Climate change in Maine encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, methane, and nitrous oxides, in the U.S. state of Maine. The United States Environmental Protection Agency reports that Maine has warmed roughly three degrees F since 1900. Sea level in Maine has risen eight inches since the 1950s.
In July 2019, Governor Janet Mills signed into law bipartisan legislation aimed at countering the effects of climate change. A 2022 report from the University of New Hampshire Sustainability Institute and the Union of Concerned Scientists found that Maine is leading all other New England states in its climate change response. The Climate Reanalyzer at the University of Maine Climate Change Institute is often mentioned in national and international news reports about heat waves and climate change.
Increasing temperature and changing precipitation patterns
Maine is experiencing more rainfall and more intense rainfall events as a result of the changing climate. This is likely to increase the severity of both floods and droughts. The Environmental Protection Agency reported that between 1895 and 2011 average annual precipitation in the Northeast increased 10%. In 2022, the Maine Climate Office reported that the state experienced almost eight inches more rain that the statewide average for the last century. In July 2023, the Portland area set a heat record when for 32 days the low temperature never dropped below 60 degrees which is the longest stretch of above 60 degree nighttime temperatures since record keeping began in 1940.
Sea level rise, wetland loss, and coastal flooding
Sea level in Maine has risen eight inches since the 1950s. Scientists predict sea levels will rise in Maine roughly a foot and a half in the next 25 years. In 2023, Maine Public reported that despite these predictions "the value of beachfront houses has skyrocketed."
The Camp Ellis community in Saco has been slowing disappearing below the ocean for years. A 2023 report from Southern Maine Planning and Development Commission identifies more than 3,500 properties in Wells, Kennebunk, and York with a combined value of $645 million that are at risk of flooding from the expected 1.6 foot increase in sea level rise over the next 30 years.
The Portsmouth Naval Shipyard is planning a $2 billion renovation of yard facilities, which includes measures to protect against higher tides, storm surges, and the dangerous combination of both. The Union of Concerned Scientists, which issued a 2016 report about military readiness for climate change, estimates that flooding events at the shipyard could rise from the current 10 tidal flood days a year to 80 to 190 tidal flood days per year.
Flooding and rising sea level increases storm damage and erodes beaches and wetland. The practice of filling in wetlands has reduced flood buffers and wildlife habitat. Shorefront buildings and infrastructure are most vulnerable.
Ecosystems
"Changing the climate threatens ecosystems by disrupting relationships between species. Wildflowers and woody perennials are blooming—and migratory birds are arriving—sooner in spring. Not all species adjust in the same way, however, so the food that one species needs may no longer be available when that species arrives on its migration. Warmer temperatures allow deer populations to increase, leading to a loss of forest underbrush, which makes some animals more vulnerable to predators. Climate change can allow invasive species to expand their ranges. For example, the hemlock woolly adelgid has recently infested hemlock trees near the coast in southern Maine. Infestation eventually kills almost all hemlock trees, which are replaced by black oaks, black birch, and other hardwoods. Warmer temperatures are likely to enable the woolly adelgid to expand inland and up the coast. The loss of hemlock trees would remove the primary habitat for the blue-headed vireo and Blackburnian warbler. It could also cause streams to run dry or become excessively warm more often, harming brook trout and brown trout".
Phytoplankton decline in the Gulf of Maine
Researchers at the Bigelow Laboratory for Ocean Sciences have been monitoring the Gulf of Maine for 25 years. Phytoplankton are crucial microscopic plants at the bottom of the food chain. The data has demonstrated that phytoplankton productivity in the Gulf of Maine dropped 65% between 2001 and 2018.