As policymakers from your local city council all the way to the U.N. struggle over what to do about climate change, it’s important to remember the climate always changes over time, and change brings benefits as well as problems. For example, Africa’s famed “city of gold,” Timbuktu, was created by salt as a result of climate change.
During the Dark Ages (600 AD to about 950 AD) Timbuktu was only a seasonal gathering place for desert-dwelling salt traders in Mali’s Niger Valley. A huge dry lake about 400 miles north of the Niger River contained massive amounts of salt, buried about five feet beneath the surface. Eventually, using slave labor captured from the farming communities to the south, the Taureg people’s salt mines became infamous—and very successful.
The Sahara had become dryer and less populated during the Dark Ages than during the previous Roman Warming. Eventually the cycle turned again, and the Medieval Warming raised temperatures about 1–2 degrees C. With the warming, the tropical rainbelts moved hundreds of miles north because the Arctic ice receded, and more rain fell on the southern Sahel. The Niger Valley could now grow millet in non-irrigated fields. “Floating rice” also could be grown, planted in the flood plains before the rains and reaching up to three feet with the rising floodwaters across an eight-mile-wide channel. More food, more people, more need for salt in the sweating tropics.
The farmers in Ghana to the south “earned their salt” by digging gold, killing elephants for their ivory, and harvesting the caffeine-laden kola nuts that later went into Coca-Cola. The farm communities even sold off some of their less-desired people as slaves for the salt mines. At times, the salt was so valuable it traded ounce-for-ounce with gold.
Timbuktu’s salt-mine wealth increased as the Medieval Warming continued. The city got noticed by the outside world when the region’s Moslem ruler, Mena Musa, made a pilgrimage to Mecca. He showed off his wealth when he stopped in Cairo—with 60,000 retainers and 250 camel-loads of gold.
At its peak, the “city of gold” had between 60,000 and 100,000 residents. A huge number of the new immigrants were Moslem scholars, attracted by the generous ruler’s gold and the cultural diversity of a trading city.
The warmth and stability of the period also triggered expanded trade across the sands, from sub-Saharan Africa to the shores of the Mediterranean and northward. Timbuktu became the central trade link between the riches of sub-Saharan Africa and Europe.
So attractive were the gold and slaves that Timbuktu continued to thrive even after the Medieval Warming shifted into the Little Ice Age—which again brought colder temperatures and stormy seas. The peak of Timbuktu’s wealth came during the sixteenth century. However, technology was about to intrude on the desert traders’ profits.
In 1598, sailors from Portugal used newly developed long-range ships and naval charts to find the Gold Coast by sea. They built a fortress-castle to protect their stake in the gold and slaves. Soon the English, Danes, and Dutch also found the source of the riches. A far safer ocean voyage replaced the slow and often-deadly trip across the Sahara, during which huge numbers of slaves died.
Most importantly, ships could carry far more cargo (especially slaves) than could desert caravans. Camels carry only about 300 pounds of cargo apiece, and it took many weeks for the goods to reach the eventual northern markets. A ship could carry hundreds of tons of trade goods and supplies while traveling much faster than a caravan.
Still, Timbuktu continued to fascinate the outside world. In the early nineteenth century, organized competitions offered prizes for explorers who reached the fabled city. Unfortunately, by then the city had fallen into poverty, with only a declining salt trade for support. The houses were just mud, the fabled golden roofs long gone.
Abrupt climate changes, like the Medieval Warming and the Little Ice Age, have been with us for at least the past million years, and they always trigger disruption. Often the changes are beneficial, as with the success of Timbuktu in the Medieval Warming. Too often, however, the “little ice ages” bring famine, invasion, drought, floods, and disease epidemics.
We are now 150 years into a beneficial warming, with abundant crops and trade fostered by mostly warm and stable weather. History says this is as good as it ever will ever get.
Dennis T. Avery (firstname.lastname@example.org), a senior fellow of The Heartland Institute, is an environmental economist and former senior analyst for the U.S. Department of State. He is coauthor, with S. Fred Singer, of Unstoppable Global Warming Every 1500 Years.