The devastating storms last winter prompt questions about the latest ocean climate science, or more specifically, what is coming this winter. While scientists can’t predict the exact timing and severity of extreme events, we can look at trends in the data and shed some light on what we might expect.
In some cases, like precipitation, we’re seeing extreme swings despite an overall trend of more rainfall—long periods of drought followed by very wet years. But for air and ocean temperatures and sea level rise, the trend is more consistent and one-way. Projections show even more drastic changes, mainly driven by greenhouse gas emissions. The key point here is simple: the more we pollute, the worse it gets.
To break it down further, here are examples from the 2024 scientific assessment done by the Maine Climate Council’s Scientific and Technical Subcommittee, an appointed group that I co-chair consisting of 45 Maine scientists and four Maine legislators.
Years 2020-2023 are ranked among the ten warmest on record in Maine.
Years 2020-2023 are ranked among the ten warmest on record in Maine. The statewide air temperature average for 2024 was not yet confirmed at the time of writing, but globally, 2024 is set to be the hottest on record. Two of Maine’s longer-term monitoring stations, Caribou and Millinocket (dating back to 1939 and 1903 respectively), also recorded 2024 as the hottest on record.
Overall Maine is getting wetter, with more intense rainfall events in association with warming-driven intensification of the hydrologic cycle. We now have one to two more days per year with 2-plus inches of precipitation and two to three more days per year with over 1 inch of precipitation.
Despite this, the variability between years is increasing. In just the last four years, we’ve seen the driest growing season on record (2020) along with the wettest (2023).
Ocean temperature increases continue to make the Gulf of Maine one of the fastest-warming ocean regions, warming faster than 97% of the world’s ocean surface. Sea surface temperatures in 2021 were the warmest on record and 2022 the second warmest.
Arctic warming and accelerating ice melt are leading to changes in global ocean circulation. With a northward shift of the Gulf Stream and a retreat of the Labrador Current, more warm, salty, low-nutrient Gulf Stream water is entering the Gulf of Maine. These climate-driven changes are impacting species from plankton to whales.
Phytoplankton’s primary production is declining in the Gulf of Maine, which is a concerning change impacting the base of the marine food web. Predator-prey dynamics are disrupted due to earlier warming. For example, the earlier onset of the lobster egg hatch is no longer aligned with the availability of their primary food source.
Additionally, right whale feeding migration patterns are changing as they search for their preferred prey that has declined in parts of the Gulf of Maine.
Sea level is 7.5 inches higher than in the early 1900s, and the rate of rise has nearly doubled in the last 30 years. As sea levels rise, historically unprecedented storm surges on top of higher seas will make coastal flooding more frequent and severe.
Sea level rise has caused coastal flooding to occur about three times more often since 2010 in Portland as compared to last century, and the frequency of minor high tide flooding will continue to increase. The state has committed to manage for 1.5 feet of sea level rise by 2050 and 4 feet by 2100.
Winter storms are projected to become more intense (due to lower central pressure and increased heavy precipitation), but their frequency remains uncertain. More investigation is needed to understand if and how climate change is impacting wind direction associated with coastal storms.
Included in the 2024 scientific assessment is a chapter on the “science of hope,” in part in response to reports from physicians that climate change is worsening the mental health of their patients. This chapter describes the importance of understanding the problem which helps people take action. Projections for Maine’s temperature show increases of 2-4 Fahrenheit by 2050 and up to 10 Fahrenheit by 2100. The severity of this increase is determined by greenhouse gas emissions trajectories. These trajectories are determined by us.
We all have a role in turning the tide on these troubling trends. Our future depends on it.
Susie Arnold is senior ocean scientist and director for the Center for Climate and Community for Island Institute, publisher of The Working Waterfront. She may be contacted at sarnold@islandinstitute.org.
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