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POSTED:

9-15-16

Greenhouse gases trapped in the upper atmosphere are acting like natural climatic forces that made some ancient droughts last for 1,000 years, UCLA researchers say.

Global warming created by these gases could be making a more arid climate, like what California has seen in its current five-year drought, “the new normal,” said UCLA geography professor Glen MacDonald, the study’s lead author.

Released today, the study in Scientific Reports — part of the Nature Publishing Group — found that carbon dioxide and methane emitted from the burning of fossil fuels may be mimicing the effects of some catastrophic environmental phenomena the planet has previously experienced.

The consequences of the buildup of greenhouse gases in the Earth’s atmosphere look a lot like the effects of storms on the surface of the sun, decreases in volcanic activity or wobbles in the Earth’s orbit.

Events such as those precipitated 60-year periods of drought in the 12th century, MacDonald wrote. Some prehistoric droughts created by those phenomena lasted as long as 1,000 years.

Man-made activity causing the Earth’s temperature to rise may take the place of these natural phenomena — known as “radiative forcing” — in creating what scientists identify as extended arid periods.

“Radiative forcing in the past appears to have had catastrophic effects in extending droughts,” said MacDonald, an international expert on drought and climate change, in a statement.

“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,’ ” MacDonald said. “That aridity is the new normal.”

While many scientists suspected that California had experienced extended dry periods in the ancient past, MacDonald’s study found new, decisive evidence of mega-droughts occurring before recorded history.

Much like how researchers can use tree rings to understand what happened to an ancient tree over the course of its life, MacDonald used sediment samples from Kirman Lake in central-eastern California to document previous droughts. He concluded that these dry periods related to sea surface temperatures in the Pacific Ocean.

Ocean temperatures help climatologists predict weather patterns like El Niño and La Niña.

Californians awaiting this year’s El Niño knew they could anticipate months of wetter weather. That didn’t happen, with scientists saying a dome of high pressure kept the storm track of the most recent El Niño confined to the northern part of the state.

If the current La Niña period, which usually means drier weather, combines with radiative forcing of global warming, this double-whammy could produce droughtlike conditions that may extend indefinitely, the study says.

If levels of greenhouse gases continue to rise, the resulting effects could wither the state’s forest preserves and decrease snowfall and rainfall, the study’s authors concluded.

The U.S. Forest Service in June said a combination of drought, a bark beetle infestation and hotter temperatures killed an estimated 66 million trees in California’s forests of the Sierra Nevada over the last six years. The mass of dead trees raised concerns that there would be more fuel for wildfires in the state this summer.

The costs of fighting wildfires during the state’s 2015-16 fiscal year, which ended June 30, jumped to $366 million, according to the California Department of Forestry and Fire Protection. That’s compared to $209 million for the previous fiscal year.

Dry brush as a result of the drought also quickened fires in Southern California, like the Blue Cut fire that raged in the San Bernardino Mountains in August.

“When we go out to hike in the Sierra Nevada mountains or the Santa Monica mountains, I worry that we will see very different wildlands by the end of this century,” MacDonald said in his statement.

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Los Angeles Times

By: Rong-Gong Lin II

June 21, 2016

6.21.16

Think today’s heat in L.A. is miserable? It’s going to become more frequent in the summers to come.

Days of extreme heat are defined as those on which the temperature reaches 95 degrees. In downtown Los Angeles, there was an average of just six extreme heat days yearly in the 1980s and 1990s. 

But by the year 2050, there could be 22 days of extreme heat in Los Angeles, and by 2100, there could be 54 such days, a study released by UCLA scientists last year said. 

It gets even worse the farther inland you go.  

The San Gabriel Valley could see its number of extreme heat days climb from 32 to 74 by 2050, and 117 by 2100. 

L.A. will keep getting hotter, scientists say — a lot hotter – LA Times

“A new season of extreme heat” likely lies in our future, the UCLA scientists warned. 

By 2050, the most likely average future August will be warmer than the hottest August of the 1980s and 1990s, they said.

In fact, L.A.’s future winters will be most similar to how April felt in the ’80s and ’90s. 

“We have to confront this,” study co-author Alex Hall, a professor at UCLA’s atmospheric and oceanic sciences department, said in an interview last year. “Climate change is inevitable in this region.”

Valleys will be hit worse than the coast, said Katharine Reich, associate director of the Center for Climate Science, part of the UCLA Institute of the Environment and Sustainability, which performed the study. 

“If you’re in the San Fernando Valley, where the Santa Monica Mountains block your access to cool sea breezes, you’ll experience more extreme heat,” she said. “The farther inland you go, the more impacted you’ll be.” 

L.A. will keep getting hotter, scientists say — a lot hotter – LA Times

There is, however, some good news. A concerted effort to control carbon emissions could make L.A.’s future less hot than it could be.

For instance, if a concerted effort were made to curb carbon emissions, downtown L.A. could see only 15 days of extreme heat by 2100, instead of 54 days if business goes on as usual.

And the San Gabriel Valley could see only 61 extreme heat days, instead of 117.

6.09.16

POSTED:

By David Downey, The Press-Enterprise
Whittier Daily News

The Godzilla of all El Niños is dead. And the big guy went out with a whimper, at least in Southern California.

On Thursday, the National Oceanic and Atmospheric Administration’s Climate Prediction Center declared the much-anticipated — and miserably disappointing — El Niño of 2015-16 history.

“There’s nothing left,” said Climate Prediction Center Deputy Director Mike Halpert. “Stick a fork in it, it’s done.”

It is the end, said Bill Patzert, a climate scientist at NASA’s Jet Propulsion Laboratory in Pasadena, for a dramatic weather show.

“This long-running El Niño had a fairly spectacular run on the world stage. It lasted for almost 15 months,” Patzert said. “And so the consensus now is, it’s time for the curtain call.”

The consensus at the outset was the event that has taken on mythical proportions and is driven by a pool of hot water in the equatorial Pacific would unleash torrential rains on Southern California and dent a stubborn drought. And while El Niño did deliver much rain to the Pacific Northwest and Northern California, it confounded experts by leaving the southern part of the state dry.

As a result, an unprecedented surge in flood-insurance buying turned out to be largely unnecessary in Southern California and the region’s water-producing lakes and underground aquifers continue to recede.

“People took action,” said Michael Glantz, a former senior scientist at the National Center for Atmospheric Research in Boulder, Colo. and operator of a website that shares information about global El Niño impacts. “People paid money taking action.”

And he said that was a result of hype about expectations.

“The problem probably started when they started calling it a ‘Godzilla’ El Niño,” Glantz said.

The label “Godzilla” was coined early on by Patzert, the colorful and quotable climate scientist at NASA. And it stuck. Pretty soon, it seemed, everyone was using the term — to the growing frustration of some in the forecasting business as storm after storm veered north.

“We actually asked NASA not to do that again,” said Alex Tardy, a warning coordination meteorologist for the National Weather Service in San Diego. “We’ve asked them nicely not to do it.”

Patzert said he’d “take the heat” for ridicule generated by the term.

“It was billed as the Great Wet Hope. And it wasn’t,” he said. “And I have to assume a little responsibility for that.”

But Patzert suggested others should share the blame.

“I’m sorry that I hurt their feelings,” he said. “But I was not the only one. Everybody, including the National Weather Service, was pretty optimistic — and exuberant — about getting a down payment on this huge drought.”

In any event, the focus is shifting toward preparing for the arrival of El Niño’s dry cousin, La Niña, which could prolong the drought, and solving the scientific puzzle of why this hot-ocean episode didn’t deliver — at least in Southern California.

If the now-dead El Niño delivered anything, it was questions. And experts plan to gather in San Diego in August to explore “what went wrong,” Tardy said.

He said a number of climate scientists are expected to publish detailed studies on the topic.

“Maybe there are a lot of flavors of El Niño that we weren’t aware of,” Tardy said.

For sure, said Glantz, this past winter and spring made clear there remains much that is not known.

“It’s time to take stock of what they really know and what they don’t know,” he said. “There’s a lot of research to be done.”

For now, Tardy said, experts believe the bypass of Southern California was due to where the pool of warmer-than-normal water was. He said the pool was 1,000 miles farther west than the one that generated the big El Niño in 1997-98 and dumped 30 inches of rain on Southern California.

“So we’re blaming it in on the position of the tropic ocean temperatures,” Tardy said.

It wasn’t, he said, because El Niño was wimpy. He said the pool was “massive,” the size of North America.

And at many places across the globe, it had a Godzilla-like impact, Patzert said, citing the flooding in Texas.

“Don’t tell the people in Texas that it was El No-Show,” he said.

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