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Climate variability and change

Climate variability includes all the variations in the climate that last longer than individual weather events, whereas the term climate change only refers to those variations that persist for a longer period of time, typically decades or more. Climate change may refer to any time in Earth's history, but the term is now commonly used to describe contemporary climate change, often popularly referred to as global warming. Since the Industrial Revolution, the climate has increasingly been affected by human activities.[1]

For the human-induced rise in Earth's average temperature and its effects, see Climate change.

The climate system receives nearly all of its energy from the sun and radiates energy to outer space. The balance of incoming and outgoing energy and the passage of the energy through the climate system is Earth's energy budget. When the incoming energy is greater than the outgoing energy, Earth's energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and Earth experiences cooling.


The energy moving through Earth's climate system finds expression in weather, varying on geographic scales and time. Long-term averages and variability of weather in a region constitute the region's climate. Such changes can be the result of "internal variability", when natural processes inherent to the various parts of the climate system alter the distribution of energy. Examples include variability in ocean basins such as the Pacific decadal oscillation and Atlantic multidecadal oscillation. Climate variability can also result from external forcing, when events outside of the climate system's components produce changes within the system. Examples include changes in solar output and volcanism.


Climate variability has consequences for sea level changes, plant life, and mass extinctions; it also affects human societies.

Terminology

Climate variability is the term to describe variations in the mean state and other characteristics of climate (such as chances or possibility of extreme weather, etc.) "on all spatial and temporal scales beyond that of individual weather events." Some of the variability does not appear to be caused by known systems and occurs at seemingly random times. Such variability is called random variability or noise. On the other hand, periodic variability occurs relatively regularly and in distinct modes of variability or climate patterns.[2]


The term climate change is often used to refer specifically to anthropogenic climate change. Anthropogenic climate change is caused by human activity, as opposed to changes in climate that may have resulted as part of Earth's natural processes.[3] Global warming became the dominant popular term in 1988, but within scientific journals global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels affect.[4]


A related term, climatic change, was proposed by the World Meteorological Organization (WMO) in 1966 to encompass all forms of climatic variability on time-scales longer than 10 years, but regardless of cause. During the 1970s, the term climate change replaced climatic change to focus on anthropogenic causes, as it became clear that human activities had a potential to drastically alter the climate.[5] Climate change was incorporated in the title of the Intergovernmental Panel on Climate Change (IPCC) and the UN Framework Convention on Climate Change (UNFCCC). Climate change is now used as both a technical description of the process, as well as a noun used to describe the problem.[5]

the (ENSO) – A large scale pattern of warmer (El Niño) and colder (La Niña) tropical sea surface temperatures in the Pacific Ocean with worldwide effects. It is a self-sustaining oscillation, whose mechanisms are well-studied.[24] ENSO is the most prominent known source of inter-annual variability in weather and climate around the world. The cycle occurs every two to seven years, with El Niño lasting nine months to two years within the longer term cycle.[25] The cold tongue of the equatorial Pacific Ocean is not warming as fast as the rest of the ocean, due to increased upwelling of cold waters off the west coast of South America.[26][27]

El Niño–Southern Oscillation

the (MJO) – An eastward moving pattern of increased rainfall over the tropics with a period of 30 to 60 days, observed mainly over the Indian and Pacific Oceans.[28]

Madden–Julian oscillation

the (NAO) – Indices of the NAO are based on the difference of normalized sea-level pressure (SLP) between Ponta Delgada, Azores and Stykkishólmur/Reykjavík, Iceland. Positive values of the index indicate stronger-than-average westerlies over the middle latitudes.[29]

North Atlantic oscillation

the – a well-understood oscillation in wind patterns in the stratosphere around the equator. Over a period of 28 months the dominant wind changes from easterly to westerly and back.[30]

Quasi-biennial oscillation

- a climate oscillation predicted by some climate models

Pacific Centennial Oscillation

the – The dominant pattern of sea surface variability in the North Pacific on a decadal scale. During a "warm", or "positive", phase, the west Pacific becomes cool and part of the eastern ocean warms; during a "cool" or "negative" phase, the opposite pattern occurs. It is thought not as a single phenomenon, but instead a combination of different physical processes.[31]

Pacific decadal oscillation

the (IPO) – Basin wide variability in the Pacific Ocean with a period between 20 and 30 years.[32]

Interdecadal Pacific oscillation

the – A pattern of variability in the North Atlantic of about 55 to 70 years, with effects on rainfall, droughts and hurricane frequency and intensity.[33]

Atlantic multidecadal oscillation

– climate variation driven by the North African Monsoon, with a period of tens of thousands of years.[34]

North African climate cycles

the (AO) and Antarctic oscillation (AAO) – The annular modes are naturally occurring, hemispheric-wide patterns of climate variability. On timescales of weeks to months they explain 20–30% of the variability in their respective hemispheres. The Northern Annular Mode or Arctic oscillation (AO) in the Northern Hemisphere, and the Southern Annular Mode or Antarctic oscillation (AAO) in the southern hemisphere. The annular modes have a strong influence on the temperature and precipitation of mid-to-high latitude land masses, such as Europe and Australia, by altering the average paths of storms. The NAO can be considered a regional index of the AO/NAM.[35] They are defined as the first EOF of sea level pressure or geopotential height from 20°N to 90°N (NAM) or 20°S to 90°S (SAM).

Arctic oscillation

– occurring on roughly 1,500-year cycles during the Last Glacial Maximum

Dansgaard–Oeschger cycles

the

Piora Oscillation

the

Middle Bronze Age Cold Epoch

the

Iron Age Cold Epoch

the

Little Ice Age

the phase of cooling c. 1940–1970, which led to hypothesis

global cooling

Climatological normal

Anthropocene

Cronin, Thomas N. (2010). Paleoclimates: understanding climate change past and present. New York: Columbia University Press.  978-0-231-14494-0.

ISBN

(2007). Solomon, S.; Qin, D.; Manning, M.; Chen, Z.; et al. (eds.). Climate Change 2007: The Physical Science Basis (PDF). Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. ISBN 978-0-521-88009-1. (pb: 978-0-521-70596-7).

IPCC

(2008). The Core Writing Team; Pachauri, R.K.; Reisinger, A.R. (eds.). Climate Change 2008: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Geneva, Switzerland: IPCC. ISBN 978-92-9169-122-7..

IPCC

Burroughs, William James (2001). Climate Change : A multidisciplinary approach. Cambridge: Cambridge university press.  0521567718.

ISBN

Burroughs, William James (2007). Climate Change : A multidisciplinary approach. Cambridge: Cambridge University Press.  978-0-511-37027-4.

ISBN

Ruddiman, William F. (2008). Earth's climate : Past and Future. New York: W. H. Freeman and Company.  978-0716784906.

ISBN

Rohli, Robert. V.; Vega, Anthony J. (2018). Climatology (4th ed.). Jones & Bartlett Learning.  978-1284126563.

ISBN

Media related to Climate variability and change at Wikimedia Commons

from NASA (US)

Global Climate Change

Intergovernmental Panel on Climate Change (IPCC)

Archived 30 May 2023 at the Wayback Machine – NASA Science

Climate Variability

Archived 21 September 2021 at the Wayback Machine

Climate Change and Variability, National Centers for Environmental Information