In early July, shortly after a high-pressure system baked the Pacific Northwest for nearly a week, the California Department of Fish and Wildlife (CDFW) made a dire prediction: All the young salmon in the Sacramento River were likely fated to die. 

“This persistent heat dome over the West Coast will likely result in earlier loss of ability to provide cool water, and subsequently, it is possible that all in-river juveniles will not survive this season,” CDFW said in a statement to CNN.

Salmon in the Klamath River have also been suffering. In May, biologists with the Yurok Tribe announced they were witnessing a disastrous die-off of young Chinook, most of which had become infected with Ceratonova shasta, a parasite that proliferates when water temperatures warm and flows slow. On June 1, the Karuk Tribe declared a climate emergency. 

On July 7 and 8, CDFW—in coordination with the Yurok, Karuk, and Hoopa Tribes and several federal agencies—tried to avert disaster by moving 1.1 million juvenile Chinook from the Iron Gate hatchery to Fall Creek, a hatchery on the Trinity River. Another million were kept at Iron Gate rather than being released (as they normally would at this time of year) into the warm, disease-infested river. The agency expects to hold the young fish at the hatcheries until conditions on the Klamath improve, hopefully in October and November.

“It was the right thing to do,” says Toz Soto, fisheries biologist for the Karuk Tribe, adding that releasing hatchery-raised juveniles into the Klamath River at “absolutely the wrong time” would have spelled certain death for many of them.

California salmon aren’t the only wildlife species that is suffering from the climate-change-intensified heat waves and drought now gripping much of the American West. The late-June heat dome events toppled dozens of high-temperature records from British Columbia to Tucson. As temperatures rose, news feeds filled with tales of desperate and dying wildlife.

Overheated bears waded into the water at South Lake Tahoe, seemingly oblivious of the human sunbathers crowding the beach. Hundreds of millions of sea creatures cooked to death on Pacific Northwest shorelines. Wildlife rescue organizations saw an influx of patients, many of them young raptors, which, too young to fly, leaped from their nests to escape the heat. 

Caspian tern chicks at a tern colony in West Seattle were observed tumbling from an industrial rooftop. According to Washington Audubon, many chicks died either on the roof or on the street after leaping off. Others were treated at a nearby wildlife rehab center.

“Where people could actually observe those baby terns jumping, it was very visceral and tangible, but there’s probably a lot that happened that we didn’t see,” says Trina Bayard, director of bird conservation at Audubon Washington. The heat waves surely caused nests to fail and young birds to die unwitnessed; the long-term and indirect effects of these events are still unfolding. 

The recent scorching heat has accelerated drying in the already parched West, further shrinking creeks that host salmon and trout and wetlands that serve as important resting and breeding grounds for birds on the Pacific Flyway. A string of wildlife refuges in the Klamath Basin on the Oregon-California border has been hit hard by the drought. Last year, thousands of ducks died from avian botulism, which took hold in shallow, warm ponds where birds were crowded together.

“What happens as [birds] move down the flyway and find other impacted landscapes in multiple places?” Bayard asks. “When you start stacking up these climate-related events and threats happening in multiple important stopover areas, that’s when I really start to worry.”

Dry, hot conditions are also sparking massive outbreaks of grasshoppers, which are gobbling up vegetation on western rangelands. And of course, the drying also escalates the risk of wildfires. Already, the West is in the throes of another brutal fire season, with mega-fires burning in Oregon and California’s Sierra Nevada. 

Western landscapes are adapted to fire, but experts agree climate change is shifting the frequency and intensity of fires in the region. In fact, fire has become one of the biggest threats to ecosystem health and birds in the vast sagebrush steppe, says Bayard. A good portion of the “sagebrush sea”—which spans parts of 11 western states and two Canadian provinces and hosts a diversity of reptiles, mammals, and birds—has been lost or compromised by agricultural conversion, development, and invasive species.

“We’ve seen fire intervals go from 30 to 100 years historically to every five to 15 years,” Bayard says. “That’s just not enough time for sagebrush to recover.” The altered fire regime allows non-native annual grasses to take hold, which act like a “carpet of fuel” that helps fire spread rapidly.  

The massive die-off of intertidal creatures during the Pacific Northwest heat wave was another stomach-churning episode that’s likely to impact birds and other creatures long after temperatures return to normal. 

During those last days of June, the Pacific Northwest intertidal zone, normally a banquet of riches, became a death belt. Temperatures in some parts of coastal British Columbia and Washington soared to over 100 degrees. The record temperatures coincided with extreme low tides during the middle of the day, leaving billions of intertidal creatures vulnerable. According to one estimate, as many as 1 billion sea animals in Canada alone may have died during the heat dome. 

“These organisms that are absolutely not used to being exposed to these temperatures were literally cooked to death,” says Karina Nielsen, executive director of San Francisco State University’s Estuary & Ocean Science Center. 

Washington Sea Grant reported in a blog that clams and cockles on many beaches wriggled to the surface and died. Many were seen gaping—a sign of stress. Mussels, crabs, oysters, and even barnacles perished. (Washington State ordered a recall of oysters raised by one of the state’s largest shellfish farms after dozens of people were sickened from eating the oysters, which likely were compromised by the high water temperatures.)

Summer is a slow time for marine birds in Puget Sound, says Bayard. But the die-off could impact the food sources for the thousands of birds that migrate through or overwinter there. Washington Sea Grant warns of another possible ripple effect: Creatures like oysters and clams filter phytoplankton, or marine algae. The loss of large numbers of shellfish could spur “unusual” algal blooms. 

“When these blooms crash, they often lead to low dissolved oxygen events, which can potentially kill fish and both mobile and sessile (immobile) invertebrates in another type of mass mortality event,” Washington Sea Grant reported. 

A one-off event is usually not a catastrophe, says Nielsen. “But the frequency and duration and extreme and scale [of these events] are changing.” She points to the string of marine heat waves in the Pacific Ocean over the past several years—the now-infamous “blob” of warm water off the West Coast that helped fuel California’s last drought. These heat waves are “unprecedented in our memory,” Nielsen says, and have sparked algal blooms and decimated kelp forests, which serve as critical habitat for hundreds of species. 

Kelp forests are the “coral reefs of the temperate zone,” Nielsen says. They act like a conveyor belt for carbon, storing it and shuttling it into the deep ocean. “It’s another carbon sequestration mechanism that’s being compromised,” she says.

In many cases, this summer’s heat waves are exacerbating—and bringing to widespread public awareness—environmental troubles that have long existed due to overdevelopment and the destruction of wildlife habitats. For example, CDFW regularly trucks salmon from hatcheries along the Sacramento River to bays near the river’s mouth, bypassing lethal conditions in the Central Valley. This April, as the drought worsened, the agency announced it would proactively move some 16.8 million young fall Chinook, 20 percent more than “normal” years. 

Low flows on the Sacramento and Klamath Rivers are nothing new, Soto says, and salmon runs on these rivers have been in steep decline for decades. “Irrigation projects were planned at a time when there was a lot more water,” he says. “Models for allocating flows were based on past records.”

Bayard says conditions are changing so quickly that it’s hard to respond. “We don’t have all the data or capacity in monitoring that we need to track what’s happening and create adaptive management plans,” she says. “We’re working with the bare minimum of capacity.”

Still, humans are trying their best to help out other species harmed by the heat and drought. The Coastal Observation and Seabird Survey Team is using citizen scientists to collect data about marine birds that wash up on Pacific Northwest beaches. In the Klamath Basin, refuge managers are concentrating water in deeper ponds to try to prevent a repeat of last year’s botulism outbreak. A multimillion-dollar grant from the Natural Resources Conservation Service will be used to fund projects that provide temporary habitat for migrating waterfowl on working farmlands. As for California salmon, CDFW says holding fish until conditions on the Klamath River improve will provide valuable data to inform the strategies they’re using.

“There is evidence that survival of fall-released fish is better,” says Soto, the fisheries biologist. “I’m encouraged by [the move], and we’ll learn something.” 

The Karuk, Yurok, and Hoopa Tribes have worked together on disease-management guidelines that stress the timing of hatchery releases and maintenance of flows on the Klamath River. More recently, the Karuk Tribe has asked the state to regulate flows on the Scott River, an important tributary to the Klamath. At the same time, Soto stresses that the pace of restoration needs to ramp up—now. “All the things we’ve done as humans have left systems less resilient to change,” Soto says. “We need to act fast.”

And for our own sake too. The June heat waves killed close to 200 people and sent hundreds more to the hospital.

The Climate Science Special report predicts a future with more frequent, intense, and prolonged heat waves. If there’s a silver lining, it’s found in a preliminary analysis by an international group of weather experts that cautiously concludes the late June heat dome was a one-in-1,000-year event—the “statistical equivalent of really bad luck, albeit aggravated by climate change.” The researchers add a caveat: We need to explore the possibility that we’ve passed a threshold in which some unknown, “nonlinear interactions in the climate” make the extreme temperatures of the June heat wave more likely than current models predict.

For the sake of birds, bivalves, and bipeds alike, let’s hope that hasn’t happened.