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Climate Hustle

How This El Niño Is And Isn’t Like 1997

Posted on 7 August 2015 by Guest Author

This is a re-post from Climate Central by Andrea Thompson

It was the winter of 1997-1998 when the granddaddy of El Niños — the one by which all other El Niños are judged — vaulted the climate term to household name status. It had such a noticeable impact on U.S. weather that it appeared everywhere from news coverage of mudslides in Southern California to Chris Farley’s legendary sketch on “Saturday Night Live.” Basically, it was the “polar vortex” of the late ‘90s.

So it’s no wonder that it is the touchstone event that people think of when they hear that name. And naturally, as the current El Niño event has gained steam, the comparisons to 1997 have been increasingly bandied about.

The most recent came this week in the form of an image from the National Oceanic and Atmospheric Administration that compares satellite shots of warm Pacific Ocean waters — a hallmark of El Niño — from this June to November 1997, when that El Niño hit its peak.

A comparison of sea surface temperatures between July 2015 and November 1997. Credit: NOAA

On the one hand, the two are comparable given that 1997 was the strongest El Niño on record and, at the moment, the best science indicates that the current event could match or rival that one — at least in terms of ocean temperatures. But on the other hand, each El Niño event is its own beast, the product of conditions in the ocean and atmosphere, of climate and weather that are unique in that particular place and time.

In the, albeit very short, modern record of El Niños, “we cannot find a single El Niño event that tracked like another El Niño event,” Michelle L’Heureux, a forecaster with NOAA’s Climate Prediction Center, said.

Forecasters like L’Heureux cringe at comparisons because there’s no guarantee the impacts of one El Niño will be just like that of a previous one, even if they look broadly similar. And it’s those impacts — like potential rains in drought-stricken California — that most really care about.

Stormy Weather

El Niño is not, as Farley’s sketch had it, an individual storm, like a hurricane. Rather it is a shift in the background state of the climate brought about by the sloshing of warm ocean water from its normal home in the western tropical Pacific over to the east. That redistribution affects how and where ocean heat is emitted into the atmosphere, which can alter the normal patterns of winds and stormy weather in the region.

Those more local shifts can telegraph through the atmosphere and, in the case of the U.S., can alter the position of the jet stream over the country during the winter months, typically leading to wetter-than-normal conditions over the southern tier of states and warmer temperatures over the north.

Those are the effects of El Niño very broadly speaking, though. Such teleconnections, as they are called, tend to be more reliable when the El Niño is a strong one.

Such was the case with both the strong events of 1997-1998 and 1982-1983. January and February 1998 were the wettest and warmest first two months to a year for the contiguous U.S. in the 104-year record at that time, according to NOAA. The position of the jet stream meant that some northern states saw temperatures up to 15 degrees above normal and both the Southeast and Southern California were awash in a series of storms.

In California, the rains were so unrelenting that they led to mudslides that caused houses to crumble off disintegrating cliffs and racked up hundreds of millions of dollars in damages.

An aerial view of a mudslide along the Southern California Coast just north of Los Angeles, taken in April 1998. Credit: USGS

With California now five years into a debilitating drought that has led to the first statewide water restrictions in its history, some El Niño-fueled rains (if not the more damaging aspects) may be quite welcome right now.

But here’s the thing: Those two strong El Niños that saw heavy winter rains in California are only that, a sample of two. In science, that’s too small a pool to make any firm conclusions, L’Heureux said.

‘Not the Only Ball Game’

There are other factors, from the inherent chaos of the atmosphere, to other large-scale climate signals, that can potentially override any push provided by El Niño.

This is exactly what happened with the El Niño of 2009-2010, which while it wasn’t as strong as 1997, was still significant. But other climate signals helped blunt its effects in the U.S., particularly in terms of temperatures, L’Heureux said. Events like that make forecasters cautious about comparing the current El Niño to 1997. (NOAA acknowledged as much by changing out the original image it used and noting that it did so to avoid confusion).

“We think that the strength of [El Niño] is important,” L’Heureux said, but the exact strength it achieves is no guarantee of impacts similar to 1997, “and that’s simply because there’s other stuff going on,” she said. “El Niño is not the only ball game in town.”

The climate impacts typically associated with an El Niño during the months of December, January, and February. Credit: NOAA

So where does that leave us in terms of looking ahead to what El Niño might bring this winter? We have an event that islooking more and more robust (when comparing June 2015 to June 1997, the broad ocean temperature patterns are very similar) and forecasting models are in pretty good agreement that that event will strengthen as we head towards winter and El Niño’s typical peak. But exactly when it will peak and what its final strength will be is still uncertain. Even more uncertain is what those other influences on U.S. weather will be.

So what forecasters can say for now is that the likelihood of those typical El Niño impacts, including rains in Southern California, are higher, but exactly where those rains might fall isn’t yet known.

One factor that may influence that is the remarkable pool of very warm waters that has been parked off the West Coast for a couple years now, a feature that was not present back in 1997. That feature could impact the typical changes El Niño brings to the jet stream, Daniel Swain, a PhD student in climate science at Stanford University, said in an email. It is possible that if the El Niño builds up enough strength, it could overcome that influence, though, he added.

“If El Niño really does make [it] into record territory during the coming winter, it's hard to envision California not experiencing a wetter-than-average winter, at least to some degree,” he said.

The only real guarantee that forecasters can make, though, is that this El Niño event “will evolve in its own way,” L’Heureux said. “It may be similar to certain past events,” but it won’t be exactly the same.

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Comments

Comments 1 to 5:

  1. How little history the experts forget. Christmas 1955 was the strom of the century.

    A series of storms belted the mountains. Ten to 13 inches of precipitation fell in one 3-day period. Balmy temperatures raised the snow level to 9,000 feet as the incessant rain saturated the ground and melted much of the region's promising, 3-foot snow pack.

    Folsom dam just completed that year was to take 3 years to fill, filled in just that one winter.- See more at: http://tahoetopia.com/news/christmas-flood-1955-storm-century#sthash.N9giuHaO.dpuf

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  2. How little context the deniers will look at.

    Fairoakien @1:

    1)  The Christmas 1955 storm was due to a jet stream event according to your own source.  Ergo it was a localized event and not comparable to the El Nino's of 1983 and 1998.  They had world wide impacts, although only the US impacts are mentioned above, including "January and February 1998 were the wettest and warmest first two months to a year for the contiguous U.S. in the 104-year record at that time", not just a limited region in Northern California and areas immediately east of that.

    2)  In any event, the storm of 1955 brought a peak 9.31 inches of rain in a 24 hour period in Blue Canyon.  That record has since been exceeded for December in 1964 (9.33 inches) and for the year in January of 1984 (10.1 inches).  The later is unexpected in that December is normally wetter than January in Blue Canyon.

    So what the "experts forgot" was only a localized storm when they were discussing US wide effects, and a storm which has since been exceeded, with the current record for the location of peak precipitation for the storm of 1955, in the El Nino year of 1984 (on some indices, a stronger El Nino year than 1998).  Perhaps they had not forgotten it at all, but were merely disinclined to mention irrelevant data.

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  3. This research scientist appreciates the eforts of climatologists in providing insight into aspects of how the climate operates by obtaining measurements to go with their understanding. However widespread understanding by politicians and the public of the fact that irreversible rapid climate change and ocean acidification is under way is only slowly growing. Discussion about measures to reduce the rate of emissions from fossil fuels usage is slowly gaining momentum even though there is little recognition that all that can do is slow down the increasing severity of climate change and ocean acidification. There should be more emphasis on measures to cope with sea level rise and more storms, droughts, floods and wild fires togther with the impact on food production and human health.

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  4. denisaf,

    I agree. The ones who currently get the most personal benefit from the burning of fossil fuels must be taxed proprotionately with the benefit they get from the burning of fossil fuels. And that tax money needs to be directed to expenditures that are certain to benefit humanity by addressing the results of the impacts of the unacceptable way they are benefiting.

    And the real challenge has to be a requirement that those who benefit the most from the burning, the likes of the Koch brothers be 'required', in addition to the tax they must pay, to be the most significant promoters, in actions including marketing, of the pursuit of the better understanding of the actual impacts of their pursuits. And they have to be the strongest proponents of the changes that better understanding points to, both the reduction of harm and the measures that are 'certain' to address the harm of the activities that must be rapidly curtailed.

    And if those getting the most benefit from the burning can be shown to not be focused on the development of that proper better understanding or the implementation of what that understanding indicates is required, including better understanding in the general population, then they must face rapid and serious penalty, prison and financial to minimize their unacceptable influence.

    And those measures need to be understood to be a transition as the damaging unsustainable pursuits that have been encouraged to develop by the current fatally flawed socioeconomic system, which is based too heavily on popularity and profit and which fails miserably at keeping those who do not really care about how their pursuits may affect others, from succeeding.

    Terrorists are not the only threat to the future of humanity. And most terrorists are likely the result of successful unacceptable pursuits of profit by already more fortunate people - the real root trouble-makers.

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  5. denisaf,

    What I presented is nothing really new. It is fundamentally the basis for the Kyoto Accord, the more fortunate biggest benfitters to date from the burning of fossil fuels leading the reduction of benefitting from burning and paying the mst to address the consequences of the burning impacts that have already been accumulated.

    What may be new is the focus on individuals rather than nations. Nations are collectives of a variety of types of individuals. The unacceptable trouble-makers exist in all the nations, just to different degrees. And the requirement of the global community is for every nation to effectively deal with the trouble-makers in their nation.

    The appreciation that certain individuals and certain attitudes, not certain nations, are the real problem will help focus efforts more effectively.

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