6,000 Years of Humanity’s 6,000 Years of Humanity’s “little ice age” Collapses“little ice age” Collapses

Dennis T. Avery, Hudson InstituteDennis T. Avery, Hudson Institute

Heartland 7th Conference on Climate Heartland 7th Conference on Climate ChangeChange

May 22, 2012May 22, 2012

        

Mayan Swamp FarmingMayan Swamp Farming

What happened? The Bronze Age Collapse What happened? The Bronze Age Collapse at 1200 BCat 1200 BC

Ice Reveals the 1,500-Yr CycleIce Reveals the 1,500-Yr Cycle

The The badbad times— times—the the blueblue “little ice ages” “little ice ages”

Seven Collapses in Today’s IraqSeven Collapses in Today’s Iraq

• Ubaid 3900 BC Drought• Uruk 2900 BC Flood\• Akkadia 2200 BC Drought• Babylon 1600 BC Famine, invasion• Assyria 1200 BC Famine, invasion• Dark Ages 600 AD Famine, Muslims• Little Ice Age 1650 AD Ottoman Empire’s

“17th Century Crisis”• All of these abrupt climate shifts were global.

Dansgaard-Oeschger: Dansgaard-Oeschger: ““moderatemoderate” climate cycles?” climate cycles?

• Colder (2-4 C)• Shorter, cloudier growing seasons• Megadroughts• Violent floods• Untimely frosts• Locusts• Nomad invasions• Bubonic plague

Bubonic plague epidemics due to Bubonic plague epidemics due to “little ice ages” too“little ice ages” too

• Rat fleas carry the plague bacteria in arid western China.

• When megadrought starves “their rats” the fleas seek new hosts—people, camels furs, ships.

• Bubonic plagues killed millions during both the Dark Ages and Little Ice Age.

Shifting Rainfall-Shifting Rainfall-worst aspect of the “little ice ages” worst aspect of the “little ice ages”

• Tropical rain belts shift 600 miles south as Arctic ice expands over centuries.

• Sahara desert moves south

• Europe floods

• China gets drought, floods and locusts

• Eurasian steppes get megadrought, so nomads invade all neighbors

• Then the rain belts cycle back

1717thth century famines finally century famines finally drive high-yield farmingdrive high-yield farming

Ancients’ response to climate change:Ancients’ response to climate change:the gods were angrythe gods were angry

The 1,500-yr Cycle says:The 1,500-yr Cycle says:

• With high-yield farming, we can feed the people.• With higher yield farming we need plow no more

wildlands.• We are more sustainable than the pessimists

believe.• With agricultural research, we can be more

sustainable than we ever dared believe—until now.

•

We finally know what happened!We finally know what happened!

• The failed cultures starved due to abrupt climate change—inflicted by Mother Nature!

• No lurking flaw in humans.

• No human-induced “tipping points.”

• Just inadequate farm technology in the past.

We can do even betterWe can do even better

Bill Gates has it right:Bill Gates has it right:

• Invest in agricultural research

• Use biotechnology

• Use energy miles to transport crops from where they grow best

• Use more nitrogen fertilizer

• Human sustainability is growing lots of food per acre!!

But the Anasazi starved during the But the Anasazi starved during the Medieval WarmingMedieval Warming

Megadrought and they lived in forts! Megadrought and they lived in forts! Abrupt climate change can happen Abrupt climate change can happen

anytime.anytime.

!!

Restart the high yield farming research yesterday!!

Books by Dennis Books by Dennis AveryAvery

Climate & Collapse: Abrupt Climate Change Thru History (forthcoming)

Unstoppable Global Warming--Every 1,500 Yrs (2007)

Saving the Planet with Pesticides and Plastic

(2005)