An ash cloud crisis worse than the Icelandic eruption that grounded thousands of flights in 2010 could be imminent, scientists have claimed.
The warning comes after the discovery that volcanic ash has travelled from Alaska to Northern Ireland in the past.
The discovery overturns previously-held assumptions about the distances deposits could drift.
It is the first evidence that ash clouds can travel across the Atlantic Ocean.
Dr Sean Pyne-O'Donnell, from Queen's University Belfast (QUB), who helped conduct the research, said it could have major implications for the aviation industry.
"The usefulness is the awareness that such a thing can happen," he said.
"Airlines are always interested in risk management. This allows them to be better prepared for such eventualities."
Academics have traced ash found in sites across Europe, including Sluggan Bog near Randalstown in County Antrim, to so-called White River ash resulting from the eruption of the Alaskan volcano, Mount Bona-Churchill, in AD 847.
Chemical "fingerprinting" was used to match the White River ash to ash layers in Ireland, Norway, Germany and Greenland which for 20 years was believed to have come from Iceland, the source of most ash in Europe.
In 2010 plumes spewed out by the volcano Eyjafjallajokull in Iceland caused major disruption and grounded more than 100,000 international flights, costing airlines more than £2bn.
Volcanoes like Mount Bona-Churchill are much more volatile and are scheduled to erupt on average every 100 years, increasing the risk of another ash cloud drama with consequences for transatlantic as well as European travel.
Dr Pyne-O'Donnell, from Queen's School of Geography, Archaeology and Paleoecology, added: "If this was to happen again, which is not improbable, it would have massive implications for airspace.
"This is a very large area and is very busy with travel. There could be large-scale disruption," he said.
The findings were made by QUB scientists in partnership with an international team of academics and have been published in the journal Geology.