Bullock and Grinspoon have shown that the climate of Venus is unstable with respect to a very large volcanic eruption, because such an event would release into the atmosphere significant quantities of water and sulfur dioxide from the erupting lavas. Climate models incorporating all of these processes indicate that for a sufficiently large eruption the excursions in surface temperature accompanying changes to the greenhouse and to the global cloud cover can exceed 100 K and can extend over periods from tens to hundreds of millions of years. Such temperature changes over these timescales diffuse deep into the interior of a planet. Differential temperature changes of this magnitude expand or contract surface and near-surface material by amounts sufficient to fracture rock. Climate change on Venus is therefore capable of affecting the deformation of the surface and the global distribution of tectonic features.
Many further tests are in progress.
These include exploring the sensitivity of climate models to changes in key parameters, incorporating a fuller description of the known volcanic flux history of the planet, and exploring whether other apparently global episodes of coherent contractional or extensional deformation might also be the result of stresses induced by climate change. A radar image of ridged plains is shown for Rusalka Planitia, Venus. The image is about 155 km wide. The predicted evolution of surface horizontal stress resulting from the climate change that accompanied and followed emplacement of ridged plains lavas is depicted here. The compressive stresses that accumulated in the first 100 million years of the model would have been sufficient to produce widespread faulting manifested in the formation of wrinkle ridges.