Maine Climate Report Forecasts Changes In Coming Years

University of Maine climate researchers’ new report Coastal Maine Climate Futures documents relationships between regional weather patterns over North America, Maine weather, blueberry crops, and lobster catch. It also identifies the way that the Arctic, global volcanic activity and El Nino/La Nina (ENSO) influence Maine weather, and creates five possible scenarios for what the years 2020-2040 could be like. The researchers found that blueberry yield is higher in years with higher summer rainfall. They also found crop yields were up during years when the Gulf of Maine sea surface temperature is higher than average, due to warmer, moister air flowing from the ocean over the land. In good news for Maine farmers but bad news for ski resorts, the growing season in Maine has gotten longer. During 2000-2015, the average season was two weeks longer than the 20th-century average. There are problems with warmer conditions: repeated freeze-thaw events in late winter and early spring and drought and heat waves during summer will damage some crops. Unsurprising to anyone who works in the lobster industry, the data analysis confirmed that lobster harvests are correlated with sea surface temperature over the Gulf of Maine — higher catches during warm years, lower catches during colder years. The researchers show how stronger winds over the North Atlantic which lead to a stronger Gulf Stream have contributed to warmer local conditions in the Gulf of Maine. Like the Gulf Stream, the Arctic region influences conditions in Maine. The eastern Arctic has warmed 8o F. in just five years, which the authors point out “is as dramatic as the abrupt change from ice-age to modern climate that took place 11,500 years ago.” Arctic Ocean sea ice has declined rapidly. At the same time, Maine has experienced a 30% increase in summer precipitation and rapid warming in summer and fall, especially of nighttime temperatures. These warmer, wetter summers have been good for blueberries and lobsters. Many would like to know if they will continue. Both the warmer Arctic region and the stronger Gulf Stream are linked to large regional pressure system patterns over North America and Greenland. During the 20th century there were two periods when a shift in these large-scale weather patterns brought years of colder conditions to the Gulf of Maine and coastal Maine: 1900 to the 1920s and the 1960s to the early 1990s. ENSO is a global phenomenon, with its origin in the equatorial Pacific. When El Nino conditions develop Maine experiences warmer, drier conditions state-wide. The state-wide record drought in 2016 was associated with the El Nino which took place during winter 2015-2016. But for the coast the impact is different; El Nino usually leads to wetter conditions. Volcanoes also influence Maine’s weather from afar. Particles from eruptions travel around the world in the upper atmosphere, veiling sunlight and making it cooler on the land’s surface. These particles also lead to stronger winds and cooler water in the North Atlantic. So both the land and ocean are colder during periods with a lot of volcanic activity. It turns out that the periods of 1900 to the 1920s and the 1960s to early 1990s, correspond to the cooler weather of the 20th century, which was also a time of increased volcanic activity around the world. Based on historic data, the research team created five scenarios for 2020-2040: The “New Normal” – a slow-down in the warming of the last few decades, so 2020-2040 looks a lot like 2000-2015. Moderate warming – warming continues apace with 2000-2015; Maine experiences even warmer, less predictable weather as the Gulf Stream continues to strengthen and the Gulf of Maine warms even more. Another abrupt Arctic warming and sea ice collapse – if the Arctic continues to warm as quickly as it has since 2000, it could be ice-free a few months each year and Maine would warm quite rapidly all year, with very little snow all winter (most would be rain or melt within a day), and more frequent extreme storms. Cooling from increased volcanic activity – if two large volcanic eruptions occur within a few years of each other, we could experience weather in Maine similar to the 1990s: lower temperatures, more snow, and less precipitation overall. More frequent and extreme El Nino events – if we move into a period of stronger El Ninos, we would experience more rapid warming state-wide, drier conditions across most of the state, and wetter weather along the coast. The researchers conclude by noting that “It can be expected in the long term that the inexorable rise of greenhouse-gas concentrations from industrial activity will warm the oceans and atmosphere.” In the long-term, Maine will feel more like New Jersey does today, unless we decrease our carbon emissions.