Maine Climate Council Scientific and Technical Subcommittee Scientific Assessment of Climate Change and Its Effects in Maine Phase I “WORKING DOCUMENT” Susie Arnold, Brian Beal, Sean Birkel, Russell Black, Alix Contosta, Amanda Cross, Adam Daigneault, Stephen Dickson, Susan Elias, Ivan Fernandez (co-Chair), Glenn Hodgkins, Brian Hubbell, Joe Kelley, Rick Kersbergen, Rebecca Lincoln, Glen Koehler, Pamela Lombard, Bradfield Lyon, Robert Marvinney (co-Chair), Andrew Pershing, Nichole Price, Jonathan Rubin, Joseph Salisbury, Pete Slovinsky, Robert Steneck, Sally Stockwell, Rick Wahle, Aaron Weiskittel, and Carl Wilson February 2020 1 Table of Contents Phase I Final “WORKING DOCUMENT” ................................................................................... 8 Preface .................................................................................................................................. 8 WORKING DOCUMENT .......................................................................................................... 9 SUMMARY HIGHLIGHTS ......................................................................................................... 9 Climate: Temperature, Precipitation, and Extreme Weather .............................................. 9 TEMPERATURE ...................................................................................................................................... 9 PRECIPITATION ...................................................................................................................................... 9 EXTREME WEATHER .............................................................................................................................. 9 Climate: Drought ............................................................................................................. 10 Hydrology ....................................................................................................................... 11 Freshwater Quality ......................................................................................................... 11 Ocean Temperature ........................................................................................................ 12 Sea Level Rise and Storm Surge ....................................................................................... 14 Ocean Acidification ......................................................................................................... 16 Marine Ecosystems ......................................................................................................... 17 Biodiversity ..................................................................................................................... 18 Forestry and Forest Ecosystems ...................................................................................... 20 Agriculture ...................................................................................................................... 21 Human Health ................................................................................................................. 22 Maine’s Economy ............................................................................................................ 25 FULL WORKING DOCUMENT ................................................................................................ 27 Climate: Temperature, Precipitation, and Extreme Weather ................................................ 27 Highlights........................................................................................................................ 27 Discussion ....................................................................................................................... 28 Temperature and Precipitation .......................................................................................................... 28 Extreme Weather ................................................................................................................................ 29 Natural Variability and Human Attribution ........................................................................................ 30 Future Projections............................................................................................................................... 31 2 Priority Needs ..................................................................................................................................... 32 Climate: Drought ................................................................................................................. 35 Highlights........................................................................................................................ 35 Discussion ....................................................................................................................... 35 Drought ............................................................................................................................................... 35 Hydrology ........................................................................................................................... 41 Highlights........................................................................................................................ 41 Discussion ....................................................................................................................... 41 Peak Streamflows ............................................................................................................................... 41 Winter and Spring Snowpack, Snow Melt, and Lake Ice..................................................................... 42 Groundwater, Low Flows, and Water Availability .............................................................................. 44 Freshwater Quality .............................................................................................................. 49 Highlights........................................................................................................................ 49 Discussion ....................................................................................................................... 49 Lake and Stream Temperatures .......................................................................................................... 49 Dissolved Organic Carbon ................................................................................................................... 50 Trophic Changes in Lakes and Freshwater Harmful Algal Blooms ...................................................... 53 Ocean Tempearture ............................................................................................................. 58 Highlights........................................................................................................................ 58 Discussion – Ocean Temperature .................................................................................... 59 General Setting ................................................................................................................................... 59 Observed Changes .......................................................................................................... 60 Impacts of Recent Warming ............................................................................................ 61 Projected Temperature Conditions .................................................................................. 62 Projected Impacts ........................................................................................................... 63 Projected Information Needs .......................................................................................... 63 Supplementary Material – Ocean Temperature ............................................................... 64 Temperature Data ............................................................................................................................... 64 Temperature Projections .................................................................................................................... 65 References ...................................................................................................................... 67 Sea Level Rise and Storm Surge ............................................................................................ 69 Highlights........................................................................................................................ 69 3 Discussion – Sea Level Rise .............................................................................................. 69 Historical Sea Level Changes ............................................................................................................... 69 Modern Sea Level Rise ........................................................................................................................ 70 Recent Sea Level Rise .......................................................................................................................... 73 Seasonal Sea Level Changes ................................................................................................................ 74 Abrupt Sea Level Rise .......................................................................................................................... 75 Potential Sea Level Rise Scenarios for Maine ..................................................................................... 76 Recommended