For more than 40 years I have dedicated my professional career to protecting and improving the lives of our sacred wildlife. For nearly as long, I have been aware of the threats that a warming world poses to wildlife, the environment, and humankind. But I never imagined I would witness the dramatic changes we have seen these past few years quite so soon. Like many others, I falsely thought “ok it’s probably going to get worse, but we have time.” More recently, as I watched the west and north go up in flames, the south hammered with hurricane winds and rains, the Midwest suffer from droughts, and the Caribbean coral reefs disappear from bleaching, I thought Maine would be relatively “safe” compared to these other areas. Sadly, I was wrong—changes are upon us now, here in Maine, as we all know from having experienced hotter days and nights, less snow and ice, warmer waters, and devastating, destructive rainstorms, windstorms, and marine storm surges.
How much has changed and what will the future bring? That’s what I and 45 other professionals have set out to discover over the past five years. We poured through the latest scientific data, studies, and technical literature to help inform the recommendations of the Maine Climate Council for how to help Maine reduce its carbon emissions, mitigate the worst effects of a warming climate, and simultaneously adapt to the changes. I focused primarily on the section on Biodiversity.
We released our first report, Scientific Assessment of Climate Change and Its Effects in Maine, in 2020, which helped inform the four-year climate action plan, Maine Won’t Wait, issued by the Maine Climate Council in December 2020. That was followed by a short update the following year, Maine Climate Science Update 2021. Our latest report, Scientific Assessment of Climate Change and Its Effects in Maine—2024 Update, describes new and updated information collected from the past two years that was not in the previous report, and clearly documents how changes are escalating in both scope and scale, especially on the wildlife front. Not only have the four years since our first report each ranked among the top ten warmest on record, but the global loss of biodiversity has skyrocketed, with the first documented extinctions due directly to climate change, and projections for the mass spread of invasives and additional extinctions. Here in Maine we are also seeing declines, with eight new species recently added to the threatened and endangered species list—most of which resulted from climate change—and notable declines in nearly all birds, amphibians, and reptiles, and anecdotal declines in insects overall.
The entire report can be viewed on the Maine Climate Council website, but here are some highlights taken directly from the latest update, organized by chapter. Refer to the report for full references.
Climate
- Maine now receives 1–2 additional days per year with 2+ inches of precipitation, and 2–3 more days per year with 1 inch of precipitation.
- The 2020 growing season was the driest on record, and summer 2023 was the wettest, creating challenges for farmers and others.
- As temperatures rise, the warm season is getting two weeks longer and the winter season is 5°F warmer and two weeks shorter compared with the previous century.
- Temperature projections for Maine are for a 2–4°F increase by 2050 and up to 10°F by 2100.
Sea Level Rise and Coastal Storms
- The rate of sea level rise has nearly doubled in the past 30 years, with record highs in 2023 and 2024.
- Rising sea levels have caused increases in coastal flooding, such as the record-breaking storm events of January 2024.
- Carbon-rich salt marshes are being flooded more frequently and deeper, including high marsh grass where endangered Saltmarsh Sparrows nest.
Marine
- The Gulf of Maine is warming faster than 97% of the world’s ocean surface with near-constant ocean heat waves, affecting the size and quality of the marine food web, causing species to shift, become less abundant, and grow faster but mature at smaller sizes.
- Warming is affecting the timing of food availability and migrations of iconic and endangered species. The migration of certain diadromous fish, including Atlantic Salmon and alewife, have advanced to earlier in the year, while other events are occurring later, including spring and fall phytoplankton blooms, fledging of Atlantic Puffin chicks, and the appearance of certain larval fish.
- Under the highest emissions scenario (RCP 8.5), the Gulf of Maine will experience ocean acidification conditions that are unfavorable for shell growth for most of the year by 2050.
Biodiversity
- The pace of change to natural systems over the past 50 years is unprecedented and accelerating, in part a function of climate change, causing significant losses in biodiversity and ecosystem function and health. A recent study of population trends of over 71,000 species from all five vertebrate taxonomic groups plus insects across the globe found declines in 48% of those species.
- Climate change impacts on biodiversity are expected to increase, but are currently less impactful than habitat loss.
- The globe experienced its first documented climate-driven extinctions of this era, along with widespread localized extirpations: a quarter of all species on earth are at risk of extinction, often driven by increases in annual high temperatures.
- Eight new wildlife species were added to the Maine State List of Endangered and Threatened Species in 2023, many of which are additions driven in full or part by climate change. New species are the Saltmarsh Sparrow, Bicknell’s Thrush, Blackpoll Warbler, Marginated Tiger Beetle, Cliff and Bank Swallows, the Tricolored Bat, and Ashton’s Cuckoo Bumblebee.
- Additional species not listed but vulnerable to climate change include bats, amphibians, turtles, salmonid fish, and moose.
- A quarter of Maine’s at-risk butterflies are threatened by climate change.
- Climate warming is expected to facilitate the establishment and spread of more invasive species in the Northeast, and Maine’s biodiverse river shores and floodplains are particularly vulnerable. Invasive species contributed to 60% of global extinctions, and were the primary driver in 16%. Examples in Maine include Common and Glossy Buckthorn (see below) and Green Crabs, which flourish in warmer winters and are a significant contributor to the decline in native soft-shell clam populations. River shores and floodplains are particularly vulnerable to the proliferation of invasive plants. Compounded by sprawling impervious development, increasing climate-associated flood severity can exacerbate the downstream colonization of aggressive exotic plants such as Japanese Knotweed.
- Due to climate change, Maine birds are on the move, expanding or shifting their ranges. Two-thirds of short-distance migrants and one-third of long distance migrants are projected to decrease. The Boreal Chickadee is already moving north, and Bicknell’s Thrush, which nest in high-elevation forests, are especially vulnerable because such forests are limited in their ability to move upslope.
- Many of Maine’s insects, foundational to most ecosystem food webs, will respond to climate change by altering their flight periods, causing a mismatch between flowering and pollination and predator and prey.
- Changes in precipitation and hydrology, especially of ephemeral or vernal pools, are likely impacting the state’s amphibians. Hydroperiod of vernal pools is particularly important, as drought and high temperatures can cause pools to dry. Along with changes in seasonal emergence, highly variable late winter and spring freeze-thaw events are negatively impacting regional amphibians.
- Old growth (older than 170-year old) forests support the largest carbon pools of all Northeast forest types while concurrently supporting the highest biodiversity, but comprise less than 1% of the state’s forests.
- Maine needs to add approximately 200,000 acres of conserved land per year to reach the national and state goal of 30% of land conserved by 2030. The state is projected to reach 30% land conserved in 2047 and would need to triple the current rate of conservation to meet the 2030 goal.
- Climate change is predicted to cause unprecedented species loss and range shifts. As climate drives species movements, conserving diverse geophysical settings and strategically located resilient and connected landscapes can protect biodiversity.
Freshwater
- Maine’s wetlands are a bright spot for biodiversity and carbon storage, with some of the highest quality and quantity of these types of ecosystems across New England, but remain at risk from poorly planned development and climate impacts.
- In Maine’s streams and rivers, intense flooding and increased temperature will impact fish species by eroding stream banks, reshaping stream channels, accelerating the spread of invasive species, and increasing sedimentation.
- For coldwater fish species, earlier onset of ice-out conditions means a longer open water season, more opportunity for water temperature increase and a longer duration of stressful or lethal high summer temperatures.
Forests and Forestry
- Treelines, the growing season, and foliage timing in Maine’s forest are all shifting; peak fall foliage is now occurring almost two weeks later than it did in 1950.
- Climate change, coupled with increased pressure from non-native pathogens, insect pests, and invasive species, will change Maine forests. Cedar and fir may be particularly sensitive to future temperature and precipitation changes. Certain tree species are especially vulnerable to pests that target only one or a few tree species (such as the Emerald Ash Borer or Hemlock Wooly Adelgid). Invasive Common and Glossy Buckthorn are replacing native understory plants.
- Maine forests and wood products store a lot of carbon and are the largest contributor to the state’s carbon neutrality target. Forests and wood products are estimated to have acted as a net carbon sink between 2017 and 2021, offsetting about 101% of Maine’s total gross greenhouse gas emissions. Keeping these forests as forests into the future will be key to continuing to provide these benefits.
There is much more info in the report, including additional information under each heading and for each bullet. We encourage you to check it out and learn more about these changes. There is also a section on hope. Having an accessible roadmap, such as Maine Won’t Wait, is a key strategy for nurturing hope. Hope helps people cast a vision of what future success will look like. Every success is an opportunity to show that the future we want is possible.
Finally, while this report was limited to the latest science, and does not include recommendations for how to address any identified concerns, the report will be used by the Maine Climate Council to develop and recommend strategies, policies, and actions that the state, communities, landowners, businesses, and individuals can take to help mitigate and adapt to the changes already underway. Some of these strategies are already happening and making a difference, as illustrated by the successful transition of many businesses and residences from oil heat to electric heat pumps, the expansion of solar power, and numerous community resilience projects underway or completed over the past four years. Yet there is much more that can and should be done, and we all have a role to play. Please join us in supporting the important work of the Maine Climate Council.
