In August, 2021, for the first time ever, the federal government declared a water shortage in the Colorado River basin. While the declaration was not necessarily surprising—the Colorado River has been in an official state of drought for the past 22 years and experts have demonstrated that drought conditions are, in fact, natural for the Colorado River basin—it served as a stark illustration of the “new normal” we have entered due to climate change. As Shi-Ling Hsu, Karrigan Bork, and Kevin Lynch argue in another Environmental Law Collaborative blog focused on 4ºC, this new normal will require reconsideration of the laws governing water rights.
It should also spur reevaluation of electricity system decarbonization models. For the past several years, a number of models have attempted to assess the technical and economic feasibility of rapidly decarbonizing the electricity system. Some models focus on pursuing “least-cost” strategies to reduce greenhouse gas emissions; others aim to demonstrate how the United States or areas of the United States could “electrify everything” through 100 percent renewable energy. All these models assume that hydropower will play a meaningful role in the decarbonized grid of the future. Although models do acknowledge that hydropower capacity will drop somewhat due to climate change, others assume that hydropower will comprise nearly 40 percent of the Pacific Northwest’s electricity supply in 2050. But as droughts worsen due to climate change, these assumptions require reconsideration. Indeed, in 2015, an extended drought reduced California’s hydropower output by 59 percent compared to the prior two decades. This year, drought maps produced by the National Oceanic Atmospheric Administration (NOAA) showed that nearly all the hydropower facilities in the western United States were in drought conditions during the week of September 9, 2021. On the other end of the spectrum, more intense storms and floods are causing entire dams to fail. Whether due to too much or too little water, the nation’s hydropower supply is at risk. And these impacts are occurring when average global temperatures have climbed by only (only!) about 1ºC. If hydropower is becoming an increasingly unreliable resource today, it’s hard to imagine what it will look like at 4ºC.
But it’s not just hydropower; the energy system as a whole will be at risk as average temperatures rise. According to the Fourth National Climate Assessment released in 2018, already vulnerable aspects of our energy infrastructure will face intense challenges, if not complete destruction, at 4ºC. The impacts will go far beyond droughts and floods eliminating hydropower production. According to the climate assessment, in a 4ºC future, wildfires caused by electricity transmission lines will burn those lines down in return; power plants that need water for cooling will face forced outages to prevent overheating; severe wind and ice storms will knock over critical infrastructure or make it inoperable; and escalating energy demand during heat waves could trigger blackouts that result in heat-related deaths. While such projections may seem like speculative fiction, many of the predictions have already come true. Today, these consequences are infrequent enough to generate headlines, but they could become commonplace if we allow a 4ºC future to become our reality.
Avoiding these consequences of a 4ºC future requires us to plan for an energy system that can withstand a 4ºC future. Otherwise, we may not be willing to make, or even model, bold changes that could help us avert not just rising temperatures but the consequences of those rising temperatures. The current approach to energy modeling usually aims to pursue the lowest-cost strategies to achieve various rates of decarbonization. Through this modeling, energy planners assume that decarbonization should involve changes to the energy system we have today, namely by replacing existing fossil-fueled power plants with renewable facilities and, in some cases, nuclear power. Most of the models project that this transition will require a substantial expansion of the existing transmission system, and, as noted, most of them also assume that hydropower will provide a meaningful amount of energy into the future. While the models show that deep decarbonization through relatively modest changes is achievable, they fail to address how and whether a decarbonized energy system can be designed to minimize, or at least not exacerbate, harms to humans and the environment that our energy system has caused.
Let’s consider hydropower once again. Although hydropower can provide abundant amounts of emissions-free electricity (assuming water supplies are sufficient and the reservoirs do not release methane created through anaerobic decomposition of organic matter), dams have exacted an enormous toll on the environment—including on species that are at greatest risk of extinction due to climate change. The famed Federal Columbia River Power System, which supplies a substantial amount of electricity in the Pacific Northwest (and in California), has so altered stream flows and warmed waters in Oregon, Washington, and Idaho that almost all the species of salmon in the Columbia Basin are listed as endangered or threatened under the Endangered Species Act. Declining salmon populations are also linked to the imperiled status of Pacific orca whales, which feed on the anadromous fish. Declining stocks of salmon have also caused profound harm to Native American tribes, who for “time immemorial” have harvested salmon and called the wild Columbia River their home. None of this information, of course, is new. But the consequences of the dams on the species and people of the Pacific Northwest have been amplified by climate change, and they will only worsen as temperatures continue to rise. If we assume that those dams will remain in place and supply power in a decarbonized energy system, we must also assume the dams’ energy production outweighs the value of the salmon, orca, and Columbia River (and countless other western) Native American tribes. I, for one, cannot accept that calculation.
What’s worse, though, is that there is a good chance that the energy models’s projections of hydropower output are wrong. The decarbonization studies all acknowledge that future hydropower production is uncertain and that existing decarbonization models cannot precisely or accurately predict how hydroelectric facilities will function in an increasingly variable climate. Nonetheless, the models assume that existing hydropower facilities will provide necessary power well into the future. But if the models are wrong, then we will seek to decarbonize via “least cost” strategies, sacrificing endangered species and tribal rights, for no good. So long as the models assume the hydropower system will function more or less as it does now, those sacrifices seem, tragically, inevitable.
But what if modelers were charged instead with modeling a decarbonized energy system for a 4ºC world? In that world, large hydropower projects would almost certainly not play a role since their ability to provide electricity in drought-affected and flood-impacted areas would be highly uncertain. The hydropower capacity in today’s decarbonization models would be replaced with other zero-emitting resources in the energy system designed for a 4ºC future, and, ideally, the dams would be removed and free-flowing waters would be restored. Of course, if we wait for 4ºC to be locked in, the salmon, the orca, and a host of other species will be gone, and the tribes will suffer even more. So, let’s not wait. Instead, let’s jettison narrow “least-cost” approaches to energy decarbonization that ignore the massive costs our current energy system already imposes on habitats, species, and humans. While tradeoffs are inevitable and there are likely no ways to decarbonize that do not exact some toll on humans and the environment, we can at least aim to eliminate the most destructive facilities. Let’s start planning for a decarbonized electricity system that can operate in a 4ºC world so that species and people have a chance in a 2ºC one.
 For example, a deep decarbonization model for California estimates an 11% decrease in hydropower output from 2015-2050. The authors of the report recognize that hydroelectric production will likely not decrease linearly and will vary on a seasonal basis, but explain that their decarbonization model cannot incorporate such variability. (pp. 25-26.) As a result, hydropower is projected to provide about 9% of total energy supply in 2050, down from about 10% in 2015.
- Melissa Powers, Jeffrey Bain Faculty Scholar & Professor of Law at Lewis & Clark Law School.