Gulf of Maine has been transformed by warming waters

Years of data that was recently analyzed by researchers at the Bigelow Laboratory for Ocean Sciences has produced some disturbing conclusions about warming in the Gulf of Maine. The warmer water temperatures are changing the basis of the food web throughout the entire gulf.

“We’ve seen that the growth rate of phytoplankton is about a third of what it was 20 years ago; that’s a really big deal,” said William Balch, lead author on the NASA-funded study. “These microscopic plants are the base of the food web on which all ocean life depends, and the change is connected to patterns and processes well beyond the Gulf of Maine.”

The data shows that waters 500 feet below the surface have warmed by almost three degrees over the last two decades. Surprisingly, shallow waters have warmed more slowly, even cooling in the spring. 

“We all work with this mantra that the Gulf of Maine is one of the fastest warming bodies of water on the planet,” said Balch. “Well, there’s an asterisk next to that now, which is really important to understanding the complex changes we’re seeing.”

The cooling effect is only being seen in waters less than 160 feet in depth and only during the spring months. This, in turn, suggests that these cooler waters are moving in from colder regions to the north. 

“It’s not like the Gulf of Maine is an isolated pond and all the warming happening here is only happening in place,” said Balch. “Rising temperatures are in large part due to this large influx of North Atlantic water, which itself is getting warmer. These changes take time, and they are fundamentally altering the planet.” 

Despite some cooling, the Gulf of Maine is warming overall, which is a disturbing trend. Even though climate change is challenging for organisms, Balch is optimistic about the possibility for many species to adapt. Animals and plants can alter their behavior, move to different niches and perhaps survive – whether human society gives them the chance or not. 

“These changes are the results of our actions, the grand experiment that we humans have run on this planet since the industrial age when we started burning fossil fuels,” Balch said. “The future of the Gulf of Maine relies on us keeping our carbon dioxide emissions down, and that choice is completely under our control.”

The research is published in the Journal of Geophysical Research Biogeosciences.

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By Zach Fitzner, Earth.com Staff Writer