THE MODELLION CONCEPT

Humanity's massive intervention in natural systems is at a pace which exceeds our ability to predict its consequence on the world in which we live. As a result, we have conceived a model planet, Modellion, with much simpler terrestrial surfaces, upon which we can carry out numerical experiments to teach us, by example, about the planet Earth. Over the last decade there have been observational studies to better define this model planet and to aid its evolution toward the Earth system. This paper reviews these studies, their purpose, and the insight they have given; it then goes on to preview elements of the observational program proposed to occur under the Global Energy and Water Cycle Experiment and International Geosphere-Biosphere Programme in the 1990s.