Time of Emergence

Created: 10/18/2017 - Updated: 2/27/2020


This tool aims to support climate change risk assessment and decision-making by providing quick and readily accessible information about when and where climate change could matter across the Pacific Northwest. This is a new approach to delivery of climate change information that focuses on identifying the time when climate change causes local conditions to deviate significantly from the past, which we call the Time of Emergence of climate change.

This tool presents the results of Time of Emergence analysis for 35 climate variables during different times of the year, for the 119 counties, 219 watersheds and for 96 streamflow locations in the Pacific Northwest. These results, combined with information on local sensitivities, design standards or critical thresholds, and the effort need to prepare for change, can be used to help prioritize decisions about when, where and for which climate change impactspreparatory actions are most urgent. 
This tool enables you to explore:

  • Which type of changes could occur first (for a specific location)?
    This pathway allows you to compare the Time of Emergence for different variables for a specific PNW county, watershed or stream location.
  • Where could changes occur first?
    This pathway allows you to examine how the Time of Emergence of a specific variable varies across the region.
  • How uncertain are these projections?
    Throughout the website, you can explore how the Time of Emergence results change under different assumptions about potential future change and the ability of the management system to cope with that change.

The Time of Emergence of management-relevant climate change is not a fixed value. It is different for different climate variables and for different locations. It depends on how management-relevance is defined, since some systems will be affected by relatively minor climate changes, while others may be robust to all but the largest expected change. And because there is no single best estimate for how climate change will unfold, Time of Emergence also differs for different climate change scenarios. That is why this tool provides information about the plausible range of Time of Emergence, as well as opportunities for exploring how Time of Emergence varies under different assumptions.



The Environmental Protection Agency has ten Regional offices, each of which is responsible for the execution of the Agency's programs within several states and territories.


Scale of Project
Regional / Subnational
Sector Addressed
Disaster Risk Management
Target Climate Changes and Impacts
Storms or extreme weather events
Type of Tool
Adaptation Planning / Decision Support
Decision Support
Type of Adaptation Action/Strategy
Capacity Building
Monitor climate change impacts and adaptation efficacy
Create/enhance resources and tools