Katla is big enough that even from it's far northern latitude it could affect climate.
From Modern Survival blog via BeforeIt'sNews:
Uh-oh! Katla Volcano Just Rumbled
Is the sleeping Katla waking up?
On May 17, 2010 08:32 UTC, The Iceland Met office indicates that a small earthquake has occurred at the Katla location. In what could be an early indication of the event that is expected to occur (an eruption of Katla), a small earthquake is reported at the site. Although a single earthquake is not a precursor of an eminent eruption, it could be the first sigh of the awakening powerful giant.