MAGICC is a model developed by the U.S. National Center for Atmospheric Research, with funding from EPA, to determine the impact
of changes in greenhouse gas concentrations on global - mean surface air temperatures.
«There are dozens of prominent global climate models and they all project different amounts of global warming for a
given change in greenhouse gas concentrations, primarily because there is not a consensus on how to best model some key aspects of the climate system,» Brown explained.
This necessitates taking into account atmospheric radiative transfer so that any SST warming is driven by radiative changes (e.g.,
changes in greenhouse gas concentrations) and resultant changes in the surface fluxes.
This research, he claims, virtually proves that the climate models used by the IPCC respond much too sensitively to external «forcing» due to
changes in greenhouse gas concentrations, variations in solar radiation, and so on.
Changes in greenhouse gas concentrations may account for about half of the simulated tropical cooling (Shin et al., 2003), and for the production of colder and saltier water found at depth in the Southern Ocean (Liu et al., 2005).
The radiative forcing of the surface - troposphere system due to the perturbation in or the introduction of an agent (say,
a change in greenhouse gas concentrations) is the change in net (down minus up) irradiance (solar plus long - wave; in Wm - 2) at the tropopause AFTER allowing for stratospheric temperatures to readjust to radiative equilibrium, but with surface and tropospheric temperatures and state held fixed at the unperturbed values.
Although the conceptual model presented here was similar to the ideas discussed by Hulburt in 1931, he did not emphasise the vertical energy flow, the hydrological cycle, and
changes in the greenhouse gas concentrations.