From the "no kidding, Sherlock" files:
At present, most models divide the world into 50-kilometre grid squares, which gives a very coarse resolution.
Changwan Seo of the University of Seoul, South Korea, and his colleagues tested four models at a variety of spatial scales, using existing data for rare plants such as Coulter pine. The larger the grid size, the more the models overestimated the range available, the team found. Within grid sizes of more than 16 by 16 kilometres, in areas like the eastern Sierra Nevada in California, conservationists overestimate the amount of habitat available to a species by two or three times (Biology Letters, DOI: 10.1098/rsbl.2008.0476).
Conservationists will have to run models with smaller grid sizes, even though this costs more and consumes more computer time, says Lee Hannah of Conservation International in Santa Barbara, California, who co-authored the paper.
Not surprising. Equally not surprising is that they do not have a mathematical model for how much space is needed for interacting species to support an ecosystem, nor have they taken into account genetic health of each species and how much space it requires for quality breeding.
We have more surprises in the future: we're taking up much more land that we should. And what did we put on it? Idiots, fast food, shopping malls, subdivisions.