![South Penghu Marine National Park (12)](https://upload.wikimedia.org/wikipedia/commons/2/2f/South_Penghu_Marine_National_Park_%2812%29.jpg)
Nature, in the broadest sense, is the
physical
Physical may refer to:
*Physical examination
In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally co ...
world or
universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. Acc ...
. "Nature" can refer to the
phenomena
A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried W ...
of the physical world, and also to life in general. The study of nature is a large, if not the only, part of
science
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earliest archeological evidence for ...
. Although humans are part of nature, human activity is often understood as a separate category from other natural phenomena.
The word ''nature'' is borrowed from the
Old French
Old French (, , ; Modern French: ) was the language spoken in most of the northern half of France from approximately the 8th to the 14th centuries. Rather than a unified language, Old French was a linkage of Romance dialects, mutually intelligib ...
''nature'' and is derived from the
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
word ''natura'', or "essential qualities, innate disposition", and in ancient times, literally meant "
birth
Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...
".
In ancient philosophy, ''natura'' is mostly used as the Latin translation of the Greek word ''
physis
Fusis, Phusis or Physis (; grc, φύσις ) is a Greek philosophical, theological, and scientific term, usually translated into English—according to its Latin translation "natura"—as "nature". The term originated in ancient Greek philosophy, ...
'' (φύσις), which originally related to the intrinsic characteristics of plants, animals, and other features of the world to develop of their own accord.
The concept of nature as a whole, the physical
universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. Acc ...
, is one of several expansions of the original notion;
it began with certain core applications of the word φύσις by
pre-Socratic
Pre-Socratic philosophy, also known as early Greek philosophy, is ancient Greek philosophy before Socrates. Pre-Socratic philosophers were mostly interested in cosmology, the beginning and the substance of the universe, but the inquiries of thes ...
philosophers (though this word had a dynamic dimension then, especially for
Heraclitus
Heraclitus of Ephesus (; grc-gre, Ἡράκλειτος , "Glory of Hera"; ) was an ancient Greek pre-Socratic philosopher from the city of Ephesus, which was then part of the Persian Empire.
Little is known of Heraclitus's life. He wrote ...
), and has steadily gained currency ever since.
During the advent of modern
scientific method
The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific m ...
in the last several centuries, nature became the passive reality, organized and moved by divine laws. With the
Industrial revolution
The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
, nature increasingly became seen as the part of reality deprived from intentional intervention: it was hence considered as sacred by some traditions (
Rousseau
Jean-Jacques Rousseau (, ; 28 June 1712 – 2 July 1778) was a Genevan philosopher, writer, and composer. His political philosophy influenced the progress of the Age of Enlightenment throughout Europe, as well as aspects of the French Revolu ...
, American
transcendentalism
Transcendentalism is a philosophical movement that developed in the late 1820s and 1830s in New England. "Transcendentalism is an American literary, political, and philosophical movement of the early nineteenth century, centered around Ralph Wald ...
) or a mere decorum for
divine providence
In theology, Divine Providence, or simply Providence, is God's intervention in the Universe. The term ''Divine Providence'' (usually capitalized) is also used as a title of God. A distinction is usually made between "general providence", which ...
or human history (
Hegel
Georg Wilhelm Friedrich Hegel (; ; 27 August 1770 – 14 November 1831) was a German philosopher. He is one of the most important figures in German idealism and one of the founding figures of modern Western philosophy. His influence extends a ...
,
Marx
Karl Heinrich Marx (; 5 May 1818 – 14 March 1883) was a German philosopher, economist, historian, sociologist, political theorist, journalist, critic of political economy, and socialist revolutionary. His best-known titles are the 1848 p ...
). However, a
vitalist
Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...
vision of nature, closer to the presocratic one, got reborn at the same time, especially after
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...
.
Within the various uses of the word today, "nature" often refers to
geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
and
wildlife
Wildlife refers to domestication, undomesticated animal species (biology), species, but has come to include all organisms that grow or live wilderness, wild in an area without being species, introduced by humans. Wildlife was also synonymous ...
. Nature can refer to the general realm of living plants and animals, and in some cases to the processes associated with inanimate objects—the way that particular types of things exist and change of their own accord, such as the weather and geology of the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. It is often taken to mean the "
natural environment
The natural environment or natural world encompasses all life, living and non-living things occurring nature, naturally, meaning in this case not Artificiality, artificial. The term is most often applied to the Earth or some parts of Earth. Th ...
" or
wilderness
Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any nonurbanized land not under extensive agricultural cultivation. The term has traditionally re ...
—wild animals, rocks, forest, and in general those things that have not been substantially altered by human intervention, or which persist despite human intervention. For example, manufactured objects and human interaction generally are not considered part of nature, unless qualified as, for example, "human nature" or "the whole of nature". This more traditional concept of natural things that can still be found today implies a distinction between the natural and the artificial, with the artificial being understood as that which has been brought into being by a human
consciousness
Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scien ...
or a human
mind
The mind is the set of faculties responsible for all mental phenomena. Often the term is also identified with the phenomena themselves. These faculties include thought, imagination, memory, will, and sensation. They are responsible for various m ...
. Depending on the particular context, the term "natural" might also be distinguished from the
unnatural or the
supernatural
Supernatural refers to phenomena or entities that are beyond the laws of nature. The term is derived from Medieval Latin , from Latin (above, beyond, or outside of) + (nature) Though the corollary term "nature", has had multiple meanings si ...
.
Earth
![The Earth seen from Apollo 17](https://upload.wikimedia.org/wikipedia/commons/9/97/The_Earth_seen_from_Apollo_17.jpg)
Earth is the only
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
known to support
life
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energ ...
, and its natural features are the subject of many fields of scientific research. Within the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
, it is third closest to the Sun; it is the largest
terrestrial planet
A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Sun: Mercury, Ve ...
and the fifth largest overall. Its most prominent climatic features are its two large polar regions, two relatively narrow
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
zones, and a wide
equator
The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
ial tropical to
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
region.
Precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
varies widely with location, from several metres of water per year to less than a millimetre. 71 percent of the Earth's surface is covered by salt-water oceans. The remainder consists of continents and islands, with most of the inhabited land in the
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
.
Earth has evolved through geological and biological processes that have left traces of the original conditions. The
outer surface is divided into several gradually migrating
tectonic plate
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
s. The interior remains active, with a thick layer of plastic
mantle and an iron-filled core that generates a
magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
. This iron core is composed of a solid inner phase, and a fluid outer phase. Convective motion in the core generates electric currents through dynamo action, and these, in turn, generate the geomagnetic field.
The
atmospheric
An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
conditions have been significantly altered from the original conditions by the presence of life-forms, which create an ecological balance that stabilizes the surface conditions. Despite the wide regional variations in climate by
latitude
In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...
and other geographic factors, the long-term average global climate is quite stable during interglacial periods, and variations of a degree or two of average global temperature have historically had major effects on the ecological balance, and on the actual geography of the Earth.
Geology
Geology is the science and study of the solid and liquid matter that constitutes the Earth. The field of geology encompasses the study of the composition,
structure
A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...
,
physical properties
A physical property is any property that is measurable, whose value describes a state of a physical system. The changes in the physical properties of a system can be used to describe its changes between momentary states. Physical properties are o ...
, dynamics, and
history
History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the History of writing#Inventions of writing, invention of writing systems is considered prehistory. "History" is an umbr ...
of
Earth materials Earth materials include minerals, rocks, soil and water. These are the naturally occurring materials found on Earth that constitute the raw materials upon which our global society exists. Earth materials are vital resources that provide the basic c ...
, and the processes by which they are formed, moved, and changed. The field is a major
academic discipline
An academy ( Attic Greek: Ἀκαδήμεια; Koine Greek Ἀκαδημία) is an institution of secondary or tertiary higher learning (and generally also research or honorary membership). The name traces back to Plato's school of philosophy ...
, and is also important for
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
and
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...
extraction, knowledge about and mitigation of
natural hazard
A natural hazard is a natural phenomenon that might have a negative effect on humans and other animals, or the environment. Natural hazard events can be classified into two broad categories: geophysical and biological.
An example of the distinct ...
s, some
Geotechnical engineering
Geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rock mechanics for the solution of its respective engineering problems. It als ...
fields, and understanding
past climates
Paleoclimatology (British spelling, palaeoclimatology) is the study of climates for which direct measurements were not taken. As instrumental records only span a tiny part of Earth's history, the reconstruction of ancient climate is important to ...
and environments.
Geological evolution
![Tectonic plate boundaries](https://upload.wikimedia.org/wikipedia/commons/4/40/Tectonic_plate_boundaries.png)
The geology of an area evolves through time as rock units are deposited and inserted and deformational processes change their shapes and locations.
Rock units are first emplaced either by
deposition onto the surface or intrude into the
overlying rock
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the l ...
. Deposition can occur when
sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
s settle onto the surface of the Earth and later
lithify
Diagenesis () is the process that describes physical change, physical and chemical changes in sediments first caused by water-rock interactions, microbial activity, and compaction after their deposition (geology), deposition. Increased pressure ...
into
sedimentary rock
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
, or when as
volcanic material
A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface.
On Ear ...
such as
volcanic ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used t ...
or
lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...
flows, blanket the surface. Igneous
intrusion
In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...
s such as
batholith
A batholith () is a large mass of intrusive igneous rock (also called plutonic rock), larger than in area, that forms from cooled magma deep in Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such ...
s,
laccolith
A laccolith is a body of intrusive rock with a dome-shaped upper surface and a level base, fed by a conduit from below. A laccolith forms when magma (molten rock) rising through the Earth's crust begins to spread out horizontally, prying ap ...
s,
dikes
Dyke (UK) or dike (US) may refer to:
General uses
* Dyke (slang), a slang word meaning "lesbian"
* Dike (geology), a subvertical sheet-like intrusion of magma or sediment
* Dike (mythology), ''Dikē'', the Greek goddess of moral justice
* Dikes, ...
, and
sills, push upwards into the overlying rock, and crystallize as they intrude.
After the initial sequence of rocks has been deposited, the rock units can be
deformed and/or
metamorphosed
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
. Deformation typically occurs as a result of horizontal shortening,
horizontal extension, or side-to-side (
strike-slip
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
) motion. These structural regimes broadly relate to
convergent boundaries
A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...
,
divergent boundaries, and
transform boundaries, respectively, between
tectonic plates
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
.
Historical perspective
![Pangea animation 03](https://upload.wikimedia.org/wikipedia/commons/8/8e/Pangea_animation_03.gif)
Earth is estimated to have formed 4.54 billion years ago from the
solar nebula
The formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a ...
, along with the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
and other
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
s. The Moon formed roughly 20 million years later. Initially molten, the outer layer of the Earth cooled, resulting in the solid crust. Outgassing and
volcanic
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates a ...
activity produced the primordial atmosphere. Condensing
water vapor
(99.9839 °C)
, -
, Boiling point
,
, -
, specific gas constant
, 461.5 J/( kg·K)
, -
, Heat of vaporization
, 2.27 MJ/kg
, -
, Heat capacity
, 1.864 kJ/(kg·K)
Water vapor, water vapour or aqueous vapor is the gaseous pha ...
, most or all of which came from
ice
Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...
delivered by
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...
s,
produced the oceans and other water sources. The highly energetic chemistry is believed to have produced a self-replicating molecule around 4 billion years ago.
![Hyperia](https://upload.wikimedia.org/wikipedia/commons/e/e0/Hyperia.jpg)
Continents formed, then broke up and reformed as the surface of Earth reshaped over hundreds of millions of years, occasionally combining to make a
supercontinent
In geology, a supercontinent is the assembly of most or all of Earth's continent, continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", ...
. Roughly 750 million years ago, the earliest known supercontinent
Rodinia
Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago.
were probably ...
, began to break apart. The continents later recombined to form
Pannotia
Pannotia (from Greek: '' pan-'', "all", '' -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neoproterozoic supercontinent ...
which broke apart about 540 million years ago, then finally
Pangaea
Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
, which broke apart about 180 million years ago.
During the
Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago.
It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is ...
era, freezing temperatures covered much of the Earth in
glacier
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...
s and ice sheets. This hypothesis has been termed the "
Snowball Earth
The Snowball Earth hypothesis proposes that, during one or more of Earth's Greenhouse and icehouse Earth, icehouse Climate, climates, the Earth's surface, planet's surface became entirely or nearly entirely Freezing, frozen. It is believed that ...
", and it is of particular interest as it precedes the
Cambrian explosion
The Cambrian explosion, Cambrian radiation, Cambrian diversification, or the Biological Big Bang refers to an interval of time approximately in the Cambrian Period when practically all major animal phyla started appearing in the fossil recor ...
in which multicellular life forms began to proliferate about 530–540 million years ago.
Since the Cambrian explosion there have been five distinctly identifiable
mass extinctions
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It ...
. The last mass extinction occurred some 66 million years ago, when a meteorite collision probably triggered the extinction of the
non-avian dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
s and other large reptiles, but spared small animals such as
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s. Over the past 66 million years, mammalian life diversified.
Several million years ago, a species of small African
ape
Apes (collectively Hominoidea ) are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and as well as Europe in prehistory), which together with its siste ...
gained the ability to stand upright.
The subsequent advent of human life, and the development of agriculture and further
civilization
A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system).
Ci ...
allowed humans to affect the Earth more rapidly than any previous life form, affecting both the nature and quantity of other organisms as well as global climate. By comparison, the
Great Oxygenation Event
The Great Oxidation Event (GOE), also called the Great Oxygenation Event, the Oxygen Catastrophe, the Oxygen Revolution, the Oxygen Crisis, or the Oxygen Holocaust, was a time interval during the Paleoproterozoic era when the Earth's atmosphere ...
, produced by the proliferation of
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
during the
Siderian
The Siderian Period (; grc, σίδηρος, sídēros, meaning "iron") is the first geologic period in the Paleoproterozoic Era and lasted from Ma to Ma (million years ago). Instead of being based on stratigraphy, these dates are defined chro ...
period, required about 300 million years to culminate.
The present era is classified as part of a mass
extinction event
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. I ...
, the
Holocene extinction
The Holocene extinction, or Anthropocene extinction, is the ongoing extinction event during the Holocene epoch. The extinctions span numerous families of bacteria, fungi, plants, and animals, including mammals, birds, reptiles, amphibians, f ...
event, the fastest ever to have occurred. Some, such as
E. O. Wilson
Edward Osborne Wilson (June 10, 1929 – December 26, 2021) was an American biologist, naturalist, entomologist and writer. According to David Attenborough, Wilson was the world's leading expert in his specialty of myrmecology, the study of an ...
of
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...
, predict that human destruction of the
biosphere
The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also be ...
could cause the extinction of one-half of all species in the next 100 years. The extent of the current extinction event is still being researched, debated and calculated by biologists.
Atmosphere, climate, and weather
![Top of Atmosphere](https://upload.wikimedia.org/wikipedia/commons/b/be/Top_of_Atmosphere.jpg)
The Earth's atmosphere is a key factor in sustaining the
ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
. The thin layer of gases that envelops the Earth is held in place by gravity. Air is mostly
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
,
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
,
water vapor
(99.9839 °C)
, -
, Boiling point
,
, -
, specific gas constant
, 461.5 J/( kg·K)
, -
, Heat of vaporization
, 2.27 MJ/kg
, -
, Heat capacity
, 1.864 kJ/(kg·K)
Water vapor, water vapour or aqueous vapor is the gaseous pha ...
, with much smaller amounts of carbon dioxide, argon, etc. The atmospheric pressure declines steadily with altitude. The
ozone layer
The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in rela ...
plays an important role in depleting the amount of
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
(UV) radiation that reaches the surface. As
DNA is readily damaged by UV light, this serves to protect life at the surface. The atmosphere also retains heat during the night, thereby reducing the daily temperature extremes.
Terrestrial weather occurs almost exclusively in the
lower part of the atmosphere, and serves as a convective system for redistributing heat.
Ocean current
An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, s ...
s are another important factor in determining climate, particularly the major underwater
thermohaline circulation
Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. The adjective ''thermohaline'' derives from '' thermo-'' referring to temper ...
which distributes heat energy from the equatorial oceans to the polar regions. These currents help to moderate the differences in temperature between winter and summer in the temperate zones. Also, without the redistributions of heat energy by the ocean currents and atmosphere, the tropics would be much hotter, and the
polar region
The polar regions, also called the frigid geographical zone, zones or polar zones, of Earth are the regions of the planet that surround its geographical poles (the North Pole, North and South Poles), lying within the polar circles. These high l ...
s much colder.
![Lightnings sequence 2 animation-wcag](https://upload.wikimedia.org/wikipedia/commons/6/67/Lightnings_sequence_2_animation-wcag.gif)
Weather can have both beneficial and harmful effects. Extremes in weather, such as
tornado
A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, altho ...
es or
hurricane
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
s and
cyclone
In meteorology, a cyclone () is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above (opposite to an anti ...
s, can expend large amounts of energy along their paths, and produce devastation. Surface vegetation has evolved a dependence on the seasonal variation of the weather, and sudden changes lasting only a few years can have a dramatic effect, both on the vegetation and on the animals which depend on its growth for their food.
Climate is a measure of the long-term trends in the weather. Various factors are known to
influence the climate, including ocean currents, surface
albedo
Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...
,
greenhouse gas
A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
es, variations in the solar luminosity, and changes to the Earth's orbit. Based on historical records, the Earth is known to have undergone drastic climate changes in the past, including
ice age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...
s.
![Dszpics1](https://upload.wikimedia.org/wikipedia/commons/1/1a/Dszpics1.jpg)
The climate of a region depends on a number of factors, especially
latitude
In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...
. A latitudinal band of the surface with similar climatic attributes forms a climate region. There are a number of such regions, ranging from the
tropical climate
Tropical climate is the first of the five major climate groups in the Köppen climate classification identified with the letter A. Tropical climates are defined by a monthly average temperature of 18 °C (64.4 °F) or higher in the cool ...
at the equator to the
polar climate
The polar climate regions are characterized by a lack of warm summers but with varying winters. Every month in a polar climate has an average temperature of less than . Regions with polar climate cover more than 20% of the Earth's area. Most of ...
in the northern and southern extremes. Weather is also influenced by the seasons, which result from the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
's
axis
An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to:
Mathematics
* Axis of rotation: see rotation around a fixed axis
*Axis (mathematics), a designator for a Cartesian-coordinate ...
being
tilted relative to its
orbital plane
The orbital plane of a revolving body is the geometric plane in which its orbit lies. Three non-collinear points in space suffice to determine an orbital plane. A common example would be the positions of the centers of a massive body (host) an ...
. Thus, at any given time during the summer or winter, one part of the Earth is more directly exposed to the rays of the
sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
. This exposure alternates as the Earth revolves in its orbit. At any given time, regardless of season, the
Northern
Northern may refer to the following:
Geography
* North, a point in direction
* Northern Europe, the northern part or region of Europe
* Northern Highland, a region of Wisconsin, United States
* Northern Province, Sri Lanka
* Northern Range, a ra ...
and
Southern
Southern may refer to:
Businesses
* China Southern Airlines, airline based in Guangzhou, China
* Southern Airways, defunct US airline
* Southern Air, air cargo transportation company based in Norwalk, Connecticut, US
* Southern Airways Express, M ...
Hemispheres experience opposite seasons.
Weather is a
chaotic system
Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to have co ...
that is readily modified by small changes to the
environment
Environment most often refers to:
__NOTOC__
* Natural environment, all living and non-living things occurring naturally
* Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
, so accurate
weather forecasting
Weather forecasting is the application of science and technology forecasting, to predict the conditions of the Earth's atmosphere, atmosphere for a given location and time. People have attempted to predict the weather informally for millennia a ...
is limited to only a few days. Overall, two things are happening worldwide: (1) temperature is increasing on the average; and (2) regional climates have been undergoing noticeable changes.
Water on the Earth
![44 - Iguazu - Décembre 2007](https://upload.wikimedia.org/wikipedia/commons/f/f4/44_-_Iguazu_-_D%C3%A9cembre_2007.jpg)
Water is a
chemical substance
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...
that is composed of
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
and
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
(H2O) and is vital for all known forms of life. In typical usage, ''water'' refers only to its liquid form or
state
State may refer to:
Arts, entertainment, and media Literature
* ''State Magazine'', a monthly magazine published by the U.S. Department of State
* ''The State'' (newspaper), a daily newspaper in Columbia, South Carolina, United States
* ''Our S ...
, but the substance also has a solid state,
ice
Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...
, and a
gas
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
eous state,
water vapor
(99.9839 °C)
, -
, Boiling point
,
, -
, specific gas constant
, 461.5 J/( kg·K)
, -
, Heat of vaporization
, 2.27 MJ/kg
, -
, Heat capacity
, 1.864 kJ/(kg·K)
Water vapor, water vapour or aqueous vapor is the gaseous pha ...
, or
steam
Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization ...
. Water covers 71% of the
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
's surface. On Earth, it is found mostly in oceans and other large bodies of water, with 1.6% of water below ground in
aquifer
An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...
s and 0.001% in the
air
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
as
vapor
In physics, a vapor (American English) or vapour (British English and Canadian English; American and British English spelling differences#-our, -or, see spelling differences) is a substance in the gas phase at a temperature lower than its critic ...
, clouds, and
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
. Oceans hold 97% of surface water,
glacier
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...
s, and polar
ice cap
In glaciology, an ice cap is a mass of ice that covers less than of land area (usually covering a highland area). Larger ice masses covering more than are termed ice sheets.
Description
Ice caps are not constrained by topographical features ...
s 2.4%, and other land surface water such as rivers, lakes, and ponds 0.6%. Additionally, a minute amount of the Earth's water is contained within biological bodies and manufactured products.
Oceans
![Ocean from Leblon](https://upload.wikimedia.org/wikipedia/commons/a/aa/Ocean_from_Leblon.jpg)
An ocean is a major body of
saline water
Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, ...
, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface (an area of some 361 million square kilometers) is covered by ocean, a
continuous body of water that is customarily divided into several principal oceans and smaller seas. More than half of this area is over deep. Average oceanic
salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
is around 35
parts per thousand
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they ...
(ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt. Though generally recognized as several 'separate' oceans, these waters comprise one global, interconnected body of salt water often referred to as the
World Ocean
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the worl ...
or global ocean.
[Distribution of land and water on the planet]
"
UN Atlas of the Oceans
This concept of a global ocean as a continuous body of water with relatively free interchange among its parts is of fundamental importance to
oceanography
Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamic ...
.
The major oceanic divisions are defined in part by the
continent
A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...
s, various
archipelago
An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands.
Examples of archipelagos include: the Indonesian Archi ...
s, and other criteria: these divisions are (in descending order of size) the
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
, the
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
, the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
, the
Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...
, and the
Arctic Ocean
The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, a ...
. Smaller regions of the oceans are called seas, gulfs,
bay
A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a Gulf (geography), gulf, sea, sound (geography), sound, or bight (geogra ...
s and other names. There are also
salt lake
A salt lake or saline lake is a landlocked body of water that has a concentration of salts (typically sodium chloride) and other dissolved minerals significantly higher than most lakes (often defined as at least three grams of salt per litre). ...
s, which are smaller bodies of landlocked saltwater that are not interconnected with the World Ocean. Two notable examples of salt lakes are the
Aral Sea
The Aral Sea ( ; kk, Арал теңізі, Aral teñızı; uz, Орол денгизи, Orol dengizi; kaa, Арал теңизи, Aral teńizi; russian: Аральское море, Aral'skoye more) was an endorheic basin, endorheic lake lyi ...
and the
Great Salt Lake
The Great Salt Lake is the largest saltwater lake in the Western Hemisphere and the eighth-largest terminal lake in the world. It lies in the northern part of the U.S. state of Utah and has a substantial impact upon the local climate, particula ...
.
Lakes
![Lake mapourika NZ](https://upload.wikimedia.org/wikipedia/commons/2/23/Lake_mapourika_NZ.jpeg)
A lake (from Latin word ''lacus'') is a
terrain feature
A landform is a natural or anthropogenic land
Land, also known as dry land, ground, or earth, is the solid terrestrial surface of the planet Earth that is not submerged by the ocean or other bodies of water. It makes up 29% of Earth's surf ...
(or
physical feature
A landform is a natural or anthropogenic land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Landforms include hills, m ...
), a body of liquid on the surface of a world that is localized to the bottom of
basin (another type of landform or terrain feature; that is, it is not global) and moves slowly if it moves at all. On Earth, a body of water is considered a lake when it is inland, not part of the ocean, is larger and deeper than a pond, and is fed by a river. The only world other than Earth known to harbor lakes is
Titan, Saturn's largest moon, which has lakes of
ethane
Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petr ...
, most likely mixed with methane. It is not known if Titan's lakes are fed by rivers, though Titan's surface is carved by numerous river beds. Natural lakes on Earth are generally found in mountainous areas, rift zones, and areas with ongoing or recent glacier, glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers. In some parts of the world, there are many lakes because of chaotic drainage patterns left over from the Last Glacial Period, last ice age. All lakes are temporary over geologic time scales, as they will slowly fill in with sediments or spill out of the basin containing them.
Ponds
![Mill Pond Sunset](https://upload.wikimedia.org/wikipedia/commons/1/11/Mill_Pond_Sunset.jpg)
A pond is a body of water, body of Water stagnation, standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens designed for aesthetic ornamentation, fish ponds designed for commercial fish breeding, and solar ponds designed to store thermal energy. Ponds and lakes are distinguished from streams via current (stream), current speed. While currents in streams are easily observed, ponds and lakes possess thermally driven micro-currents and moderate wind driven currents. These features distinguish a pond from many other aquatic terrain features, such as stream pools and tide pools.
Rivers
![View from Cairo Tower 31march2007](https://upload.wikimedia.org/wikipedia/commons/b/b2/View_from_Cairo_Tower_31march2007.jpg)
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including stream, creek, brook, rivulet, and rill; there is no general rule that defines what can be called a river. Many names for small rivers are specific to geographic location; one example is ''Burn'' in Scotland and North-east England. Sometimes a river is said to be larger than a creek, but this is not always the case, due to vagueness in the language. A river is part of the hydrological cycle. Water within a river is generally collected from Precipitation (meteorology), precipitation through surface runoff, groundwater recharge, Spring (hydrology), springs, and the release of stored water in natural ice and snowpacks (i.e., from
glacier
A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...
s).
Streams
![Hawaii Creek](https://upload.wikimedia.org/wikipedia/commons/e/e4/Hawaii_Creek.jpg)
A stream is a flowing body of water with a Current (stream), current, confined within a stream bed, bed and stream banks. In the United States, a stream is classified as a watercourse less than wide. Streams are important as conduits in the water cycle, instruments in groundwater recharge, and they serve as corridors for fish and
wildlife
Wildlife refers to domestication, undomesticated animal species (biology), species, but has come to include all organisms that grow or live wilderness, wild in an area without being species, introduced by humans. Wildlife was also synonymous ...
migration. The biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing
Holocene extinction
The Holocene extinction, or Anthropocene extinction, is the ongoing extinction event during the Holocene epoch. The extinctions span numerous families of bacteria, fungi, plants, and animals, including mammals, birds, reptiles, amphibians, f ...
, streams play an important wildlife corridor, corridor role in connecting Habitat fragmentation, fragmented habitats and thus in conserving biodiversity. The study of streams and waterways in general involves many branches of inter-disciplinary natural science and engineering, including hydrology, geomorphology, fluvial geomorphology, aquatic ecology, Freshwater fish, fish biology, riparian, riparian ecology, and others.
Ecosystems
![Chicago Downtown Aerial View](https://upload.wikimedia.org/wikipedia/commons/6/6f/Chicago_Downtown_Aerial_View.jpg)
Ecosystems are composed of a variety of biotic component, biotic and abiotic components that function in an interrelated way. The structure and composition is determined by various environmental factors that are interrelated. Variations of these factors will initiate dynamic modifications to the ecosystem. Some of the more important components are soil, atmosphere, radiation from the
sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
, water, and living organisms.
Central to the ecosystem concept is the idea that living organisms interact with every other element in their local environment (biophysical), environment. Eugene Odum, a founder of ecology, stated: "Any unit that includes all of the organisms (ie: the "community") in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (i.e.: exchange of materials between living and nonliving parts) within the system is an ecosystem."
[Odum, EP (1971) ''Fundamentals of ecology'', 3rd edition, Saunders New York] Within the ecosystem, species are connected and dependent upon one another in the food chain, and exchange energy and matter between themselves as well as with their environment. The human ecosystem concept is based on the human/nature dichotomy and the idea that all species are ecologically dependent on each other, as well as with the abiotic constituents of their biotope.
A smaller unit of size is called a microecosystem. For example, a microsystem can be a stone and all the life under it. A ''macroecosystem'' might involve a whole ecoregion, with its drainage basin.
Wilderness
![Biogradska suma](https://upload.wikimedia.org/wikipedia/commons/b/bc/Biogradska_suma.jpg)
Wilderness is generally defined as areas that have not been significantly modified by human activity. Wilderness areas can be found in preserves, estates, farms, conservation preserves, ranches, :national forests, national forests, national parks, and even in urban areas along rivers, gulches, or otherwise undeveloped areas. Wilderness areas and protected parks are considered important for the survival of certain species, ecological studies, Habitat conservation, conservation, and solitude. Some nature writers believe wilderness areas are vital for the human spirit and creativity,
[Botkin, Daniel B. (2000) ''No Man's Garden'', Island Press, pp. 155–57, .] and some ecologists consider wilderness areas to be an integral part of the Earth's self-sustaining natural ecosystem (the
biosphere
The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also be ...
). They may also preserve historic genetics, genetic traits and that they provide habitat for wild flora (plants), flora and fauna (animals), fauna that may be difficult or impossible to recreate in zoos, arboretums, or laboratory, laboratories.
Life
![Malards in Golden Gate Park](https://upload.wikimedia.org/wikipedia/commons/f/f6/Malards_in_Golden_Gate_Park.jpg)
Although there is no universal agreement on the definition of life, scientists generally accept that the biological manifestation of life is characterized by Organism, organization, metabolism, cell growth, growth, adaptation, response to stimulus (physiology), stimuli, and reproduction. Life may also be said to be simply the characteristic state of organisms.
Properties common to terrestrial organisms (plants, animals, Fungus, fungi, protists, archaea, and bacteria) are that they are cellular, carbon-and-water-based with complex organization, having a metabolism, a capacity to grow, respond to stimuli, and reproduce. An entity with these properties is generally considered life. However, not every definition of life considers all of these properties to be essential. Human-made Artificial life, analogs of life may also be considered to be life.
The
biosphere
The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also be ...
is the part of Earth's outer shell—including land, surface rocks, water, air and the atmosphere—within which life occurs, and which Biology, biotic processes in turn alter or transform. From the broadest Geophysiology, geophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere (rocks), hydrosphere (water), and atmosphere (air). The entire Earth contains over 75 billion tons (150 ''trillion'' pounds or about 6.8×10
13 kilograms) of biomass (ecology), biomass (life), which lives within various environments within the biosphere.
Over nine-tenths of the total biomass on Earth is plant life, on which animal life depends very heavily for its existence. More than 2 million species of plant and animal life have been identified to date, and estimates of the actual number of existing species range from several million to well over 50 million. The number of individual species of life is constantly in some degree of flux, with new species appearing and others ceasing to exist on a continual basis. The total number of species is in rapid decline.
Evolution
![Amazon Manaus forest](https://upload.wikimedia.org/wikipedia/commons/4/4b/Amazon_Manaus_forest.jpg)
The origin of life on Earth is not well understood, but it is known to have occurred at least 3.5 billion years ago,
during the hadean or archean eons on a Early Earth, primordial Earth that had a substantially different environment than is found at present.
These life forms possessed the basic traits of self-replication and inheritable traits. Once life had appeared, the process of evolution by natural selection resulted in the development of ever-more diverse life forms.
Species that were unable to adapt to the changing environment and competition from other life forms became extinct. However, the fossil record retains evidence of many of these older species. Current fossil and
DNA evidence shows that all existing species can trace a continual ancestry back to the first primitive life forms.
[
When basic forms of plant life developed the process of photosynthesis the sun's energy could be harvested to create conditions which allowed for more complex life forms. The resultant ]oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
accumulated in the atmosphere and gave rise to the ozone layer
The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in rela ...
. The incorporation of smaller cells within larger ones resulted in the endosymbiotic theory, development of yet more complex cells called eukaryotes. Cells within colonies became increasingly specialized, resulting in true multicellular organisms. With the ozone layer absorbing harmful ultraviolet radiation, life colonized the surface of Earth.
Microbes
The first form of life to develop on the Earth were microbes, and they remained the only form of life until about a billion years ago when multi-cellular organisms began to appear. Microorganisms are single-celled organisms that are generally microscopic, and smaller than the human eye can see. They include Bacteria, Fungus, Fungi, Archaea, and Protista.
These life forms are found in almost every location on the Earth where there is liquid water, including in the Earth's interior.
Their reproduction is both rapid and profuse. The combination of a high mutation rate and a horizontal gene transfer ability makes them highly adaptable, and able to survive in new environments, including outer space. They form an essential part of the planetary ecosystem. However, some microorganisms are pathogenic and can post health risk to other organisms.
Plants and animals
Originally Aristotle divided all living things between plants, which generally do not move fast enough for humans to notice, and animals. In Carl Linnaeus, Linnaeus' system, these became the kingdom (biology), kingdoms Vegetabilia (later Plantae) and Animalia. Since then, it has become clear that the Plantae as originally defined included several unrelated groups, and the fungus, fungi and several groups of algae were removed to new kingdoms. However, these are still often considered plants in many contexts. Bacterial life is sometimes included in flora, and some classifications use the term ''bacterial flora'' separately from ''plant flora''.
Among the many ways of classifying plants are by regional floras, which, depending on the purpose of study, can also include ''fossil flora'', remnants
of plant life from a previous era. People in many regions and countries take great pride in their individual arrays of characteristic flora, which can vary widely across the globe due to differences in climate and terrain.
Regional floras commonly are divided into categories such as ''native flora'' and ''agricultural and garden flora'', the lastly mentioned of which are intentionally grown and cultivated. Some types of "native flora" actually have been introduced centuries ago by people migrating from one region or continent to another, and become an integral part of the native, or natural flora of the place to which they were introduced. This is an example of how human interaction with nature can blur the boundary of what is considered nature.
Another category of plant has historically been carved out for ''weeds''. Though the term has fallen into disfavor among Botany, botanists as a formal way to categorize "useless" plants, the informal use of the word "weeds" to describe those plants that are deemed worthy of elimination is illustrative of the general tendency of people and societies to seek to alter or shape the course of nature. Similarly, animals are often categorized in ways such as ''domestic'', ''farm animals'', ''wild animals'', ''pests'', etc. according to their relationship to human life.
Animals as a category have several characteristics that generally set them apart from other living things. Animals are eukaryote, eukaryotic and usually multicellular (although see Myxozoa), which separates them from bacteria, archaea, and most protists. They are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungus, fungi by lacking cell walls.
With a few exceptions—most notably the two Phylum, phyla consisting of sponges and placozoans—animals have bodies that are differentiated into biological tissue, tissues. These include muscles, which are able to contract and control locomotion, and a nervous system, which sends and processes signals. There is also typically an internal digestion, digestive chamber. The eukaryotic cells possessed by all animals are surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. This may be calcified to form structures like Animal shell, shells, bones, and spicule (sponge), spicules, a framework upon which cells can move about and be reorganized during development and maturation, and which supports the complex anatomy required for mobility.
Human interrelationship
Human impact
Although humans comprise only a minuscule proportion of the total living Biomass (ecology), biomass on Earth, the human impact on the environment, human effect on nature is disproportionately large. Because of the extent of human influence, the boundaries between what humans regard as nature and "made environments" is not clear cut except at the extremes. Even at the extremes, the amount of natural environment that is free of discernible human influence is diminishing at an increasingly rapid pace. A 2020 study published in ''Nature (journal), Nature'' found that anthropogenic mass (human-made materials) outweighs all living biomass on earth, with Plastic pollution, plastic alone exceeding the mass of all land and marine animals combined. And according to a 2021 study published in ''Frontiers in Forests and Global Change'', only about 3% of the planet's terrestrial surface is ecologically and faunally intact, with a low human footprint and healthy populations of native animal species.
The development of technology by the human race has allowed the greater exploitation of natural resources and has helped to alleviate some of the risk from natural hazards. In spite of this progress, however, the fate of human civilization
A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system).
Ci ...
remains closely linked to changes in the environment. There exists a highly complex feedback loop between the use of advanced technology and changes to the environment that are only slowly becoming understood. Man-made threats to the Earth's natural environment include pollution, deforestation, and disasters such as oil spills. Humans have contributed to the Holocene extinction, extinction of many plants and animals, with roughly 1 million species threatened with extinction within decades. The biodiversity loss, loss of biodiversity and ecosystem functions over the last half century have impacted the extent that nature can contribute to human quality of life, and continued declines could pose a major threat to the continued existence of human civilization, unless a rapid course correction is made. The value of natural resources to human society is not reflected in market failure, market prices because mostly natural resources are available free of charge. This distorts market pricing of natural resources and at the same time leads to underinvestment in our natural assets. The annual global cost of public subsidies that damage nature is conservatively estimated at $4–$6 trillion (million million). Institutional protections of these natural goods, such as the oceans and rainforests, are lacking. Governments have not prevented these economic externalities.
Humans employ nature for both leisure and economic activities. The acquisition of natural resources for industrial use remains a sizable component of the world's economic system. Some activities, such as hunting and fishing, are used for both sustenance and leisure, often by different people. Agriculture#History, Agriculture was first adopted around the 9th millennium BCE. Ranging from food production to energy, nature influences economic wealth.
Although early humans gathered uncultivated plant materials for food and employed the medicinal plant, medicinal properties of vegetation for healing, most modern human use of plants is through agriculture. The land conversion, clearance of large tracts of land for crop growth has led to a significant reduction in the amount available of forestation and wetlands, resulting in the loss of habitat for many plant and animal species as well as increased erosion.
Aesthetics and beauty
Beauty in nature has historically been a prevalent theme in art and books, filling large sections of libraries and bookstores. That nature has been depicted and celebrated by so much art, photography, poetry, and other literature shows the strength with which many people associate nature and beauty. Reasons why this association exists, and what the association consists of, are studied by the branch of philosophy called aesthetics. Beyond certain basic characteristics that many philosophers agree about to explain what is seen as beautiful, the opinions are virtually endless. Nature and wildness have been important subjects in various eras of world history. An early tradition of landscape art began in China during the Tang Dynasty art, Tang Dynasty (618–907). The tradition of representing nature ''as it is'' became one of the aims of Chinese painting and was a significant influence in Asian art.
Although natural wonders are celebrated in the Psalms and the Book of Job, wilderness
Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any nonurbanized land not under extensive agricultural cultivation. The term has traditionally re ...
portrayals in art became more prevalent in the 1800s, especially in the works of the Romantic movement. Kingdom of Great Britain, British artists John Constable and J. M. W. Turner turned their attention to capturing the beauty of the natural world in their paintings. Before that, paintings had been primarily of religious scenes or of human beings. William Wordsworth's poetry described the wonder of the natural world, which had formerly been viewed as a threatening place. Increasingly the valuing of nature became an aspect of Western culture.[History of Conservation]
BC Spaces for Nature. Accessed: May 20, 2006. This artistic movement also coincided with the Transcendentalism, Transcendentalist movement in the Western world. A common classical idea of beautiful art involves the word mimesis, the imitation of nature. Also in the realm of ideas about beauty in nature is that the perfect is implied through perfect mathematical Substantial form, forms and more generally by patterns in nature. As David Rothenburg writes, "The beautiful is the root of science and the goal of art, the highest possibility that humanity can ever hope to see".
Matter and energy
Some fields of science see nature as matter in motion, obeying certain laws of nature which science seeks to understand. For this reason the most fundamental science is generally understood to be "physics"—the name for which is still recognizable as meaning that it is the "''study of nature''".
Matter is commonly defined as the substance of which physical objects are composed. It constitutes the observable universe. The visible components of the universe are now believed to compose only 4.9 percent of the total mass. The remainder is believed to consist of 26.8 percent cold dark matter and 68.3 percent dark energy. The exact arrangement of these components is still unknown and is under intensive investigation by physicists.
The behaviour of matter and energy throughout the observable universe appears to follow well-defined physical laws. These laws have been employed to produce Physical cosmology, cosmological models that successfully explain the structure and the evolution of the universe we can observe. The mathematical expressions of the laws of physics employ a set of twenty physical constants that appear to be static across the observable universe. The values of these constants have been carefully measured, but the reason for their specific values remains a mystery.
Beyond Earth
Outer space, also simply called ''space'', refers to the relatively empty regions of the Universe outside the atmospheres of celestial bodies. ''Outer'' space is used to distinguish it from airspace (and terrestrial locations). There is no discrete boundary between atmosphere of Earth, Earth's atmosphere and space, as the atmosphere gradually attenuates with increasing altitude. Outer space within the Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
is called interplanetary medium, interplanetary space, which passes over into interstellar medium, interstellar space at what is known as the Heliosphere#Heliopause, heliopause.
Outer space is sparsely filled with several dozen types of organic chemistry, organic molecules discovered to date by rotational spectroscopy, microwave spectroscopy, cosmic microwave background, blackbody radiation left over from the Big Bang and the origin of the universe, and cosmic rays, which include ionized atomic nucleus, atomic nuclei and various subatomic particles. There is also some gas, plasma (physics), plasma and dust, and small meteors. Additionally, there are signs of human life in outer space today, such as material left over from previous crewed and uncrewed launches which are a potential hazard to spacecraft. Some of this space debris, debris re-enters the atmosphere periodically.
Although Earth is the only body within the Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
known to support life, evidence suggests that in the distant past the planet Mars possessed bodies of liquid water on the surface. For a brief period in Mars' history, it may have also been capable of forming life. At present though, most of the water remaining on Mars is frozen.
If life exists at all on Mars, it is most likely to be located underground where liquid water can still exist.
Conditions on the other terrestrial planets, Mercury (planet), Mercury and Venus, appear to be too harsh to support life as we know it. But it has been conjectured that Europa (moon), Europa, the fourth-largest moon of Jupiter, may possess a sub-surface ocean of liquid water and could potentially host life.
Astronomers have started to discover extrasolar Earth analogs – planets that lie in the circumstellar habitable zone, habitable zone of space surrounding a star, and therefore could possibly host life as we know it.
See also
* Force of nature (disambiguation), Force of nature
* Human nature
* Natural history
* Naturalism (disambiguation), Naturalism
* Natural landscape
* Natural law
* Natural resource
* Natural science
* Natural theology
* Nature reserve
* Nature versus nurture
* Nature worship
* Naturism
* Rewilding (conservation biology), Rewilding
Media:
* ''National Wildlife (magazine), National Wildlife'', a publication of the National Wildlife Federation
* ''Natural History (Pliny), Natural History'', by Pliny the Elder
* ''Natural World (TV series), Natural World'' (TV series)
* ''Nature (essay), Nature'', by Ralph Waldo Emerson
* ''Nature (journal), Nature'', a prominent scientific journal
* ''Nature (TV series), Nature'' (TV series)
* ''The World We Live In (Life magazine)''
Organizations:
* Nature Detectives
* The Nature Conservancy
Philosophy:
* Balance of nature (biological fallacy), a discredited concept of natural equilibrium in predator–prey dynamics
* Mother Nature
* Naturalism (philosophy), Naturalism, any of several philosophical stances, typically those descended from materialism and pragmatism that do not distinguish the supernatural from nature;[Papineau, David (2016]
"Naturalism"
The Stanford Encyclopedia of Philosophy, Edward N. Zalta (ed.), > this includes the ''methodological naturalism'' of natural science, which makes the methodology, methodological assumption that observation, observable events in nature are explained only by natural causes, without assuming either the existence or non-existence of the supernatural
* Nature (philosophy)
Notes and references
Further reading
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* Farber, Paul Lawrence (2000), ''Finding Order in Nature: The Naturalist Tradition from Linnaeus to E. O. Wilson''. Johns Hopkins University Press: Baltimore.
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External links
The IUCN Red List of Threatened Species (iucnredlist.org)
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{{Authority control
Nature,
Environmental science
Environmental social science concepts
Main topic articles