California’s Mediterranean climate has gives it the most variable weather of any U.S. state, so it’s no stranger to catastrophic droughts and disastrous floods. Still, even in a drought-prone region, recent years have been exceptional – the result of natural climate cycles colliding with a warming planet. From fires in the Sierra to clouds of windblown dust at the Salton Sea, the effects of drought driven by climate change are impossible to ignore.
The latest science confirms that climate change has arrived and that we are in the middle of a megadrought. In August, 2021, a report by the United Nations’ Intergovernmental Panel on Climate Change found that climate change is quickening and intensifying. Even in a best-case scenario, global temperatures will likely rise by 1.5 degrees Celsius by 2040.
In May, 2021, the U.S. Environmental Protection Agency (EPA) declared that the nation has entered uncharted territory in which climate effects are more visible, changing faster and becoming more extreme. Temperatures are rising, snow and rainfall patterns are shifting, and more extreme climate events –like heavier rainstorms and record high temperatures –are already happening. Some, like hotter forest fires, are directly related to historic drought conditions gripping the U.S. West.
The consequences for both California’s avian and human populations are likely to be devastating. Simply put, climate change is the number one threat to the survival of our nation’s birds. In 2019, the National Audubon Society released Survival by Degrees, a study examining the impacts of various climate change scenarios on North America’s birds. Under a worst-case rise of 3.0 C, up to two-thirds of bird species face extinction, including from specific factors like extreme heat and fires. The report came on the heels of another by Cornell’s Lab of Ornithology that the continent has already lost an estimated three billion birds since 1970 due to habitat loss and climate change.
The Central Valley
Just 200 years ago, the Central Valley was a vast, seasonal wetland teeming with bird life. Only about five percent of California’s historic wetlands have survived two hundred years of colonization and intensive agriculture. Those that remain are heavily managed, for the most part receiving water allocations from the state water system together with California’s cities and farms. In addition, some agricultural lands, like flooded rice fields, serve as “surrogate wetlands,” providing vital habitat to migrating waterfowl and wading birds. However, as of August, 2021, the state’s largest reservoirs, Lake Shasta and Lake Oroville, were respectively at 35 and 24 percent of capacity, with proportionate impacts on water deliveries to farms, cities and wildlife refuges in the Central Valley and elsewhere in California. Our last remaining Central Valley wetlands are expected to receive less than 60 percent of their usual water supply. Winter flooded rice fields, which provide half of winter waterfowl food supply, are expected to be reduced by 75 percent. The importance of keeping water flowing in the Central Valley is difficult to overstate. Tens of millions of birds depend on the area’s rivers and wetlands as they migrate through an otherwise arid region. Flooded habitat provided by the region’s farms, refuges, and other managed areas supports between 5-7 million waterfowl and 350,000 shorebirds each year- that’s over 60 percent of the total population along the Pacific Flyway and 20 percent of the nation's waterfowl population. Migrating landbirds also rely heavily on Central Valley stopovers; an estimated 65 million birds pass through during fall migration, along with 48 million each spring. Those numbers include a quarter of all North American Tree Swallows and a whopping 80 percent of Lawrence’s Goldfinches. In addition, the Valley is a year-round home to several species found nowhere else, including the Yellow-Billed Magpie.
The Far North and the Sierra
Years of fire suppression in western forests and California’s years-long drought have created a trifecta of conditions perfect for explosive wildfires: extreme heat, low humidity and abundant, desiccated vegetation fire needs to spread. In fact, the state’s worst-ever fires, the 2020’s August Complex Fire at more than a million acres and the 2021 Dixie fire, at more than 960,000, both dwarf all previous fires in both size and ferocity.
The increasingly apocalyptic wildfires of the past five years have cost California dozens of lives and billions of dollars, though the toll on birds is somewhat harder to quantify. While most birds can easily escape advancing flames, extensive wildfires across the western United States in 2020 are suspected at least in part for causing a mysterious die-off of migrating birds in the Southwest. Fire can cause birds to migrate to winter habitats before their bodies have stored enough fat for the arduous journey and thick smoke may disorient some and kill others outright. While western forests – and their birds – evolved with fire as a natural part of the ecosystem, vital in maintaining diverse habitats, no analog exists for the megafires of the past decade. Experts expect that temperatures in the Sierra will rise by some 10 degrees Fahrenheit over the next century and that the snowpack to melt almost a month earlier. By the end of the century, that could double the acreage burned by wildfires each year.
The Salton Sea
California’s largest lake is located in one of its most arid regions. The Salton Sea formed in 1905 when an irrigation canal from the Colorado River broke and flooded a historic lakebed. The breach was fixed within a few years, but the Salton Sea, fed by agricultural runoff, remained and became a vital stopover for migrating birds that no longer found wetlands available farther north.
But the Sea is evaporating quickly.
Drip irrigation, and the diversion of the water saved to thirsty San Diego, means that not enough water is flowing to the Sea to maintain it. The retreating shoreline has exposed thousands of acres of playa, or dry lakebed, which contains a century’s worth of agricultural fertilizers, pesticides, heavy metals and salts. Those contaminants, blown airborne by desert winds, waft towards surrounding towns as a choking dust, causing high rates of respiratory illness in some of California’s most disadvantaged communities. Meanwhile, as the surface area of the lake decreases, its salinity increases, killing the fish on which many species of migratory birds depend.
While limited restoration work on the Salton Sea is beginning to proceed – after years of delays – the Sea’s future in a warming climate remains very much in question. Audubon is working with the state of California and partner organizations to maintain the Sea as an asset both for wildlife and for surrounding communities.
While there’s no denying the gravity of the climate crisis, it’s not too late to limit warming and stave off the worst impacts of climate change. With rapid action, we can still limit warming to 1.5 degrees and push lawmakers to enact water policy good for both humans and birds as we all adapt to this warmer, drier new normal. Audubon and our many partners are working to complete science to better understand how drought impacts birds, we are working with land managers to roll-out emergency drought relief funding to create bird habitat, and we are advocating for long-term policy and infrastructure solutions that will make California, our communities and our birds more resilient to this new climate reality.
This piece is part of a week-long series examining the effects of climate change along the Pacific Flyway.