August 2023 #ElNiño update: back to school — NOAA #ENSO

Click the link to read the article on the NOAA website (Emily Becker):


It’s that time again! And by “that time,” I mean the El Niño forecast update, of course. The chance that El Niño—the warm phase of the El Niño Southern Oscillation (aka “ENSO”) climate pattern—will continue through the winter is greater than 95%, so let’s sharpen our pencils and get into the details of what that means for upcoming seasons.


Greater than 95% is a very strong chance! Forecasters’ confidence that El Niño will continue is based on a few factors. First, the east-central tropical Pacific is quite warm. Specifically, our primary El Niño-monitoring metric, the Niño-3.4 Index—the average sea surface temperature in the Niño-3.4 region in the east-central tropical Pacific—was 1.0 °Celsius (about 2 °Fahrenheit) warmer than the long-term average in July, according to our most reliable dataset, ERSSTv5. (Long-term = 1991–2020.)

2-year history of sea surface temperatures in the Niño-3.4 region of the tropical Pacific for all events evolving into El Niño since 1950 (gray lines) and the current event (purple line). NOAA image based on a graph by Emily Becker and monthly Niño-3.4 index data from CPC using ERSSTv5.

The three-month-average Niño-3.4 Index, the Oceanic Niño Index, was 0.8 °C above the long-term mean for the May­–July average, the second three-month-period in a row above the El Niño threshold of 0.5 °C. We need to see five consecutive three-month averages above this threshold before these periods will be considered a historical “El Niño episode” and colored red in our ENSO record). Two is a good start, especially with the 0.8 °C recording from May­–July. If this El Niño were to collapse after hitting this high, dropping back below the threshold of this magnitude before next winter, it would be the first time in our historical record, dating back to 1950.

Social studies

El Niño is a coupled phenomenon, meaning the changes we see in the ocean surface temperature must be matched by changes in the atmospheric patterns above the tropical Pacific. The average atmospheric circulation over the tropical Pacific, the Walker circulation, is like a conveyor belt: rising air over the very warm far western Pacific, west-to-east winds high up in the atmosphere, descending air and dry conditions over the east-central Pacific, and returning east-to-west winds near the surface—the trade winds.

Generalized Walker Circulation (December-February) during ENSO-neutral conditions. Convection associated with rising branches of the Walker Circulation is found over the Maritime continent, northern South America, and eastern Africa. NOAA drawing by Fiona Martin.

During El Niño, the warmer east-central tropical Pacific Ocean surface leads to lower surface air pressure and more rising air, clouds, and rain over that region, weakening the overall circulation. The trade winds slow, and drier conditions and higher-than-average air pressure are observed over the western Pacific and Indonesia. The ocean-atmosphere coupling is both how El Niño perpetuates itself, as the atmospheric changes feed back into the oceanic changes, and how El Niño affects global weather and climate.

Generalized Walker Circulation (December-February) anomaly during El Niño events, overlaid on map of average sea surface temperature anomalies. Anomalous ocean warming in the central and eastern Pacific (orange) help to shift a rising branch of the Walker Circulation to east of 180°, while sinking branches shift to over the Maritime continent and northern South America. NOAA drawing by Fiona Martin.

In July, we observed more rain and clouds over the central Pacific, with somewhat drier conditions in Indonesia, and some reduced trade wind activity in the western Pacific. The Equatorial Southern Oscillation Index, which measures the relationship between surface air pressure across the Pacific, was -0.9 in July, indicating weaker pressure in the eastern Pacific and higher in the western. Taken together, these are all signs of the atmospheric component of El Niño, providing more confidence that the system is engaged and that these conditions will last through the winter.

Computer science

Our global climate models are predicting that the warmer-than-average Pacific ocean conditions will not only last through the winter, but continue to increase. There is a good chance—approximately 2 in 3—that the peak Oceanic Niño Index this winter will match or exceed 1.5 °C, our informal threshold for a “strong” El Niño event. This is more confident than last month, in large part because the peak of this El Niño is one month closer, and, as I mentioned above, the surface is already 1.0 °C warmer than average.

Animation of maps of sea surface temperatures in the Pacific Ocean compared to the long-term average over five-day periods from the end of May to early August 2023. The waters in the key monitoring region, which scientists call “the Niño-3.4 region,” progressively become warmer than average (red) as El Niño builds. NOAA, based on Coral Reef Watch maps available from NOAA View.

The sea surface temperature changes associated with El Niño events usually peak in November–January or thereabouts. Why? We still don’t know exactly why ENSO’s seasonal cycle is timed the way it is, with most events peaking in the winter and decaying through the spring. There is still a lot to learn!


El Niño’s most extensive impacts on global climate also occur during the winter and early spring. (I’m using Northern Hemisphere seasonal terms here.) Typical impacts include more rain and storms across the southern tier of the United States, southeastern South America, around the horn of Africa, and eastern Asia. Drier conditions are often found in December–February during El Niño through the Maritime continent/Indonesia, southeastern Africa, and northeastern South America. El Niño affects summer (June–August) climate, too, including drier conditions through the Caribbean, Indonesia, India, northern South America, parts of Central America, and eastern Australia.

These maps show winter and summer global ENSO impacts.

El Niño is also known to interact with the Atlantic and Pacific hurricane seasons, with El Niño years tending to be less active in the Atlantic. In the hurricane season outlook released in May, NOAA scientists expected the potential suppressing effect of El Niño may be offset by the much warmer than average Atlantic Ocean surface, as warm water provides fuel for hurricanes. NOAA’s update to the outlook will be released later today, so be sure to keep an eye out for that!

Experimental psychology

Speaking of the warm Atlantic, you’ve probably heard about the recent unusually high global average temperatures. Some of the world’s oceans are extremely warm (North Atlantic, Southern Ocean, and so on), and there have been long-lasting heat waves across many land regions. El Niño is linked to higher global averages, although this El Niño is just getting going and can’t be blamed for all the heat events that have occurred already this year. (In fact, over North America, impacts tend to be very weak during the summer). There’s a good chance, though, that it will contribute to (at the very least) a top-3 average temperature for 2023. In a guest post in June, Karin Gleason discussed how NOAA predicts the global average temperature.

But what are the computer climate models predicting? Michael Tippett of Columbia University, noted friend-of-the-blog, took a look at some of the predictions from the North American Multi-Model Ensemble. These graphs are a lot, so bear with me!

Global average temperature forecasts from the North American Multi-Model Ensemble, from an original by Michael Tippett of Columbia University. Each panel shows the forecast from one model, relative to the “pre-industrial” period—that is, the increase in global average temperature since 1850. The black line shows the observed global temperature, from the Hadley Center’s HADCRUT5 temperature record. The gray lines are forecasts starting in April, May, June, July, and August from previous years, starting in 2013. The most recent forecasts, from April, May, June, July, and August of 2023, are on the right-hand end, in colors. For most models, the forecasts extend out 12 months—for example, the forecast made in June 2014 goes out to May 2015. These forecasts have the same structure as our Niño-3.4 forecasts, but instead of predicting the average sea surface temperature in the Niño-3.4 region, they’re predicting the average temperature over the entire globe. For help visualizing the separate forecasts, take a look at this animation showing Niño-3.4 forecasts from 2015–16. Figure by based on data from Michael Tippett, obtained from the IRI Data Library.

Each panel shows the global average temperature forecast from one model, relative to the “pre-industrial” period—that is, the increase in global average temperature since 1850. To see how the predictions vary from month-to-month, Mike has included forecasts made in April, May, June, July, and August of each year, starting in 2013. The most recent forecasts, from April, May, June, July, and August of 2023, are on the right-hand end, in colors.

The gray lines are forecasts from previous years. For most models, the forecasts extend out 12 months—for example, the forecast made in June 2014 goes out to May 2015. The black line shows the observed global temperature, from the Hadley Center’s HADCRUT5 temperature record. These forecasts have the same structure as our Niño-3.4 forecasts, but instead of predicting the average sea surface temperature in the Niño-3.4 region, they’re predicting the average temperature over the entire globe. (For help visualizing what I mean, take a look at this animation showing Niño-3.4 forecasts from 2015–16.)

The different models and the different monthly forecasts show that there is some variation in the predictions overall. Most models suggest that the global average temperature will substantially exceed that of early 2016, our last strong El Niño event, but not all of them. Month-to-month, the predicted average can shift around. You can also see that the 2016 record was pretty well predicted by the models. There are a lot of things to note in these graphs, but I’m running out of space here, so I leave you to your studies. What do you observe? Let us know in the comments!

Campaign against more #Colorado mountain freight trains advances in litigation and letters: #ClimateChange, other environmental risks spur opposition to proposed Uinta Basin Railway — Colorado Newsline #ActOnClimate #ColoradoRiver #COriver

Anglers fish on the Colorado River near an idle Union Pacific freight train in western Grand County on June 12, 2023. (Chase Woodruff/Colorado Newsline)

Click the link to read the article on the Colorado Newsline website (Chase Woodruff):

Elected officials in Glenwood Springs are quite certain of two realities facing the largest town between the Denver metro area and Grand Junction on Union Pacific’s Central Corridor rail line: Freight rail, especially for fossil fuels, is king. And climate change is an everyday reality.

“Glenwood Springs is the poster child for climate change,” said former Glenwood mayor and current City Council member Jonathan Godes, an outspoken opponent of the proposed Uinta Basin Railway oil-train project in Utah. “Something that contributes 53 million metric tons of carbon a year … is absolutely something that our community and every other mountain community in Colorado that relies on it not being 100 degrees every day in the summer or 50 degrees in the winter should be fighting on its face.”

But the fact that the new 88-mile railroad in northeast Utah would send up to five fully loaded, two-mile-long oil trains a day through Glenwood and Denver on their way to Gulf Coast refineries has prompted the Colorado River city of 10,300 in Garfield County to support Eagle County’s litigation opposing federal approval of the project, and, more recently, to fire off letters to federal officials opposing tax-exempt funding for the railway and a Utah loading facility expansion.

On Aug. 3, Glenwood Mayor Ingrid Wussow wrote U.S. Transportation Secretary Pete Buttigieg urging him to “deny issuing funding through tax-exempt Private Activity Bonds (PABs) to the Uinta Basin Railway Project. The approval of and funding for the Railway carries grave implications for both the environmental health and economic stability of Glenwood Springs and other communities along the Railway’s corridor.”

Wussow added she’ll be in Washington, D.C., Sept. 18 to 20, with a delegation from the city and requested a meeting with Buttigieg to discuss the oil train project, which would travel along the climate-change endangered Colorado River for approximately 100 miles. In a separate letter dated Aug. 7, Wussow wrote Greg Sheehan, Utah state director of the U.S. Bureau of Land Management to request a full environmental impact statement for an oil truck and rail loading facility on BLM land in Utah rather than a less-intensive environmental assessment.

“Glenwood Springs is a world destination for outdoor recreation and the home for irreplaceable natural wonders,” Wussow wrote. “Given the magnitude of the Railway project, these risks to the natural environment are significant.”

Godes can doom scroll through a long list of climate calamities in Glenwood Springs he says are directly attributable to the burning of fossil fuels, rising temperatures and increased aridification of Colorado. He points to the Storm King Fire in 1994 that killed 14 wildland firefighters, the Coal Seam Fire in 2002 that burned down 29 Glenwood structures, and the Grizzly Creek Fire in 2020 that scoured Glenwood Canyon and shut down Interstate 70 for two weeks. The following summer, a 500-year rain event hit the burn scar and dumped mud and rock on the highway and train tracks below, shutting down I-70 for another two weeks.

“So climate change, it’s not just, ‘It’s hot in America right now,’” Godes said. “Climate change is something that threatens us in Glenwood Springs on a year-in and year-out basis. It’s ever-present. It is where our insurance rates are determined. It is where we allow houses to be built. It is where streets are contemplated for escape routes.”

One might think the environmental benefits of trains — up to 75% lower greenhouse gas emissions than moving freight by truck, according to the rail industry — would ease some of Glenwood’s concerns, but Godes argues that depends on the freight. The Uinta Basin oil should stay in the ground to begin with, he argues, while also scoffing at the notion of enhanced passenger trains as a potential tourism-boon side effect of increased rail traffic overall. [ed. emphasis mine]

“My mom comes from Iowa every year on the California’s Zephyr,” Godes said of the daily Amtrak service through Glenwood to Chicago and San Francisco. “She gets on near Burlington, Iowa, and then she comes out here, and it’s always four or five hours late. And most of the time it’s because somewhere in Colorado, and most likely between Denver and here, there was a train with a higher priority, whether it was oil or coal or other materials or commodities.”

While there are specialty tourist trains such as the Denver-to-Moab, Utah, Rocky Mountaineer and the seasonal Denver-to-Winter Park Express ski train — a partnership with federally run Amtrak — talk of a daily Colorado Zephyr from Denver to Grand Junction and back has largely remained just talk. And the broader push for intercity Amtrak expansion under President “Amtrak Joe” Biden is focused on Front Range Passenger Rail.

In 2020, a billionaire New York real estate tycoon and owner of vast swaths of agricultural land in southeastern Colorado promised Pueblo-to-Minturn daily passenger service in his plan to revive the long-dormant Tennessee Pass rail line that connects to the Central Corridor at Dotsero, but he’s since pulled the plug on that concept.

“I’d love to have some kind of passenger rail like the California Zephyr be able to service the tourism industry to get tourists from the Front Range to Vail, from Pueblo, Colorado Springs, over Tennessee Pass,” Godes said. “That’s all fine and dandy. It’s a really nice, fun idea that could be helpful to our tourist economy. But if it comes with the risk of opening the door, even a crack, to regular freight rail on the Tennessee line, I think that is going to be incredibly — and it doesn’t affect me because we get that freight rail through Glenwood no matter what — but I think that is incredibly problematic for Eagle County, Chaffee County, for all the communities on that line.”

Fears about derailments

Eagle County Commissioner Kathy Chandler-Henry, whose government is the lead litigant in efforts to block the Uinta Basin project from sending oil trains through a corner of the county, was initially open to passenger rail but very leery of freight returning to the Tennessee Pass tracks along the Eagle River, which bisects the county before flowing into the Colorado River.

“If there’s going to be cargo trains and no passengers, then all we have is the impacts of noise and train crossings to deal with again,” Chandler-Henry said in 2020. “But if we also have people moving on those lines, I think this could be a great benefit to us.” A small segment of Union Pacific’s Tennessee Pass Line is currently leased by the scenic Royal Gorge Route

Beginning in the 1950s, the United States government, at the behest of the auto and aviation industries, prioritized interstate highways and airports over passenger rail, relegating rail to primarily freight lines with little tolerance for passenger service. In 1997, the only other rail line through the Colorado Rockies — the Tennessee Pass Line — was mothballed in favor of the Central Corridor. But it had not seen passengers on its tracks since 1964.

Terry Armistead, the Minturn mayor pro tem and a member of the Minturn Railroad Committee, does not speak for the whole committee or the entire town council, but she does not want to see the revival of either freight or passenger service in the former rail and mining town off the back side of Vail Mountain.

“We’re not Europe. I just was there riding the trains, and it was incredible. But this mountain corridor is really problematic for commuter traffic and any kind of freight traffic,” Armistead said. “I have real fears about derailments, and Minturn is finally recovering from the disaster that was the Eagle Mine, with the river running orange. We can’t afford to do that again.”

Eagle Mine

The Eagle Mine is an EPA Superfund site.

“People have this romantic idea of it, but they don’t really quite understand the logistics of this rail line. I don’t think it will work for commuter traffic,” even for people who live in Leadville and work in Vail, Armistead said. “If you drove the Leadville 100 at 8 a.m. or 5 p.m. back up to Leadville, you’d understand. People aren’t giving up their cars to spend an extra hour on a train every day. I mean, people are not going to do it. They don’t have the time.”

Sal Pace, a former Pueblo County commissioner and state lawmaker who serves on the Front Range Passenger Rail board of directors, said in a previous interview that the primary focus of FRPR is passenger rail along the Front Range between Pueblo and Fort Collins, where more than 80% of the state’s population is located.

But Pace acknowledges his group has been, to a much lesser degree, exploring connectivity to the west, including the passenger trains already using Union Pacific’s Central Corridor through the Moffat Tunnel, but also by connecting to Amtrak’s Southwest Chief, which cuts through southeast Colorado on its route between Chicago and Los Angeles.

“We’re also going to explore other potential opportunities,” Pace said of currently active segments of the Tennessee Pass Line. “There’s already potential for connectivity from Pueblo to the Royal Gorge Route and it’s not out of the question that individuals could purchase a train ticket from Denver to the Royal Gorge after we build out Front Range Passenger Rail, where in Pueblo they’d change trains. The infrastructure is there, and it’s something that needs to be examined and explored.”

The Colorado Department of Transportation has identified the Tennessee Pass Line as a priority alternative to the Central Corridor line and in the past suggested the state should attempt to purchase the dormant line if it ever becomes available.

But until passenger service becomes the top-line priority over freight on Colorado’s historic rail lines, fears of frequent derailments and toxic spills in headwater rivers will color perceptions in the state’s mountain towns, especially as federal rail safety legislation languishes amid relentless lobbying by the freight-rail industry.