Editing Climate model (section)

{{short description|Quantitative methods used to simulate climate}}
{{about|the theories and mathematics of climate modeling|computer-driven prediction of Earth's climate|General circulation model}}
{{Use dmy dates|date=November 2019}}
{{broader|Atmospheric model|Oceanic model}}
[[File:Global Climate Model.png|thumb|right|350px|Climate models divide the planet into a 3-dimensional grid and apply [[differential equation]]s to each grid. The equations are based on the basic laws of [[physics]], [[Fluid dynamics|fluid motion]], and [[chemistry]]. ]]
Numerical '''climate models''' (or '''climate system models''') are [[mathematical model]]s that can simulate the interactions of important drivers of [[climate]]. These drivers are the [[Earth's atmosphere|atmosphere]], [[ocean]]s, [[land surface]] and [[cryosphere|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.<ref>{{cite 
 | author = IPCC
 | year = 2014
 | title = AR5 Synthesis Report - Climate Change 2014. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change
 | page = 58
 | url = https://www.ipcc.ch/site/assets/uploads/2018/02/SYR_AR5_FINAL_full.pdf#page=74
 | quote = Box 2.3.   ‘Models’ are typically numerical simulations of real-world systems, calibrated and validated using observations from experiments or analogies, and then run using input data representing future climate. Models can also include largely descriptive narratives of possible futures, such as those used in scenario construction.  Quantitative and descriptive models are often used together.
 }}</ref>

Climate models take account of incoming [[energy]] from the Sun as well as outgoing energy from Earth. An imbalance results in a [[First law of thermodynamics|change in temperature]]. The incoming energy from the Sun is in the form of short wave [[electromagnetic radiation]], chiefly [[Visible spectrum|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, 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 model]]s. 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 model|Earth System Models]] include also [[land use]] as well as [[land use change]]s. This allows researchers to predict the interactions between climate and [[ecosystems]].

Climate models are systems of [[differential equation]]s based on the basic laws of [[physics]], [[Fluid dynamics|fluid motion]], and [[chemistry]]. Scientists divide the planet into a 3-dimensional grid and apply the basic equations to those grids. [[Atmospheric model]]s calculate [[winds]], [[heat transfer]], [[radiation]], [[relative humidity]], and surface [[hydrology]] within each grid and evaluate interactions with neighboring points.  These are coupled with [[oceanic model]]s to simulate [[climate variability and change]] that occurs on different timescales due to shifting [[ocean current]]s and the much larger [[ocean heat content|heat storage capacity]] of the global ocean.  [[climate forcing|External drivers]] of change may also be applied. Including an [[ice-sheet model]] better accounts for long term effects such as [[sea level rise]].