Future Projected Changes in Date of Last Freeze and Date of First Warm Day

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

Key Findings

  • Future projections show that the region as a whole might experience the onset of warm spring temperatures 15–26 days earlier than normal by the end of the century, and the last day of frost 12–20 days earlier.
  • Under both future-emissions scenarios, the southern portion of the Mid-Atlantic is projected to continue experiencing the date of last freeze earlier than the northern half of the region.
  • Future projections indicate that the region could experience an increase in the number of counties with dates of last freeze in February and a decrease in the number of counties with dates of last freeze in May and June. This trend toward earlier dates of last freeze is stronger in the southern half of the region.
  • In both high and low future-emissions scenarios, the majority of the southern half of the region might experience the date of the first 70°F day in January and the date of first 80°F day by March by the end of the century.

How to Use the Tool

Selecting time periods and future-emissions scenarios: Use the slider to the right of the maps to adjust the 30-year period used to calculate the average month displayed for each metric. Users can also select the future-emissions scenario (Low or High Emissions).
Viewing variability within a county: Hover over or tap on a county of interest. A window will pop up that displays the percentage of dates for a given metric per month in each decade.

Technical Notes

Localized Constructed Analogs (LOCA) 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, Representative Concentration Pathway (RCP) 4.5,2 and a high-emissions future, RCP 8.5.3 For this study, we used LOCA data over the Chesapeake Bay watershed from 1981–2100 (or 2099 for some models). Access LOCA datasets and learn more about the methodology.

Data were processed by the Northeast Regional Climate Center to extract the annual dates of last frost, first 70°F maximum temperature and first 80°F maximum temperature. We averaged values across 30-year periods: 1981–2010, 2011–2040, 2041–2070, and 2071–2099 for LOCA data for a low-emissions future (RCP 4.5)4 and a high emissions future (RCP 8.5).5 A weighted average was provided by the Northeast Regional Climate Center to average across climate models for each grid cell in the LOCA data set.6 The LOCA datasets were masked to the boundaries of the Mid-Atlantic region.

Footnotes

  1. http://loca.ucsd.eduReturn to text ⤴

  2. More information on RCP 4.5 can be found in Allison M. Thomson, Katherine V. Calvin, Steven J. Smith, G. Page Kyle, April Volke, Pralit Patel, Sabrina Delgado-Arias, Ben Bond-Lamberty, Marshall A. Wise, Leon E. Clarke, and James A. Edmonds, “RCP4.5: A Pathway for Stabilization of Radiative Forcing by 2100,” Climatic Change, Vol. 109, 2011, pp. 77–94. As of June 8, 2020: https://doi.org/10.1007/s10584-011-0151-4Return to text ⤴

  3. More information on RCP 8.5 can be found in Keywan Riahi, Shilpa Rao, Volker Krey, Cheolhung Cho, Vadim Chirkov, Guenther Fischer, Georg Kindermann, Nebojsa Nakicenovic, and Peter Rafaj, “RCP 8.5—A Scenario of Comparatively High Greenhouse Gas Emissions,” Climatic Change, Vol. 109, 2011, pp. 33–57. As of June 8, 2020: https://doi.org/10.1007/s10584-011-0149-y Return to text ⤴

  4. More information on RCP 4.5 can be found in Thomson et al., 2011. Return to text ⤴

  5. More information on RCP 8.5 can be found in: Riahi et al., 2011. Return to text ⤴

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

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