The state of California could be locked into a state of prolonged drought it has been revealed by a new study led by UCLA scientist.
According to professor Glen MacDonald and team, today’s increasing greenhouse gas levels and the Pacific Ocean’s response could lead to an extended drought in California. The study, published in Scientific Reports, the warming forces of greenhouse gases and the resulting radiative forces will extend drought-like conditions more or less indefinitely. The findings and the predictions are based on examination of how natural climatic forces contributed to centuries-long and even millennia-long periods of dryness in California during the past 10,000 years.
Researcher say that phenomena such as sun spots, a slightly different earth orbit, a decrease in volcanic activity intermittently warmed the region through a process called radiative forcing with the latest entrant in the trio being greenhouse gases. According to scientists, these radiative forcing have had catastrophic effects in the past in the form of extended droughts.
For the study, researchers tracked California’s historic and prehistoric climate and water conditions by taking a sediment core in the Sierra Nevada mountains. They pulled a 2-inch-wide, 10-foot-deep cylinder of sediment from the bottom of Kirman Lake and analyzed it in third-of-an-inch sections, creating the most detailed and continuous paleoenvironmental record of California.
They then correlated their findings with other studies of California climate history, and for the first time, united all the studies and cross-referenced them with histories of the Pacific Ocean’s temperature taken from marine sediment cores and other sources.
What they found was not only that periods of increased radiative forcing could produce drought-like conditions that extended indefinitely, but that these conditions were closely tied to prolonged changes in Pacific Ocean surface temperatures.
Changes in ocean temperatures are linked to El Niño and La Niña conditions, which increase and decrease precipitation in California. Until now, no one had the long, detailed record of California’s dry periods needed to show that that aridity went hand-in-hand with changes in the prehistoric climate records of the Pacific Ocean, MacDonald said.
The researchers chose Kirman Lake in central-eastern California for its sensitivity to climate changes and its stable geologic history. Today, it’s a small, freshwater lake full of trout and about 16 feet deep, with a small marsh at one edge.
The team found evidence though that through the millennia Kirman Lake has grown more and less salty, dried until it was exclusively marshland and refilled again. All the while, sediment accumulated on the lake’s bottom, forming a record of lake conditions, the changing climate and the surrounding environment.