Astronomers would like to pin down the masses of the planets (information difficult to acquire with Kepler), as well as getting that data on atmospheric composition.

BBC: Kepler telescope spies 'most Earth-like' worlds to date

As an explanation for the conundrum of the ice ages, this notion could only hold water if a mechanism for such large changes in atmospheric composition might be found in the real world.

FORBES: Global Warming Is No Threat?

Each day, the scientific community collects millions of individual Earth observations, allowing us to examine, monitor, and model atmospheric composition, seismic activity, ecosystem health, weather patterns, and hundreds of other characteristics of our planet.

WHITEHOUSE: Office of Science and Technology Policy Blog