Mysterious pre-Incan peoples ruled present-day Chile, Peru and Bolivia. From the arid northern coastal plains of Peru rose the blood thirsty Moche. And from the Altiplano Plateau — second highest plateau in the world — 2 miles above sea level and 994 miles southeast of the Moche peoples, rose the mighty civilization of Tiwanaku. Despite their exceptional ingenuity and agricultural prowess cities of hundreds of thousands of people perished overnight.
At the height of the Moche empire they ruled the 12 northern most watersheds that crossed, at that time, the coastal plains from the Andes to the Pacific Ocean.
In normal years the northern half of Peru’s coastal plains are one of the driest places on Earth. The Moche built colossal public aqueducts and irrigation systems enabling them to grow food and prosper.
A typical Moche lived a couple decades and experienced two or three significant rainfalls in their lifetime. They believed that drinking blood sustained the life force of the arid land.
In the middle of the 6th century a great flood scooped 10 to 13 feet of topsoil from the fields in the Moche River Valley to the sea. The sea returned the topsoil back to the shoreline over the next few decades burying the damaged capital city and most of the valley to the south. The Moche vanished.
Lake Titicaca sits 2.4 miles above sea level on the Altiplano Plateau in the Andes straddling the border of Peru and Bolivia. More than 25 rivers empty into Titicaca and it has about 41 islands.
The Tiwanaku peoples emerged as a loose-knit collection of fishing villages along the Lake’s edge between 100 and 300 A.D. They used the lake to create and eventually support a capital city of 350,000 people on an otherwise very high and dry plateau.
Around 950 A.D. Tiwanaku disappeared. Furthermore, several other cultures flourished and mysteriously perished prior to the Incas. What happened?
The pre-Incan cultures were decimated by abrupt climate change.
The surface of the Pacific Ocean off the coast of Peru and Ecuador is cold. Icy water from Antarctica is carried northward upwelling near the equator. These frigid waters are known as the Humboldt Current. These waters are home to rich plankton. Plankton feeds anchovies. Millions of aquatic birds including Guanay cormorants, Peruvian booby’s and gray pelicans nest on small rocky islands off the coast and feed on anchovies. These birds produce tons of guano used as commercial fertilizer.
There is a seesaw in air pressure that exists between the eastern equatorial Pacific and Australia and Indonesia.
As early as 1923, Sir Gilbert Walker, director-general of the Indian Meteorological Service, noticed that a high pressure in Australasia and warming of the western Pacific waters usually accompanied by drought in Australia, India and parts of sub-Saharan Africa with warmer winters in southwestern Canada and cold winters in southeast U.S.
The Spanish noted this phenomenon and called it El Nino — Christ Child — because it arrived during Christmas off the coast of Peru disrupting the cold Antarctic waters from upwelling, removing plankton, anchovies and starving millions of birds.
In the 1960s Jacob Bjerknes and Carl Gustov Rossby created a global circulation model and connected the differences in seesawing pressures or the Southern Oscillation with the El Nino events off Peru.
They created an index measuring the differences in air pressure between Tahiti in the central Pacific and Darwin in northern Australia.
Normally the pressure is lower in Darwin than it is in Tahiti. Under these conditions the trade winds blow east to west and move sun-heated waters away from the coast of South America enabling the Humboldt Current to rise and replace warmer water and a strip of cold water stretches west along the equator.
When El Nino occurs the process is disrupted. Following El Nino is his sister La Nina. During La Nina vast amounts of moisture are sucked into the air above Indonesia forming the Indonesian Low. It acts like a giant radiator creating trade winds and 8,699 miles away when the upper air sinks over Peru it is extremely dry.
The oscillation between Tahiti and Darwin is likened to a seesaw because it’s never stable.
Scientists can track El Nino, predict it pretty well, but we don’t know exactly what causes it.
The tropical glaciers in the Andes hold climate records of the past 20,000 years. Cores of ice resemble tree rings. Atmospheric dust and different molecular forms of oxygen accurately show warm and cold periods.
The ice cores revealed what happened to the Moche, Tiwanaku and other pre-Incan cultures.
Viscous El Nino’s occurred between 562-594 A.D., precipitation dropped by 30 percent and the Moche perished. Around 950 A.D. a drought set in on the Altiplano Plateau and reduced precipitation by 15 percent and Lake Titicaca dropped 49 feet within 50 years. The drought annihilated the Tiwanaku.
Today, every known glacier in the tropics is retreating. They are melting at a rate of 15 feet a year. It’s likely that the ice caps in Africa and South America will be gone in 15 years.
The changes in glacial ice are harbingers of immense global warming to come.
Dr. Reese Halter is a public speaker and conservation biologist. His latest book is “The Incomparable Honey Bee.” He can be reached through www.DrReese.com.
