Some 4,000 years ago, during a period of low atmospheric CO2 levels, the Harappan Civilization collapsed - researchers determined that extreme climate change was the culprit
(click to enlarge image, source)
Read here. The climate doomsday scientists and alarmists have claimed that high levels of atmospheric CO2 levels (from human CO2 emissions) causes extreme climate change and severe weather events.
While there exists no solid evidence that higher atmospheric CO2 levels cause extreme climate change, there is certainly a plethora of evidence that extreme climate change does happen during a low CO2 environment. Case in point: researchers just completed a new study, which determined that the disappearing of the ancient Harappan Civilization was due to extreme climate change - during a low CO2 environment.
"An international, interdisciplinary team of geologists, archeologists, mathematicians and geomorphologists collected samples from the area once occupied by the little-known civilization...analysis suggested that climate change that weakened monsoon rains and tamed the tributaries of the Indus River and reduced run-off from the Himalayan mountains enabled the Harappans to practice agriculture on the river banks...But when monsoon rains began to decline, the rivers and regular flooding the civilization relied on to maintain a strong agriculture dried up, and they were forced to move east toward the Ganges River basin and were no longer able to sustain large cities."