I recently toured Portugal and Spain, where the clashes between civilizations and “little ice ages” were especially violent. The effects of climate change on the Iberian Peninsula over the centuries vividly demonstrate why we should not fear global warming: The effects of any plausible warming scenario for the coming decades will only be positive and contribute to human flourishing. They always do.
Iberia’s first towns and cities emerged during the long Bronze Age Warming that began around 3300 BC. The Bronze Age was spurred by the discovery of the new metal, which mixed tin with copper to produce superior axes, plowshares, and other edged tools. Calm seas allowed traders to bring the tin from such sources as Cornwall and northern Turkey.
The first large towns and port cities were created then, for the metalworkers and the traders who brought the tin. Then the bronze-forges became targets for marauders, so the urban centers were fortified.
After 1200 BC, the Bronze Age Warming ended and a thousand-year Iron Age Cooling began. It brought short, cloudy, summers, prolonged drought, heavy floods, and failed crops. The towns were abandoned, and the seas became too stormy for the tin merchants to travel. Iberia’s survivors moved back to scattered farms, mostly in the few places where there were still reliable sources of water.
Around 200 BC, the climate changed again, into the long Roman Warming. The Romans were poised with the engineering and energy to create humanity’s first big empire. They welded what today are more than 30 different countries into a trading bloc that stretched from Britain and Germany in the north to Morocco and Egypt in the south, and east to Hungary, Constantinople, and Turkey.
For the next 800 years, Iberia was best known as a Roman province whose grain exports helped feed the Empire. Spain’s gravity-fed irrigation was organized by the Romans. But then, around 600 AD, the long Roman Warming ended and the awful cold of the Dark Ages began. Prolonged drought struck both Spain and North Africa. Rome’s population fell from more than a million people to just 20,000 in a century. The bubonic plague may have been almost as bad as the famines, killing millions of the former Roman Empire’s population.
That was when the Muslim religion sprang up out of the desert and quickly spread among the weakened and despondent cultures around the Mediterranean. Spain was invaded in 711 AD by an Arab prince whose troops reached across both Spain and Portugal and even into southern France. The Muslim Moors ruled much of Iberia for the next thousand years.
Spain suffered less than most of Europe during the climate chaos of the Dark Ages. For one thing, Rome was no longer carrying most of its grain away to feed the Empire. The Muslims also brought a new irrigation technique—the water wheel, which allowed water to be raised instead of always running downhill. The new irrigation system coupled with new crops brought by the Moors—-including rice, oranges, figs, and sugar cane—produced relative abundance. Even so, the region didn’t really prosper until the Medieval Warming’s stable climate tripled Europe’s food production and wealth.
There was constant combat across Iberia over these years, and it was not primarily religious in motivation. During much of the period, Christians, Muslims, and Jews fought with and for each other, depending on fragile alliances. After the Dark Ages ended, about 950 AD, there was food for all—and the Moorish culture of Cordoba and Seville produced a surge of learning, the rescue of ancient knowledge, and the Moors’ fabulous architecture.
The darkest chapter for Iberia occurred during the Little Ice Age, after 1300 AD. Crops again failed repeatedly, people burned “witches” who had supposedly cursed their farms, and the Spanish Inquisition arose to persecute “heretics,” many of them Jews or Muslims who had publicly converted to Christianity. The bubonic plague spread and became known as the Black Death. Ultimately, Christian armies finally conquered Cordoba and the last of the Moors in 1614.
Fortunately, we’ve had no “little ice age” since 1850. Inevitably, however, another one will test our mettle sometime during the coming centuries. We should be happy to be living in a period of relative warmth, and we should not fear the continuation and mild increase of that warmth.