If a volcano releases heat from the earth's interior, it absolutely will find it's way up to the surface and eventually out into space. (dotearth.blogs.nytimes.com)
As they heat up, the oceans, land and atmosphere release heat in the form of IR thermal radiation, which passes out of the atmosphere and into space. (livescience.com)
In the case of freezing temperatures, the water actually releases heat as it freezes, further protecting the plants. (fieryfoodscentral.com)