Extreme cooling event caused extinction of first early humans in Europe

Recent findings have shed new light on the early human occupation of Europe. A study spearheaded by UCL researchers reveals that a significant climate shift, resulting in extreme cooling conditions, occurred around 1.1 million years ago. This dramatic climate change possibly led to the extinction of early humans inhabiting southern Europe.

Interestingly, the earliest known human remains in Europe, dating back 1.4 million years ago, have been excavated from Iberia. These remnants suggest that our ancient ancestors migrated from southwest Asia to settle in regions that enjoyed a warm, wet climate interspersed with mild cold spells.

The dominant theory till date posited that these early inhabitants managed to endure various climate cycles and adapted to the progressively severe conditions post the 900,000-year mark.

However, Professor Chronis Tzedakis of UCL Geography remarks, “Our discovery of an extreme glacial cooling event around 1.1 million years ago challenges the idea of continuous early human occupation of Europe.”

How the study was done

To reach this revelation, paleoclimate experts from several institutions joined forces. Researchers from UCL, the University of Cambridge, and CSIC Barcelona delved into marine micro-organisms’ chemical composition and studied pollen in deep-sea sediment cores sourced off Portugal’s coast.

Their investigations exposed the occurrence of sudden climatic shifts leading to severe glacial cooling. These changes were so drastic that ocean surface temperatures near Lisbon plummeted below 6°C. This lead to the spread of semi-deserts on nearby land.

Reflecting on the findings, Dr. Vasiliki Margari, the study’s lead author from UCL Geography, expressed, “To our surprise, we found that this extreme cooling at 1.1 million years ago was comparable to some of the most severe events of recent ice ages.”

Early humans would have really struggled

Such intense cooling would have presented immense challenges for small bands of hunter-gatherers. Professor Nick Ashton of the British Museum commented on this. He observed that early humans perhaps lacked the adaptive traits needed to survive in such hostile conditions.

Ashton noted, “Early humans may have lacked adaptations such as sufficient fat insulation and also the means to make fire, effective clothing or shelters.”

To understand the climate’s direct impact on these early populations, Professor Axel Timmermann and his team from the IBS Center for Climate Physics employed their supercomputer, Aleph, to simulate the extreme conditions of the period.

Merging this data with fossil and archaeological evidence, the team crafted a human habitat model to evaluate how conducive the environment was for early human habitation.

Timmermann explained the startling outcome. He said, “The results showed that 1.1 million years ago climate around the Mediterranean became too hostile for archaic humans.”

Absence of remains and tools from fossil record

This data convergence indicates that during the Early Pleistocene, areas such as Iberia and larger regions of southern Europe saw a decline in human population. The conspicuous absence of human remains and stone tools over the subsequent 200,000 years hints at a potential extended gap in European habitation.

Adding another layer to the evolving narrative, Professor Chris Stringer from the Natural History Museum in London proposes, “According to this scenario, Europe may have been recolonized around 900,000 years ago by more resilient humans with evolutionary or behavioral changes that allowed survival in the increasing intensity of glacial conditions.”

The study saw collaboration between UCL Geography, the IBS Center for Climate Physics at Pusan National University, and researchers from several esteemed institutions such as Cambridge University, CSIC Barcelona, and museums in London.

More about extreme cooling

Extreme cooling, while seemingly counter-intuitive in our present age of global warming, has occurred numerous times throughout Earth’s history. These events have transformed landscapes, influenced evolutionary paths, and even played roles in mass extinctions.

What is Extreme Cooling?

Extreme cooling refers to rapid, significant decreases in global or regional temperatures over relatively short geological timespans. These events can be triggered by various factors. Eventually, they lead to the formation of ice sheets, sea level drops, and massive ecosystem shifts.

Causes of extreme cooling

Volcanic activity

Massive volcanic eruptions can spew millions of tons of ash and sulfur dioxide into the atmosphere. These particles reflect sunlight, causing a reduction in global temperatures. The 1815 eruption of Mount Tambora in Indonesia led to the “Year Without a Summer” in 1816.

Asteroid impacts

Large asteroid or comet impacts can throw enormous amounts of dust into the atmosphere. This dust, by blocking sunlight, can lead to cooling. The impact that wiped out the dinosaurs 65 million years ago is believed to have caused such a cooling event.

Changes in Earth’s orbit

The Milankovitch cycles, which are variations in Earth’s orbital parameters, can lead to significant cooling periods, advancing the onset of ice ages.

Ocean current changes

Shifts in ocean currents can redistribute warm and cold water across the globe, significantly affecting global climates. For instance, a shutdown of the Gulf Stream could lead to cooling in Europe.

Solar dimming

Decreases in solar radiation, due to factors like sunspot activity, can influence Earth’s temperatures. Prolonged periods of low sunspot activity, such as the Maunder Minimum, coincide with cooler epochs like the Little Ice Age.

Consequences of extreme cooling

Formation of ice sheets

Extended cooling can result in the spread of glaciers and the formation of vast ice sheets, which occurred during the last Ice Age.

Sea level drops

As water gets trapped in ice sheets and glaciers, sea levels can drop, exposing large areas of continental shelves.

Shifts in ecosystems

Cold temperatures can force species to migrate, adapt, or face extinction. During the last Ice Age, mammoths, saber-toothed cats, and giant ground sloths roamed the Earth.

Economic and social impact

Extreme cooling can affect agriculture, leading to food shortages. The “Year Without a Summer” caused widespread crop failures and food scarcity in the Northern Hemisphere.

Historical Instances of Extreme Cooling

The Snowball Earth

Occurring over 700 million years ago, the Snowball Earth hypothesis proposes that the planet was entirely or nearly entirely covered in ice.

The Last Glacial Maximum

Around 20,000 years ago, vast ice sheets covered much of North America, Northern Europe, and Asia.

The Little Ice Age

Spanning from the 14th to the 19th century, this period saw cooler temperatures worldwide, with particularly cold spells in Europe.

In summary, while the world today grapples with global warming, history reminds us of the Earth’s ever-changing climate. Extreme cooling events, with their profound impacts, underscore the planet’s climatic dynamism and the need for societies to be resilient and adaptable in the face of environmental changes.

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