Eurasia
Eurasia (/jʊəˈreɪʒə/, also UK: /-ʃə/) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago and the Russian Far East to the east. The continental landmass is bordered by the Atlantic Ocean and Africa to the west, the Pacific Ocean to the east, the Arctic Ocean to the north, and by Africa, the Mediterranean Sea, and the Indian Ocean to the south. The division between Europe and Asia as two continents is a historical social construct, as many of their borders are over land; thus, in some parts of the world, Eurasia is recognized as the largest of the six, five, or four continents on Earth. In geology, Eurasia is often considered as a single rigid megablock. However, the rigidity of Eurasia is debated based on paleomagnetic data.
Eurasia covers around 55 million square kilometres (21 million square miles), or around 36.2% of the Earth's total land area. It is also home to the largest country in the world, Russia. The landmass contains well over 5 billion people, equating to approximately 70% of the human population. Humans first settled in Eurasia between 60,000 and 125,000 years ago. Some major islands, including Great Britain, Iceland, Ireland, and Sri Lanka, and parts of Japan, the Philippines, and most of Indonesia, are often included in the popular definition of Eurasia, despite being separate from the contiguous landmass.
According to some geographers, physiographically, Eurasia is a single continent. The concepts of Europe and Asia as distinct continents date back to antiquity, but their borders are geologically arbitrary and have historically been subjected to occasional change. Eurasia is connected to Africa at the Suez Canal, and Eurasia is sometimes combined with Africa to make the largest contiguous landmass on Earth, called Afro-Eurasia. Due to the vast landmass and differences in latitude, Eurasia exhibits all types of climates under the Köppen classification, including the harshest types of hot and cold temperatures, high and low precipitation, and various types of ecosystems.
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area. With 1.4 billion people as of 2021, it accounts for about 18% of the world's human population. Africa's population is the youngest amongst all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Despite a wide range of natural resources, Africa is the least wealthy continent per capita and second-least wealthy by total wealth, behind Oceania. Scholars have attributed this to different factors including geography, climate, tribalism, colonialism, the Cold War, neocolonialism, lack of democracy, and corruption. Despite this low concentration of wealth, recent economic expansion and the large and young population make Africa an important economic market in the broader global context.
The continent is surrounded by the Mediterranean Sea to the north, the Isthmus of Suez and the Red Sea to the northeast, the Indian Ocean to the southeast and the Atlantic Ocean to the west. The continent includes Madagascar and various archipelagos. It contains 54 fully recognised sovereign states, eight territories and two de facto independent states with limited or no recognition. Algeria is Africa's largest country by area, and Nigeria is its largest by population. African nations cooperate through the establishment of the African Union, which is headquartered in Addis Ababa.
Africa straddles the equator and the prime meridian. It is the only continent to stretch from the northern temperate to southern temperate zones. The majority of the continent and its countries are in the Northern Hemisphere, with a substantial portion and number of countries in the Southern Hemisphere. Most of the continent lies in the tropics, except for a large part of Western Sahara, Algeria, Libya and Egypt, the northern tip of Mauritania, the entire territories of Morocco, Ceuta, Melilla, and Tunisia which in turn are located above the tropic of Cancer, in the northern temperate zone. In the other extreme of the continent, southern Namibia, southern Botswana, great parts of South Africa, the entire territories of Lesotho and Eswatini and the southern tips of Mozambique and Madagascar are located below the tropic of Capricorn, in the southern temperate zone.
Africa is highly biodiverse; it is the continent with the largest number of megafauna species, as it was least affected by the extinction of the Pleistocene megafauna. However, Africa also is heavily affected by a wide range of environmental issues, including desertification, deforestation, water scarcity and pollution. These entrenched environmental concerns are expected to worsen as climate change impacts Africa. The UN Intergovernmental Panel on Climate Change has identified Africa as the continent most vulnerable to climate change.
The history of Africa is long, complex, and has often been under-appreciated by the global historical community. Africa, particularly Eastern Africa, is widely accepted as the place of origin of humans and the Hominidae clade (great apes). The earliest hominids and their ancestors have been dated to around 7 million years ago, including Sahelanthropus tchadensis, Australopithecus africanus, A. afarensis, Homo erectus, H. habilis and H. ergaster— the earliest Homo sapiens (modern human) remains, found in Ethiopia, South Africa, and Morocco, date to circa 233,000, 259,000, and 300,000 years ago respectively, and Homo sapiens is believed to have originated in Africa around 350,000–260,000 years ago. Africa is also considered by anthropologists to be the most genetically diverse continent as a result of being the longest inhabited.
Early human civilizations, such as Ancient Egypt and Carthage emerged in North Africa. Following a subsequent long and complex history of civilizations, migration and trade, Africa hosts a large diversity of ethnicities, cultures and languages. The last 400 years have witnessed an increasing European influence on the continent. Starting in the 16th century, this was driven by trade, including the Trans-Atlantic slave trade, which created large African diaspora populations in the Americas. From the late 19th century to the early 20th century, European nations colonized almost all of Africa, reaching a point when only Ethiopia and Liberia were independent polities. Most present states in Africa emerged from a process of decolonisation following World War II.
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Caribbean Sea, and to the west and south by the Pacific Ocean. Because it is on the North American Tectonic Plate, Greenland is included as a part of North America geographically.
North America covers an area of about 24,709,000 square kilometres (9,540,000 square miles), about 16.5% of Earth's land area and about 4.8% of its total surface. North America is the third-largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 579 million people in 23 independent states, or about 7.5% of the world's population. In human geography and in the English-speaking world outside the United States, particularly in Canada, "North America" and "North American" can refer to just Canada and the United States together.
North America was reached by its first human populations during the Last Glacial Period, via crossing the Bering land bridge approximately 20,000 to 17,000 years ago. The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago (the beginning of the Archaic or Meso-Indian period). The classic stage spans roughly the 6th to 13th centuries. The first recorded Europeans to visit North America (other than Greenland) were the Norse around 1000 AD. Christopher Columbus's arrival in 1492 sparked a transatlantic exchange which included migrations of European settlers during the Age of Discovery and the early modern period. Present-day cultural and ethnic patterns reflect interactions between European colonists, indigenous peoples, African slaves, immigrants from Europe, Asia, and the descendants of these groups.
Owing to Europe's colonization of the Americas, most North Americans speak European languages such as English, Spanish or French, and their cultures commonly reflect Western traditions. However, in parts of Canada, the United States, Mexico, and Central America, there are indigenous populations continuing their cultural traditions and speaking native languages.
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southern subregion of a single continent called America.
South America is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the northwest. The continent generally includes twelve sovereign states: Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Uruguay, and Venezuela; two dependent territories: the Falkland Islands and South Georgia and the South Sandwich Islands; and one internal territory: French Guiana. In addition, the ABC islands of the Kingdom of the Netherlands, Ascension Island (dependency of Saint Helena, Ascension and Tristan da Cunha, a British Overseas Territory), Bouvet Island (dependency of Norway), Panama, and Trinidad and Tobago may also be considered parts of South America.
South America has an area of 17,840,000 square kilometers (6,890,000 sq mi). Its population as of 2021 has been estimated at more than 434 million. South America ranks fourth in area (after Asia, Africa, and North America) and fifth in population (after Asia, Africa, Europe, and North America). Brazil is by far the most populous South American country, with more than half of the continent's population, followed by Colombia, Argentina, Venezuela and Peru. In recent decades, Brazil has also generated half of the continent's GDP and has become the continent's first regional power.
Most of the population lives near the continent's western or eastern coasts while the interior and the far south are sparsely populated. The geography of western South America is dominated by the Andes mountains; in contrast, the eastern part contains both highland regions and vast lowlands where rivers such as the Amazon, Orinoco and Paraná flow. Most of the continent lies in the tropics, except for a large part of the Southern Cone located in the middle latitudes.
The continent's cultural and ethnic outlook has its origin with the interaction of indigenous peoples with European conquerors and immigrants and, more locally, with African slaves. Given a long history of colonialism, the overwhelming majority of South Americans speak Spanish or Portuguese, and societies and states are rich in Western traditions. Relative to Europe, Asia and Africa, 20th-century South America has been a peaceful continent with few wars.
Australia/Oceania
The continent of Australia, sometimes known in technical contexts by the names Sahul (/səˈhuːl/), Australia-New Guinea, Australinea, Meganesia, or Papualand to distinguish it from the country of Australia, is located within the Southern and Eastern hemispheres. The name "Sahul" takes its name from the Sahul Shelf, which is a part of the continental shelf of the Australian continent. The continent includes mainland Australia, Tasmania, the island of New Guinea (Papua New Guinea and Indonesian 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, 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. 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.
Papua New Guinea, a country within the continent, is one of the most culturally and linguistically diverse countries in the world. It is also one of the most rural, as only 18 percent of its people live in urban centres. West Papua, a province of Indonesia, is home to an estimated 44 uncontacted tribal groups. Australia, the largest landmass in the continent, is highly urbanised, and has the world's 14th-largest economy with the second-highest human development index globally. Australia also has the world's 9th largest immigrant population.
Antarctica
Antarctica (/ænˈtɑːrktɪkə/ (listen)) is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of 14,200,000 km2 (5,500,000 sq mi). Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of 1.9 km (1.2 mi).
Antarctica is on average the coldest, driest, and windiest of the continents, and it has the highest average elevation. It is mainly a polar desert, with annual precipitation of over 200 mm (8 in) along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which if melted would raise global sea levels by almost 60 metres (200 ft). Antarctica holds the record for the lowest measured temperature on Earth, −89.2 °C (−128.6 °F). The coastal regions can reach temperatures over 10 °C (50 °F) in summer. Native species of animals include mites, nematodes, penguins, seals and tardigrades. Where vegetation occurs, it is mostly in the form of lichen or moss.
The ice shelves of Antarctica were probably first seen in 1820, during a russian expedition led by Fabian Gottlieb von Bellingshausen and Mikhail Lazarev. The decades that followed saw further exploration in French, American, and British expeditions. The first confirmed landing was by a Norwegian team in 1895. In the early 20th century, there were a few expeditions into the interior of the continent. British explorers were the first to reach the magnetic South Pole in 1909, and the geographic South Pole was first reached in 1911 by Norwegian explorers.
Antarctica is governed by about 30 countries, all of which are parties of the 1959 Antarctic Treaty System. According to the terms of the treaty, military activity, mining, nuclear explosions, and nuclear waste disposal are all prohibited in Antarctica. Tourism, fishing and research are the main human activities in and around Antarctica. During the summer months, about 5,000 people reside at research stations, a figure that drops to around 1,000 in the winter. Despite its remoteness, human activity has a significant impact on the continent via pollution, ozone depletion and climate change.
