Meghalayan Stage (Late Holocene, 4.2 ka–present)

The Meghalayan Stage (equivalent to the Late Holocene Subepoch) encompasses the most recent millennia to the present day. Its onset is marked by the “4.2 ka event,” which is recognized across global records as a temperature anomaly with widespread drought conditions at mid- to low latitudes. This most recent stage of the Holocene marks a shift away from the prevailing warm conditions of the Northgrippian Stage (Middle Holocene) with a long-term cooling trajectory that lasted until the onset of recent warming of the industrial era. This cooling trend was marked by amplified instability compared to the preceding Northgrippian Stage. The Meghalayan Stage was punctuated by several climatic events evident across North Atlantic and European records, reflecting shifts between warmer and cooler conditions with spatially variable hydrological impacts. These are events broadly recognized as the Bronze Age Cold Epoch, Bronze Age Optimum, Iron Age Cold Epoch (2.7 ka event), Iron Age Optimum, Roman Warm/Humid Period (c. 350 bce–350 ce), and Dark Ages Cold Period (c. 400–765 ce) including Late Antique Little Ice Age (536–660 ce), Medieval Warm Period/Medieval Climate Anomaly (c. 800–1250 ce), the Little Ice Age (c. 1250–1860 ce), and recent warming since the 19th century and especially over the last 50 years. The drivers of change during this complex and dynamic stage include solar variability (including several “quiet” Sun intervals such as the Maunder Minimum), volcanic eruptions, changes in ocean circulation and sea-ice extent in the North Atlantic, shifts in prevailing modes of climate variability such as the North Atlantic Oscillation and Atlantic Multidecadal Oscillation, and, from the industrial era onward, anthropogenic activity. Almost certainly, interactions and feedbacks between these drivers, operating on different spatial and temporal scales, contribute to the complexity of climate changes of the Meghalayan Stage.