In this Tuesday, Sept. 11, 2018 photo, live lobsters are packed in coolers for shipment to China at The Lobster Company in Arundel, Maine. Credit: Robert F. Bukaty | AP

Climate change has helped Maine’s lobster yield increase fourfold since the 1980s, as warming waters to the south have propelled lobsters north in search of colder waters. But if summer sea temperatures along Maine’s coast continue rising and cross a potentially perilous threshold, lobsters’ survival in a more temperate Gulf of Maine could be in doubt.

The Gulf of Maine has warmed faster than 99 percent of the world’s oceans, and the trend is expected to continue. The warming that has taken place so far, as well as the decline of cod, has proven favorable for Maine’s lobster yields in recent years, but if sea temperatures during the summer rise above 68 degrees Fahrenheit, lobster mortality will increase.

That’s one conclusion from a new report detailing the potential effects of climate change on Maine’s coast. The report, released earlier this month by the Climate Change Institute at the University of Maine, took a close look at how climate change could affect fishing and agriculture. It imagines five climate change scenarios, how they would unfold over the next two decades and the impacts from each one.

The report by Paul Mayewski, the institute’s director, and Maine State Climatologist Sean Birkel predicts an overall trend of warmer, wetter weather with rising sea temperatures, shorter winters, longer summers and more frequent storms.

These predictions are in line with the National Climate Assessment that the Trump administration published the day after Thanksgiving and came a week after Mayewski and Birkel’s report. The national assessment predicts an increase in extreme weather events due to climate change, and major economic losses and heightened health risks as a result.

A global or national climate change assessment might not be applicable to all states or even regions within a state, however, which is why UMaine’s Climate Change Institute has focused on specific regions of Maine, Mayewski said. Mayewski and Birkel used past climate change data collected through Birkel’s Climate Reanalyzer tool to make predictions about coastal Maine’s climate future, and they plan to do the same for other regions in the state.

“Our goal through reports like this is to give people a better idea of how the climate has changed in the past few decades, and understanding what the plausible scenarios are for future climate and how this might impact, in this case, fisheries and blueberries,” Mayewski said.

The five scenarios Mayewski and Birkel lay out in the report describe different degrees of warming that could play out, ranging from little to no change in climate to an abrupt Arctic sea-ice collapse that would signal a rapid increase in global temperature.

Even without extreme changes to global climate, sea levels are still predicted to rise along Maine’s coast, and average annual temperatures in the region will most likely increase by 1 degree. One result would be summers that are, on average, a week longer and winters a week shorter.

One scenario Mayewski and Birkel detail predicts no additional global climate change — as if the climate change underway suddenly stopped. Even in that case, unusual weather patterns including cold stretches, heat waves and heavy rainfall that have already increased in frequency over the past few decades would simply become the new normal.

Four of their five climate change scenarios predict overall temperature increases by 2040, and more extreme weather as a result.

One scenario predicts extreme El Nino warming events, which would mean drought conditions for coastal Maine and reduced sea levels along the coast.

Another scenario predicts abrupt Arctic warming, which would lead to a 3-degree increase in coastal Maine’s average temperatures, and would bring about more frequent rainstorms and less snow.

The volcanic eruptions accounted for in one of the researchers’ scenarios would bring about the only situation in which temperatures actually cool down for one to three years, resulting in more snow than rain for the coast. However, volcanic events are impossible to predict, according to the report.

In general, a warmer and wetter climate means longer growing periods. Scenarios that include drought or lower temperatures would be detrimental for the state’s agriculture industry.

Fishing predictions are complicated by other factors, but an increase in sea surface temperatures will yield more lobsters, as long as the summer temperatures stay below 68 degrees, the report says.

In addition to developing region-specific reports, Mayewski and Birkel are working on a tool that will allow anyone to access climate data and find the most pertinent information.

A farmer, for example, would be able to access past climate data and follow simple instructions to look at predicted temperature and precipitation for the next year or two to determine whether growing conditions are optimal.

“We want to make it a publicly available platform, which we’re going to start working on this year so people can answer these questions for themselves,” Mayewski said. “Once they begin to realize there is or isn’t a link between something they do and climate they become more engaged, they vote that way and they can come to us and talk about learning more.”

The Climate Change Institute is one of the first of its kind in North America. It sends researchers and students across the world to study climate change patterns using geological indicators such as ice cores and lake sediments.

“Climate is a global system and by studying purely in Maine you don’t necessarily know how Maine climate will change in the future, so we study in the Arctic and other places,” Mayewski said. “The fact that we’re cold in Maine does not mean that warming isn’t happening.”

With more regionalized reports, Mayweski said he and institute researchers are hoping to grow awareness about climate change and help people better prepare for its impact.

“Climate change is the biggest security threat we have in the world,” he said. “We need to be smart about knowing what’s going to happen, plan for it, and, in some situations, we can even use it to our advantage.”