Last year was the second warmest on record for the Gulf of Maine, with the average surface temperature falling just short of the 2021 record but continuing the historic trend of being one of the fastest-warming ocean areas on the planet.

The Gulf of Maine’s average annual sea surface temperature was 53.66 degrees Fahrenheit, which is 3.72 degrees above the long-term average, according to the Gulf of Maine Research Institute, which published its annual Gulf of Maine warming report on Wednesday.

That’s 0.43 degrees cooler than 2021, the Gulf of Maine’s warmest, and 0.08 degrees warmer than 2012.

“Continually warming waters mean that the way we interact with the marine environment is changing,” said Dave Reidmiller, the director of GMRI’s climate center and one of the report’s authors. “The past is no longer a reliable indicator of future conditions.”

The report found 2022 consistent with the long-term warming trend driven primarily by human-caused climate change, although the authors noted individual years could be influenced by large-scale patterns of natural variability, especially on a regional level.

“It may be startling to realize that the last two years were the warmest on record,” Reidmiller said. “It’s even more sobering to recognize that they’re likely to be among the coolest ones we’ll experience for the foreseeable future.”


But all is not lost, Reidmiller said. Mainers across the state are starting to recognize and act on this data.

“We’re asking the right questions, gathering as much data as possible, and importantly beginning to take ambitious action to ensure communities reliant on the marine environment for their livelihoods and well-being can continue to thrive in a warmer world,” Reidmiller said.

The Gulf of Maine, whose 36,000 sprawling square miles stretch from Cape Cod to Nova Scotia, is home to rare whales and seabirds like the Atlantic puffin, iconic fish stocks like cod and haddock, and the $1.5 billion U.S. lobster industry, all of which are impacted by warming waters.

Past ocean heat waves have had devastating impacts on some of these iconic species.

In 2021, when the Gulf of Maine was hottest, only 6% of puffin hatchlings at the Gulf’s largest puffin colony made it to the fledgling stage, when they fly away at the end of the season, compared to the usual 75%. They were starving due to a lack of nutrient-rich cold-water fish.

But GMRI scientists note that every year is different and that it can be misleading to draw a straight line between high temperatures in any given year and a single ecological effect, like a devastating year for the puffin, an early lobster shed, or an explosion in the invasive green crab population.


Sea level rise is another consequence of a warming Gulf, Reidmiller noted.

“As water warms, it expands,” Reidmiller said. “Rates of sea level rise in the Gulf of Maine are greater than the national or global average. The recent December 23 storm gave Mainers of all stripes, with any connection to the coast, a sense of what the coming decades have in store.”


The Gulf of Maine is warming faster than 97 percent of the world’s ocean areas. The warmest year, 2021, shattered the previous high set during an “ocean heat wave” in 2012 that triggered green crab invasions, the starvation of puffin chicks and an early lobster shed.

According to climatologists, almost all of 2022 – 353 out of 365 days – qualified as a marine heat wave. That’s defined as a period when the daily average sea surface temperature exceeds the 90th percentile of the long-term sea surface temperature for five or more consecutive days.

Record daily high sea surface temperatures were set in all months except July, according to the data. Overall, record-high daily temperatures were reached on 169 days in 2022, which represents almost half, or 46 percent, of the year, the report concluded.


In fact, marine heat waves have become so common that GMRI scientists are joining the rest of the international scientific community to discuss new ways to define and talk about a concept that began as a rare phenomenon but now has become commonplace, the report states.

The past year was unusual because the most extreme warm weather anomalies happened in the winter, GMRI said. November and December set new records for the highest monthly averages. In past years, the warm weather anomalies happened in the spring, like in 2012, or in summer, like in 2021.

Fall and winter should be a time when Gulf waters mix and cool off, said Janet Duffy-Anderson, GMRI’s chief scientific officer. A long, cold winter allows the water to mix, cool and sink to the bottom, increase in oxygen concentrations, and pick up nutrients, she said. Cut it short and productivity suffers.

Warm winter waters also draw in warm-water species such as blue crabs and black sea bass, she said. A species that overwinter in the Gulf of Maine could potentially spawn here in the spring and colonize the Gulf as a new habitat, Duffy-Anderson said.

The arrival of the blue crab, a species closely tied to the mid-Atlantic’s Chesapeake Bay, set off an alarm bell for Rick Wahle, the director of the Lobster Institute and research professor in the School of Marine Sciences at the University of Maine.



“I never thought I’d see the day where I’d say it is no longer uncommon to see blue crab in Maine,” Wahle said. “We’ve been seeing warm-water fish species in the Gulf of Maine for years now, but to see a blue crab, a crustacean, well, that’s something. It’s a poster child for climate change.”

Wahle has documented other consequences of a warming Gulf of Maine, or what he calls the increasing “southernization” of our coastal waters. One example: lobsters are now reaching sexual maturity at a younger age and smaller size, and the females produce fewer and less viable eggs.

More troubling is the shifting distribution of the lobster population northward over time, away from Maine’s coastal waters and toward Canada, Wahle said. This does not spell immediate trouble for Maine, where lobstering will remain strong for decades, he said, yet it does signal the start of the decline.

For Hannah Pingree, director of the Maine Office of Policy Innovation & the Future and the co-chair of the Maine Climate Council, the GMRI report is both sobering and inspiring. It reinforces that climate change is still accelerating, but reminds her why Maine must pursue its ambitious climate action plan.

“It’s locally produced science like this that reminds us that it’s real, it’s alarming and it’s getting worse,” Pingree said. “That’s why we as a state are doing so much. Not just the state, but our communities. Not just on the coast, either, but inland, too. A warming ocean affects all Mainers.”

The state’s climate action plan, Maine Won’t Wait, has a whole section dedicated to the study of how the changing climate is impacting Maine’s coastal and marine resources and communities, ranging from the fishing industry to coastal infrastructure to residential flood insurance, Pingree said.

The Gulf of Maine wasn’t the only ocean area that experienced exceptional warmth in 2022, GMRI data found. Globally, 2022 was the third-warmest year for average annual sea surface temperatures, and the sixth-warmest year for combined land and ocean temperatures.

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