End of Last Ice Age
Around 10,000 BCE, the long cold interval known as the Last Glacial Period was giving way to the warmer conditions of the Holocene. The date is a convenient marker rather than a sharp boundary. The transition unfolded unevenly over several thousand years, and it transformed landscapes, coastlines, plants and animals, and the lives of the people who depended on them. In Europe, where ice sheets had blanketed the north, the change opened up vast territories to resettlement and set the stage for later developments such as farming.
The ice age was not a single deep freeze but a long series of colder and milder swings. At its peak, roughly 26,000 to 20,000 years ago, ice sheets covered Scandinavia, the British Isles' northern reaches, and much of northern Europe, while the Alps held their own glaciers. Sea levels were well over 100 meters lower than today, exposing land such as Doggerland, a plain connecting Britain to the continent. Much of Europe south of the ice was cold, dry steppe or tundra, home to mammoths, woolly rhinoceroses, reindeer and horses, hunted by Upper Paleolithic peoples. Slow changes in Earth's orbit are generally seen as the underlying trigger for warming, amplified by rising greenhouse gases and shrinking ice cover.
Warming began in earnest after about 19,000 years ago, but it was punctuated by abrupt reversals. A warm phase called the Bølling-Allerød gave way to the Younger Dryas, a sharp return to near-glacial conditions in the North Atlantic region lasting roughly 1,000 years. It ended around 11,700 years ago, which is the date scientists commonly use for the start of the Holocene. Its cause remains debated, with meltwater disrupting ocean circulation being the leading hypothesis.
As the ice retreated, tundra gave way to birch and pine, then to broadleaf forests. Many large grazing animals declined or vanished from Europe, including the woolly mammoth on the mainland, through a combination of climate change and, according to some researchers, human hunting. The relative weight of these causes is still argued. People adapted by hunting forest game such as deer and boar, fishing, and gathering plants, a way of life archaeologists call the Mesolithic. Hunter-gatherer groups moved northward into newly habitable lands, including Scandinavia and Britain.
Rising seas gradually flooded low-lying areas. Doggerland shrank and was eventually submerged, turning Britain into an island several millennia later. Similar flooding reshaped coastlines worldwide. In the Near East, the warmer, more stable climate is widely thought to have encouraged the first experiments in cultivating plants and herding animals, practices that later spread into Europe.
The end of the Ice Age stands as the most dramatic natural change in the human past, and it provides scientists today with a detailed record of how climate, ecosystems, and societies respond to global warming.