The ongoing drought in California is caused by natural factors and not global warming, according to a study sponsored by the National Oceanic and Atmospheric Administration (NOAA) of the United States Department of Commerce.
The drought, claims the report, is primarily caused by natural atmospheric and oceanic patterns.
A ridge of high pressure located off the West Coast, which is a usual trait of previous droughts, has remained for the past three winter seasons. The ridge, which has blocked important storms of the wet season, is supported by the temperature patterns of the surface of the ocean.
The usual winter season of the state provides California with most of its yearly rainfall and snow, replenishing the water supplies of the ecosystems and communities in the region. However, the presence of the high-pressure ridge, along with the blockage of the wet season storms, has prevented the replenishment from normally occurring.
However, a good note on the phenomenon is that additional studies on the ocean conditions and their resulting effects on the climate of California could lead to advancements in the development of early warning systems for droughts, which could assist industries and water managers in preparing for future droughts.
"It's important to note that California's drought, while extreme, is not an uncommon occurrence for the state. In fact, multi-year droughts appear regularly in the state's climate record, and it's a safe bet that a similar event will happen again," said lead author of the study Richard Seager, who is also a professor at the Lamont Doherty Earth Observatory at Columbia University.
The study builds upon the finding of earlier studies that were published back in September, which state that there was no evidence found that links the current drought in California with climate change caused by human activities. The study noted that the high-pressure ridge in the North Pacific, which has caused lower levels of snowfall and rain since 2011, features characteristics that are almost the opposite of what models predict would be present in human-caused global warming.
The report projects that rainfall in the middle of the winter will actually increase over most of California from human-caused climate change. However, higher temperatures will drain the benefits of the increased rainfall from water resources. Global warming will only cause rainfall in the spring to decrease.
"There is immense value in examining the causes of this drought from multiple scientific viewpoints," according to co-author Marty Hoerling, who is also a researcher at the Earth System Research Laboratory of NOAA.
