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Nature is an inherent character or constitution,
particularly of the
ecosphere or the
universe
The universe is all of space and time and their contents. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...
as a whole. In this general sense nature refers to the
laws
Law is a set of rules that are created and are law enforcement, enforceable by social or governmental institutions to regulate behavior, with its precise definition a matter of longstanding debate. It has been variously described as a Socia ...
, elements and
phenomena
A phenomenon ( phenomena), sometimes spelled phaenomenon, is an observable Event (philosophy), event. The term came into its modern Philosophy, philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be ...
of the physical world, including
life
Life, also known as biota, refers to matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes. It is defined descriptively by the capacity for homeostasis, Structure#Biological, organisation, met ...
. Although humans are part of nature, human activity or humans as a whole are often described as at times at odds, or outright
separate and even superior to nature.
During the advent of modern
scientific method
The scientific method is an Empirical evidence, empirical method for acquiring knowledge that has been referred to while doing science since at least the 17th century. Historically, it was developed through the centuries from the ancient and ...
in the last several centuries, nature became the passive
reality
Reality is the sum or aggregate of everything in existence; everything that is not imagination, imaginary. Different Culture, cultures and Academic discipline, academic disciplines conceptualize it in various ways.
Philosophical questions abo ...
, organized and moved by divine laws. With the
Industrial Revolution
The Industrial Revolution, sometimes divided into the First Industrial Revolution and Second Industrial Revolution, was a transitional period of the global economy toward more widespread, efficient and stable manufacturing processes, succee ...
, nature increasingly became seen as the part of reality deprived from intentional intervention: it was hence considered as sacred by some traditions (
Rousseau, American
transcendentalism) or a mere decorum for
divine providence or human history (
Hegel
Georg Wilhelm Friedrich Hegel (27 August 1770 – 14 November 1831) was a 19th-century German idealism, German idealist. His influence extends across a wide range of topics from metaphysical issues in epistemology and ontology, to political phi ...
,
Marx
Karl Marx (; 5 May 1818 – 14 March 1883) was a German philosopher, political theorist, economist, journalist, and revolutionary socialist. He is best-known for the 1848 pamphlet '' The Communist Manifesto'' (written with Friedrich Engels) ...
). 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 pre-Socratic one, got reborn at the same time, especially after
Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...
.
Within the various uses of the word today, "nature" often refers to
geology
Geology (). is a branch of natural science concerned with the Earth and other astronomical objects, the rocks of which they are composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth ...
and
wildlife
Wildlife refers to domestication, undomesticated animals and uncultivated plant species which can exist in their natural habitat, but has come to include all organisms that grow or live wilderness, wild in an area without being species, introdu ...
. Nature can refer to the general realm of
living beings, 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 Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
. It is often taken to mean the "
natural environment
The natural environment or natural world encompasses all life, biotic and abiotic component, abiotic things occurring nature, naturally, meaning in this case not artificiality, artificial. The term is most often applied to Earth or some parts ...
" or
wilderness
Wilderness or wildlands (usually in the plurale tantum, plural) are Earth, Earth's natural environments that have not been significantly modified by human impact on the environment, human activity, or any urbanization, nonurbanized land not u ...
—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 awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, an ...
or a human
mind
The mind is that which thinks, feels, perceives, imagines, remembers, and wills. It covers the totality of mental phenomena, including both conscious processes, through which an individual is aware of external and internal circumstances ...
. Depending on the particular context, the term "natural" might also be distinguished from the
unnatural
Unnatural or The Unnatural(s) may refer to:
Film
* ''Alraune'' (1952 film), also known as ''Unnatural'', a West German science fiction horror film
*'' The Unnaturals'', a 1969 Italian-West German gothic horror film directed and written by Antonio ...
or the
supernatural
Supernatural phenomena or entities are those beyond the Scientific law, laws of nature. The term is derived from Medieval Latin , from Latin 'above, beyond, outside of' + 'nature'. Although the corollary term "nature" has had multiple meanin ...
.
Etymology
The word ''nature'' is borrowed from the
Old French
Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th ''nature'' and is derived from the Latin">-4; we might wonder whether there's a point at which it's appropriate to talk of the beginnings of French, that is, when it wa ...
''nature'' and is derived from the Latin word ''natura'', or "essential qualities, innate disposition", and in ancient times, literally meant "birth".
In ancient philosophy, ''natura'' is mostly used as the Latin translation of the Greek word ''physis'' (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. It comprises all of existence, any fundamental interaction, physical process and physical constant, and therefore all forms of matter and energy, and the structures they form, from s ...
, 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 the ...
philosophers (though this word had a dynamic dimension then, especially for
Heraclitus
Heraclitus (; ; ) was an Ancient Greece, ancient Greek Pre-Socratic philosophy, pre-Socratic philosopher from the city of Ephesus, which was then part of the Achaemenid Empire, Persian Empire. He exerts a wide influence on Western philosophy, ...
), and has steadily gained currency ever since.
Earth

Earth is the only
planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
known to support
life
Life, also known as biota, refers to matter that has biological processes, such as Cell signaling, signaling and self-sustaining processes. It is defined descriptively by the capacity for homeostasis, Structure#Biological, organisation, met ...
, 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 "Sola ...
, it is third closest to the Sun; it is the largest
terrestrial planet
A terrestrial planet, tellurian 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 ...
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 (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...
zones, and a wide
equator
The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...
ial tropical to
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...
region.
Precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
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 by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...
.
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 (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
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 (sometimes called B-field) is a physical 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 ...
. 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 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 geographic coordinate system, geographic 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 t ...
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, dynamics, and
history
History is the systematic study of the past, focusing primarily on the Human history, human past. As an academic discipline, it analyses and interprets evidence to construct narratives about what happened and explain why it happened. Some t ...
of
Earth materials, and the processes by which they are formed, moved, and changed. The field is a major
academic discipline
An academic discipline or academic field is a subdivision of knowledge that is taught and researched at the college or university level. Disciplines are defined (in part) and recognized by the academic journals in which research is published, a ...
, and is also important for
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...
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 Hydrophobe, hydrophobic; their odor is usually fain ...
extraction, knowledge about and mitigation of
natural hazard
A natural disaster is the very harmful impact on a society or community brought by natural phenomenon or hazard. Some examples of natural hazards include avalanches, droughts, earthquakes, floods, heat waves, landslides - including submarin ...
s, some
Geotechnical engineering
Geotechnical engineering, also known as geotechnics, is the branch of civil engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rock mechanics to solve its engineering problems. I ...
fields, and understanding
past climates and environments.
Geological evolution

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. Deposition can occur when
sediment
Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...
s settle onto the surface of the Earth and later
lithify into
sedimentary rock
Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...
, or when as
volcanic material such as
volcanic ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to r ...
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 Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
flows, blanket the surface. Igneous
intrusions such as
batholith
A batholith () is a large mass of intrusive rock, intrusive igneous rock (also called plutonic rock), larger than in area, that forms from cooled magma deep in the Earth's crust. Batholiths are almost always made mostly of felsic or intermediate ...
s,
laccoliths,
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. 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,
divergent boundaries, and
transform boundaries, respectively, between
tectonic plates
Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...
.
Historical perspective

Earth is estimated to have formed 4.54 billion years ago from the
solar nebula
There is evidence that the formation of the Solar System began about 4.6 bya, 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, whil ...
, along with the
Sun and other
planet
A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
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 commonly defined as a vent or fissure 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 fo ...
activity produced the primordial atmosphere. Condensing
water vapor
Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...
, most or all of which came from
ice
Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...
delivered by
comet
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...
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.

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 (Ga) and broke up 750–633 million years ago (Ma). wer ...
, began to break apart. The continents later recombined to form
Pannotia
Pannotia (from Greek: ''wikt:pan-, pan-'', "all", ''wikt:νότος, -nótos'', "south"; meaning "all southern land"), also known as the Vendian supercontinent, Greater Gondwana, and the Pan-African supercontinent, was a relatively short-lived Neo ...
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 period approximately 335 mi ...
, which broke apart about 180 million years ago.
During the
Neoproterozoic
The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic geologic eon, eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era an ...
era, freezing temperatures covered much of the Earth in
glacier
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
s and ice sheets. This hypothesis has been termed the "
Snowball Earth
The Snowball Earth is a historical geology, geohistorical hypothesis that proposes that during one or more of Earth's greenhouse and icehouse Earth, icehouse climates, the planet's planetary surface, surface became nearly entirely freezing, fr ...
", and it is of particular interest as it precedes the
Cambrian explosion 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. 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 Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...
s and other large reptiles, but spared small animals such as
mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s. Over the past 66 million years, mammalian life diversified.
Several million years ago, a species of small African
ape gained the ability to stand upright.
The subsequent advent of human life, and the development of agriculture and further
civilization
A civilization (also spelled civilisation in British English) is any complex society characterized by the development of state (polity), the state, social stratification, urban area, urbanization, and symbolic systems of communication beyon ...
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, produced by the proliferation of
algae
Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
during the
Siderian 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 fall in the diversity and abundance of multicellular organisms. It occ ...
, the
Holocene extinction
The Holocene extinction, also referred to as the Anthropocene extinction or the sixth mass extinction, is an ongoing extinction event caused exclusively by human activities during the Holocene epoch. This extinction event spans numerous families ...
event, the fastest ever to have occurred. Some, such as
E. O. Wilson of
Harvard University
Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...
, predict that human destruction of the
biosphere
The biosphere (), also called the ecosphere (), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to mat ...
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

The Earth's atmosphere is a key factor in sustaining the
ecosystem
An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...
. The thin layer of gases that envelops the Earth is held in place by gravity. Air is mostly
nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
,
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
,
water vapor
Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...
, 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 absorption (electromagnetic radiation), absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the a ...
plays an important role in depleting the amount of
ultraviolet
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
(UV) radiation that reaches the surface. As
DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
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 seawater 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, sh ...
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 current, ocean circulation driven by global density gradients formed by surface heat and freshwater fluxes. The name ''thermohaline'' is derived from ''wikt:thermo-, thermo-'', r ...
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 regions much colder.

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 the surface of 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, although the ...
es or
hurricane
A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its ...
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 ant ...
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 fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
,
greenhouse gas
Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...
es, variations in the solar luminosity, and changes to the Earth's orbit. Based on historical and geological records, the Earth is known to have undergone drastic
climate change
Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
s 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 g ...
s.
The climate of a region depends on a number of factors, especially
latitude
In geography, latitude is a geographic coordinate system, geographic 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 t ...
. 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 or higher in the coolest month, featuring hot te ...
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 a polar climate has an average temperature of less than . Regions with a 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 Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
's
axis
An axis (: axes) may refer to:
Mathematics
*A specific line (often a directed line) that plays an important role in some contexts. In particular:
** Coordinate axis of a coordinate system
*** ''x''-axis, ''y''-axis, ''z''-axis, common names ...
being
tilted relative to its
orbital plane. 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. This exposure alternates as the Earth revolves in its orbit. At any given time, regardless of season, the
Northern and
Southern Hemispheres experience opposite seasons.
Weather is a
chaotic system that is readily modified by small changes to the
environment, so accurate
weather forecasting
Weather forecasting or weather prediction 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 info ...
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 Earth
Water is a
chemical substance
A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be com ...
that is composed of
hydrogen
Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...
and
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
(H2O) and is vital for all known forms of life. In typical usage, "water" refers only to its liquid
form, but it also has a solid state,
ice
Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...
, and a
gaseous state,
water vapor
Water vapor, water vapour, or aqueous vapor is the gaseous phase of Properties of water, water. It is one Phase (matter), state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from th ...
, or
steam
Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...
. Water covers 71% of the
Earth
Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...
'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 material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...
s and 0.001% in the
air
An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...
as
vapor
In physics, a vapor (American English) or vapour (Commonwealth 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 critical temperature,R ...
, clouds, and
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
. Oceans hold 97% of surface water,
glacier
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
s, and polar
ice caps 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

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 wat ...
, 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 (chemistry), 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 dimensio ...
is around 35
parts per thousand (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 is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian, Antarctic/Southern, and ...
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, sea science, ocean science, and marine science, is the scientific study of the ocean, including its physics, chemistry, biology, and geology.
It is an Earth science, which covers a wide range of to ...
.
The major oceanic divisions are defined in part by the
continent
A continent is any of several large geographical regions. Continents are generally identified by convention (norm), convention rather than any strict criteria. A continent could be a single large landmass, a part of a very large landmass, as ...
s, various
archipelago
An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the o ...
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 Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...
, the
Atlantic Ocean
The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...
, the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...
, 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 60th parallel south, 60° S latitude and encircling Antarctica. With a size of , it is the seco ...
, and the
Arctic Ocean
The Arctic Ocean is the smallest and shallowest of the world's five oceanic divisions. It spans an area of approximately and is the coldest of the world's oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, ...
. Smaller regions of the oceans are called seas, gulfs,
bays 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 liter). I ...
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 and the
Great Salt Lake.
Lakes

A lake (from Latin word ''lacus'') is a
terrain feature (or
physical feature), 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
Titan most often refers to:
* Titan (moon), the largest moon of Saturn
* Titans, a race of deities in Greek mythology
Titan or Titans may also refer to:
Arts and entertainment
Fictional entities
Fictional locations
* Titan in fiction, fictiona ...
, Saturn's largest moon, which has lakes of
ethane
Ethane ( , ) is a naturally occurring Organic compound, organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is List of purification methods ...
, most likely mixed with
methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...
. 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 zone
A rift zone is a feature of some volcanoes, especially shield volcanoes, in which a set of linear cracks (or rifts) develops in a volcanic edifice, typically forming into two or three well-defined regions along the flanks of the vent. Believed ...
s, and areas with ongoing or recent
glaciation
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...
. Other lakes are found in
endorheic basin
An endorheic basin ( ; also endoreic basin and endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water (e.g. rivers and oceans); instead, the water drainage flows into permanent ...
s 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 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

A pond is a
body of
standing water
Water stagnation occurs when water stops Environmental flow, flowing for a long period of time. Stagnant water can be a significant environmental hazard.
Dangers
Malaria and dengue are among the main dangers of still water, which can become ...
, either natural or human-made, that is usually smaller than a lake. A wide variety of human-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 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

A river is a natural
watercourse
A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...
, usually
freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...
, 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
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
through
surface runoff
Surface runoff (also known as overland flow or terrestrial runoff) is the unconfined flow of water over the ground surface, in contrast to ''channel runoff'' (or ''stream flow''). It occurs when excess rainwater, stormwater, meltwater, or other ...
,
groundwater
Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...
recharge,
springs, and the release of stored water in natural ice and snowpacks (i.e., from
glacier
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...
s).
Streams

A stream is a flowing body of water with a
current, confined within a
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
The water cycle (or hydrologic cycle or hydrological cycle) is a biogeochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth across different reservoirs. The mass of water on Earth remains fai ...
, instruments in
groundwater recharge, and they serve as corridors for fish and
wildlife
Wildlife refers to domestication, undomesticated animals and uncultivated plant species which can exist in their natural habitat, but has come to include all organisms that grow or live wilderness, wild in an area without being species, introdu ...
migration. The biological
habitat
In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing
Holocene extinction
The Holocene extinction, also referred to as the Anthropocene extinction or the sixth mass extinction, is an ongoing extinction event caused exclusively by human activities during the Holocene epoch. This extinction event spans numerous families ...
, 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

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, 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 (i.e.: 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

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. 155–157, .] and some ecologists consider wilderness areas to be an integral part of the Earth's self-sustaining natural ecosystem (the
biosphere
The biosphere (), also called the ecosphere (), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to mat ...
). They may also preserve historic genetics, genetic traits and that they provide
habitat
In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
for wild flora (plants), flora and fauna (animals), fauna that may be difficult or impossible to recreate in zoos, arboretums, or laboratory, laboratories.
Life

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.
Present day organisms from viruses to humans possess a self-replicating informational molecule (genome), either
DNA
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
or RNA (as in some viruses), and such an informational molecule is probably intrinsic to life. It is likely that the earliest forms of life were based on a self-replicating informational molecule (genome), perhaps RNA or a molecule more primitive than RNA or DNA. The specific deoxyribonucleotide/ribonucleotide sequence in each currently extant individual organism contains sequence information that functions to promotes survival, reproduction, and the capacity to acquire resources necessary for reproduction, and such sequences probably emerged early in the evolution of life. Survival functions present early in the evolution of life likely also included genomic sequences that promote the avoidance of damage to the self-replicating molecule and also the capability to DNA repair, repair such damages that do occur. Repair of some genome damages may have involved using information from another similar molecule by a process of genetic recombination, recombination (a primitive form of sexual reproduction, sexual interaction).
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 (), also called the ecosphere (), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to mat ...
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

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
Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...
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 a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
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 absorption (electromagnetic radiation), absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the a ...
. 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 unicellular, and they remained the only form of life until about a billion years ago when multi-cellular organisms began to appear. Microorganisms or microbes are microscopic, and smaller than the human eye can see. Microorganisms can be single-celled, such as Bacteria, Archaea, many Protista, and a minority of Fungus, Fungi.
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 and sometimes very harsh 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.
Virus, Viruses are pathogen, infectious agents, but they are not autonomous Outline of life forms, life forms, as it is the case for viroid, viroids, satellite (biology), satellites, Defective interfering particle, DPIs and prion, prions.
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'' or ''agricultural and garden flora''. 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, 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 Exoskeleton, 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 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. Philip Cafaro, professor of philosophy at the School of Global Environmental Sustainability at Colorado State University, wrote in 2022 that "the cause of global biodiversity loss is clear: other species are being displaced by a rapidly growing human economy."
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 (also spelled civilisation in British English) is any complex society characterized by the development of state (polity), the state, social stratification, urban area, urbanization, and symbolic systems of communication beyon ...
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. Human-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 existence of human civilization, unless a rapid course correction is made. The value of natural resources to human society is poorly reflected in market failure, market prices because except for labour costs the 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 plurale tantum, plural) are Earth, Earth's natural environments that have not been significantly modified by human impact on the environment, human activity, or any urbanization, nonurbanized land not u ...
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
The natural sciences view matter as obeying certain scientific law , laws of nature which scientists seek to understand.
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 "Sola ...
is called interplanetary medium, interplanetary space, which passes over into interstellar medium, interstellar space at what is known as the Heliopause (astronomy), 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 "Sola ...
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
* Biophilic design
* Force of nature (disambiguation), Force of nature
* Human nature
* Natural building
* Natural history
* Natural landscape
* Natural law
* Natural resource
* Natural science
* Natural theology
* Naturalism (disambiguation), Naturalism
* Nature reserve
* Nature versus nurture
* Nature worship
* Nature-based solutions
* 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