Craig Miller

The new normal? A temperature display in the Kern County town of Taft shows 105 degrees on a late afternoon in July.

Granted, it’s been a relatively cool summer in many parts of California. But state officials are saying, “Don’t get used to it.” How would you like to see the number of “extremely hot” days (105 or hotter) in Sacramento increase fivefold in the next few decades? That’s just one of many new projections from the state’s latest official climate assessment.

One hundred-twenty scientists worked on the report, entitled California’s Changing Climate (PDF). Funded by the California Energy Commission, it’s actually a portfolio of studies and contains some of the most specific warnings we’ve seen. For instance, it projects that going forward, average temperatures in the state will warm at three times last century’s pace. It’ll mean heat waves happening more often and lasting longer.

And there’s new evidence from a refined set of models that the state will be drying out. “By mid-century, already we’re seeing a drying trend which could be up to ten percent drier by the end of the century, says Susanne Moser, identified as the principal researcher for the report, “and that is significant for a lot of people.” Especially if you live in say, the San Joaquin Valley, where the report projects that the frequency of “dry years” could increase by about a third in the “latter half of this century,” compared to the late 20th century.

And authors expect the weird weather to get worse, projecting that as soon as 2050, what’s now considered a 100-year storm could become ‘an annual event.”

State officials nearly fell over each other to say that it’s not too late to blunt some of the worst effects, however, with astute planning and aggressive action to reduce global warming emissions. Ken Alex, who heads Governor Jerry Brown’s Office of Planning & Research, characterized the mounting climate threats as, “a series of plagues,” but added that, “we’re not helpless. We need to adapt and we need to understand what that adaptation requires.”

Some interesting numbers from the study:

• 1.7: increase in statewide average temp from 1895 to 2011, in degrees Fahrenheit
• 2.7: likely increase by 2050, compared to 2000
• 20: Number of days per year that the temp could reach 105 in Sacramento by 2050 (versus four, historically)
• 10-18: Likely range of additional sea rise along California by 2050 (v. 2000)
• 23: Number of San Francisco fire stations that would likely be inaccessible with 16 inches of additional sea rise (considered likely by 2050)

CA Climate Change Center

Scientists say how much temperatures eventually rise will depend on the pace of continued global warming emissions.

The study suggests that temperatures will rise more in the summer and inland, with springtime warming “particularly pronounced” and fewer cold nights. Farmers depend on chilly nights to produce some high-value crops, such as stone fruits. Officials at the Energy Commission expressed concern about potential impacts that rising temperatures will have on the state’s power grid, some of which we addressed in a previous post.

As for reducing emissions enough to make a tangible difference, Moser concedes that’s not a job that California can do alone. But she said this report is the first to target findings to the kinds of questions that officials and planners have been asking (like the aforementioned matter of how many triple-digit days they can expect–and how soon).

Getty Images

Some science teachers face opposition from students, parents and even administrators when they teach basic climate science.

As the climate change debate creeps into classrooms across the country, an Oakland non-profit vows to stem the tide of climate denial in California. They also plan to conduct a comprehensive review of science textbooks to help teachers separate the sound from the shaky in climate science.

The Oakland-based National Center for Science Education (NCSE) has announced that it will now offer support to teachers facing resistance to climate science in the classroom, similar to their long-standing work to keep the instruction of evolution in schools. “We’ve already had a couple of calls along the lines of, ‘I know you guys do evolution, but I’ve got this problem with [teaching] climate change and do you have any suggestions for me,’” said Dr. Eugenie Scott, executive director of NSCE.

Scott says parents often argue that schools should teach both sides of a controversial scientific issue. But she doesn’t consider the fundamental conclusions of climate science to be controversial. “The idea that scientific topics that are well grounded in basic science, like evolution or climate change, should be balanced, or that all views should be taught, is not one that is very scientifically or pedagogically supportable,” said Scott. She readily agrees that many of the details of climate science are debated between scientists, such as differing approaches to modeling climate change. However, she maintains that “the science community is pretty uniform in its acceptance of the fact that the planet is getting warmer.” Nevertheless, Scott said skepticism toward climate science has gained traction with the general public, so legislators and some school boards are starting to demand that science curricula provide room for doubt.

The Center’s approach to dealing with these issues has always been local. “We provide information to people in communities,” Scott emphasized. “We get local people to appear at school board meetings because all politics is local and this is politics.” The Center’s staff isn’t nearly big enough to fly around the country defending climate science in 1,500 school districts. So it provides support to teachers who ask for it. “Teachers in general are conflict-averse; they just want to do their jobs,” explained Scott. Unfortunately that means that it is often easier for a teacher to avoid the issue completely than to stand up for the climate science.

California is not immune. The Center in Oakland has documented at least two cases of climate change flare-ups in California classrooms. When an Advanced Placement environmental science class was introduced in Los Alamitos, a small city in Orange County, the school board ruled that global warming should be taught as a “controversial subject,” meaning that the teacher should present both sides of the controversy to students. And, in Portola Valley, a stone’s throw from Stanford University, a parent demanded a debate between a climate scientist and a climate denier after learning that the teacher had shown Al Gore’s documentary An Inconvenient Truth in class.

One of the biggest challenges to NCSE’s new initiative will be the distinctly political nature of the climate change debate. In their battles to allow science teachers to instruct on evolution, NCSE always leaned on the First Amendment and its directive to separate church and state as a backstop to its argument. “There is no constitutional amendment supporting good science,” sighed Scott. “We merely have to try to persuade people to try to do what’s best.” Largely that persuasion has focused on moving the “controversy” part of the topic into the social science sphere, where policy is debated, and leaving the science alone.

USGS

Suisun Slough in the lower Sacramento Delta. Twenty-five million Californians depend on the Delta for at least some of their water.

“Today’s extremes could become tomorrow’s norms”

That’s the upshot of an ambitious study by the US Geological Survey, which would appear to affirm some dire predictions for California’s most important water system.

The study, authored by nearly a dozen scientists, is billed as “the first integrated assessment of how the Bay-Delta system will respond to climate change.” It’s presented as a “flash forward” to what California’s Sacramento-SanJoaquin Delta could become by the end of this century. It ran a series of nine indicators through multiple models to project trends in temperature, precipitation, salinity, runoff and sea level rise.

The result: Pretty much what climate scientists have been saying; that we’ll see “potentially longer dry seasons,” a shrinking Sierra snow pack and “earlier snowmelt leaving less water for runoff in the summer.”

“Our biggest reservoir in the state is our snowpack,” said Greg Zlotnick, who chairs the groundwater committee for the Association of California Water Agencies. “We’re going to get less snow, more rain, it’s going to run off more quickly, and that water will not be there late in the year.” Unfortunately, late in the year is when farms need it most for irrigation. Zlotnick says peak runoff has already shifted by about a month earlier in the season.

The study also tries to assess impacts from rising sea levels and increasing intrusion of salt water farther inland, and warned that “increased intensity and frequency of winter flooding could also occur as a result of earlier snowmelt and a shift from snow to rain.”

In a statement issued with the report, USGS Director Marcia McNutt called “protection” of California’s Bay-Delta system “a top priority for maintaining the state’s agricultural economy, water security to tens of millions of users, and essential habitat to a valuable ecosystem.”

Authors of the study ran their models under both rapid-and-moderate-warming scenarios developed by the UN’s climate panel. These yielded some differences in the outcomes. The authors write that those and other uncertainties in the process make it challenging for planners to respond to their projections. In their article for the open-access journal PLoS One, the researchers write that planners and risk managers “should anticipate shifts into regimes of environmental conditions unprecedented in the period of our social and economic development.”

In other words, the next 90 years will take us into pretty much unexplored territory.

A new study finds large losses of springtime snow cover in the West in recent years, raising concerns about water supplies.

Spring snowpack in the West is an essential water resource, particularly in Southwestern states that are prone to summer drought, like California, Nevada, Arizona and New Mexico. (Credit: Wolfgang Staudt on Flickr)

Head south across the 40^th parallel, however, and things are dramatically different. While there is still above average snow throughout the Sierra, a relatively snow-less winter and spring has left much of the Southwest in a drought that has fostered record wildfires. Already local officials are worried there won’t be enough water to get through the summer months ahead.

This kind of contrast for the western spring snowpack is not unusual, though. It’s completely normal, and it’s exactly what climate scientists and meteorologists expect during years when the average weather pattern is influenced by La Niña, a climate cycle associated with cooler than average water temperatures in the tropical Pacific Ocean.

But while this north-south dichotomy turns out to be a regular feature of western climate, new research published today in the journal Science shows that, when compared to typical snowfall during the past 1,000 years, snowpack patterns appear to be changing as average temperatures climb. Scientists say that as temperatures continue to rise, this reduced snowpack will lead to more frequent water shortages in increasingly thirsty western states.

“We’re talking about simultaneous snowpack decline in the western watershed that supports 70 million people,” says U.S. Geological Survey (USGS) climatologist Julio Betancourt, who co-authored the new study. “We have to be concerned.”

For several years, scientists have observed that spring snowpack all across the West — in both northern and southern areas — has been decreasing. But now, Betancourt and a group of other climate scientists have found that the recent decline is a departure from patterns of the past 1,000 years. As part of the study published in Science, USGS ecologist Greg Pederson investigated tree ring data to learn how snowpack in the West, on either side of 40^th parallel, changed from year-to-year and from decade-to-decade. Looking back over nearly a millennium, he found that when the north had high snowpack, the south typically experienced low snowpack, and vice versa.

But Pederson and Betancourt noticed a change starting in the mid-1980’s. On average, the amount of snow on the ground at the beginning of April each year was decreasing everywhere across the West. It’s a trend that other scientists studying snowpack have pointed out. This has important consequences for water supplies for drinking water and agriculture, since many areas, including much of interior California, are dependent upon spring runoff for much of their water supplies.

Betancourt says that as average spring temperatures have risen, the snowpack has begun to melt earlier in the year (not the case this year, with record cold weather locking in substantial amounts of snow in many western ranges). Moreover, he says that in many places, the warmer temperatures mean that precipitation falls more as rain than as snow. So while the actual amount of precipitation hasn’t changed dramatically, the amount of rain has.

Snowpack in much of the West remains well above average, thanks to a cold and snowy winter and spring. In the Southwest, however, snowpack was well below average. (Image: NRCS)

“Snowpack is the water resources of the West,” says Greg McCabe, a USGS hydrology expert who was not directly involved in the new study, “and temperature has a dominant impact on the snowpack.” If warming temperatures in the West cause the snowpack to decrease even more, McCabe says, or if the timing of the melt each spring changes, then summer water shortages could happen a lot more often.

McCabe says the research provides valuable evidence about how snowpack has changed historically, and also how unusual the recent patterns appear to be.

According to Pederson and Betancourt’s findings, the way snowpack has changed in the past 30 years isn’t entirely unprecedented. There were two brief periods in the mid-1300’s and early 1400’s where there was less snow built up throughout the West.

“At both those other times in the past, we know it was warm then too,” explains Betancourt.

Now, however, climate scientists are predicting that average temperatures in the West are going to keep rising this century, due in large part to the buildup of greenhouse gases in the atmosphere. Compared to the past, when snowfall returned to normal as temperatures dropped, researchers now expect that warmer spring weather could keep spring snowpack on the decline for years to come.

“What’s happening in the spring for snow is critically important [for water availability] compared to what is happening in the dead of winter,” says Betancourt.

So what do the authors make of a year like this, which has brought frequent snowfall to the Sierra, even into June?

“There isn’t anything that has happened this year that isn’t consistent with what our new findings are,” says Pederson. Even as average temperatures increase in the coming years, there will still be cool years where above average snowpack builds up in parts of the West, particularly during La Niña years. “But these years will tend to be weather noise over top of the larger climate changes we will see over many years,” he says.

NPR’s Richard Harris interviews Pederson in this story for Morning Edition.

A version of this post also appears at Climate Central, a content partner of KQED Climate Watch.