## Ice Component of Models

CLIMATE MODELS HAVE developed from mathematical formulas used in the 19th century to try to predict the weather. The lack of accurate and comprehensive data and the need to rely on manual calculation techniques made these approaches very difficult, and ultimately, they were abandoned as it became clear that the results of the equations did not match real-world conditions. During World War II, military expediencies demanded that more data be collected about the atmosphere, and this capacity remained in force after the war. The quantity of data available enabled researchers to check their calculations against real-world conditions. The advent of computers reduced the time needed to complete calculations.

The result is that climate models were refined and developed to a far more sophisticated degree than had previously been imagined possible. One implication of this is that modelers have been able to include a number of new variables in their models, or else to increase the complexity with which existing variables are treated. As a result, the atmosphere is divided into an increasingly large number of layers, and land cover is divided into different elevations, types, and albedos, for example. The insertion of ice into climate models is a further example of the refinement. Models that include ice components may be referred to as oceanic models, and they are a necessary part of comprehensive Coupled Atmosphere-Oceanic General Climate Models.

Ice may be considered both as land cover and as part of the sea. The composition of the ice, as well as its size and structure, will have an impact on its albedo, which represents the degree to which light is reflected from its surface. Ice is involved in the exchange of salt from water to ice, and also has an impact on the surrounding land cover. Ice will increase or decrease according to fairly predictable patterns. However, the calving process by which icebergs divide is less easy to predict. The momentum of ice is now more accurately calculated by using scaling arguments, while incremental remapping is now used to consider horizontal advection.

In addition to modeling the presence of ice, researchers must also consider the ways in which the different components of the models interact with each other. Atmosphere, ocean, land, and sea-ice components exist in a dynamic state of change, depending on their interactions with each other and with external sources of energy. The impact of rapid ice-loss now experienced, for example, is being studied with great urgency, as it has unforeseen impacts upon the rest of the climate system, as well as the possibility of earthquakes and other tectonic activity. The release of more water into the seas will have an impact upon the amount of land above sea level and will, therefore, have an affect on patterns of human settlement.

As global warming and climate change continue to intensify, the amount of ice on the Earth's surface will continue to decrease. Estimates suggest that, if current trends continue, Himalayan ice will have disappeared within three decades, while polar ice is breaking up and melting at an ever-increasing rate. This will probably obviate the need to integrate the presence of ice into climate models in the future.

SEE ALSO: Albedo; Climate Models; Computer Models; Ice Ages; Ice Albedo Feedback.

BIBLIOGRAPHY. Canadian Centre for Climate Modelling and Analysis, www.ccma.ec.gc.ca (cited November 2007); W.M. Connolley, et al., "On the Consistent Scaling of Terms in the Sea Ice Dynamics Equation," Journal of Physical Oceanography (v.34, 2004); C.C. Gordon, et al., "The Simulation of SST, Sea Ice Extents and Ocean Heat Transports in a Version of the Hadley Centre Coupled Model without Flex Adjustments," Climate Dynamics (v.16/2-3, 2000); W.H. Libscomb and E.C. Hunke, "Modeling Sea-Ice Transport Using Incremental Remapping," Monthly Weather Review (v.132, 2004).

John Walsh Shinawatra University