What might planning for an 11 million acre foot or 10 million acre foot #ColoradoRiver look like? — @jfleck #COriver #aridification

Brad Udall: Here’s the latest version of my 4-Panel plot thru Water Year (Oct-Sep) of 2021 of the Colorado River big reservoirs, natural flows, precipitation, and temperature. Data (PRISM) goes back or 1906 (or 1935 for reservoirs.) This updates previous work with
@GreatLakesPeck.

From InkStain (John Fleck):

One of the central questions dimly visible in the early discussions around the upcoming renegotiation of the Colorado River’s water operations and allocations rules is the question of how bad a “worst case” scenario should be considered.

This is crucial, because it constrains what sort of questions must then be confronted. The lower the future flows considered, the more likely it is that the negotiators will have to stare down the third rail question of how much water the Upper Basin can delivery hydrologically, and must deliver legally, at Lee Ferry, the dividing point between the Upper and Lower Basins.

For the century since the Colorado River Compact was signed, we’ve avoided dealing with that central question – what happens if the river’s flows are so low that the Upper Basin cannot deliver the 7.5 million acre feet per year (or 8.25 million acre feet, we can’t even agree about which number to argue about) contemplated by the compact’s Article III.

This question is so untouchable that in work done for the 2012 Basin Study, the Bureau of Reclamation’s modelers famously added what came to be called “miracle water” at Lee Ferry every time one of their model runs dropped below the threshold that might have otherwise triggered this legal argument.

Under the low flows possible under climate change, we face a stark choice – either we reduce the Upper Basin’s Lee Ferry deliveries below 7.5/8.25 maf, or we will have to curtail existing Upper Basin uses. Advocates of modeling such low flows in the planning scenarios are essentially saying – Let’s have that conversation now.

At the tale end of yesterday’s (Friday 10/15/2021) House Natural Resources Sucommittee on Water, Oceans, and Wildlife, it was California Rep. Jim Costa, a congressman from outside the Colorado River Basin, who asked the question pointed at the heart of the matter – how do we redo water allocations that make no sense in a river much smaller than contemplated in our hallowed Law of the River?

He was addressing a panel of representatives from each of the Colorado River Basin states (his comments start around 2:30 here):

“The Law of the River and the quantification of the Upper and Lower Basin states amounted to some 17 million acre feet of water that was determined at that time was the annual flow of the Colorado River, and we know that in the last two decades its been more like 12.4 million acre feet, and that doesn’t account for other Native American tribes that have reserved water right claims that have yet to be resolved. So there’s just a tremendous amount of demand. And with climate change, we know the yield is only going to decline.

“This is the question I’d like to submit to all of you, and if you want to provide written statement to your answer I think we would appreciate that.

“Let’s say the annual yield over the next 30 years is 10 million acre feet. I don’t know, with climate change, maybe it’s plus or minus. How do we take into account how we got to the original allocation, with the Upper and Lower Basin States and the Native tribes, the sovereign nations, and then reallocate that on a lot less water.”

At this point all we can see through the public windows into discussions about next-step Colorado River management guidelines is shadow boxing on this question.

But testimony yesterday from Southern Nevada’s John Entsminger suggests the public shadowboxing we’re seeing on this question is representative of disagreements in the private discussions. (I quote here from John’s written testimony.)

Climate change is causing the Southwest to aridify. (Left) Since the 1930s, increasing temperatures have caused the percentage of precipitation going to evapotranspiration (ET) to increase at the expense of precipitation going to Colorado River flow, resulting in an unprecedented and still ongoing megadrought (shading) starting in 1999 (8). (Right) Higher temperatures have already reduced Colorado River flow by 13%, and projected additional warming, assuming continued high emissions of greenhouse gases, will increase ET while reducing river flow even more through the 21st century. Data on Left are 20-y running means from ref. 5, and data on Right are calculated from Representative Concentration Pathways (RCP) 8.5 multimodel Coupled Model Intercomparison Project–Phase 5 (CMIP5) ensemble temperature increases projected for the Upper Colorado River Basin combined with temperature sensitivity of −9.3%/°C estimated by ref. 5, assuming no change in precipitation.

“Despite the fervent warnings from internationally renowned scientists like Jonathan Overpeck and Brad Udall that urge us to plan for a future with even less than 12.3 million acre-feet, the river community is far from consensus about how dry of a future to plan for. And, while this panel was asked to talk about drought, on-the-ground evidence suggests the Colorado River basin is not experiencing drought but aridification – a permanent transition to a drier future. If we are to build upon the river’s many successes over the last 25 years, we must confront the magnitude of the challenge in front of us and quickly reach agreement on what future scenario we’re willing to plan for. (emphasis added)”

Speaking two weeks ago at this year’s Getches-Wilkinson Center conference in Boulder, Entsminger put a number to Southern Nevada’s thinking. In the next iteration of its long range water resources plan, Entsminger’s Southern Nevada Water Authority will include a “what if” planning scenario for how the agency would deal with an 11 million acre foot per year Colorado River. This is not to say that Southern Nevada expects an 11 million acre foot river, but rather than it believes it needs to have a plan in place should that happen.

I could be wrong, but so far I’ve seen no public evidence that any of the states of the Upper Basin are willing to entertain flows that low in the planning scenarios to be considered in the modeling done to support the upcoming negotiations. I look forward to seeing the written answers the basin states’ representatives submit to Costa’s question.

#ClimateChange wreaks havoc on the electricity grid — @HighCountryNews #ActOnClimate

From The High Country News [July 27, 2021] (Jonathan Thompson):

In late June, a blistering heat wave settled over the Pacific Northwest, shattering high-temperature records from California to Canada. Hundreds of outdoor laborers or those who lacked air conditioning were hospitalized for heat-related ailments, and dozens died. Portland’s transit operator suspended rail service because of heat-damaged cables, while highways in Washington were closed due to buckling asphalt.

But the heat’s biggest — and perhaps most consequential — infrastructure victim was the vast electricity grid that powers nearly every aspect of modern life, including potentially life-saving air conditioning. Extreme weather exacerbated by climate change can mess with the grid in any number of ways: Cold can freeze gas lines, while hurricanes topple transmission towers. But heat, particularly when combined with hydropower-depleting drought, has an especially deleterious effect, wreaking havoc on the power system just when the warmer climes need it most.

Meanwhile, power plants — the fossil-fueled “heart” of the grid — make climate change worse and the planet even warmer, creating a feedback loop that resembles a gigantic electrical monster swallowing its own tail.

Climate grid. Graphic credit: The High Country News

Sources: California Independent System Operator (CAISO); Energy Information Administration; California Clean Energy Almanac; Bonneville Power Administration.

Jonathan Thompson is a contributing editor at High Country News. He is the author of River of Lost Souls: The Science, Politics and Greed Behind the Gold King Mine Disaster. Email him at jonathan@hcn.org or submit a letter to the editor. Follow @Land_Desk.

Eagle River Watershed Council: A deeper diver into the #EagleRiver MOU — The Vail Daily

Ken Neubecker, formerly of American Rivers, gives a presentation about the Eagle River Memorandum of Understanding during a hike and public outreach event organized by the Eagle River Watershed Council. The 1998 MOU, which lays out the amounts of water the signatories are entitled to develop, may be based on hydrology that is outdated due to climate change impacts of the last 20 years.
CREDIT: HEATHER SACKETT/ASPEN JOURNALISM

From The Current (Ken Neubecker) via The Vail Daily:

This is Part II of a three-part series.

In the previous column, we reviewed the history of water development in the Homestake Valley, as well as some of the key points contained in the Eagle River Memorandum of Understanding that was agreed to and signed by the principal parties in 1998. Of primary interest in this column is what is referred to as “Exhibit 2” in the MOU, and pertains to Homestake Creek-based alternatives.

As a reminder, the Eagle River Assembly and signatories of the MOU were Aurora and Colorado Springs (named the Cities in the memorandum), Colorado River Water Conservation District (River District), Climax Molybdenum Company (Climax) and the Vail Consortium, consisting of Vail Associates, the Eagle River Water and Sanitation District, and the Upper Eagle Regional Water Authority. The Vail Consortium and the River District together are known as the “Reservoir Company” in the MOU.

The primary objective of the MOU was to create a joint project from one of four options, which were explained in the previous column. The idea was to develop a water supply project that “minimizes environmental impacts, can be permitted by local, state and federal agencies, and provides sufficient yield to meet the water requirements of project participants…”

The baseline sharing of water would provide as much as 10,000 acre-feet (an acre foot is enough water to cover one acre — about a football field — one foot deep), on average, for the Eagle County participants, 20,000 acre-feet on average for the east slope participants and 3,000 acre-feet average for Climax. These amounts were based on a firm dry year yield, which means the maximum quantity of water which can be guaranteed during a critical dry period.

Ken Neubecker via LinkedIn

There are provisions in the MOU for the range of needs and timelines of the parties. Any party or parties wishing to build a project must seek the participation of all the other parties. If the other party or parties do not wish to participate at that time, then the initial parties may “proceed independently of the others…,” with additional caveats regarding money, infrastructure and “rights of refusal” to water, depending on the final size of a project.

If the proposed project is a joint project, the parties shall all apply for permits as co-applicants for federal, state and county permits. But, what happens if one or more of the parties decline to participate?

The MOU outlines the following: “To the extent that any party exercises its right not to participate… such party shall nevertheless support any application that is consistent with the terms of this MOU.” The non-participating parties will “provide favorable testimony and letters of support in any permit proceedings…” If any party or parties fail to support a proposed project than “the Cities shall have no obligation to subordinate their water rights…”

Such refusal of support would also jeopardize a specific exchange of water.

The MOU considers the need to study and mitigate potential environmental impacts. It is designed to focus primarily on compiling all information on existing wetlands, identifying and quantifying wetlands in the area, estimating mitigation costs and “identifying potential benefits for recreation, fish and wildlife in a qualitative sense.” This last comment is important and reflects a long history of resistance by Front Range water diverters to any quantification of flow needs for environmental protection or recreation.

If any flow rates, seasonal or otherwise, including any range of flows needed for the environment, fish, wildlife and recreation were provided, the diverters might be expected to provide for flows through depletions, or when their diversion is impacting local stream flows.

The MOU calls for an environmental analysis of the various alternatives to identify impacts to wetlands and concerns from inundation, or the flooding of the valley floor and surrounding landscapes. It specifically states that, “If it is found that there are less environmentally damaging practicable alternatives [any of these proposed projects] may prove difficult to permit.”

Now that’s an understatement.

The third column will explore some serious questions brought to mind by both the MOU and the assumptions underlying the work of the Eagle River Assembly. The significant cultural, hydrologic and climatic changes that have occurred since 1998 will also be investigated. The world and problems we face with water and rivers in the West in 2021 are not the same as those the Eagle River Assembly was trying to address in the early 1990s.

Ken Neubecker is a founder of and former board president for Eagle River Watershed Council and recently retired from his position as the Colorado Project Director at American Rivers. The Watershed Council has a mission to advocate for the health of the Upper Colorado and Eagle River basins through research, education and projects. Contact the Watershed Council at (970) 827-5406 or visit erwc.org.

At #Climate Summit, Can the World Move from Talk to Action? — Yale Environment 360 #ActOnClimate #COP26

Cars pass the Shanghai Waigaoqiao Power Generator Company coal power plant in Shanghai on March 22, 2016. – Environmental watchdog Greenpeace warned on March 22, 2019 the world’s coal plants are “deepening” the global water crisis as the water consumed by them can meet the basic needs of one billion people. China, the world’s largest emitter, has promised to reach zero net carbon emissions by 2060. (Photo by JOHANNES EISELE / AFP) via Voice of America

From Yale Environment 360 (Fred Pearce):

Negotiators at the Glasgow climate conference will face a critical choice: Set firm emissions targets for 2030, or settle for goals of achieving “net zero” by 2050? The course they set could determine if we have a shot at avoiding the worst impacts of climate change.

Glasgow, once the second city of the British Empire and the biggest shipbuilder on the planet, next month hosts the 26th conference of nations aiming to halt dangerous climate change. The negotiators face the challenge of turning the aspiration of the 2015 Paris Agreement to achieve “net zero” emissions by mid-century into the detailed near-term action plans necessary to turn those hopes into reality in time to halt warming at or near 1.5 degrees Celsius (2.7 degrees Fahrenheit).

Sadly, while aspiration is going well, progress on action is slow, say scientists. Most big emitters have in recent months promised to achieve national net-zero targets by 2050, allowing the British hosts to claim that Glasgow will “keep 1.5 alive.” But scientists warn that such ambition remains hot air. They say we have to all but halve greenhouse gas emissions by 2030, or net zero by 2050 will slip out of sight. Yet most of the national plans unveiled so far do little more than prevent further rises in emissions over the coming decade.

The question for delegates meeting in Scotland comes down to this: Should the focus be on 2050 aspiration or 2030 action, on “keeping 1.5 alive” or on delivering credible plans to make it happen?

It is six years now since governments meeting in Paris committed to restricting warming to “well below” 2 degrees C from pre-industrial levels while “pursuing efforts” to cap it at 1.5 degrees. They agreed that would require bringing net greenhouse-gas emissions (total emissions less any agreed carbon capture) to zero by mid-century.

But even amid the euphoria, negotiators recognized that there was a gap between national emissions pledges on the table in Paris and the declared goal. So they set up a timetable for ratcheting up commitments and for taking account of emerging science. The first deadline for new pledges, known as nationally determined contributions, was set for 2020 and postponed until 2021 because of the pandemic.

So the Glasgow Conference of Parties (COP26) should be high noon for delivery — for turning aspiration into action.

Its importance has grown because it is the first COP since the return of the United States to the negotiating table after the Trump years. And the urgency has been reinforced by escalating extreme weather events — wildfires, floods, droughts, and extreme heat waves — and by modeling studies suggesting such extremes will increase sharply if global temperatures rise beyond 1.5 degrees C.

The potential for achieving the ambition of Paris has improved since that conference, because of the advance of technology. Electric cars were barely on the horizon in 2015. And solar power and battery prices have more than halved since then.

So how are we doing? More than 130 countries have made net-zero pledges since Paris. Those nations are collectively responsible for more than 70 percent of current global emissions. That is a diplomatic triumph of sorts. But pledges are no substitute for action. And with warming already above 1 degree C, time is short.

In a 2018 assessment, the UN’s Intergovernmental Panel on Climate Change concluded that if current trends continue, 1.5 degrees would be reached about 2040, but potentially as early as 2030 or as late as 2052. It found that for a 50-50 chance of halting warming at that point, the world has to reduce emissions by 45 percent from 2010 levels by 2030 and then go on to reach net zero by 2050. For climate scientists, securing that trajectory is the benchmark for success in Glasgow.

But national pledges to make the required 45 percent cut by 2030 remain a distant prospect (only the United Kingdom comes close). And since the Paris Agreement is based on voluntary targets, there is no legal means for closing the gap or sanctioning backsliders.

The most definitive assessment of where the world stands came in a detailed comparison of climate models and national pledges published in the journal Nature Climate Change last month. It found that emissions in 2030 are set to be almost the same as today — almost double what is needed to be on target for net zero.

2100 warming projections. Graphic credit: Yale Environment 360

The prognosis for temperatures will be devastating. The report found that policies currently in place will lead to a rise of around 3 degrees C. If pledges for 2030 so far submitted for Glasgow were implemented in full, they would limit the rise to 2.4 degrees, at best. And even if there were a systematic advance toward net zero, it would deliver only a 50-50 chance of keeping warming to below 2 degrees, according to one method used in the study.

“The good news is that the 2050 net-zero targets for the first time put the ‘well below’ 2 degrees and 1.5 limits of the Paris Agreement within reach,” the study’s chief author, Niklas Hohne of the NewClimate Institute in Cologne, Germany, told Yale Environment 360. “But the bad news is that no single country is on target to implement the short-term 2030 policies needed to be on track to meet their own net-zero targets.”

The paper is optimistically titled: “Wave of net-zero emissions targets opens window to meeting the Paris Agreement.” But the current pledges, Hohne says, “will lead to roughly stable emissions from now until 2030,” not the required 45 percent cut. Co-author Joeri Rogelj of Imperial College London agrees that the national pledges to date are “not at all consistent” with reaching net zero.

So can the tide be turned? Will climate diplomacy and public pressure force delegates in Glasgow to up their game? The British government’s chief negotiator, former business secretary Alok Sharma, who will be president of the COP, conceded in March that current 2030 targets were “nowhere near enough,” but declared that “the UK is using the COP presidency to urge all countries to set 2030 emissions reductions targets that put us on a path to net zero.”

Six months on, his advisors are now reported to privately concede that the hoped-for big improvements won’t happen on anything like the scale needed. Probably in consequence, the hosts’ narrative has shifted.

Sharma has been traveling the world in recent months, pushing countries such as Russia and Australia to join others in committing to net zero. But he has been downplaying the importance of 2030 targets. He no longer talks of putting the world “on a path” to net zero. Rather he speaks repeatedly of aiming to “keep 1.5 alive” through 2050 pledges.

Perhaps, say optimists, national emissions pledges at big UN negotiating events matter less now that there is more potential economic gain from switching to cheap low-carbon technologies. “The world has changed a lot since Paris,” economists Kingsmill Bond and Sam Butler-Sloss of the UK-based think tank Carbon Tracker noted last month. “The old trade-off between development and climate mitigation … has been solved.” Shifting to the new technologies was now about “gain not pain,” since that would give nations a head start on the low-cost energy technologies of the future.

Maybe so, but despite apparent technological tipping points, overall carbon dioxide emissions have continued to rise since Paris. The main obstacle, Bond and Butler-Sloss argue, comes from “the forces of incumbency and inertia,” reflected in government subsidies for fossil fuels that a report published by the International Monetary Fund this month estimates at $11 million every minute.

Glasgow will debate many issues besides national emissions targets. Sharma’s agenda has broadened in recent months to embrace commitments phasing out coal, promoting electric vehicles, reducing non-CO2 greenhouse-gas emissions such as methane, and funding both for forest planting to keep more carbon in natural ecosystems and for helping developing countries adapt to future extreme weather.

Alok Sharma, Britain’s chief climate negotiator and president of COP26, leaving 10 Downing Street in March. WIKTOR SZYMANOWICZ / NURPHOTO VIA GETTY IMAGES

The push to banish coal burning in power stations may have triggered China’s September promise to end all funding for overseas coal power stations. It is also behind a recently announced plan for rich nations to provide funding to South Africa to end its reliance on coal burning.

But of much greater moment for many of the developing-world governments, whose votes will dominate in Glasgow, is finance. Twelve years ago, at the otherwise failed Copenhagen COP, developed nations promised that by 2020 they would collectively provide an annual $100 billion to developing countries to help them both bring down their own emissions and adapt to climate change.

Those promises were reaffirmed in Paris. The UN’s chief Paris negotiator, Christiana Figueres, says that the risk of missing this target “looms the largest” for her successors. Delivering this funding is a prerequisite for a successful conference for countries whose contribution to climate change is very small compared to that of rich industrialized nations. “Promises must be kept,” says Figueres, “otherwise a lack of trust undermines the whole process.”

But faith and trust are in short supply. The formal accounting process on the 2020 financial payments will not be completed until next year, but sources familiar with the process told Bloomberg that payments fell at least $10 billion short. And there are continuing concerns about how the money is being allocated by donors. Most of it has so far funded reducing emissions, with only a small portion going for helping countries adapt to the impacts of climate change, such as hurricanes, floods, and droughts.

Other outstanding business for Glasgow includes completing the technical rules for implementing the Paris deal. Delegates still have to decide how often countries should report and update their pledges in the future. The European Union this month agreed to join the U.S. and many poor climate-vulnerable nations in pushing for updating targets every five years. But others want a 10-year cycle, and China and India oppose any internationally agreed time frame. Some observers say that without synchronized reporting, it will be impossible to align national targets with the changing science of climate change.

There is continuing controversy too over rules on accounting for, and trading in, credits for carbon captured by forest conservation and planting. These “nature-based solutions” are seen as a crucial element in achieving net-zero emissions, which will allow countries to continue greenhouse-gas emissions provided they are offset by carbon-uptake elsewhere. But nobody is sure how to prevent bogus offsets and carbon fraud.

Though apparently technical issues, rule-book resolution depends a lot on political goodwill. A big unknown here remains the role that China will take, and how its diplomatic relations with the U.S. will play out on the conference floor.

There is history here. A major cause of failure in Copenhagen in 2009 was a stand-off between the two nations; but Paris succeeded in part because of a deal on climate reached between the two nations in Washington the previous year.

John Kerry, then U.S. secretary of state, with China’s special representative on climate change, Xie Zhenhua, at the 2015 Paris climate conference. FRANCOIS MORI / AP PHOTO

In recent months, diplomatic relations between the China and the U.S. have been increasingly frosty, leading to Biden’s climate envoy John Kerry pleading with his Chinese counterpart Xie Zhenhua to separate climate from other issues.

But China has rejected such overtures. It has committed in advance of Glasgow to what it believes is a generous pledge for a still-developing nation, by promising to peak emissions by 2030 and reach net zero by 2060. But the West is not satisfied. In September, Sharma publicly called for China to “pick up the pace” and present “more detailed plans.” And Kerry’s chief negotiator Todd Stern, a veteran of the process, called testily on Twitter for China to “pledge a major cut in its emissions now, in this decade.”

Such calls may seem unfair, given the much greater responsibility for overloading the atmosphere with CO2 born by early-industrializing nations such as the U.S. and UK. This “carbon debt” is an increasingly hot topic as the world edges towards its carbon limits.

So, how should we judge the success or failure of the Glasgow COP? The hosts appear tempted to paint aspiration as victory. They may hope that delegates less versed in the science of climate change will fly home satisfied that they have delivered a “wave” of net-zero pledges for 2050 and “kept 1.5 alive.” For others, an absence of concrete plans for 2030 would make the aspirations look like delusion.

Almost 30 years ago, at the Earth Summit in Rio, nations agreed to a convention that promised to prevent “dangerous” climate change. The Glasgow COP is the 26th conference of the parties to that treaty. If it can deliver on 1.5 degrees, it will be the most important. But it could be another 30 years before we know for sure.

Fred Pearce is a freelance author and journalist based in the U.K. He is a contributing writer for Yale Environment 360 and is the author of numerous books, including The Land Grabbers, Earth Then and Now: Amazing Images of Our Changing World, and The Climate Files: The Battle for the Truth About Global Warming.

October 2021 #ENSO update: #LaNiña is here! — NOAA

From NOAA (Emily Becker):

Our second-year La Niña has materialized, as indicated by the ocean and atmosphere in the tropical Pacific. There’s an 87% chance of La Niña this winter, the season when North American weather and climate are most affected by ENSO (El Niño/Southern Oscillation, the entire El Niño/La Niña system).

The winning numbers

The first step on our “Is it La Niña?” decision tree asks “is the monthly Niño-3.4 Index equal to or less than -0.5°C?” The Niño-3.4 Index, our primary metric for ENSO, is the anomaly in sea surface temperature in the central equatorial Pacific (anomaly = the difference from the long-term average; “average” is 1991–2020 nowadays).

Flowchart showing decision process for determining La Niña conditions. Figure by Fiona Martin, adapted by Climate.gov.

The September Niño-3.4 Index was -0.5°C, according to ERSSTv5, our primary dataset. So it’s on to the next box on the decision tree! Do we think that anomaly will remain cooler than the La Niña threshold? Again, yes! Nearly all computer models are currently predicting that the cooler-than-average conditions will remain through the winter. Another source of confidence for the Niño-3.4 Index to remain cooler than the La Niña threshold is the large amount of cooler-than-average water beneath the surface of the equatorial Pacific. This subsurface water provides a source for the surface, and it has been intensifying in recent weeks.

Water temperatures in the top 700 meters (2,300 feet) of the tropical Pacific Ocean compared to the 1991-2020 average in late summer 2021. NOAA Climate.gov animation, based on data from NOAA’s Climate Prediction Center.

The final requirement to get to La Niña conditions is that the atmosphere is showing signs of responding to that cooler-than-average surface water. Over the past month, the low-level winds near the equator, which usually blow from east to west (the trade winds), were stronger than average, as were the west-to-east winds high up in the atmosphere.

These signs, along with more rain than average over Indonesia and less in the central Pacific, tell us that the Walker circulation is juiced up. A stronger Walker circulation is the expected atmospheric response to La Niña. The Walker circulation is driven by the difference between the very warm ocean surface in the far western Pacific and the relatively cool eastern Pacific; during La Niña, this difference is enhanced, leading to a stronger Walker circulation.

Follow the blue brick road, and we get to La Niña!

Buy one, get one free

La Niña has probably earned silver-elite, frequent-flier status here, as this is the fourth time we’ve written a “La Niña is here” post on the ENSO Blog! (Earlier posts are September 2020, November 2017, and November 2016.) That’s four of the seven-and-a-half years we’ve been standing on this digital street corner yelling about ENSO.

Overall, La Niña is not more common that El Niño—in the historical record dating back to 1950, there have been 25 El Niños and 24 La Niñas (counting this year). However, La Niña often occurs in consecutive winters, while El Niño rarely does. The reason for this is difficult to explain in brief, but researchers think it’s partly due to differences in atmosphere-ocean coupling between La Niña and El Niño.

As you can see int he map below, the center of the ocean surface temperature anomaly tends to be a bit weaker and a bit farther west during La Niña than El Niño. The difference in strength and location means the trade winds response is not exactly opposite in La Niña and El Niño—unsurprisingly, the response tends to be weaker and centered farther west during La Niña than El Niño.

Average November – January sea surface temperature anomalies (°C) for the top 10 strongest (top) El Niño and (bottom) La Niña events since 1950 based on the November – January Niño3.4 index. Anomalies are calculated with respect to 30-year base periods updated every 5 years (see here for a description). NOAA Climate.gov figure with ERSSTv5 data obtained from the NOAA Physical Sciences Laboratory.

El Niño events end when the equatorial temperature anomalies are dispersed away from the equator, and this process tends to be less robust in La Niña. The less-clean end to La Niña means that it’s not hard for the system to tip back into La Niña the next year. For more on how this works, check out Nat’s excellent post on double-dip La Niña.

Holiday sale

We’ve already seen one likely effect of La Niña this year—a more active Atlantic hurricane season, with nearly twice as many storms as average so far this year. But the most substantial La Niña effect on North American rain, snow, and temperature happens during winter. In summary, La Niña winters tend to be drier and warmer across the southern third of the U.S., and cooler in the northern U.S. and Canada. The Pacific Northwest, the Tennessee/Ohio Valleys, and parts of the Midwest tend to see more rain and snow than average.

La Niña intensifies the average atmospheric circulation—surface and high-altitude winds, rainfall, pressure patterns—in the tropical Pacific. Over the contiguous United States, the average location of the jet stream shifts northward. The southern tier of the country is often drier and warmer than average. NOAA Climate.gov illustration.

For more information, check out these posts on how La Niña affects the Jet Stream, drougAnd, of course, we’ll be here at the ENSO Blog to keep you updated as La Niña 2021–22 progresses. Till next time!ht during second-year La Niña, snow during La Niña winters, and La Niña’s role in South American climate. NOAA’s Climate Prediction Center’s winter weather outlook will be released soon, and you can find the current seasonal forecasts here.

And, of course, we’ll be here at the ENSO Blog to keep you updated as La Niña 2021–22 progresses. Till next time!

@DWR_CO Announces Public Meetings on Proposed Over-Appropriation in the #YampaRiver Basin #GreenRiver #ColoradoRiver #COriver #aridification

Yampa River Basin via Wikimedia.

From email from the Colorado Department of Natural Resources (Chris Arend):

The Colorado Division of Water Resources and Community Agriculture Alliance are partnering to educate the community and solicit public comment about the proposal to designate the Yampa River Basin as over-appropriated.

An over-appropriated stream system is one in which at some or all times of the year, the water supplies of a stream system are insufficient to satisfy all the decreed water rights within that system. Two public meetings will be held to outline how the over-appropriation proposal affects new and existing residential well permits.

A recording will be available after the Moffat County event for those who are unable to attend in-person.

For more information on the proposed designation see: https://dwr.colorado.gov/news-article/yampa-river-over-appropriation. To submit comments on or any questions about the proposed plan please contact Erin Light, Division Engineer, Water Division 6, at erin.light@state.co.us or 970-879-0272 Ext. 3.

WHO: Colorado Division of Water Resources and Community Agriculture Alliance

WHAT: Public Meetings on Proposed Designation of Yampa River as Over-Appropriated and impacts to new and existing residential well permits

WHEN/WHERE:

Monday, October 25, 2021, 6 PM to 8 PM, Moffat County Fairgrounds, 640 E Victory Way, Craig, CO, 81625

Thursday, October 28, 2021, 5 PM to 7 PM, Routt County Fairgrounds, 398 S Poplar St, Hayden, CO, 81639

Opinion: The #ColoradoRiver #drought contingency plan is no longer a contingency — The #Colorado Sun #COriver #aridification #DCP

From The Colorado Sun (Rebecca Mitchell):

Seven states will negotiate access to what’s left in the river. My job is to represent all of Colorado’s interests.

Photo: DNR Director Dan Gibbs, Gov. Polis, CWCB Director Rebecca Mitchell, Colorado River District General Manager Andy Mueller at Elkhead Reservoir. Photo credit: Colorado Water Conservation Board

If you live in Colorado—you get it. We don’t quit when challenged. Whether you live in a city, on a farm or ranch, in a rural town, or somewhere in between—you are part of the dynamic group of people who call Colorado home; people who understand when it comes to protecting Colorado water, specifically the Colorado River’s water, we must rise together to meet the challenge.

From its headwaters in the Rocky Mountains, the Colorado River flows broadly across 1,450 miles of the southwestern United States, changing elevation by a remarkable 10,000 feet. More than 40 million people rely on the Colorado, the nation’s fifth-longest river, for drinking water and energy through hydroelectric power. In addition, the river supports an estimated $25 billion recreational economy and an agricultural economy of about $1.4 trillion a year.

About 100 years ago, the seven states in the Colorado River Basin created an agreement known as the 1922 Colorado River Compact and divided the seven states into two groups, the Upper Basin states (Colorado, New Mexico, Utah and Wyoming), and the Lower Basin states (Arizona, California and Nevada). It was the beginning of these seven states acting cooperatively to take the lead in managing and allocating the Colorado River’s annual flow of water.

Brad Udall: Here’s the latest version of my 4-Panel plot thru Water Year (Oct-Sep) of 2021 of the Colorado River big reservoirs, natural flows, precipitation, and temperature. Data (PRISM) goes back or 1906 (or 1935 for reservoirs.) This updates previous work with
@GreatLakesPeck.

Yet, in the early 1900s, it was impossible to foresee that in the 21st Century, the dwindling supply of water due to climatic forces, coupled with growing demand, would result in the present-day low water levels in our nation’s two largest reservoirs.

Extensive drought that began over 20 years ago in 2000—and continues to this day—has been a major factor leading to Lake Powell, on the Utah-Arizona border, reaching its lowest level since being filled. Lake Mead, the nation’s largest reservoir on the Arizona-Nevada border, also is at its lowest level since filling.

The state of the river is important to every Coloradan – all 6 million of us. It is critical to providing for the needs of current and future generations of Coloradans. More broadly, it is critical to the 40 million people who directly rely on the water of the Colorado River.

That is why all seven states agree that working collaboratively is critical to solving our own river management issues through cooperative agreements like the 2019 Colorado River Drought Contingency Plan.

Signing ceremony for the Colorado River upper and lower basin Drought Contingency Plans. Back Row Left to Right: James Eklund (CO), John D’Antonio (NM), Pat Tyrell (WY), Eric Melis (UT), Tom Buschatzke (AZ), Peter Nelson (CA), John Entsminger (NV), Front Row: Brenda Burman (US), and from DOI – Assistant Secretary of Water and Science Tim Petty. Photo credit: Colorado River Water Users Association

The Colorado River Drought Contingency Plan provides that, should Lake Powell’s water levels fall too low, Upper Basin states would release more of the river’s water from other reservoirs, to be stored in Lake Powell as part of the Drought Response Operations Agreement in the Upper Colorado River Basin.

The agreement has been activated and the states now are in planning mode.

Demand management engagement pyramid. Graphic credit: The Colorado Water Conservation Board

Another tool could involve an effective demand-management program, which provides compensation for water users, such as farmers and ranchers and municipalities, to voluntarily conserve water on a temporary basis — without the loss of their ongoing water rights — while allowing for more water to be stored in Lake Powell with greater downstream water flow.

So, where do we stand? The seven Colorado River Basin States soon will be negotiating new interim guidelines for Lake Powell and Lake Mead to coordinate operations of both reservoirs.

As Commissioner representing Colorado’s interest in these negotiations, I am charged with effectively representing and protecting the state’s water and the water users’ interests, while also working collaboratively with the other six states and the federal government. As a state, we will continue leading the effort in conjunction with all the Colorado River Basin states.

From the 2018 Tribal Water Study, this graphic shows the location of the 29 federally-recognized tribes in the Colorado River Basin. Map credit: USBR

Throughout the process, I commit to hearing the voices of tribal nations, key stakeholders, non-governmental organizations, and our fellow Coloradans. To learn how to make your voice heard, visit EngageCWCB.org.

As we continue to face the challenges of climate change, persistent drought, and growing populations, we cannot quit.

Rebecca Mitchell, of Denver, is Colorado commissioner for the Upper Colorado River Commission.

#LakePowell is seen in a November 2019 aerial photo from the nonprofit EcoFlight. Keeping enough water in the reservoir to support downstream users in Arizona, Nevada and California is complicated by climate change, as well as projections that the upper basin states of Colorado, Utah, Wyoming and New Mexico will use as much as 40% more water than current demand. A recent white paper from a lineup of river experts calls those use projections into question. CREDIT: ECOFLIGHT via Aspen Journalism