By Andrew Freedman

Photo by Sandy Huffaker/Getty Images

In 2010, a series of strong storms linked to El Niño caused major flooding in Southern California.

If you thought the first six months of the year were chock full of weird weather events, just wait — according to climate scientists there is an increasing likelihood that El Niño conditions will soon develop in the tropical Pacific Ocean. El Niño events, which are characterized by an area of unusually warm sea surface temperatures in the tropical Pacific Ocean, can have a huge influence on global weather patterns. Its effects on the U.S. tend to peak during the winter.

The U.S. has already had a record warm January-to-June period, and has already had two extremely rare heat waves this year, one in March and the other in mid-June to early July. Entering mid-summer, drought conditions are covering 56 percent of the lower 48 states, a record drought extent in the 21st century.

Depending where you’re located, the prospect of a new El Niño event may be good news. The drought-parched Texas Panhandle, for example, tends to be wetter during El Niño years. It could also be decidedly unwelcome news — just ask residents of California who dealt with El Niño-related flooding in 2010.

El Niño is a natural source of climate variability, and typically occurs every three to seven years. The question of whether manmade global warming will influence El Niño cycles is an area of active research. One recent study does suggest, though, that global warming could intensify the effects of an El Niño episode, even if it doesn’t influence its occurrence.

NOAA

During El Niño, the sea surface temperature in the Pacific Ocean is warmer than normal.

Citing factors such as warming ocean temperatures in the tropical Pacific, the Climate Prediction Center, which is part of the U.S. National Oceanic and Atmospheric Administration (NOAA), said on July 5 that there is a better than 50 percent chance that El Niño conditions will develop sometime between July and September.

Because of El Niño’s effects on seasonal climate conditions, farmers and ranchers, ski area operators, water planners, hurricane forecasters, and many more closely monitor such El Niño forecasts.

Tony Barnston, chief forecaster for the International Research Institute for Climate and Society, which works with the Climate Prediction Center, said an El Niño event could help relieve the ongoing drought conditions in some areas, but potentially worsen the drought for others.

“The southern tier of U.S. states tends to have above-normal precipitation during winter when there is an El Niño. So this would be helpful for the droughts currently lingering in Texas/New Mexico, and Georgia/Alabama,” he said in an email conversation. “It would not help the ones in Kentucky/Indiana though, and could cause a new one in the northern Rockies.”

El Niño events can also help boost global average surface temperatures. A strong El Niño event led to the record warm year of 1998, and some climate scientists, including NASA’s James Hansen, have pointed out that a new El Niño event would likely lead to another record warm year given the combination of El Niño and manmade global warming.

NOAA

Sea surface temperature index in the tropical Pacific Ocean, showing the cycle of El Niño events (warmer than average) and La Niña events (cooler than average).

A strong, two-year La Niña event, which was characterized by cooler-than-average sea surface temperatures in the tropical Pacific, dissipated in April of this year, and it held down global average temperatures somewhat.

This El Niño event, if it does occur, is more likely to be on the weak-to-moderate end of the spectrum, according to Barnston.

One of the key indicators that El Niño conditions are developing is a growing area of warmer-than-average equatorial Pacific sea surface temperatures, and an increase in the oceanic heat content as well. “The observations . . . reflect a likely progression towards El Niño,” the Climate Prediction Center said.

Forecasters use computer models to help anticipate El Niño and La Niña events. Right now, most of the simulations of air and sea conditions show a developing El Niño.

According to Barnston, who is a veteran researcher and forecaster of El Niño events, there are many unknowns that forecasters are currently facing. “We don’t know, first, whether there will be an El Niño or not. Currently we think there is about a 60-70 percent chance for one, and a 30-40 percent [chance] of not having one,” he said. “If we do get one, we don’t know how strong it would be. We doubt it will be a giant one like 1997-98 because those usually develop by May or even earlier. But it could be moderate or weak. Most of us think it is likely to be in either of those two categories, and think that it would last from about August through January.”

The development of an El Niño or La Niña event depends on feedbacks between the ocean and atmosphere, and Barnston said that currently the prevailing weather pattern in the tropical Pacific is not particularly conducive to El Niño formation, despite the warming sea surface temperatures, but this could change. “We’re in a transition stage,” he said.

“The development of El Niño depends greatly on what happens in the coming two months. If we do not get at least some development by the end of August, then the chances of getting development later become much lower.”

A version of this post also appears at Climate Central, Climate Watch’s content partner.

Dr. Seuss, Bartholomew and the Oobleck (1949)

"And it's going to keep on falling," he shouted, "until your whole great marble palace tumbles down!"

From droughts and wildfires to tornadoes and hurricanes – and let’s not forget flooding, hail and that Halloween snowstorm — last year will go down as one of the most extreme weather years on record.

This week the National Oceanic and Atmospheric Administration (NOAA) released the final tally for 2011.

The two latest disasters to make the grim list are September’s Tropical Storm Lee which swept up the East Coast to cause record flooding and 21 deaths, and July’s severe weather that brought high winds, hail, and flooding to the Rocky Mountains and the Midwest, and took two lives.

Across the planet it was the 15th consecutive year of above-average temperatures. Here in the U.S., the portion of the nation in extreme drought or very wet conditions was the highest ever:  58%, and that’s nearly three times normal. No surprise that temperatures in Texas made for the second warmest year on record, with the drought there surpassing the severity of ones in the 1930s and 1960s.  Seven states across the Midwest and Northeast had their wettest years ever.

Even effects from the El Nino Southern Oscilliation (ENSO) — and it’s current, opposite La Nina phase — are changing, according to NOAA; both El Nino and La Nina years are tending to be warmer. The 2011 global surface temps during this La Nina were, “as warm as anything we’ve seen in the past,” said Thomas Karl, director of the agency’s subcommittee on Global Change Research.

The global La Nina/El Nino graph shows a steep rise in temps since 1990 and last year, the phenomenon was responsible for the warmest summers recorded in Norway and Spain, the second warmest for the UK. “The extreme conditions witnessed in 2011 are consistent with trends driven by global warming,” Karl said. Of course, no single year’s data necessarily links to long-term climate changes, but scientists say last year’s weather roller coaster is consistent with what they expect from global climate change.

Over the next three months, NOAA expects temps in California to be close to normal, slightly cooler north of the Golden Gate, and precipitation will be slightly below normal south of San Francisco.  Still sunny in here in L.A.  Send (some) rain.  Not too much.

You can find all the hard numbers and graphs on the NOAA website.

Precipitation outlook for winter 2011-12, showing the likelihood of below average precipitation in Texas and other drought-stricken states.

Does this mean Texas is toast?

By Michael D. Lemonick

As most Californians know, El Niño is a periodic unusual warming of the surface water in the eastern and central tropical Pacific Ocean. Actually, that’s pretty much a lie. Most people don’t know the definition of El Niño or its mirror image, La Niña, and truthfully, most people don’t much care.

What you do care about if you’re a Texan suffering through the worst one-year drought on record, or a New Yorker who had to dig out from massive snowstorms last winter (tied in part to La Niña), or a Californian who has ever had to deal with the torrential rains that trigger catastrophic mudslides (linked to El Niño), is that these natural climate cycles can elevate the odds of natural disasters where you live.

At the moment, we’re now entering the second year of the La Niña part of the cycle. La Niña is one key reason why the Southwest was so dry last winter and through the spring and summer, and since La Niña is projected to continue through the coming winter, Texas and nearby states aren’t likely to get much relief.

But Niñas and Niños (the broader cycle, for you weather/climate geeks, is known as the “El Niño-Southern Oscillation,” or “ENSO”) don’t just operate in isolation. They’re part of the broader climate system, which means that climate change could theoretically change how they operate — make them develop more frequently, for example, or less frequently, or be more or less pronounced. Climate change could also intensify the effects of El Niño and La Niña events.

Climate scientists have been wrestling with the first question for a while now, and they still don’t really have a definitive answer. Some climate models have suggested that global warming has already begun to cause subtle changes in ENSO cycles, and that the changes will become more pronounced later this century. But a new study, published in the Journal of Climate, doesn’t find much evidence for that.

But on the second question, the new study is a lot more definitive. “Due to a warmer and moister atmosphere,” said co-author Baylor Fox-Kemper, of the University of Colorado in a press release, “the impacts of El Niño are changing even though El Niño itself doesn’t change.”

That’s because global warming has begun to change the playing field on which El Niño and La Niña operate, just as it’s changing the background conditions that give rise to our everyday weather. The Texas drought is a prime example. It’s most likely cause is reduced rainfall from La Niña-related weather patterns. But however dry Texas and Oklahoma might have been otherwise, the killer heat wave that plagued the region this past summer — the sort of heat wave global warming is already making more commonplace — baked much of the remaining moisture out of both the soil and vegetation. No wonder large parts of the Lone Star State have gone up in smoke.

A map of sea surface temperature anomalies, showing a swath of cooler than average waters in the central and eastern tropical Pacific Ocean - a telltale sign La Niña conditions.

When the next El Niño occurs in a year or two, it will probably bring heavy rains to places like Southern California, whose unstable hillsides tend to slide when soggy. Except now, thanks to global warming, the typical El Niño-related storms that roll in off the Pacific may well be turbocharged, since a warmer atmosphere can hold more water. This is the reason, say many climate scientists, that downpours have become heavier in recent decades across broad geographical areas.

La Niña, plus the added moisture in the air from global warming, have also been partially implicated in the massive snowstorms that struck the Northeast and Mid-Atlantic states during the last two winters. Those could get worse as well, suggests the new analysis. “What we see,” says Fox-Kemper, “is that certain atmospheric patterns, such as the blocking high pressure south of Alaska typical of La Niña winters, strengthen…so, the cooling of North America expected in a La Niña winter would be stronger in future climates.” So to pre-answer the question that will inevitably be asked next winter: no, more snow does NOT contradict the idea that the planet is warming. Quite the contrary.

Finally, for those who really do want to know what El Niño and La Niña actually are, as opposed to what they do, you can go to NOAA’s El Niño page. But be warned: there will be a quiz, and the word “thermocline” will appear.

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

By Andrew Freedman

California’s freakishly cool summer has been bucking a global trend this season. You’ve seen the headlines from Moscow and Pakistan–but that’s just part of the story. 2010 has featured several extreme heat events, as well as record flooding, in many countries worldwide. The number of countries that have set new national records for the warmest temperature recorded — 17 — would beat the old record of 14, provided that all of the new records are verified by meteorological agencies. According to meteorologist Jeff Masters of the private weather forecasting firm Weather Underground in Ann Arbor, Michigan, the countries that have set new records thus far this year comprise about 19 percent of the earth’s surface area.

This graphic shows the new record-high temperatures for the 17 nations that have broken their national records so far in 2010. If verified, the record set in Pakistan would also stand as the warmest temperature ever recorded in the continent of Asia. Click on the graphic for a larger version. (Graphic: Russell Freedman).

Masters wrote on his blog: “This is the largest area of Earth’s surface to experience all-time record high temperatures in any single year in the historical record. Looking back at the past decade, which was the hottest decade in the historical record, 75 countries set extreme hottest temperature records (33% of all countries.) For comparison, fifteen countries set extreme coldest temperature records over the past ten years (six percent of all countries).” According to Masters, Guinea, which is located in northwestern Africa, is the one nation so far this year to break its coldest temperature record, which occurred in early January.

The new record high temperature set in Belarus occurred during the Russian heat wave, which is still gripping portions of that country. Although Russia did not set any all-time record high temperatures, Moscow did, breaking 100 degrees Fahrenheit for the first time since records have been kept.

Temperature departures from average for July 2010, as measured by NASA. Note the warmth (in red) centered over western Russia. (Map: NASA Goddard Institute for Space Studies)

For the planet as a whole, 2010 has been extremely warm, with the June-to-July period ranking as the warmest on record for those two months combined.

Part of the warmth earlier this year may have been due to an El Nino event in the Pacific Ocean, which tends to warm the planet, but that event is no longer taking place. According to scientists, including Climate Central’s Claudia Tebaldi, man-made global warming is likely also playing a role in the record heat. Tebaldi and others have published studies showing that as the planet warms due to increasing concentrations of greenhouse gases, warm temperature extremes become more likely to occur.

With the Flatiron Mountains as a backdrop, architect I. M. Pei used the Mesa Verde cliff dwellings as inspiration for the NCAR headquarters building, in Boulder. Photo: Craig Miller

While NCAR works closely with NOAA (which also has a major research center in town), it is not part of it. NCAR is funded by the National Science Foundation and managed by something called the University Corporation for Atmospheric Research (UCAR), a consortium of about 75 North American universities, as well as major institutions abroad.

About 400 scientists work under the NCAR umbrella, including Kevin Trenberth, a leading authority on the link between El Nino and global climate. Right before hopping a plane for Australia this week, Trenberth, head of NCAR’s Climate Analysis Section, reaffirmed what NOAA and others have been saying; that we may be in for a significant El Nino event this fall and winter.

“There are good signs below the surface of the ocean in the tropical Pacific that this is the real deal,” said Trenberth. He echoed some of the optimism expressed by many Californians that the result could be an overdue dousing after three years of accumulating drought conditions. “The odds are, if it’s a good El Nino,” said Trenberth, “that there is more likelihood of a southerly storm track that’ll bring a lot of weather systems into southern California in particular. It’s not always clear what happens in northern California but the odds are that there’s a much more active southern storm track right across the U.S. and in particular in California.”

The IBM Bluefire 76-teraflop computer, centerpiece of NCAR's supercomputing center. Photo: Craig Miller

NCAR scientists continue to refine their climate models, which have been downloaded by more than 10,000 scientists around the world. UCAR invests $20-to-$30 million every four years in it’s Computational & Information Systems Lab (CISL), to maintain it’s state-of-the-art status. CISL chief Rich Loft says it’s probably the most advanced supercomputing center devoted largely to climate analysis.

Even so, NCAR is busy building a bigger, faster one–but not here. The new supercomputer, which may be ready by 2012, will be sited near Cheyenne, Wyoming, mostly to take advantage of the cheap, abundant electric power in that area. Loft and NCAR Director Eric Barron both concede the paradox that the most advanced computer assault on global warming is itself a huge gobbler of electricity, much of which comes from coal-fired power plants. The Wyoming facility will suck down 4.5 megawatts of power. Barron says at least there’s a major wind farm “right next door.”

The center’s carbon footprint is probably also swollen slightly by its own air force. NCAR operates two aircraft packed with advanced instrumentation; a hulking C-130 Hercules and a sleek, high-altitude Gulfstream V. Sadly, no rides were offered this week.

Warm water patterns in the Pacific during normal (upper) and El Nino (lower) years. The lower image is from 1995-96. Image from NASA

Scientists with the National Oceanic and Atmospheric Administration today confirmed what many had pretty much surmised: El Nino is back.

Officially the El Nino Southern Oscillation (ENSO), the cyclical pattern of ocean conditions has broad implications for weather and the Pacific food chain.

According to the NOAA news release:

“NOAA expects this El Niño to continue developing during the next several months, with further strengthening possible. The event is expected to last through winter 2009-10.”

NOAA’s Climate Prediction Center suggested about a month ago that conditions were right for the return of El Nino.

More recently, the high incidence of underweight sea lion pups turning up along the California coast was taken by some as a harbinger of ENSO. During El Nino cycles, normal upwelling of deep, cold water slows down, essentially shutting down the “food elevator” for many species.

Of course, there can be an upside. According to NOAA:

“El Niño’s impacts depend on a variety of factors, such as intensity and extent of ocean warming, and the time of year. Contrary to popular belief, not all effects are negative. On the positive side, El Niño can help to suppress Atlantic hurricane activity. In the United States, it typically brings beneficial winter precipitation to the arid Southwest, less wintry weather across the North, and a reduced risk of Florida wildfires.”

Links to climate change are less clear. Some scientists have suggested that warming air and sea temperatures might bring about more and longer El Nino events.

Photos by Victoria Carpenter

I thought the highlight of my trip to Point Reyes last week would be the cows grazing on spectacular cliffs covered with yellow lupine. I was visiting a historic dairy there for an upcoming story on crashing milk prices.

But then I noticed a white van marked “rescue” driving down to a dock near the Pt. Reyes lighthouse, and decided to follow it. Turns out, I stumbled upon an incredible scene: rescue workers releasing baby sea lions and elephant seal pups back into the waves.

Volunteers lugged what looked like over-sized pet carriers out of the van and slid them onto a cement boat dock. Then a trio of sea lion pups poked their heads out, sniffed the salt air, and flippered their way across the cement and into the water, playfully nuzzling each other.

They seemed exhilarated–but thin. These pups had been rescued near Monterey, revived in the Marine Mammal Center’s Sausalito hospital, and were now healthy enough to return to the ocean, though you could still see their rib cages poking through their fur.

The sea lions swam out quickly but the elephant seals were a little more sluggish. One pup kept swimming back toward the humans, begging for fish. Then a giant female came out of the waves, perhaps offering herself as an adoptive mom, nudging the baby into the water.

Jim Oswald of the Marine Mammal Center (MMC) says the staff is seeing an unprecedented spike in rescue calls. In just the first two weeks of June, nearly 1,300 people phoned in, worried about stranded sea lions and other mammals. Most of them are malnourished sea lions who can’t seem to find enough anchovies, herring, or sardines to snack on.

Researchers aren’t quite sure why–but haven’t ruled out some kind of climate connection. The MMC is reporting its findings to the National Oceanic and Atmospheric Administration (NOAA) to try and figure out the cause. Possible El Nino Conditions? Warming oceans sending schools of smaller fish northwards? No one quite knows at this point.

“If it’s a climate change variable, that’s going to affect the fish the animals feed on,” says NOAA Wildlife Biologist  Joe Cordaro. “That could be a very long temporary shift in the bait fish distribution, or it could be long-term depending on how severely climate change affects the surface temperature of the ocean.”

But Cordaro says at this point, the sea lion strandings are “one big puzzle,” with climate change as just one possible factor. We could simply be witnessing a high-birth year for sea lions, with  a lot more pups than usual, or early signs of a returning El Nino weather pattern. Meteorologists won’t know until the fall whether California actually meets the criteria for a strong El Nino year. If so, Cordaro predicts “things are going to get a lot worse for the sea lions this fall and next spring.”

[Editor's Note: The case for a return to El Nino was advanced on Wednesday, when the Australian Bureau of Meteorology reported that indications are almost certain at this point]

Regardless of the cause, the MMC’s Oswald says it’s cause for concern.

“These young sea lion pups get to the point where they’re so weak, they end up on the land and they’re too weak to go back,” Oswald explains. “It’s easier for them to waddle along, hoping they’ll find another waterway where they can find some food. They’re using up all their reserves if they stay out in the ocean.”

Stranded sea lion pups have even turned up on Bay Area freeways. Last week, rescuers found one on the 880 freeway in Oakland.

“His name is Fruitvale,” reports Oswald, “for the district in Oakland he was rescued from. He seems to be doing okay. He’s still being tube fed. I’m told from veterinarians that he’s feisty, moving around, and nippy, which is a good sign.”

The Marine Mammal Center’s Sausalito headquarters lets visitors watch volunteers in action. There’s an interactive exhibit with a sea lion on a gurney, where you can see its x-rays and test results. You can watch volunteers prepare fish meal, or even witness a post-mortem in the necropsy room.

Sounds grim, but until sea lion pups start finding more fish to eat–and humans start to figure out what’s causing the food chain to collapse, the Marine Mammal Rescue Squad plans on a very busy summer.

Sasha Khokha is chief of KQED’s Central Valley Bureau and a frequent contributor to Climate Watch.

And for more about the Marine Mammal Center’s sea lion rescue efforts, listen to Amy Standen’s recent radio report on KQED’s Quest. You can also view her slideshow and read her Reporter’s Notes on the Quest blog.

2006 El Nino conditions, as observed by the Jason satellite. Photo: NASA

The ocean conditions formally known as ENSO, or the El Nino/Southern Oscillation, arise when normal upwelling of deep, cold water abates, causing warmer surface temperatures (SST).

El Nino and its opposite, La Nina, have far-reaching implications on weather patterns. Here on the West Coast, it usually means wetter winters in southern California and drier ones in the Pacific Northwest.  Because northern and central California lie in between, things there can go either way.

El Nino can also have a significant impact on fisheries, as much of the food chain is interrupted when upwelling slows.

Here’s a good overview of El Nino “mechanics” from UC Berkeley.

With a global average surface temperature of 79 degrees Fahrenheit, 2008 was the coolest year since 2000, according to climatologists at the NASA Goddard Institute for Space Studies (GISS). But it’s also the ninth-warmest year since 1880, so it’s probably not time to invest in a ski resort just yet.

Including the 2008 dip, the 10 warmest years on record (since 1880) have all occurred between 1997 and 2008, according to NASA.

The NASA scientists attribute 2008′s relatively lower temperature to a cooler Pacific Ocean, due to a strong La Nina pattern in the first half of 2008. La Nina and El Nino are opposite phases of a natural oscillation of  upwelling and subsequent temperatures in the equatorial Pacific Ocean.

2008 temperatures in the United States were cooler than any other year this decade, but, as illustrated on the map below, other parts of the world such as Eurasia and the Arctic were exceptionally warm.

Director of GISS James Hansen predicts that because a shift to El Nino is expected to start this year or next, it “still seems likely” that we’ll see a new record high for the average global surface air temperature in that time frame.

The short version: It’s bleak.

As I noted last week, Lake Oroville, a key reservoir on the Feather River, stood at 31% of capacity as of midnight on September 30. Readings from the same hour showed the state’s largest reservoir, Shasta Lake, at 30%; Folsom Lake (American River, east of Sacramento) at 28%; and San Luis Reservoir, east of Silicon Valley at 12–yes, twelve percent of capacity.

Capacity figures by themselves can be misleading. We expect reservoirs to be low this time of year, right at the end of the dry season. But as DWR was taking these readings, Oroville, to use one example, was at 49%–less than half–of “normal” for this time of year.

So, much depends on the coming winter. Even with all the advanced tools that forecasters have at their disposal in this first decade of the 21st Century, it’s hard to say how much water we’ll wring out of the skies this winter. Lynn says we’re in a “La Nada” pattern, meaning the Pacific Ocean isn’t giving a strong signal for either El Nino or its opposite, La Nina. The two conditions describe the degree–or lack–of cold water upwelling from the ocean depths, which has a strong influence on California’s precipitation patterns.

But Lynn says the consensus among forecasters is “leaning toward a dry-to-average” winter and average won’t get us there. We’ll need several soggy months to make up for lost water and avoid more severe water restrictions throughout the state next summer.