Read the linked article for the details, but the quick summary is as follows.
- Eruptions of other volcanoes in Iceland have been historically linked to the (currently erupting) Eyjafjallajokull. Large volcanic eruptions have been known to cause significant worldwide cooling.
- The longest and deepest solar minimum of the last 100 years has ended recently. Long solar cycles have been linked to global cooling trends in the following cycle.
- The now famous (?) El Nino and La Nina ocean warming patterns point to a rise of La Nina which would serve to lower temperatures further.
The net result of this could be bitterly cold winters and unnaturally cold summers for a few years.
While I didn’t care for the tone the author Horn takes in his article–he has too many overreaching statements attacking global warming science–the sources he links are quite interesting and worth a read.