How are the waters off Nova Scotia's Scotian Shelf changing?

The waters off Nova Scotia's Scotian Shelf have been gradually warming over the past three decades, with surface temperatures rising by about 1.5 degrees and bottom waters warming twice as much, by about 3 degrees.

What is causing the warming in the Scotian Shelf?

The warming is primarily driven by longer and more intense marine heat waves, as well as fewer cold spells. The number of heat wave days at the bottom of the Scotian Shelf has been rising by roughly 4 days per year, resulting in an additional 120 days of heat waves over the past 30 years.

How is the warming affecting lobster in the region?

The warming waters are already affecting species that live on or near the sea floor, including lobster. As the water temperature rises, lobsters become more active and need to eat more, which can lead to faster growth and larger catches in the short term. However, the report warns that continued warming could eventually push the conditions beyond the species' tolerance.

Home / Environment / Scotian Shelf Heats Up: Marine Heat Waves Intensify in Nova Scotia

Scotian Shelf Heats Up: Marine Heat Waves Intensify in Nova Scotia

30 Sep, 2025

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Summary

Waters off Nova Scotia warming due to longer, more intense marine heat waves
Bottom waters warming twice as fast as surface waters, by about 3 degrees
Fewer cold spells causing temperatures to not reset between heat waves

According to a recent report by the European Union's marine monitoring service, the waters off Nova Scotia have been experiencing a concerning trend of gradual warming over the past three decades. The report, released on September 30, 2025, reveals that surface waters on the Scotian Shelf have risen by about 1.5 degrees, while the bottom waters have warmed twice as much, by approximately 3 degrees.

The team of scientists, led by Li Zhai from the Department of Fisheries and Oceans, found that the warming is primarily driven by longer and more intense marine heat waves, as well as fewer cold spells. At the bottom of the Scotian Shelf, the number of heat wave days has been rising by roughly 4 days per year, resulting in an additional 120 days of heat waves over the past 30 years.