Climate researchers at the University of Maine have laid out five scenarios for environmental conditions in coastal Maine over the next two decades, including the possibility of substantial change that could impact the region’s weather, sea levels and wildlife.

The report, “Coastal Maine Climate Futures,” offers five plausible climate scenarios between now and 2040 based on historical patterns of natural variability and human-driven climate change. Research Assistant Professor Sean Birkel said the study can benefit community, commercial and government planners seeking insights into “extreme rainfall, drought, and warming in recent decades.”

The UMaine report issued November 20 came just days before the federal government released a landmark assessment of possible climate change consequences in the United States for the next century. The assessment gauged the effects that increased climate alterations, due in large part to human activity, could have on the nation’s health, economy, infrastructure, and environment.

Paul Mayewski, director of the UMaine Climate Change Institute in Orono, conducted the study with Birkel that forecasts climate scenarios for Maine’s coastal region. The possibilities include no alteration to what is now considered the “new normal” rate of change; moderate warming; abrupt Arctic warming resulting in greater sea ice collapse; climate cooling due to increased volcanic activity; and drying from more frequent and extreme El Niño events.

El Niño-Southern Oscillation (ENSO), a climate pattern that repeats every two to seven years across the tropical region of the Pacific Ocean, includes a warm phase, El Niño, and a cool phase, La Niña. This affects Maine by delivering either warm and dry conditions or cool and wet weather. In October the National Oceanic and Atmospheric Administration (NOAA) predicted a mild winter this year due to a 70-75 percent chance of an El Niño occurrence.

Birkel said the scenarios in the UMaine report outline possible temperature and precipitation regimes, but do not attempt to sway responses to the information. “There is not judgment per se; the intent is more to outline how these future climates could impact agriculture and fisheries,” he said.

“What we highlight here is that there is significant variability in the historical record, and that, while we can expect an overall warming in the next century, it is important to consider that broad changes across the North Atlantic could temporarily moderate temperatures in the gulf,” Birkel said, noting that Maine’s most profitable fishery may suffer over the long term. “Other researchers have found that warming in the Gulf of Maine has been beneficial to lobsters, but beyond some threshold temperature, already reached off southern New England, the habitat could start to deteriorate.”

Since January 1895, according to the research, coastal Maine’s average annual temperature increased 3 degrees Fahrenheit, with annual precipitation up approximately six inches. “One underlying point is that we should be prepared for variability over the next 20 years, even though over the next century the globe is expected to warm,” Birkel said.

Additional rainfall should benefit Maine crops such as blueberries, apples and cranberries, although natural variability prevents the researchers from discounting the possibility of droughts as well. Birkel cited the example of “the record late March 2012 heat wave that was followed by a hard freeze.”

The National Assessment

The UMaine report arrived shortly before the November 23 release of the Fourth National Climate Assessment (NCA4) overseen by NOAA. The national study analyzes how climate change, specifically global warming, will affect American agriculture, infrastructure, tourism, indigenous people, oceans, and other interconnected issues including health and the economy.

Arctic warming related to a rise in greenhouse gas emissions, one of the trends most often connected to human activity by climate scientists, is mentioned in both the UMaine study and NOAA’s large-scale assessment. Birkel said the two reports “are fully compatible, but different in scale and scope.”

“The assessment discusses recent impacts and emphasizes the likely negative economic impacts over the next century,” Birkel said. “Coastal Maine Climate Futures is a targeted study utilizing plausible scenarios for what climate impacts could impact coastal Maine, with general applicability to the broader state, over the next 20 years.”

The NCA4 document, which is more than 1,000 pages, took two and a half years to produce and includes the work of more than 300 authors, half of those from outside the federal government. Anticipating questions about the influence of climate change deniers inside the Trump administration, David Easterling, one of the report coordinators, told a conference call of journalists there was “no external interference” by political entities.

The conclusions are blunt.

“Observations of global average temperature provide clear and compelling evidence that global average temperature is much higher and is rising more rapidly than anything modern civilization has experienced. And this warming trend can only be explained by human activities, especially emissions of greenhouse gases into the atmosphere,” according to Easterling, director of NOAA’s Technical Support Unit.

“Sea level continues to rise and will increase in the future, leading to increased risk in coastal regions. Extreme events such as heavy precipitation continue to increase, and will increase in the future, leading to increased risk of flooding and other hazards,” he said, noting that the changes will continue to occur throughout this century and beyond. “After mid-century, how much the climate changes will depend primarily on global emissions of greenhouse gases and on the response of the Earth’s climate system to this human-induced warming.”

He explained that risks posed by climate change vary by geographic regions and commercial sectors, as well as the vulnerability of people experiencing the developments.

“Many extreme weather and climate-related events and impacts are expected to become more frequent and more intense in a warmer world, creating greater risks of infrastructure disruption and failure that can cascade across economic sectors,” Easterling said. “Regional economies and industries that depend on favorable climate conditions such as agriculture, tourism and fisheries are increasingly vulnerable to impacts driven by climate change.”

Among the findings in the NCA4, declining snow and ice caused by warmer winter temperatures could bring rising costs and lower property values to coastal homeowners hit by flooding, as well as Northeast businesses involved in winter recreation.

“In turn, this affects the well-being of the people who make their living supporting these economies, including rural, coastal, and Indigenous communities,” the report stated.

The assessment notes that water temperatures in the Atlantic Northeast Continental Shelf warmed by 0.06 degree Fahrenheit per year between 1982 and 2016, three times faster than the global average of 0.018 degree. The Northeast regional warming rate between 2007 and 2016 was also four times faster than the overall trend.

The changes will affect the health of humans and wildlife in the Northeast, both onshore and off, the report stated.

“Less distinct seasons with milder winter and earlier spring conditions are already altering ecosystems and environments in ways that adversely impact tourism, farming, and forestry. The region’s rural industries and livelihoods are at risk from further changes to forests, wildlife, snowpack, and streamflow,” according to the report. “By the middle of this century, winters are projected to be milder still, with fewer cold extremes, particularly across inland and northern portions of the Northeast.”

Fisheries indigenous to Maine’s waters are likely to change as well. “Rising ocean temperatures have also affected the productivity of marine populations,” the report explained, offering mixed reviews for Maine’s fisheries. Warming northern waters have raised the recent productivity of lobsters, but changing conditions may also increase disease, impacting the numbers and safety of lobsters and other seafood varieties.

“In general, species in the southern portion of the region are expected to remain stable through mid-century, but many species in the northern portion are expected to be negatively affected by warming and acidification over that timeframe,” the study predicted, noting that projections “indicate declines of species that support some of the most valuable and iconic fisheries in the Northeast, including Atlantic cod, Atlantic sea scallops, and American lobster.”

Coastal fisheries, particularly in the Gulf of Maine, are sensitive to alterations in ocean chemistry caused by climate change, the study found. “Increasing prevalence of shell disease in lobsters and several pathogens in oysters have been associated with rising water temperatures; other pathogens that infect shellfish pose risks to human health,” the report stated.

Human efforts could still yield positive results. According to the NCA4, “More than half of the damages to coastal property are estimated to be avoidable through well-timed adaptation measures. Substantial and sustained reductions in global greenhouse gas emissions would also significantly reduce projected risks to fisheries and communities that rely on them.”