Growing Season: Thermal Sums

Summary:
Thermal sums such as Growing Degree Days are the cumulative degrees in Celsius above a chosen threshold temperature over a period of time. For GDD > 5, a day which averaged 15 degrees would accumulate 10 Growing Degree Days > 5.  This metric is used to estimate where the winegrapes are in their growth cycle.

Between the months of April and October mark the growing season of winegrapes. Increasing temperatures are predicted to translate the harvest date to be earlier than previously observed. The following maps depict the change from the historical average of GDD > 5 in the Okanagan Valley of British Columbia, Canada.

More information about these maps can be found below, here. 

 

Growing Degree Days > 5: May through October

Features: Zoom Control: Zoom Measuring Tool: Zoom Layer Control: Zoom
SD Comparison Legend:
MW: Moderate Warming Scenario
HW: High Warming Scenario
SD ComparisonLegend:
MW: Moderate Warming Scenario
HW: High Warming Scenario

Growing Degree Days > 5: April through September

Features: Zoom Control: Zoom Measuring Tool: Zoom Layer Control: Zoom
Value Comparison Legend:
MW: Moderate Warming Scenario
HW: High Warming Scenario
SD Comparison Legend:
MW: Moderate Warming Scenario
HW: High Warming Scenario
SD: Standard Deviation

More Information

Anomalies:
Anomalies are a metric which highlight the change in a variable from
the recent historical average (1970 – 1989). Positive values indicate a projected increase from the past.

Warming Scenarios:
Two warming scenarios are represented in the data. The Moderate Warming (MW) and High Warming (HW) scenarios are represented by averaging the data for the periods of years between 2040 – 2059 and 2070 – 2089, respectively. These warming scenarios represent two instances in the spectrum of potential climate realizations.

Average Anomalies (Warming Scenario – Historical):

    • GDD > 5:
      • May through October: the historical GDD > 5 mean is 1896, with warming the sum will rise:
        • Moderate Warming – 898 GDD
        • High Warming – 1507 GDD
      • April through September: the historical GDD > 5 mean is 1894, with warming the sum will rise:
        • Moderate Warming – 885 GDD
        • High Warming – 1483 GDD

General Circulation Models (GCMs):
We leverage prediction from General Circulation Models (GCMs) created by climate scientists worldwide. These models are designed to predict how environments are likely to change using atmospheric physics to project future temperatures, precipitation, and more variables for different greenhouse gas emission scenarios. Currently, each scenario is categorized by Representative Concentration Pathways, summarizing how emissions change through 2100. The RCP with the greatest emissions (RCP 8.5) was used to generate the data shown in the maps. A consensus on climate variables was reached by using an ensemble of 15 GCMs.