[5] While Oldest Dryas was still significantly colder than the current epoch, the Holocene, globally it was a period of warming from the very cold Last Glacial Maximum, caused by a gradual increase in CO2 concentrations.

[1] For human populations of the Northern Hemisphere, Bølling–Allerød Interstadial had represented the first pronounced warming since the end of the Last Glacial Maximum (LGM).

In contrast, the rest of the glacial period was so cold that the dominant plant in the area was a small, cold-adapted flower called Dryas octopetala.

[3] Additional evidence for this period involves the gathering of oxygen isotope stages (OIS) from stratified deep-sea sediment cores.

[18] It raised temperatures in the northern Atlantic region to almost present-day levels, before they declined again in the Younger Dryas, which was followed by the present warm Holocene.

The authors postulated that this warm salty water (WSW) layer, situated beneath the colder surface freshwater in the North Atlantic, generated ocean convective available potential energy (OCAPE) over decades at the end of HS1.

[24] The deep oceans were depleted in radiocarbon during the deglaciation following the LGM, which has been hypothesised to be the result of sluggish meridional overturning circulation or due to a release of volcanic carbon or methane clathrates into abyssal waters.

[38][39] As the Fennoscandian ice sheet continued to shrink, plants and people began to repopulate the freshly deglaciated areas of southern Scandinavia.

[41] Periglacial loess-steppe environments prevailed across the East European Plain, but climates improved slightly during several brief interstadials and began to warm significantly after the beginning of the Late Glacial Maximum.

Kostenki archaeological sites of multiple occupation layers persist from the Last Glacial Maximum on the eastern edge of the Central Russian Upland, along the Don River.

[42] The time of the Epigravettian also reveals evidence for tailored clothing production, a tradition persisting from preceding Upper Paleolithic archaeological horizons.

Fur-bearing small mammal remains abound such as Arctic fox and paw bones of hares, reflecting pelt removal.

Insights into the technology of the time can also be seen in features such as structures, pits, and hearths mapped on open-air occupation areas scattered across the East European Plain.

In the southwest region around the middle Dnestr Valley, sites are dominated by reindeer and horse, accounting for 80 to 90% of the identifiable large mammal remains.

That is what forced human groups to remain dispersed and mobile, as is reflected in the lithic technology, as tiny blades were typically manufactured, often termed microblades less than 8 mm wide with unusually sharp edges indicating frugality from low resource levels.

[37] δ18O records from Valmiki Cave in southern India indicate extreme shifts in Indian Summer Monsoon intensity at Termination 1a, which marks the start of the Bølling–Allerød and occurred about 14,800 BP.

[43] In the Middle East, the pre-agricultural Natufian settled around the Eastern Mediterranean coast to exploit wild cereals, such as emmer and two-row barley.

Clear skies reduced precipitation, and loess deposition promoted well-drained, nutrient-rich soils that supported diverse steppic plant communities and herds of large grazing mammals.

Cold temperatures and massive ice sheets covered most of Canada and the northwest coast, thus preventing human colonization of North America prior to 16,000 years ago.

Rising temperatures and increased moisture accelerated environmental change after 14,000 years ago, as shrub tundra replaced dry steppe in many parts of Beringia.

In central Alaska up the northern foothills at the Dry Creek site c. 13,500-13,000 years ago near Nenana Valley, small bifacial points were found.

The European distribution of Y-chromosome haplogroup I and various associated subclades has also been explained as resulting from male postglacial recolonization of Europe from refugia in the Balkans, Iberia, and the Ukraine/Central Russian Plain.

[48] The distribution of mtDNA haplogroup H has been postulated as representing the major female repopulating of Europe from the Franco-Cantabrian region after the Last Glacial Maximum.