Climate change will be the baseline for scenarios in the 2021 Northwest Power Plan, according to the ­Northwest Power and Conservation Council.

The forecasted effects of climate change have the ­biggest influence on temperatures, which will affect demand; and on precipitation, which will affect energy supplied by hydroelectric generation.

Council staff is currently refining how it incorporates climate change’s secondary effects into the power plan. This spring representatives from BPA and several utilities in the region expressed reservations that new ­methodology proposed for consideration by Council staff relied on too many new assumptions. Accordingly, staff members told Clearing Up they are considering recommending more traditional forecasts for climate change’s follow-on effects.

Relying on more traditional models likely would not result in significantly different outcomes, though, staffers told Clearing Up, noting that any differences would likely be captured in the range of uncertainty in the modeling.

Incorporating climate change’s effects in the ­upcoming power plan is in stark contrast to the bulk of i­ntegrated resource plans for utilities across the Northwest. A ­Council review of IRPs found “very little ­deliberate ­modifications to specifically reflect climate change in forecasts,” ­according to a presentation at a May 1 ­workshop by the Council’s System Integration Forum on proposed climate change modeling in the 2021 Power Plan.

Staff presented its recommended scenarios to include in the plan to the Power Committee at the ­Council’s July meeting. The final proposed set of ­scenarios is scheduled to be presented to the committee at the agency’s Aug. 13 meeting.

In the 2021 Power Plan’s demand forecast, Council staff is recommending eschewing historical observed ­temperature data in favor of “a smaller, more recent set of observed temperature data” filled out with future ­temperature forecasts drawn from climate models, Mike Starrett, an energy policy analyst with the Council, told Clearing Up in an email.

For the hydroelectric supply, staff is proposing using a climate-adjusted forecast covering 2020 through 2049, rather than relying on the historic 80-year record for hydro data. The climate-adjusted forecast comes from climate modeling by the River Management Joint Operating ­Committee. The committee drew on 19 climate models, which it fine-tuned to forecast future Northwest stream flows.

“This is a change,” Starrett said.

Previous plans sampled from historic data to model future water and temperature years.

Council staff plans to winnow down the 19 models to a more manageable number and use the same shortlist of models for generating demand forecasts and future ­hydropower supply.

On the demand side, Council staff is grappling with how best to model the significance of secondary effects on future loads.

The upcoming power plan’s demand forecast will be directly affected by climate-adjusted temperature and precipitation projections.

Changes in temperature can directly drive loads higher. Hotter weather means more cooling degree days, which will spur greater use of air conditioning. That means increased load, using the structural equation for air conditioning penetration employed by council staff.

How climate change will influence population change is a trickier question. The Council relies on the economic consultant Global Insight for forecasts of population, housing stock, commercial floor space and other related variables. However, the firm’s projections specifically do not account for climate change, Starrett noted.

NWPCC staff initially proposed an ambitious methodology for forecasting secondary effects. This approach would have considered how climate change could spur greater migration into the Northwest, as well as other impacts. For example, this approach would have considered how climate change might decrease timber activity and could increase wildfires, resulting in decreased air quality, leading to increased health care demand.

However, representatives from utilities in the region expressed reservations about this approach.

Based on the reaction, Council staff “concluded that at this time there may not be enough experience [or well-vetted studies] yet for this type of discussion,” Starrett said.

That lack of experience likely means employing more traditional elastic models, according to Starrett and ­Gillian Charles, a fellow energy policy analyst at the Council.

To account for the potential secondary effects, “we plan to increase our band of uncertainty” beyond what would typically be used for the models, he said.

Staff is still exploring options and has not made any recommendations, noted Ben Kujala, NWPCC’s director of power planning.

All scenarios will consider climate change. “The ­reason is that there is no scenario in reality where we do not have climate change. We have climate change,” ­Starrett said.

None of these proposed modeling changes dictate future portfolio choices, he noted.