Changes in Future Freeze-Thaw Days

This tool is excerpted from Chesapeake Bay Watershed Climate Impacts Summary and Outlook for Winter 2019-2020.

Key Findings

  • In both low and high emission futures, the southeastern Mid-Atlantic is projected by an ensemble of climate models to experience significant decreases in freeze-thaw days by mid- to late-century.
  • In high emissions futures, parts of eastern Virginia could see fewer than ten freeze-thaw days per year by late-century.
  • The northern reaches and northwestern portions of the Chesapeake Bay watershed could see similar levels of freeze-thaw days in low emissions futures by mid-century.
  • In both low and high emission futures, nearly all regions within the watershed may see a 20-50% decrease in freeze-thaw cycles by 2099.

How To Use the Tool

Selecting time periods and future emissions scenarios: To view percent changes in freeze-thaw days for select 30-year time increments and future greenhouse gas emissions scenarios, users can use the 30-year period slider bar and future emissions scenario options (Low and High Emissions) to the right of the map. Users can also hover over a location on the map to see a pop-up window of annual freeze-thaw days for a given location from 1981-2099.

Technical Notes

LOCA or Localized Constructed Analogs is a downscaled climate data product available at 1/16th degree (6 km) resolution over the continental United States. LOCA datasets1 include the 32 climate models available in the Coupled Model Intercomparison Project 5 (CMIP5) archive, for two future greenhouse gas concentration trajectories—a low emissions future, RCP 4.5,2 and a high emissions future, RCP 8.5.3 For this study, we utilized LOCA data over the Chesapeake Bay watershed from 1981–2100 (or 2099 for some models). Access LOCA datasets and learn more about the methodology.

Freeze-thaw days were calculated as those with a maximum temperature greater than or equal to 32 degrees F and a minimum temperature less than or equal to 28 degrees F in the same day. We averaged values across 30-year periods—1981–2010, 2011–2040, 2041–2070, 2071–2099 for LOCA data4 for a low emissions future (RCP 4.5)5 and a high emissions future (RCP 8.5).6 To average across climate models for each grid cell in the LOCA dataset, we employed a weighted average provided by the Northeast Regional Climate Center.7 The LOCA datasets were masked to the boundaries of the Chesapeake Bay watershed.

Footnotes

  1. http://loca.ucsd.edu Return to text ⤴

  2. More information on RCP 4.5 can be found in: Thomson, A.M., Calvin, K.V., Smith, S.J. et al. Climatic Change (2011) 109: 77. https://doi.org/10.1007/s10584-011-0151-4 Return to text ⤴

  3. More information on RCP 8.5 can be found in: Riahi, K., Rao, S., Krey, V. et al. Climatic Change (2011) 109: 33. https://doi.org/10.1007/s10584-011-0149-y Return to text ⤴

  4. http://loca.ucsd.edu Return to text ⤴

  5. More information on RCP 4.5 can be found in: Thomson, A.M., Calvin, K.V., Smith, S.J. et al. Climatic Change (2011) 109: 77. https://doi.org/10.1007/s10584-011-0151-4 Return to text ⤴

  6. More information on RCP 8.5 can be found in: Riahi, K., Rao, S., Krey, V. et al. Climatic Change (2011) 109: 33. https://doi.org/10.1007/s10584-011-0149-y Return to text ⤴

  7. http://www.nrcc.cornell.edu Return to text ⤴

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