Warming forces like greenhouse gases caused millennia of dryness in prehistoric California and they could do the same again.
California was hit hard by the recent drought. The drought, which has entered into the record fifth consecutive year, has intensified wildfires, ruined forests, threatened animal species and above all deprived thousands of people from accessing clean water. And a new research suggests that the situation is not going to change anytime soon.
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By studying prehistoric droughts and current climate in California, researchers suggest that increasing greenhouse gases could extend the California drought for centuries if something has not done to limit them.
California is currently experiencing the worst drought in its recorded history and it is getting worse with every passing year. Besides creating crises, the extended arid period has prompted many questions such as how long will it take to end this drought and what are the natural climate forces acting upon it.
To answer these questions, researchers from UCLA collected sediments deep down in Sierra Nevada Mountains and reconstructed California's historic and prehistoric climate and water conditions. The model helped them look at how exactly natural climate forces contributed to extend dry periods in California over the past 10,000 years.
Researchers then compared their findings with the changing temperatures of Pacific Ocean and found a link between prolonged changes in ocean surface temperatures and arid periods in California.
Radiative forcing contributes to climate change. In other words, greenhouse gas emissions released in atmosphere increase the temperature. Climate change driven by greenhouse gas emissions affects ocean dynamics and cause to increase and decrease precipitation in California.
“Radiative forcing in the past appears to have had catastrophic effects in extending droughts," said Professor Glen MacDonald from University of California, Los Angeles. “When you have arid periods that persist for 60 years, as we did in the 12th century, or for millennia, as we did from 6,000 to 1,000 B.C., that's not really a 'drought.' That aridity is the new normal.”
As warming forces like greenhouse gases will likely exist and aridity could possibly become the "new normal" in California for centuries to come, it is necessary to find new ways to deal with these extended periods of dryness. Researchers believe that California might remain an agricultural state despite the aridness, thanks to technology, but productivity might decrease over time.
"I think we would find a way to keep our cities going through prolonged drought, but we're not going to engineer a way to conserve or preserve the ecosystems of the state," said MacDonald.
“Climate models today have a challenging time predicting what will happen with Pacific sea-surface temperatures in the face of climate change, and we hope that our research can improve that.”