Climate Change has Decimated Societies Around the World
13 hours ago Guest Blogger
By Jim Steele
The Great Famine of the 1870s resulted in 50 million deaths from drought-induced mass starvation across South America, Africa, and Asia. It was an all-natural climate event during colder times with lower CO2 concentrations and those drought-causing climate dynamics are still in play today. To understand if the world could again suffer such a drought, it helps to view climate change from a 10,000-year perspective starting with the African Humid Period. During the Holocene Optimum the Sahara was covered with lakes and rivers and abundant wildlife as depicted by the rock art of the many African societies that thrived in the Sahara (graphics B & C). Then around 6,000 years ago it turned to desert.
In the tropics, rainy and dry seasons alternate depending on the position of the Intertropical Convergence Zone (ITCZ- graphic D). The ITCZ is seen in satellites as a narrow band of clouds where world’s greatest amounts of precipitation fall. The ITCZ is very sensitive to solar heating. During the northern hemisphere’s summer when the sun’s strongest rays move northward, so does the ITCZ. As the sun migrates southward, so does the ITCZ and its band of rains.
A 40,000+ year cycle of the changing tilt of the earth’s axis, referred to as obliquity, also determines how far north and south the suns strongest rays will migrate. Ten thousand years ago the tilt was at a maximum and the ITCZ migrated further north than today, bringing more moisture to the Sahara (graphic F; ITCZ average northern location=yellow dashed line). As the tilt decreases to its minimum, the ITCZ moves southward (graphic G). Thus, as the ITCZ migrated southward, the rains decreased enough over the Humid Sahara to turn it to a desert. The axis tilt will continue to decline for another 10,000 years. Another orbital cycle, precession, contributed to the ITCZ southward migration by causing the southern hemisphere to slightly warm while the northern hemisphere slightly cooled.
https://wattsupwiththat.com/2024/06/16/climate-change-has-decimated-societies-around-the-world/
