We’ve been warned that man-made global warming will cause unprecedented turmoil within and among the Earth’s human societies. Yet the Earth’s history over the past 2,000 years shows that wars, disease epidemics, and famine were all far more likely when the Earth’s climate was cold.
Equally interesting? The war-likely periods occurred in cycles — clearly tied to the temperature variations during the cold phase of the solar-linked 1,500-year climate cycle.
When an agricultural society suffers cold and cloudy summers, early frosts, and more crop-destroying hailstorms and floods, food production is severely hampered. When food production is reduced year after year, it impacts population numbers through starvation, disease, and warfare.
David Zhang at the University of Hong Kong writes that China’s three historic “peak war clusters” all occurred during cold periods. As did all seven periods of Chinese nationwide social unrest, and nearly 90 percent of changes in its imperial dynasties.
The “peak war” problem impacted both Europe and China during the same cold climate periods — though the two regions were completely separate.
Zhang’s team notes the “General Crisis” of the Earth’s 17th century: The Thirty Years War (1618 to 1648) occurred while nearly every European country had massive crop destruction, famine, and disease. Elsewhere around the globe, internal revolts spread through the Ottoman Empire in the Middle East. Berbers fought Arab immigrants in Mauritania. The Shimabara peasant rebellion occurred in Japan, and the Ming Dynasty collapsed in China.
Earlier, a similar global cold period saw Mediterranean temperatures drop about 1.5 degrees C after 1250 BC. The Mycenaean culture collapsed in Greece, along with the Hittite Empire in the Fertile Crescent and the Harappan culture in the Indus Valley of India. China lost another dynasty, as the Zhou replaced the Shang.
Can such widespread violence and suffering really be tied to weather? Famine speaks for itself.
Cold droughts have repeatedly killed livestock and forced the Mongols to invade northwestern China. They also triggered the Mongols’ invasion of Europe after 1200 AD.
Bubonic Plague depopulated Europe during both the Dark Ages and the Little Ice Age, as cold and drought drove Asian rats carrying the “plague fleas” to hitchhike westward on traders’ ships and camels.
What about our modern warming? We’ve had less than 0.7 degrees C of warming in the 160 years since the Little Ice Age ended. Both the Roman and Medieval Warmings were somewhat warmer than now. The warming cycle typically delivers about half its total warming in its early decades — implying only another 0.7 degrees of warming over the next several centuries. Not enough to disrupt modern crop production.
Dutch researchers recently pointed out that U.S. corn yields have soared 240 percent since 1961, despite rising temperatures. Some seed experts predict they will double again by 2030. Mexican soybeans are averaging higher soybean yields than the U.S. despite higher temperatures, and Brazil is getting higher cotton yields than the U.S. despite much higher Brazilian temperatures.
In addition, higher levels of CO2 in the air will buffer the impact of any warming on agriculture. Doubling the level of CO2 in the air stimulates the growth of crop plants by 30 to 50 percent.
Extended droughts will be the biggest warming danger, but crop water use efficiency will greatly increase through technology that is waiting on the shelf. In the modern world, trade can move food surpluses from Canada to California if necessary.
The outlook for today’s cultures is far brighter than the warfare, disease, and decimated populations that Mother Nature imposed on the Greek Dark Ages (1200–200 BC), the Dark Ages (540–900 AD), and the Little Ice Age (1300–1850 AD).
Rejoice, but fear a future cold cycle.