GOM 2050 Report

Climate change today already determines Gulf of Maine conditions in 2050

by Fishermen’s Voice Staff

Climate change is happening now, but it will be 30 years before its full impact will become apparent.

That’s why it’s important, today, to identify what’s known about the future, steps can be taken in the next few years to adapt to change, and whether even more challenging conditions can be avoided if CO2 conditions continue to rise.

To that end, the Gulf of Maine Research Institute, Gulf of Maine Council on the Marine Environment, and the Huntsman Marine Science Centre brought leaders from across New England and the Maritime Provinces together for the “Gulf of Maine 2050 International Symposium: Challenges and Opportunities for Regional Resilience,” held in early November in Portland.

The symposium considered environmental, economic, social, and institutional perspectives on climate resilience in the Gulf of Maine. According to an introductory paper by the Gulf of Maine Research Institute’s Andrew Pershing and Robert Stephenson with Canada’s Department of Fisheries and Oceans; St. Andrews Biological Station, “2050 marks the threshold between the inevitable changes the climate system that we must prepare for and the even more challenging conditions that we will hopefully avoid.”

An insidious aspect of climate change is that it takes several decades for the climate system to fully respond to a change in carbon dioxide (CO2), they wrote.

“This means that we are only now feeling the effects of CO2 that was released when Bill Clinton was president and Jean Chrétien was prime minister,” they wrote. “For the next 30 years, we will experience the changes in weather patterns, ocean temperatures, ocean chemistry, and sea level as the Earth adjusts to the CO2 emitted up until today.”

However, they wrote, the presence of strong climate change makes some things more predictable.

“Global warming causes other changes in the climate system,” they wrote. “The amount of ice in the Arctic decreases, glaciers in Greenland and Antarctica melt, weather patterns and ocean currents shift. Changes like these go beyond simple warming and are why scientists prefer to talk about climate change rather than merely global warming.”

Climate scientists have developed sophisticated computer models that represent the

interaction between carbon dioxide in the atmosphere, heating at the earth’s surface, warming in the ocean, changes in ice, and shifts in weather patterns and ocean currents.

Prediction highlights for 2050 are as follows:

• Atmospheric temperature: It’s expected the Gulf of Maine region will be warmer—likely 2-3.4°C above the current average. This will lead to a longer growing season but an extended spring frost period and an increase in extremely hot days.

• Precipitation and storms: Precipitation is likely to increase over the Gulf of Maine, but some models suggest drier conditions (decline of 3.2% to a 13.2% increase). Thefrequency of tropical and winter storms is hard to predict, but it is likely that storm intensity will increase.

• Sea level: In the western Gulf of Maine (Massachusetts to New Brunswick), water levels in 2050 will be 19-27 cm higher. Levels in Nova Scotia will be higher by 24-32 cm.

• Ocean temperature: The surface waters of the Gulf of Maine will continue to warm, from 1°C to as much as 2.4°C above the 1975-2006 average. Those conditions represent the baseline climate around 2050. Individual years could be as much as 0.5° cooler or warmer than projections.

• Ocean salinity: Models suggest that surface waters of the Gulf of Maine are likely to be slightly fresher. Salinity varies with temperature: the cooler projections have lower salinities.

• Ocean acidification: The Gulf of Maine will be more acidic, but predictions are more uncertain. Unlike temperature, ocean acidification responds quickly to CO2, so there is a

bigger difference between emissions pathways. Scenarios with less warming and more freshening are likely to be more acidic.

• Ecosystem conditions: The Gulf of Maine ecosystem will become more temperate, with subarctic species like Calanus finmarchicus, cod, and lobster declining and mid-Atlantic species like longfin squid becoming more prominent.

• Human impacts: Declines in traditional fisheries like those for cod and lobster will impact coastal communities. Ocean acidification will become an increasing challenge for shellfish aquaculture. Rising sea levels will cause more frequent flooding of coastal infrastructure and increased saltwater intrusion into aquifers.

The figures above were taken from climate projections that used “business as usual” carbon emission scenarios. Under those scenarios, emissions continue to rise. But because of the delays in the climate system, the difference between the high CO2 and low CO2 scenarios in 2050 is small.

Beyond 2050, the differences between high and low emissions are stark. By 2100, under high emissions, lobster fishing would not be viable, shell-forming organisms would be severely stressed, and sea levels would be more than 1 meter higher.

The 2100 predictions are not inevitable—these conditions can be avoided if the world shifts rapidly away from fossil fuels.

However, evolving policies will impact how people interact with the Gulf of Maine. For example, it is likely that the Gulf of Maine region will have a viable lobster fishery in 2050, but a fishery prosecuted by diesel-powered boats would be inconsistent with a world trying to avoid catastrophic global warming.

Warming waters and lobster

In a related development, two new studies published by University of Maine scientists attribute warming waters and local differences in oceanography to the rise and fall of American lobster populations in the Gulf of Maine.

The studies are based on a long-standing survey of the American lobster’s earliest life stages. The survey is considered an early warning system for trends in the fishery.

One of the papers, published in the scientific journal “Ecological Applications,” was led by Noah Oppenheim, who completed his research as a UMaine graduate student in 2016, with co-authors Richard Wahle, Damian Brady, and Andrew Goode from UMaine’s School of Marine Sciences, and Andrew Pershing from the Gulf of Maine Research Institute. They report that the numbers of young-of-year lobsters populating shallow coastal nursery habitats each year, and temperature, provide a reasonably accurate prediction of trends in the lobster fishery some four to six years later.

Their model predicted regional differences in the recent record-breaking boom over the past decade, and now suggests the Gulf of Maine lobster fishery may be entering a period of decline; in effect a “cresting wave” of lobster abundance that may be heading northward in the region’s changing climate.

“Our model projects that the Gulf of Maine’s lobster landings will return to previous historical levels,” Oppenheim, who is now executive director of the Pacific Coast Federation of Fishermen’s Associations and the Institute for Fisheries Resources in San Francisco, said in a press release. “These results don’t suggest a lobster crash, but this tool could give the fishing industry and policymakers additional lead time as they make decisions about their businesses and communities in the years ahead.”

The second article, led by UMaine marine science Ph.D. student Andrew Goode, underscored the importance of local differences in the oceanography of the Gulf of Maine for understanding where the lobster boom occurred.

“We suggest that this increase resulted from a complex interplay between lobster larval settlement behavior, climate change and local oceanographic conditions,” wrote Goode and his co-authors in their paper published in the journal “Global Change Biology.” The paper was co-authored by Brady, Wahle and Robert Steneck, all of the School of Marine Sciences.

Goode and his collaborators observed that an expanded area of thermally suitable habitat for larval settlement in the eastern Gulf of Maine may have helped drive and amplify the lobster boom in the region over the last decade — a boom that elevated the fishery to its current status as the most valuable single-species fishery in the nation. This cooler deepwater habitat may provide refuge for juvenile lobster from the negative impacts of ocean warming and buffer the Maine lobster fishery from similar declines as observed in southern New England.

While the paper points to a “brighter side of climate change” in this case, it does not deny the adverse effects of a warming ocean south of Cape Cod for other species.

At the center of these studies is the American Lobster Settlement Index (ALSI), a long-standing shallow water monitoring study serving as an important indicator of the strength of new lobster year classes repopulating coastal nursery habitats each year. The survey generating the annual index was founded in 1989 by Wahle, a UMaine research professor, director of the Lobster Institute, and co-author of both studies.

The ALSI collaborative includes government marine resource agencies, academic institutions and industry members in New England and Atlantic Canada who undertake and pay for the divers and boats to survey more than 100 sites spanning Rhode Island to Newfoundland. Wahle’s lab serves as the data hub for the survey.

“No one has a crystal ball, but in a field where sweeping statements are made about the global impacts of climate change, these studies underscore the importance of having a fine scale, local, understanding of both oceanography and organism biology as we project the impacts of a changing climate on the future of our coastal communities and economy,” Wahle said in the release.