Progress in Earth System Science: What Does It Take to Make Our Ideas Clear? - Towards an Interdisciplinary Approach in Earth System Science - page 27

3 Building of Models and Expressing the Scienti c

Discoveries

Another type of model can be even as short as a metaphor. Metaphors can pre-
structure and prepare the building of a model in science: the diagram of the par-
allelism predicate is less complicated than its subject. Its simpler composition helps
to structure the subject by emphasizing special features of the complicated structure
(Br ning and Lohmann 1999 ).

One prominent example is to be found in oceanography (Fig. 3 ): The ocean
conveyor is driven by deepwater formation in the northern North Atlantic, making
it the engine of conveyor belt circulation (Broecker 1991 ). The conveyor belt
metaphor necessarily simpli

ü

es the ocean system, it is of course not a full
description of the deep ocean circulation, but contains different aspects of it
(Br s( 1991 ) concept provides a successful

approach for global ocean circulation, although several features are strongly sim-
pli

ü ning and Lohmann 1999 ). Broecker '

ed like the missing Antarctic bottom water, the upwelling areas etc. One is
tempted to say: The ocean is of course not a conveyor belt! However, the global
conveyor belt metaphor inspired principally new ideas of halting or reversing the
ocean circulation and put it into a global climate context (e.g., Bryan 1986 ). The
halting ocean circulation was helpful for the interpretation of Greenland ice core

Fig. 3 Broecker ( 1991 ) s great ocean conveyor. Warm and salty water entering the North Atlantic

region is cooled. The dense water formed at the surface is conveyed to the deep ocean and is part
of the southward return

'

s findings, it was necessary to a identify the relevance
of North Atlantic deep water production, and b realize the possibility of multiple equilibriums of
ocean circulation states and their association with two different climatic states

fl ow. For Broecker '