  The Kepler era of exoplanetary discovery has presented the Astronomical
community with a cornucopia of planetary systems very different from the one
which we inhabit. It has long been known that Jupiter plays a major role in the
orbital parameters of Mars and it's climate, but there is also a long-standing
belief that Jupiter would play a similar role for Earth if not for its large
moon. Using a three dimensional general circulation model (3-D GCM) with a
fully-coupled ocean we simulate what would happen to the climate of an
Earth-like world if Mars did not exist, but a Jupiter-like planet was much
closer to Earth's orbit. We investigate two scenarios that involve evolution of
the Earth-like planet's orbital eccentricity from 0--0.283 over 6500 years, and
from 0--0.066 on a time scale of 4500 years. In both cases we discover that
they would maintain relatively temperate climates over the time-scales
simulated. More Earth-like planets in multi-planet systems will be discovered
as we continue to survey the skies and the results herein show that the
proximity of large gas giant planets may play an important role in the
habitability of these worlds. These are the first such 3-D GCM simulations
using a fully-coupled ocean with a planetary orbit that evolves over time due
to the presence of a giant planet.
