Last Glacial Maximum in the context of "Sea surface temperature"

The continent of Australia, sometimes known in technical contexts as Sahul (/səˈhuːl/), Australia-New Guinea, Australinea, or Meganesia to distinguish it from the country of Australia, is located within the Southern and Eastern hemispheres, near the Maritime Southeast Asia. The continent includes mainland Australia, Tasmania, the island of New Guinea (Papua New Guinea and Western New Guinea), the Aru Islands, the Ashmore and Cartier Islands, most of the Coral Sea Islands, and some other nearby islands. Situated in the geographical region of Oceania, more specifically in the subregion of Australasia, Australia is the smallest of the seven traditional continents.

The continent includes a continental shelf overlain by shallow seas which divide it into several landmasses—the Arafura Sea and Torres Strait between mainland Australia and New Guinea, and Bass Strait between mainland Australia and Tasmania. When sea levels were lower during the Pleistocene ice age, including the Last Glacial Maximum about 18,000 BC, they were connected by dry land into the combined landmass of Sahul. The name "Sahul" derives from the Sahul Shelf, which is a part of the continental shelf of the Australian continent. During the past 18,000 to 10,000 years, rising sea levels overflowed the lowlands and separated the continent into today's low-lying arid to semi-arid mainland and the two mountainous islands of New Guinea and Tasmania. With a total land area of 8.56 million square kilometres (3,310,000 sq mi), the Australian continent is the smallest, lowest, flattest, and second-driest continent (after Antarctica) on Earth. As the country of Australia is mostly on a single landmass, and comprises most of the continent, it is sometimes informally referred to as an island continent, surrounded by oceans.

Cro-Magnons or European early modern humans (EEMH) were the first early modern humans (Homo sapiens) to settle in Europe and North Africa, migrating from Western Asia, continuously occupying the continent possibly from as early as 56,800 years ago. They interacted and interbred with the indigenous Neanderthals (H. neanderthalensis) of Europe and Western Asia, who went extinct 35,000 to 40,000 years ago. The first wave of modern humans in Europe (Initial Upper Paleolithic) left no genetic legacy to modern Europeans; however, from 37,000 years ago a second wave succeeded in forming a single founder population, from which all subsequent Cro-Magnons descended and which contributes ancestry to a majority of present-day Europeans, West Asians as well as some North Africans. Cro-Magnons produced Upper Palaeolithic cultures, the first major one being the Aurignacian, which was succeeded by the Gravettian by 30,000 years ago. The Gravettian split into the Epi-Gravettian in the east and Solutrean in the west, due to major climatic degradation during the Last Glacial Maximum (LGM), peaking 21,000 years ago. As Europe warmed, the Solutrean evolved into the Magdalenian by 20,000 years ago, and these peoples recolonised Europe. The Magdalenian and Epi-Gravettian gave way to Mesolithic cultures as big game animals were dying out, and the Last Glacial Period drew to a close.

Cro-Magnons were generally more robust than most living populations, having larger brains, broader faces, more prominent brow ridges, and bigger teeth. The earliest Cro-Magnon specimens also exhibit some features that are reminiscent of those found in Neanderthals. The first Cro-Magnons would have generally had darker skin tones than most modern Europeans and some West Asians and North Africans; natural selection for lighter skin would not have begun until 30,000 years ago. Before the LGM, Cro-Magnons had overall low population density, tall stature similar to post-industrial humans, and expansive trade routes stretching as long as 900 km (560 mi), and hunted big game animals. Cro-Magnons had much higher populations than the Neanderthals, possibly due to higher fertility rates; life expectancy for both species was typically under 40 years. Following the LGM, population density increased as communities travelled less frequently (though for longer distances), and the need to feed so many more people in tandem with the increasing scarcity of big game caused them to rely more heavily on small or aquatic game (broad spectrum revolution), and to more frequently participate in game drive systems and slaughter whole herds at a time. The Cro-Magnon arsenal included spears, spear-throwers, harpoons, and possibly throwing sticks and Palaeolithic dogs. Cro-Magnons likely commonly constructed temporary huts while moving around, and Gravettian peoples notably made large huts on the East European Plain out of mammoth bones.

The sea level has been rising since the end of the Last Glacial Maximum, which was around 20,000 years ago. Between 1901 and 2018, the average sea level rose by 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This was faster than the sea level had ever risen over at least the past 3,000 years. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022. Climate change due to human activities is the main cause of this persistent acceleration. Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise, with another 42% resulting from thermal expansion of water.

Sea level rise lags behind changes in the Earth's temperature by decades, and sea level rise will therefore continue to accelerate between now and 2050 in response to warming that has already happened. What happens after that depends on future human greenhouse gas emissions. If there are very deep cuts in emissions, sea level rise would slow between 2050 and 2100. The reported factors of increase in flood hazard potential are often exceedingly large, ranging from 10 to 1000 for even modest sea-level rise scenarios of 0.5 m or less. It could then reach by 2100 between 30 cm (1 ft) and 1.0 m (3+1⁄3 ft) from now and approximately 60 cm (2 ft) to 130 cm (4+1⁄2 ft) from the 19th century. With high emissions it would instead accelerate further, and could rise by 50 cm (1.6 ft) or even by 1.9 m (6.2 ft) by 2100. In the long run, sea level rise would amount to 2–3 m (7–10 ft) over the next 2000 years if warming stays to its current 1.5 °C (2.7 °F) over the pre-industrial past. It would be 19–22 metres (62–72 ft) if warming peaks at 5 °C (9.0 °F).

The Mesolithic (Greek: μέσος, mesos 'middle' + λίθος, lithos 'stone') or Middle Stone Age is the Old World archaeological period between the Upper Paleolithic and the Neolithic. The term Epipaleolithic is often used synonymously, especially for outside northern Europe, and for the corresponding period in the Levant and Caucasus. The Mesolithic has different time spans in different parts of Eurasia. It refers to the final period of hunter-gatherer cultures in Europe and the Middle East, between the end of the Last Glacial Maximum and the Neolithic Revolution. In Europe it spans roughly 15,000 to 5,000 BP; in the Middle East (the Epipalaeolithic Near East) roughly 20,000 to 10,000 BP. The term is less used of areas farther east, and not at all of those beyond Eurasia and North Africa.

The type of culture associated with the Mesolithic varies between areas, but it is associated with a decline in the group hunting of large animals in favour of a broader hunter-gatherer way of life, and the development of more sophisticated and typically smaller lithic tools and weapons than the heavy-chipped equivalents typical of the Paleolithic. Depending on the region, some use of pottery and textiles may be found in sites allocated to the Mesolithic, but generally indications of agriculture are taken as marking transition into the Neolithic. The more permanent settlements tend to be close to the sea or inland waters offering a good supply of food. Mesolithic societies are not seen as very complex, and burials are fairly simple; in contrast, grandiose burial mounds are a mark of the Neolithic.

An ecosystem, short for ecological system, is defined as a collection of interacting organisms within a biophysical environment. Ecosystems are never static, and are continually subject to both stabilizing and destabilizing processes. Stabilizing processes allow ecosystems to adequately respond to destabilizing changes, or perturbations, in ecological conditions, or to recover from degradation induced by them. Yet, if destabilizing processes become strong enough or fast enough to cross a critical threshold within that ecosystem, often described as an ecological 'tipping point', then an ecosystem collapse (sometimes also termed ecological collapse) occurs.

Ecosystem collapse does not mean total disappearance of life from the area, but it does result in the loss of the original ecosystem's defining characteristics, typically including the ecosystem services it may have provided. Collapse of an ecosystem is effectively irreversible more often than not, and even if the reversal is possible, it tends to be slow and difficult. Ecosystems with low resilience may collapse even during a comparatively stable time, which then typically leads to their replacement with a more resilient system in the biosphere. However, even resilient ecosystems may disappear during the times of rapid environmental change, and study of the fossil record was able to identify how certain ecosystems went through a collapse, such as with the Carboniferous rainforest collapse or the collapse of Lake Baikal and Lake Hovsgol ecosystems during the Last Glacial Maximum.

The 6th millennium BC spanned the years 6000 BC to 5001 BC (c. 8 ka to c. 7 ka). It is impossible to precisely date events that happened around the time of this millennium and all dates mentioned here are estimates mostly based on geological and anthropological analysis. The only exceptions are the felling dates for some construction timbers from Neolithic wells in Central Europe.

This millennium is reckoned to mark the end of the global deglaciation, which had followed the Last Glacial Maximum and caused sea levels to rise by some 60 m (200 ft) over a period of about 5,000 years.

It is believed that the peopling of the Americas began when Paleolithic hunter-gatherers (Paleo-Indians) entered North America from the North Asian Mammoth steppe via the Beringia land bridge, which had formed between northeastern Siberia and western Alaska due to the lowering of sea level during the Last Glacial Maximum (26,000 to 19,000 years ago). These populations expanded south of the Laurentide Ice Sheet, either by sea or land, and spread rapidly southward, occupying both North and South America no later than 14,000 years ago, and possibly before 20,000 years ago. The earliest populations in the Americas, before roughly 10,000 years ago, are known as Paleo-Indians. Indigenous peoples of the Americas have been linked to Siberian populations by proposed linguistic factors, the distribution of blood types, and in genetic composition as reflected by molecular data, such as DNA.

While there is general agreement that the Americas were first settled from Asia, the pattern of migration and the place(s) of origin in Eurasia of the peoples who migrated to the Americas remain unclear. The most generally accepted theory is that Ancient Beringians moved when sea levels were significantly lowered due to the Quaternary glaciation, following herds of now-extinct Pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets. Another proposed route has them migrating down the Pacific coast to South America as far as Chile, either on foot or using boats. Any archaeological evidence of coastal occupation during the last Ice Age would now have been covered by the sea level rise, up to a hundred metres since then.

The Penultimate Glacial Period (PGP) is the glacial period that occurred before the Last Glacial Period. The penultimate glacial period is officially unnamed just like the Last Glacial Period. The PGP lasted from ~194,000 years ago at the end of the Marine Isotope Stage 7 (MIS 7) interglacial, to ~135,000 years ago, and was succeeded by the Last Interglacial. The PGP approximately coincides with Marine Isotope Stage 6 (MIS 6). At the glacial ages' height, it is known to be the most extensive expansion of glaciers in the last 400,000 years over Eurasia, and could be the second or third coolest glacial period over the last 1,000,000 years, as shown by ice cores. Due to this, the global sea level dropped to between 92 and 150 metres below modern-day global mean sea level. The penultimate glacial period expanded ice sheets and shifted temperature zones worldwide, which had a variety of effects on the world's environment, and the organisms that lived in it. At its height, the penultimate glacial period was a more severe glaciation than the Last Glacial Maximum. The PGP covers the last period of the Saalian glaciation in Europe, called the Wolstonian Stage in Britain, and is equivalent to the Illinoian in North America.