Who wouldn’t enjoy a bright summer's day? But the climate crisis we are all living through has brought home the fact that there is a downside to constant sunshine — heatwaves, for instance, leading to drought and poor harvests. That is still the case today and was no different in the past.

But how did earlier societies manage to survive natural climate crises with the limited means at their disposal? That’s what we in the CRC 1266 are looking to understand.

Climate crises — now and then

Today’s climate crisis is one of the great challenges of our times. Rising global temperatures make periods of drought or extreme weather events more likely. More and more people worldwide are suffering the consequences and fleeing the worst affected areas. By the year 2050 up to 143,000,000 people may have become climate migrants.

Natural climate events occurred in the past that bear comparison with today’s climate emergency. Particularly notable are climate events that occurred between 2200 and 1500 BCE. Though their effects were felt nearly everywhere in the world, they were particularly consequential in the Mediterranean region.

Bronze Age climate crises

Our research shows that the southern portion of the Iberian Peninsula was rocked by three climate crises over the course of the Bronze Age. First, around 2200 BCE, near the beginning of the Bronze Age, there was a marked decline in winter precipitation. Later, dry summers particularly affected people in the south-east, where rain was a rarity for much of the period between 2000 and 1800 BCE. The summers, always dry, now often lasted from May to September. Another sharp decline in winter rain and snow occurred around 1600/1500 BCE.

  • Excursion

    Reconstructing seasonal fluctuations in precipitation in the Bronze Age

  • In order to reconstruct past precipitation, we must look for suitable archives. We usually find these in the form of sediment cores, but also in dripstones from caves. These archives are then examined for useful indicators. There are several possible indicators that can help us reconstruct precipitation.

  • On the Iberian Peninsula, plant pollen is one such indicator we use. Plants are sensitive to fluctuations in climate, which means that these fluctuations register in the spectrum of species found in pollen samples. Certain trees, for instance, cannot endure long periods of drought.

  • Another indicator is the quantity of matter of onshore origin (e.g. plant remains) found in maritime sediment cores. Such matter largely enters the seas via rivers, which carry more material at times of high precipitation.

  • The reconstruction of seasonal changes is based on modern findings that be applied to the Bronze Age. The rainy season in the Iberian Peninsula lasts from October to March. That is when many trees produce their pollen and rivers carry more onshore matter than they do in summer.

Possible climate migration and its challenges

In spite of these considerable challenges, the people in the south-east of the Iberian Peninsula definitely remained where the sun shone. Yet there are also indications that groups from the south-west of the peninsula sought to escape the sun around this time. Perhaps they even became part of El Argar society.

Whether as a consequence of immigration or not: the society grew rapidly. This meant that a fundamentally dry region had more and more people to support. Dramatic decline in winter precipitation, setting in around 1600/1500 BCE, almost inevitably caused the El Argar society to collapse. Even doubling down on the cultivation of barley (already intensively pursued) could not save the El Argar culture, and the region was largely deserted around 1500 BCE.

  • In El Argar society, the dead were buried in small graves within their dwellings.

  • Excursion

    Indications of climate migration in the Bronze Age Iberian Peninsula

  • Unfortunately, bronze age people were not yet able to record their experiences in writing. That is why, when addressing the question of possible climate migration, we must once more rely on indicators. Fortunately, we have several at our disposal.

  • The distribution of radiocarbon dates tell us that, as the climate crisis set in around 2200 BCE, human activity in the southern Iberian Peninsula shifted from the Atlantic to the Mediterranean coast. A plausible explanation may be migration.

  • Moreover, work carried out by international researchers show that some of the people within El Argar society came from other regions. This can be deduced from strontium isotopes or remains of DNA in human bones.


  • Kiel University students carrying out a magnetometric survey of the Monte da Contenda earthworks in Portugal.

  • Excavation of the great earthworks at Perdigões (Portugal).

  • Excavation of the great earthworks at Perdigões (Portugal).

  • Excavation of the great earthworks at Perdigões (Portugal).

  • Drilling for sediment cores for climate reconstruction near Seville.

  • Drilling for sediment cores for climate reconstruction near Seville.

Climate migration today

A global problem

Climate migration is one of the great challenges of our time. Across nearly all continents, people are trying to escape extreme weather events, droughts or rising sea levels. People in Africa, Asia, South America and the Pacific are particularly affected. Yet in Europe too each summer brings new heat waves, forest fires or floods. In Germany, the Ahr valley suffered severe flooding in 2021.

The root cause of global warming is clear, it is the result of growing emissions of greenhouse gases such as carbon dioxide or methane. Global warming triggers a chain reaction, with rising sea levels and extreme weather events causing floods, and droughts and heat waves leading to poor harvests and deaths. If we want to help climate migrants, we must tackle climate change.