Every summer, people descend on the wildflower capital of Colorado to see grasslands flush with corn lilies, aspen sunflowers and sub-alpine larkspur. In January 1991, scientists set up a unique experiment in these Rocky Mountain meadows. It was one of the first (and longest running) to work out how the changing climate would affect an ecosystem. At the time, it was believed a temperature increase could lead to longer, lusher grasses.