California’s Mediterranean climate has given it the most changeable weather of any US state. catastrophic droughts and devastating floods are not unknown. But even in a drought-prone region, the past few years have been extraordinary – the result of natural climate cycles colliding with a warming planet. From fires in the sierra to wind-blown dust clouds on the Salton Sea, the effects of the drought caused by climate change cannot be overlooked.
The latest science confirms that climate change has arrived and we are in the middle of one Mega drought. In August 2021, a report noted by the United Nations Intergovernmental Panel on Climate Change that climate change is accelerating and intensifying. Even in the best case scenario, global temperatures are expected to rise by 1.5 degrees Celsius by 2040.
In May 2021, the U.S. Environmental Protection Agency announced that the country had broken into uncharted territory where climate impacts are more visible, changing faster and becoming more extreme. Temperatures are rising, snow and precipitation patterns are shifting and more extreme climatic events – such as heavy downpours and record temperatures – are already taking place. Some, like hotter forest fires, are directly related to historic drought conditions in the western United States.
The consequences for both California’s avian and human populations are likely to be devastating. Put simply, climate change is the greatest threat to the survival of our nation’s birds. In 2019 the National Audubon Society published Survival by degrees, a study examining the effects of various climate change scenarios on North America’s birds. With a worst-case increase of 3.0 ° C, up to two thirds of bird species are threatened with extinction, also due to specific factors such as extreme heat and fire. The report followed another from Cornell’s Lab of Ornithology that the continent is estimated to have already lost three billion birds since 1970 due to habitat loss and climate change.
The central valley
200 years ago the Central Valley was a huge, seasonal wetland full of bird life. Only about five percent of California’s historic wetlands have survived 200 years of colonization and intensive agriculture. The remaining are heavily managed and for the most part receive water allocations from the state water system along with California’s cities and farms. In addition, some agricultural areas, such as flooded rice fields, serve as “replacement wetlands” and provide vital habitats for migratory waterbirds and waders. However, as of August 2021, the state’s largest reservoirs, Lake Shasta and Lake Oroville, were 35 and 24 percent of their capacity, respectively, affecting water supplies to farms, cities, and wildlife sanctuaries in the Central Valley and elsewhere in California. Our last remaining wetlands in the Central Valley are expected to receive less than 60 percent of their usual water supply. Rice fields flooded in winter, which provide half of the winter food supply for waterfowl, are expected to decline by 75 percent. It’s hard to overestimate the importance of keeping the water flowing in the Central Valley. Millions of birds depend on the region’s rivers and wetlands as they migrate through an otherwise arid region. Flooded habitat provided by the region’s farms, shelters, 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 country’s waterfowl population. Migratory land birds are also heavily reliant on stopovers in the Central Valley; An estimated 65 million birds migrate during the autumn migration, along with 48 million each spring. Those numbers include a quarter of all North American tree swallows and a whopping 80 percent of goldfinches. In addition, the valley is home to several species not found anywhere else, including the yellow-billed magpie, all year round.
The far north and the sierra
Years of fighting fires in western and California forests years of drought created three perfect conditions for explosive forest fires: extreme heat, low humidity, and abundant parched vegetation fire must spread. In fact, the state’s worst fires, the August 2020 Complex Fire with more than one million acres and the 2021 Dixie Fire with more than 960,000, dwarf all previous fires in size and severity.
The increasingly apocalyptic forest fires of the past five years have cost California dozens of lives as well billion dollarsalthough the number of birds is a little more difficult to quantify. While most birds can easily escape the advancing flames, widespread forest fires in the western United States in 2020 will be blamed, at least in part, for causing mysterious migratory bird extinctions 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 can confuse some and kill others instantly. While western forests – and their birds – evolved with fire as a natural part of the ecosystem essential to maintaining diverse habitats, there is no analogue for the mega-fires of the past decade. Experts expect temperatures in the Sierra to rise by around 10 degrees Celsius over the next century and that the snowpack will melt almost a month earlier. By the end of the century, this could double the area burned annually by forest fires.
The Salton Sea
California’s largest lake is in one of its driest regions. The Salton Sea was formed in 1905 when an irrigation canal of the Colorado River broke and flooded a historic lake bed. The break was fixed within a few years, but the Salton Sea, fed by agricultural runoffs, remained and became an important stopover for migratory birds that could no longer find wetlands further north.
But the sea evaporates quickly.
Drip irrigation and the diversion of the water saved into the thirsty San Diego means there isn’t enough water flowing into the ocean to sustain it. The retreating coastline has exposed thousands of acres playa, or dry lake bed that contains a century’s worth of agricultural fertilizers, pesticides, heavy metals, and salts. Blown into the air by desert winds, these pollutants blow into the surrounding cities as choking dust, causing high rates of respiratory illness in some of California’s most deprived communities. Meanwhile, as the lake’s surface area decreases, its salinity increases, killing the fish on which many migratory bird species depend.
While limited restoration work begins on the Salton Sea – after years of delays – the future of the sea in a warming climate remains very questionable. Audubon works with the State of California and partner organizations to preserve the ocean for both wildlife and the surrounding communities.
While the severity of the climate crisis cannot be denied, it is not too late to limit warming and avert the worst effects of climate change. With quick action, we can still limit warming to 1.5 degrees and get lawmakers to enact water policies that are good for both humans and birds as we all adjust to this warmer, drier new normal. Audubon and our many partners are working to complete the science to better understand how drought will affect birds, making California, our communities, and our birds more resilient to this new climatic reality.
This article is part of a week-long series examining the effects of climate change along the Pacific Flyway.