On January 23, 2006, this weblog summarized the reasons that there is a warm bias
in the diagnosed global average surface temperature record (see “Why there is a Warm Bias in the Existing Analyses of the Global Average Surface Temperature”). The identification of this bias in the peer reviewed literature provides a challenge to the established dogma that the surface temperature trend data is robust.
This issue is fundamental to the media reports that we are past a âtipping pointâ? (e.g. see ) with respect to climate change, as the global surface temperature trend is the icon that has been adopted by many in the policy making arena (inappropriately; see There is Confusion on What is Meant Regarding the Terms âGlobal Warmingâ? and âClimate Changeâ? ).
Not only is there a problem with the observational interpretation of the data, there is also a major problem with the multi-decadal climate modeling of this icon. As will be reported in a soon to be published special issue of Boundary Layer Meteorology on the âGEWEX Atmospheric Boundary-Layer Study (GABLS) on stable boundary layersâ?, most of the surface air temperature increase predicted by climate models occurs during stable atmospheric conditions, and that the climate models poorly represent the stable boundary layer. This special issue will be reported on in the Climate Science weblog in more detail when it appears.
The modeling of the stable boundary layer is so difficult due to the need to accurately represent the interaction of long-wave radiative flux divergence and turbulence. These processes significantly affect the surface temperature trend that is predicted by the models. In stable boundary layers, the turbulence is often intermittent, and the vertical temperature profile complex.
A challenge to the multi-decadal global modeling community, and to the IPCC and CCSP assessments that use this information, is how accurately can they predict the stable boundary layer contribution to surface temperature trends. It is remarkable that policy has been implemented which has not even adequately evaluated this icon of the global warming community.