Changes in the Gulf Stream preceded rapid warming of the Northwest Atlantic Shelf

The Northwest Atlantic Shelf provides ecological and economic benefits along the heavily populated North American coastline and beyond. In 2009-2010, abrupt warming prompted an ecosystem shift with consequences for fisheries, yet the cause of this event is unclear. Here we use satellite altimetry and in situ measurements to show that, in 2008, the Gulf Stream migrated closer to the Tail of the Grand Banks, a shift that has persisted ever since. This change reduced the westward connectivity of the Labrador Current that otherwise supplies cold, fresh, oxygen-rich waters to the shelf. Within one year after the appearance of anomalously warm and saline water at the Tail of Grand Banks, subsurface warming progressed south-westwards. Historical observations suggest a similar sequence of events may have occurred in the 1970s. Therefore, monitoring water properties at the Tail of Grand Banks may offer predictability for shelf properties and ecosystem perturbations with substantial lead time. A northward shift of the Gulf Stream in 2008 interrupted the Labrador Current and may have contributed to abrupt warming and an ecosystem shift in the Northwest Atlantic Shelf a year later, suggest satellite altimetry and direct subsurface measurements.

Automated summary

Research indicates a northward shift of the Gulf Stream towards the Tail of the Grand Banks on the Northwest Atlantic Shelf in 2008, disrupting the connectivity of the Labrador Current and potentially contributing to abrupt warming and an ecosystem shift a year later. Historical observations suggest similar events may have occurred in the 1970s.