A story by David Reidmiller, Gulf of Maine Research Institute from 2023
David Reidmiller Ph.D. Director, Climate Center Gulf of Maine Research Institute
The Gulf of Maine is experiencing physical, chemical, and biological changes as a result of climate change. The unprecedented accumulation of greenhouse gasses in the atmosphere over the past century traps excess heat in the Earth system, with world oceans absorbing more than 90%.
As a result of its shape, bathymetry (the measurement of depth of water), and changes in large-scale ocean currents like the Gulf Stream, the rate of warming in the Gulf of Maine is faster than that of more than 95% of the world’s oceans. At the surface, this additional heat can impede vertical mixing of ocean water, preventing life-sustaining nutrients from reaching organisms closer to the surface. Throughout the water column, warming waters create a friendlier environment for certain fish species and pathogens that can disrupt ecosystems, causing population declines and shifts.
Oceans provide us with an “ecosystem service” because they absorb carbon dioxide (CO2)—the primary greenhouse gas—from the atmosphere as a natural part of Earth’s carbon cycle. But the unnatural pace that humanity is emitting CO2 into the atmosphere is causing an increase in CO2 absorption by the world’s oceans, resulting in a gradual acidification of seawater—a 30% increase in acidity since pre-industrial times. More acidic water makes it more difficult for shellfish like lobsters, oysters, and clams to form their exoskeleton or shells. These changes present risks to coastal communities who rely on the ocean for their livelihoods and well-being.
But changes offer opportunities to create new markets for emergent species and adapt business practices to the continually changing marine environment as a result of climate change. In the process, Maine’s marine-dependent communities can serve as a global model for adapting and thriving in a warmer world.
Gulf of Maine warming data, seasonally.
Gulf of Maine warming data, annually.
The Gulf of Maine is warming much faster than the global average. These graphs illustrate the long-term sea surface temperature (SST) anomalies for the Gulf of Maine, from satellite observations. Annual SST anomalies represent the deviation in any given year from the long term (1982-2011) average. Annual average SST for the Gulf of Maine [black line] with the long-term warming trend in that data [blue] compared to the long-term warming trend for all ocean surfaces in the world [green]. The same as in the top plot but broken down by season to illustrate that while the rates of change across seasons is relatively similar for the global ocean, taken as a whole, there are stark differences in seasonal rates of warming for the Gulf of Maine.
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