothing, Among World’s Oldest, Found in Moroccan Cave by Brian Handwerk

• The Impact of Upper Pleistocene Climatic and Environmental Change on Hominin Occupations and Landscape Use by Andreas Taller, Nicholas J. Conrad

• ‘Scary’ new data on the last ice age raises concerns about future sea levels by Kasha Patel, Chris Mooney

• Climate explained: what the world was like the last time carbon dioxide levels were at 400ppm by James Shulmeister