Not an argument for the fact it's driven by human activity. However it suggests that you paint the past climate as some harmonious system on short time ranges:
>the 8.2-kiloyear event was a sudden decrease in global temperatures that occurred approximately 8,200 years before the present, or c. 6,200 BC, and which lasted for the next two to four centuries.
>[...]
>Estimates of the cooling vary and depend somewhat on the interpretation of the proxy data, but decreases of around 1 to 5 °C (1.8 to 9.0 °F) have been reported.
>Starting around 2200 BC, it probably lasted the entire 22nd century BC. It has been hypothesised to have caused the collapse of the Old Kingdom in Egypt, the Akkadian Empire in Mesopotamia, and the Liangzhu culture in the lower Yangtze River area.[4][5] The drought may also have initiated the collapse of the Indus Valley Civilisation, with some of its population moving southeastward to follow the movement of their desired habitat,[6] as well as the migration of Indo-European-speaking people into India.
>The African humid period (AHP; also known by other names) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses, trees and lakes was caused by changes in the Earth's axial tilt; changes in vegetation and dust in the Sahara which strengthened the African monsoon; and increased greenhouse gases.
>One study in 2003 showed that vegetation intrusions in the Sahara can occur within decades after strong rises in atmospheric carbon dioxide[952] but would not cover more than about 45% of the Sahara.[53] That climate study also indicated that vegetation expansion can only occur if grazing or other perturbations to vegetation growth do not hamper it.[953] On the other hand, increased irrigation and other measures to increase vegetation growth such as the Great Green Wall could enhance it.[950] A 2022 study indicated that while increased greenhouse gas concentrations by themselves are not sufficient to start an AHP if greenhouse gas-vegetation feedbacks are ignored, they lower the threshold for orbital changes to induce Sahara greening.
Not an argument for the fact it's driven by human activity. However it suggests that you paint the past climate as some harmonious system on short time ranges:
https://en.wikipedia.org/wiki/8.2-kiloyear_event
>the 8.2-kiloyear event was a sudden decrease in global temperatures that occurred approximately 8,200 years before the present, or c. 6,200 BC, and which lasted for the next two to four centuries.
>[...]
>Estimates of the cooling vary and depend somewhat on the interpretation of the proxy data, but decreases of around 1 to 5 °C (1.8 to 9.0 °F) have been reported.
https://en.wikipedia.org/wiki/4.2-kiloyear_event
>Starting around 2200 BC, it probably lasted the entire 22nd century BC. It has been hypothesised to have caused the collapse of the Old Kingdom in Egypt, the Akkadian Empire in Mesopotamia, and the Liangzhu culture in the lower Yangtze River area.[4][5] The drought may also have initiated the collapse of the Indus Valley Civilisation, with some of its population moving southeastward to follow the movement of their desired habitat,[6] as well as the migration of Indo-European-speaking people into India.
https://en.wikipedia.org/wiki/African_humid_period
>The African humid period (AHP; also known by other names) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses, trees and lakes was caused by changes in the Earth's axial tilt; changes in vegetation and dust in the Sahara which strengthened the African monsoon; and increased greenhouse gases.
>One study in 2003 showed that vegetation intrusions in the Sahara can occur within decades after strong rises in atmospheric carbon dioxide[952] but would not cover more than about 45% of the Sahara.[53] That climate study also indicated that vegetation expansion can only occur if grazing or other perturbations to vegetation growth do not hamper it.[953] On the other hand, increased irrigation and other measures to increase vegetation growth such as the Great Green Wall could enhance it.[950] A 2022 study indicated that while increased greenhouse gas concentrations by themselves are not sufficient to start an AHP if greenhouse gas-vegetation feedbacks are ignored, they lower the threshold for orbital changes to induce Sahara greening.