Time of Emergence results are currently available for the climate variables listed in Table 1. Some of these may be for general purposes; others may be proxies for a critical ecological or regulatory threshold, design standards, management or operating criteria associated with drought, energy, fish, flood, human health, infrastructure, streamflow and water quality. These variables were selected in collaboration with regional stakeholders and derived from existing regional climate change projections.
|Climate variable||Variable ID||Input dataset|
|Temperature, each calendar month [monthly average of daily average temperature]||T_month||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with daily maximum temperature above 65°F (18.3°C), each calendar month (Mar-Nov)||#Tmax>65degF_month||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with daily average temperature below 25°F (–3.9°C), winter (Dec-Feb)||#Tavg<25degF_DecFeb||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with daily average temperature above 68°F (20°C), spring (Mar-May) and fall (Sep-Nov)||#Tavg>68degF_months||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with daily maximum temperature above 90°F (32.2°C), annual||#Tavg>90degF||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with daily maximum temperature at or above 80°F (26.7°C), spring-summer (21 April-21 August)||#Tmax≥80degF_Apr-Aug||BCSD5, BCSD3, ECHAM5-WRF|
|Number of daytime heat waves (3 consecutive days with daily maximum temperature above historical 99th percentile), annual||#3dTmax>99th||BCSD5, BCSD3, ECHAM5-WRF|
|Number of nighttime heat waves (3 consecutive days with daily minimum temperature above historical 99th percentile), annual||#3dTmin>99th||BCSD5, BCSD3, ECHAM5-WRF|
|Precipitation, each calendar month [monthly average of daily average precipitation]||P_month||BCSD5, BCSD3, ECHAM5-WRF|
|Precipitation, fall (Oct-Dec), winter (Jan-Mar), spring (Apr-Jun), and summer (Jul-Sep) [seasonal average of daily precipitation]||P_months||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with 24-hour precipitation exceeding historical 90th percentile, October-March||Pwet>90th_OctMar||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with 24-hour precipitation exceeding historical 95th percentile, October-March||Pwet>95th_OctMar||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with 24-hour precipitation exceeding historical 99th percentile, October-March||Pwet>99th_OctMar||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with 24-hour precipitation exceeding 2 inches (50.8 mm), annual||#24hP>2"||BCSD5, BCSD3, ECHAM5-WRF|
|Maximum 48-hour precipitation accumulation, annual||48hPmax||BCSD5, BCSD3, ECHAM5-WRF|
|Maximum 24-hour precipitation accumulation, annual||24hPmax||BCSD5, BCSD3, ECHAM5-WRF|
|Number of days with 24-hour precipitation equal to 3 inches (76.2 mm) or more, annual||#24hP≥3"||BCSD5, BCSD3, ECHAM5-WRF|
|Number of wet sequences (18-day cumulative precipitation exceeding 3.5 inches (88.9 mm)), October-March||#18dPwet>3.5"_OctMar||BCSD5, BCSD3, ECHAM5-WRF|
|Runoff, annual [annual average of daily runoff]||Qcombined||BCSD3, ECHAM5-WRF|
|Runoff, each calendar month [monthly average of daily runoff]||Qcombined_month||BCSD3, ECHAM5-WRF|
|Dryness ratio (fraction of input precipitation lost to evapotranspiration), each calendar month [fraction of input precipitation lost to evapotranspiration]||Dryness_month||BCSD3, ECHAM5-WRF|
|Potential evapotranspiration (PET), each calendar month [calculated by VIC using Penman-Monteith equation where there is assigned natural vegetation and no water limit]||PET_month||BCSD3, ECHAM5-WRF|
|Actual evapotranspiration (AET), each calendar month [calculated by VIC using calculated sum of evaporation and plant transpiration equation]||AET_month||BCSD3, ECHAM5-WRF|
|Soil moisture, each calendar month||Soil_month||BCSD3, ECHAM5-WRF|
|Snow water equivalent (SWE), each calendar month||SWE_month||BCSD3, ECHAM5-WRF|
|Coefficient of variation of runoff, annual [annual runoff standard deviation divided by annual mean]||RunoffCV||BCSD3, ECHAM5-WRF|
|Highest spring runoff date||SpringRunoff||BCSD3, ECHAM5-WRF|
|Streamflow, each calendar month||Stream_month||BCSD5, BCSD3|
|Streamflow center of timing [number of days from 1st of October at which 50% of the year's flow volume for that water year has passed]||Centroid||BCSD5, BCSD3|
|Maximum daily streamflow per year||Qmax||BCSD5, BCSD3|
|Maximum daily streamflow, each calendar month||Qmax_month||BCSD5, BCSD3|
|Minimum daily streamflow, each calendar month||Qmin_month||BCSD5, BCSD3|
|Number of flood flows per year [number of days per year where flow is more than historical (1950-1999) 90th percentile (high) flow]||#Qflood||BCSD5, BCSD3|
|Number of 7-day low flows per year [number of days per year where the consecutive average 7-day flow is less than historical (1950-1999) 10th percentile (low) flow]||#Q7low||BCSD5, BCSD3|
|Number of low flows per year [number of days per year where flow is less than historical (1950-1999) 10th percentile (low) flow]||#Qlow||BCSD5, BCSD3|
|Lowest mean streamflow for 30 consecutive days per year||30dLow||BCSD5, BCSD3|
BCSD5: Bias-Corrected Statistically Downscaled CMIP5 projections.
BCSD3: Bias-Corrected Statistically Downscaled CMIP3 projections.
WRF: Dynamically-downscaled projections from a single CMIP3 global climate model.
See Input Datasets for more information
How were these climate variables identified?
Selection criteria included: stakeholder interest, key regional climate vulnerabilities, data availability, and suitability for Time of Emergence analysis.
Specifically, identifying a list of candidate variables for Time of Emergence analysis involved consideration of:
- The potential impacts caused by climate change (such as droughts, floods, human health, energy supply, water availability, fish survival) that could have implications for stakeholders’ planning, management, operations or regulatory responsibilities.
- The underlying climate drivers of these climate change impacts.
- PNW stakeholders’ existing or anticipated vulnerabilities, concerns and priorities as climate changes.
How regional stakeholders are addressing or plan to address the issues or potential impacts related to climate change.
- Availability of climate change projections – either already available within the relevant existing downscaled climate and hydrology datasets or feasibly derived therefrom using techniques established in the literature
Variable identification proceeded by the combined efforts of:
- Consultation with regional stakeholders, including federal, state and local government agencies, and tribal entities
- Review of peer-reviewed publications on projected PNW climate change and climate impacts
- Review of information prepared by, and for, specific stakeholders: goals and strategies, official and unofficial documents, climate change-related studies, regulatory standards, guidelines and mandates.
How were the streamflow locations selected?
Time of Emergence results are currently available for streamflow-related variables at 96 locations (~50 from each of the BCSD5 and BCSD3 datasets; Figure 1). These locations were selected for analysis using the following criteria:
1. Locations common to both datasets (i.e., within 5 km)
2. Locations close to (~50 km) the Puget Sound Basin
3. Locations showing diversity in watershed type, for example, rain dominant vs. snow dominant
Figure 1. Streamflow locations for Time of Emergence analysis of streamflow-related variables listed in Table 1. CMIP3 and CMIP5 indicate source datasets described in the text as BCSD3 and BCSD5, respectively.
The Time of Emergence project was conceived and funded by U.S. Army Corps of Engineers Climate Preparedness & Resilience programs & U.S. Environmental Protection Agency-Region 10. Methodologies and stakeholder engagement were developed and implemented by the University of Washington's Climate Impacts Group. The Time of Emergence online tool was developed with support from the Center for Data Science, University of Washington-Tacoma.