Greenhouse Gases Could Trap California in Drought
A scary forecast draws on data about ancient dry spells.
Even with the stringent water-conservation measures imposed by Gov. Jerry Brown's administration, Californians have to wonder: How much longer will this go on?
The answer could be a whole a lot longer, perhaps even centuries, due to the effects of rising greenhouse gas levels in the atmosphere and the resulting climate change. Those dire findings are revealed in a newly-published article in Scientific Reports, which analyzed the role that climate has played in California's history of drought.
In the study, researchers looked at how climate contributed to drought and periods of dryness in California, stretching back 10,000 years into prehistoric times. They dug up a 10-foot deep core of sediment taken from the bottom from Kirman Lake in the Sierra Nevada mountains, which is known for its sensitivity to climate fluctuations.
Material in the sample's layers -- such as charcoal deposits that remain from ancient forest fires, fossilized pollen, algae and mollusk shells -- enabled them to reconstruct a climate timeline that stretches back 10,000 years.
Historically, natural phenomena such as sun spots, a slightly different earth orbit and a decrease in volcanic activity have intermittently warmed California through a process called radiative forcing. But in modern times, those have been joined by a new force: greenhouse gases generated by the burning of fossil fuels and other human sources.
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In a press release, the study's lead author, UCLA climate expert Glenn McDonald warned that as long as warming forces like greenhouse gases are present, the resulting radiative forcing can extend drought-like conditions more or less indefinitely, "Radiative forcing in the past appears to have had catastrophic effects in extending droughts," said McDonald, a distinguished professor of geography, ecology and evolutionary biology at the university. "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."
The longest ancient drought in California lasted for nearly 5,000 years, from 6,000 to 1,000 BC. It was triggered by a combination of a slight variation in the Earth's orbit, which increased the amount of solar energy received in the summer by the Northern Hemisphere, with a long-term La Niña-like state in the Pacific Ocean, which probably reduced precipitation.
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You've heard a lot about how human-driven climate change will lead to hotter temperatures, cause sea levels to rise and make storms more intense. But it's projected to have plenty of other unpleasant and even disastrous effects as well. Here are 10 of them. Scientists believe that rising temperatures will lead to increased evaporation of the Great Lakes' water, and precipitation won't make up the difference. That means we're likely to see declines in water levels over the next century, and one study predicts they may drop as much as 8 feet.
Thanks to climate change, jumbo-sized ragweed plants will spew out more pollen for a longer, more miserable allergy season.
By altering the wild environment, climate change makes it easier for newly mutated microbes to jump between species, and it's likely that as a result, diseases will emerge and spread across the globe even more rapidly.
A recent Nature article reported that male Australian central bearded dragons have been growing female genitalia because of rising temperatures, a phenomenon that had not previously been observed in that species.
Rising sea levels are wiping out beaches all over the world already. Importing fresh sand and building them up again is only a temporary solution. To make matters worse, there's currently a sand shortage, due to demand from fracking, glass and cement making.
Bark beetles are eating old growth forests, because the winters aren't cold enough to kill them off. So more trees like this American Elm will die.
Warmer temperatures mean there will be more water vapor trapped in the atmosphere, leading to more lightning. A University of California-Berkeley study predicts that lightning strikes will increase by about 12 percent for every degree Celsius gained.
Wine grape harvests are being hurt. Regions that have historically supplied the world's best wine will no longer be hospitable climates to grow wine grapes, according to research by the Environmental Defense Fund and others.
Coffee flavor depends upon really narrow conditions of temperature and moisture, and climate change is going to wreak havoc with that. Worse yet, as coffee growing regions become warmer, pests that couldn't survive in the past will ravage the crops. This is already being seen in Costa Rica, India and Ethiopia, which have experienced sharp declines in crop yields.
Scientists say that as ice sheets and glaciers melt, the weight that's removed from the Earth's crust changes the stresses upon volcanoes. That unloading effect can trigger eruptions.