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66-610: A Climate Data Record ( CDR ) is a specific definition of a climate data series, developed by the Committee on Climate Data Records from NOAA Operational Satellites of the National Research Council at the request of NOAA in the context of satellite records. It is defined as "a time series of measurements of sufficient length, consistency, and continuity to determine climate variability and climate change .". Such measurements provide an objective basis for
132-570: A biome classification, as climate is a major influence on life in a region. One of the most used is the Köppen climate classification scheme first developed in 1899. There are several ways to classify climates into similar regimes. Originally, climes were defined in Ancient Greece to describe the weather depending upon a location's latitude. Modern climate classification methods can be broadly divided into genetic methods, which focus on
198-526: A 30-year period. A 30-year period is used as it is long enough to filter out any interannual variation or anomalies such as El Niño–Southern Oscillation , but also short enough to be able to show longer climatic trends." The WMO originated from the International Meteorological Organization which set up a technical commission for climatology in 1929. At its 1934 Wiesbaden meeting, the technical commission designated
264-413: A common software infrastructure shared by all U.S. climate researchers, and holding an annual climate modeling forum, the report found. Cloud-resolving climate models are nowadays run on high intensity super-computers which have a high power consumption and thus cause CO 2 emissions. They require exascale computing (billion billion – i.e., a quintillion – calculations per second). For example,
330-419: A day; the ocean is MOM-3 ( Modular Ocean Model ) with a 3.75° × 3.75° grid and 24 vertical levels. Box models are simplified versions of complex systems, reducing them to boxes (or reservoirs ) linked by fluxes. The boxes are assumed to be mixed homogeneously. Within a given box, the concentration of any chemical species is therefore uniform. However, the abundance of a species within a given box may vary as
396-419: A few global datasets exist. Global climate models can be dynamically or statistically downscaled to regional climate models to analyze impacts of climate change on a local scale. Examples are ICON or mechanistically downscaled data such as CHELSA (Climatologies at high resolution for the earth's land surface areas). The most talked-about applications of these models in recent years have been their use to infer
462-405: A function of elevation (i.e. relative humidity distribution). This has been shown by refining the zero dimension model in the vertical to a one-dimensional radiative-convective model which considers two processes of energy transport: Radiative-convective models have advantages over simpler models and also lay a foundation for more complex models. They can estimate both surface temperature and
528-573: A function of time due to the input to (or loss from) the box or due to the production, consumption or decay of this species within the box. Simple box models, i.e. box model with a small number of boxes whose properties (e.g. their volume) do not change with time, are often useful to derive analytical formulas describing the dynamics and steady-state abundance of a species. More complex box models are usually solved using numerical techniques. Box models are used extensively to model environmental systems or ecosystems and in studies of ocean circulation and
594-565: A robust and unambiguous picture of significant climate warming in response to increasing greenhouse gases." The World Climate Research Programme (WCRP), hosted by the World Meteorological Organization (WMO), coordinates research activities on climate modelling worldwide. A 2012 U.S. National Research Council report discussed how the large and diverse U.S. climate modeling enterprise could evolve to become more unified. Efficiencies could be gained by developing
660-608: A simple radiant heat transfer model treats the Earth as a single point and averages outgoing energy. This can be expanded vertically (radiative-convective models) and horizontally. More complex models are the coupled atmosphere–ocean– sea ice global climate models . These types of models solve the full equations for mass transfer, energy transfer and radiant exchange. In addition, other types of models can be interlinked. For example Earth System Models include also land use as well as land use changes . This allows researchers to predict
726-403: A wider sense is the state, including a statistical description, of the climate system." The World Meteorological Organization (WMO) describes " climate normals " as "reference points used by climatologists to compare current climatological trends to that of the past or what is considered typical. A climate normal is defined as the arithmetic average of a climate element (e.g. temperature) over
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#1732765381743792-413: Is where The constant parameters include The constant π r 2 {\displaystyle \pi \,r^{2}} can be factored out, giving a nildimensional equation for the equilibrium where The remaining variable parameters which are specific to the planet include This very simple model is quite instructive. For example, it shows the temperature sensitivity to changes in
858-630: Is a type of climate model. It employs a mathematical model of the general circulation of a planetary atmosphere or ocean. It uses the Navier–Stokes equations on a rotating sphere with thermodynamic terms for various energy sources ( radiation , latent heat ). These equations are the basis for computer programs used to simulate the Earth's atmosphere or oceans. Atmospheric and oceanic GCMs (AGCM and OGCM ) are key components along with sea ice and land-surface components. GCMs and global climate models are used for weather forecasting , understanding
924-562: Is as follows: "Climate in a narrow sense is usually defined as the "average weather", or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in
990-542: Is considerable confidence that climate models provide credible quantitative estimates of future climate change, particularly at continental scales and above. This confidence comes from the foundation of the models in accepted physical principles and from their ability to reproduce observed features of current climate and past climate changes. Confidence in model estimates is higher for some climate variables (e.g., temperature) than for others (e.g., precipitation). Over several decades of development, models have consistently provided
1056-462: Is discussed in terms of global warming , which results in redistributions of biota . For example, as climate scientist Lesley Ann Hughes has written: "a 3 °C [5 °F] change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km [190–250 mi] in latitude (in the temperate zone) or 500 m [1,600 ft] in elevation. Therefore, species are expected to move upwards in elevation or towards
1122-400: Is still useful in that the laws of physics are applicable in a bulk fashion to unknown objects, or in an appropriate lumped manner if some major properties of the object are known. For example, astronomers know that most planets in our own solar system feature some kind of solid/liquid surface surrounded by a gaseous atmosphere. A very simple model of the radiative equilibrium of the Earth
1188-439: Is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorological variables that are commonly measured are temperature , humidity , atmospheric pressure , wind , and precipitation . In a broader sense, climate is the state of the components of the climate system , including the atmosphere , hydrosphere , cryosphere , lithosphere and biosphere and
1254-580: Is used in studying biological diversity and how climate change affects it. The major classifications in Thornthwaite's climate classification are microthermal, mesothermal, and megathermal. Finally, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates. Paleoclimatologists seek to explain climate variations for all parts of
1320-406: Is what you expect, weather is what you get." Over historical time spans, there are a number of nearly constant variables that determine climate, including latitude , altitude, proportion of land to water, and proximity to oceans and mountains. All of these variables change only over periods of millions of years due to processes such as plate tectonics . Other climate determinants are more dynamic:
1386-549: The Frontier exascale supercomputer consumes 29 MW. It can simulate a year’s worth of climate at cloud resolving scales in a day. Techniques that could lead to energy savings, include for example: "reducing floating point precision computation; developing machine learning algorithms to avoid unnecessary computations; and creating a new generation of scalable numerical algorithms that would enable higher throughput in terms of simulated years per wall clock day." Climate models on
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#17327653817431452-595: The NOAA Geophysical Fluid Dynamics Laboratory AOGCMs represent the pinnacle of complexity in climate models and internalise as many processes as possible. However, they are still under development and uncertainties remain. They may be coupled to models of other processes, such as the carbon cycle , so as to better model feedback effects. Such integrated multi-system models are sometimes referred to as either "earth system models" or "global climate models." Simulation of
1518-542: The carbon cycle . They are instances of a multi-compartment model . In 1961 Henry Stommel was the first to use a simple 2-box model to study factors that influence ocean circulation. In 1956, Norman Phillips developed a mathematical model that realistically depicted monthly and seasonal patterns in the troposphere. This was the first successful climate model. Several groups then began working to create general circulation models . The first general circulation climate model combined oceanic and atmospheric processes and
1584-407: The climate , and forecasting climate change . Atmospheric GCMs (AGCMs) model the atmosphere and impose sea surface temperatures as boundary conditions. Coupled atmosphere-ocean GCMs (AOGCMs, e.g. HadCM3 , EdGCM , GFDL CM2.X , ARPEGE-Climat) combine the two models. The first general circulation climate model that combined both oceanic and atmospheric processes was developed in the late 1960s at
1650-484: The thermohaline circulation of the ocean leads to a 5 °C (9 °F) warming of the northern Atlantic Ocean compared to other ocean basins. Other ocean currents redistribute heat between land and water on a more regional scale. The density and type of vegetation coverage affects solar heat absorption, water retention, and rainfall on a regional level. Alterations in the quantity of atmospheric greenhouse gases (particularly carbon dioxide and methane ) determines
1716-495: The Arctic region and oceans. 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 systematically and occurs at random times. Such variability is called random variability or noise . On
1782-459: The EU's Copernicus Climate Change Service, average global air temperature has passed 1.5C of warming the period from February 2023 to January 2024. Climate models use quantitative methods to simulate the interactions and transfer of radiative energy between the atmosphere , oceans , land surface and ice through a series of physics equations. They are used for a variety of purposes, from the study of
1848-449: The Earth as a single point and average outgoing energy. This can be expanded vertically (as in radiative-convective models), or horizontally. Finally, more complex (coupled) atmosphere–ocean– sea ice global climate models discretise and solve the full equations for mass and energy transfer and radiant exchange. Climate model Numerical climate models (or climate system models ) are mathematical models that can simulate
1914-554: The Earth during any given geologic period, beginning with the time of the Earth's formation. Since very few direct observations of climate were available before the 19th century, paleoclimates are inferred from proxy variables . They include non-biotic evidence—such as sediments found in lake beds and ice cores —and biotic evidence—such as tree rings and coral. Climate models are mathematical models of past, present, and future climates. Climate change may occur over long and short timescales due to various factors. Recent warming
1980-481: The Sun as well as outgoing energy from Earth. An imbalance results in a change in temperature . The incoming energy from the Sun is in the form of short wave electromagnetic radiation , chiefly visible and short-wave (near) infrared . The outgoing energy is in the form of long wave (far) infrared electromagnetic energy. These processes are part of the greenhouse effect . Climate models vary in complexity. For example,
2046-462: The amount of solar energy retained by the planet, leading to global warming or global cooling . The variables which determine climate are numerous and the interactions complex, but there is general agreement that the broad outlines are understood, at least insofar as the determinants of historical climate change are concerned. Climate classifications are systems that categorize the world's climates. A climate classification may correlate closely with
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2112-498: The atmosphere in the late 19th century. Other EBMs similarly seek an economical description of surface temperatures by applying the conservation of energy constraint to individual columns of the Earth-atmosphere system. Essential features of EBMs include their relative conceptual simplicity and their ability to sometimes produce analytical solutions . Some models account for effects of ocean, land, or ice features on
2178-426: The causes of climate, and empiric methods, which focus on the effects of climate. Examples of genetic classification include methods based on the relative frequency of different air mass types or locations within synoptic weather disturbances. Examples of empiric classifications include climate zones defined by plant hardiness , evapotranspiration, or more generally the Köppen climate classification which
2244-413: The climate system in full 3-D space and time was impractical prior to the establishment of large computational facilities starting in the 1960s. In order to begin to understand which factors may have changed Earth's paleoclimate states, the constituent and dimensional complexities of the system needed to be reduced. A simple quantitative model that balanced incoming/outgoing energy was first developed for
2310-482: The consequences of increasing greenhouse gases in the atmosphere, primarily carbon dioxide (see greenhouse gas ). These models predict an upward trend in the global mean surface temperature , with the most rapid increase in temperature being projected for the higher latitudes of the Northern Hemisphere. Models can range from relatively simple to quite complex. Simple radiant heat transfer models treat
2376-557: The context of environmental policy , the term "climate change" often refers only to changes in modern climate, including the rise in average surface temperature known as global warming . In some cases, the term is also used with a presumption of human causation, as in the United Nations Framework Convention on Climate Change (UNFCCC). The UNFCCC uses "climate variability" for non-human caused variations. Earth has undergone periodic climate shifts in
2442-583: The dynamics of the weather and climate system to projections of future climate. All climate models balance, or very nearly balance, incoming energy as short wave (including visible) electromagnetic radiation to the Earth with outgoing energy as long wave (infrared) electromagnetic radiation from the Earth. Any imbalance results in a change in the average temperature of the Earth. Climate models are available on different resolutions ranging from >100 km to 1 km. High resolutions in global climate models require significant computational resources, and so only
2508-423: The effect of ice-albedo feedback on global climate sensitivity has been investigated using a one-dimensional radiative-convective climate model. The zero-dimensional model may be expanded to consider the energy transported horizontally in the atmosphere. This kind of model may well be zonally averaged. This model has the advantage of allowing a rational dependence of local albedo and emissivity on temperature –
2574-421: The global temperature and produce an interglacial period. Suggested causes of ice age periods include the positions of the continents , variations in the Earth's orbit, changes in the solar output, and volcanism. However, these naturally caused changes in climate occur on a much slower time scale than the present rate of change which is caused by the emission of greenhouse gases by human activities. According to
2640-621: The interactions between climate and ecosystems . Climate models are systems of differential equations based on the basic laws of physics , fluid motion , and chemistry . Scientists divide the planet into a 3-dimensional grid and apply the basic equations to those grids. Atmospheric models calculate winds , heat transfer , radiation , relative humidity , and surface hydrology within each grid and evaluate interactions with neighboring points. These are coupled with oceanic models to simulate climate variability and change that occurs on different timescales due to shifting ocean currents and
2706-533: The interactions between them. The climate of a location is affected by its latitude , longitude , terrain , altitude , land use and nearby water bodies and their currents. Climates can be classified according to the average and typical variables, most commonly temperature and precipitation . The most widely used classification scheme is the Köppen climate classification . The Thornthwaite system , in use since 1948, incorporates evapotranspiration along with temperature and precipitation information and
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2772-456: The interactions of important drivers of climate . These drivers are the atmosphere , oceans , land surface and ice . Scientists use climate models to study the dynamics of the climate system and to make projections of future climate and of climate change . Climate models can also be qualitative (i.e. not numerical) models and contain narratives, largely descriptive, of possible futures. Climate models take account of incoming energy from
2838-456: The modern time scale, their observation frequency, their known error, their immediate environment, and their exposure have changed over the years, which must be considered when studying the climate of centuries past. Long-term modern climate records skew towards population centres and affluent countries. Since the 1960s, the launch of satellites allow records to be gathered on a global scale, including areas with little to no human presence, such as
2904-404: The most common atmospheric variables (air temperature, pressure, precipitation and wind), other variables such as humidity, visibility, cloud amount, solar radiation, soil temperature, pan evaporation rate, days with thunder and days with hail are also collected to measure change in climate conditions. The difference between climate and weather is usefully summarized by the popular phrase "Climate
2970-412: The much larger heat storage capacity of the global ocean. External drivers of change may also be applied. Including an ice-sheet model better accounts for long term effects such as sea level rise . There are three major types of institution where climate models are developed, implemented and used: Big climate models are essential but they are not perfect. Attention still needs to be given to
3036-518: The nature of questions asked and the pertinent time scales, there are, on the one extreme, conceptual, more inductive models, and, on the other extreme, general circulation models operating at the highest spatial and temporal resolution currently feasible. Models of intermediate complexity bridge the gap. One example is the Climber-3 model. Its atmosphere is a 2.5-dimensional statistical-dynamical model with 7.5° × 22.5° resolution and time step of half
3102-418: The new reprocessed data record will replace the old CDR. A Fundamental Climate Data Record is a long-term data record of calibrated and quality-controlled data designed to allow the generation of homogeneous products that are accurate and stable enough for climate monitoring. Climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it
3168-705: The other hand, periodic variability occurs relatively regularly and in distinct modes of variability or climate patterns. There are close correlations between Earth's climate oscillations and astronomical factors ( barycenter changes, solar variation , cosmic ray flux, cloud albedo feedback , Milankovic cycles ), and modes of heat distribution between the ocean-atmosphere climate system. In some cases, current, historical and paleoclimatological natural oscillations may be masked by significant volcanic eruptions , impact events , irregularities in climate proxy data, positive feedback processes or anthropogenic emissions of substances such as greenhouse gases . Over
3234-402: The past state of the climate. It demonstrates periods of stability and periods of change and can indicate whether changes follow patterns such as regular cycles. Details of the modern climate record are known through the taking of measurements from such weather instruments as thermometers , barometers , and anemometers during the past few centuries. The instruments used to study weather over
3300-416: The past, including four major ice ages . These consist of glacial periods where conditions are colder than normal, separated by interglacial periods. The accumulation of snow and ice during a glacial period increases the surface albedo , reflecting more of the Sun's energy into space and maintaining a lower atmospheric temperature. Increases in greenhouse gases , such as by volcanic activity , can increase
3366-531: The planet's surface, have an average emissivity of about 0.5 (which must be reduced by the fourth power of the ratio of cloud absolute temperature to average surface absolute temperature) and an average cloud temperature of about 258 K (−15 °C; 5 °F). Taking all this properly into account results in an effective earth emissivity of about 0.64 (earth average temperature 285 K (12 °C; 53 °F)). Dimensionless models have also been constructed with functionally separated atmospheric layers from
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#17327653817433432-520: The poles can be allowed to be icy and the equator warm – but the lack of true dynamics means that horizontal transports have to be specified. Early examples include research of Mikhail Budyko and William D. Sellers who worked on the Budyko-Sellers model . This work also showed the role of positive feedback in the climate system and has been considered foundational for the energy balance models since its publication in 1969. Depending on
3498-508: The poles in latitude in response to shifting climate zones." Climate (from Ancient Greek κλίμα 'inclination') is commonly defined as the weather averaged over a long period. The standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations. The Intergovernmental Panel on Climate Change (IPCC) 2001 glossary definition
3564-461: The radiative heat transfer processes which underlie the greenhouse effect. Quantification of this phenomenon using a version of the one-layer model was first published by Svante Arrhenius in year 1896. Water vapor is a main determinant of the emissivity of Earth's atmosphere. It both influences the flows of radiation and is influenced by convective flows of heat in a manner that is consistent with its equilibrium concentration and temperature as
3630-437: The real world (what is happening and why). The global models are essential to assimilate all the observations, especially from space (satellites) and produce comprehensive analyses of what is happening, and then they can be used to make predictions/projections. Simple models have a role to play that is widely abused and fails to recognize the simplifications such as not including a water cycle. A general circulation model (GCM)
3696-506: The solar constant, Earth albedo, or effective Earth emissivity. The effective emissivity also gauges the strength of the atmospheric greenhouse effect , since it is the ratio of the thermal emissions escaping to space versus those emanating from the surface. The calculated emissivity can be compared to available data. Terrestrial surface emissivities are all in the range of 0.96 to 0.99 (except for some small desert areas which may be as low as 0.7). Clouds, however, which cover about half of
3762-494: The surface budget. Others include interactions with parts of the water cycle or carbon cycle . A variety of these and other reduced system models can be useful for specialized tasks that supplement GCMs, particularly to bridge gaps between simulation and understanding. Zero-dimensional models consider Earth as a point in space, analogous to the pale blue dot viewed by Voyager 1 or an astronomer's view of very distant objects. This dimensionless view while highly limited
3828-595: The surface. The simplest of these is the zero-dimensional, one-layer model , which may be readily extended to an arbitrary number of atmospheric layers. The surface and atmospheric layer(s) are each characterized by a corresponding temperature and emissivity value, but no thickness. Applying radiative equilibrium (i.e conservation of energy) at the interfaces between layers produces a set of coupled equations which are solvable. Layered models produce temperatures that better estimate those observed for Earth's surface and atmospheric levels. They likewise further illustrate
3894-440: The temperature variation with elevation in a more realistic manner. They also simulate the observed decline in upper atmospheric temperature and rise in surface temperature when trace amounts of other non-condensible greenhouse gases such as carbon dioxide are included. Other parameters are sometimes included to simulate localized effects in other dimensions and to address the factors that move energy about Earth. For example,
3960-489: The thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982, the WMO agreed to update climate normals, and these were subsequently completed on the basis of climate data from 1 January 1961 to 31 December 1990. The 1961–1990 climate normals serve as the baseline reference period. The next set of climate normals to be published by WMO is from 1991 to 2010. Aside from collecting from
4026-478: The understanding and prediction of climate and its variability , such as global warming . An Interim Climate Data Record (ICDR) is a dataset that has been forward processed, using the baselined CDR algorithm and processing environment but whose consistency and continuity have not been verified. Eventually it will be necessary to perform a new reprocessing of the CDR and ICDR parts together to guarantee consistency, and
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#17327653817434092-479: The variability or average state of the atmosphere over time scales ranging from decades to millions of years. These changes can be caused by processes internal to the Earth , external forces (e.g. variations in sunlight intensity) or human activities, as found recently. Scientists have identified Earth's Energy Imbalance (EEI) to be a fundamental metric of the status of global change. In recent usage, especially in
4158-448: The years, the definitions of climate variability and the related term climate change have shifted. While the term climate change now implies change that is both long-term and of human causation, in the 1960s the word climate change was used for what we now describe as climate variability, that is, climatic inconsistencies and anomalies. Climate change is the variation in global or regional climates over time. It reflects changes in
4224-568: Was developed in the late 1960s at the Geophysical Fluid Dynamics Laboratory , a component of the U.S. National Oceanic and Atmospheric Administration . By 1975, Manabe and Wetherald had developed a three-dimensional global climate model that gave a roughly accurate representation of the current climate. Doubling CO 2 in the model's atmosphere gave a roughly 2 °C rise in global temperature. Several other kinds of computer models gave similar results: it
4290-520: Was impossible to make a model that gave something resembling the actual climate and not have the temperature rise when the CO 2 concentration was increased. The Coupled Model Intercomparison Project (CMIP) has been a leading effort to foster improvements in GCMs and climate change understanding since 1995. The IPCC stated in 2010 it has increased confidence in forecasts coming from climate models: "There
4356-533: Was originally designed to identify the climates associated with certain biomes . A common shortcoming of these classification schemes is that they produce distinct boundaries between the zones they define, rather than the gradual transition of climate properties more common in nature. Paleoclimatology is the study of past climate over a great period of the Earth 's history. It uses evidence with different time scales (from decades to millennia) from ice sheets, tree rings, sediments, pollen, coral, and rocks to determine
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