Why do volcanoes cause earth's climate to get colder?

Lightweight volcanic ejecta, particularly ash and small cinders cause a "block" in the atmosphere preventing incoming solar radiation from reaching the earth's surface, thus lowering the surface temperature of the planet. read more

The distance from the sun has very little to do with the temperature. It is directly related to the inclination of the earths rotational axis. read more

No. Convection currents which could lead to volcanism in the crust occur in the mantle. The crust is too cold and brittle for convection currents to occur. read more