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There’s a La Nina Developing — So Why is the World Still Heating Up?

Long term, there’s no doubt what’s in control of the world’s temperature trend. The vast belching of greenhouse gasses by fossil fuel industry and related non-renewable based machinery has caused atmospheric carbon levels to hit 405 ppm CO2 and 490 ppm CO2e this year. All this added carbon has caused the world to warm by a record 1.22 C since 1880s levels during 2016 (approx). But superimposed over this long term warming trend is the natural variability based ebb and flow of atmospheric and surface ocean heat that is the El Nino Southern Oscillation (ENSO) cycle.

ENSO — A Wave Pattern Overlying the Long Term Warming Trend

Think of it as a smaller wave pattern that overlaps the current global upswing in temperatures. As El Nino builds and comes into the fore, natural forcings caused by periodic ocean surface warming in the Equatorial Pacific push global temperatures higher. This tends to add to the human forced global warming trend. So, often, El Nino years are also record warm years.

global-temperatures-enso

(El Nino to La Nina temperature variations create a wavy pattern in the overall global warming trend. Note — the record warm year of 2016 is not included in this graph. Image source: NOAA.)

Conversely, La Nina, which generates a periodic cooling in the Equatorial Pacific tends to pull a bit against the long term warming trend. So periods of La Nina tend to show average global atmospheric temperatures in the annual measure drop off by about 0.2 to 0.4 C from the peak periods of atmospheric heating during El Nino. Of course, since the ENSO variability typically follows a range of +0.2 C to -0.2 C but does not affect long term temperature trends, it only takes about a decade for La Nina years to be about as warm as recent El Nino years.

Slight Warming During Fall of 2016 Despite La Nina

During fall of 2015 and the winter and spring of 2016 a powerful El Nino helped to push global surface temperatures into new record high ranges. This happened because greenhouse gasses the world over had been loading heat into the Earth System for some time and the strong El Nino served as a kind of trip wire that opened the flood gates for a surge of atmospheric heat. Which is why 2016 will be about 1.22 C hotter than 1880s temperatures (1 C hotter than NASA 20th Century baseline temps) and why the years from 2011 to 2016 will average above 1 C hotter than 1880s values overall (0.8 C hotter than 20th Century baselines).

But now, with the 2016 El Nino in the rear view mirror and with a La Nina forming in the Pacific, we would expect global temperatures to cool down somewhat. For the most part, this has happened. Back in January and February, monthly average temperatures were as much as 1.5 C above 1880s averages. Since summer, the averages have dipped to around 1 to 1.1 C above 1880s values.

gfs_anomaly_timeseries_global

(Global temperatures bottomed out at around 1 C above 1880s or 0.4 C above the 1981 to 2010 average in this GFS based graph by Karsten Haustein during June then began to slowly climb through fall even as a weak La Nina began to develope.)

With La Nina continuing to form, we would expect these monthly values to continue to fall for a bit as La Nina strengthened. But that doesn’t appear to be happening. Instead, global atmospheric temperatures bottomed out at around 1 to 1.1 C above 1880s levels in June, July, August and September and now they appear to be rebounding.

Polar Amplification Signal Shows Up as a Blip in the Global Measure

In other words, we see a rise in the global temperature trend when we should see a steady counter-trend decline forced by natural variability.

Why is this happening?

The climate evidence points to a rather obvious set of suspects. First, the long term Pacific Decadal Oscillation value has continued to push into the positive range. And this state would tend to favor more heat radiating back into the atmosphere from the ocean surface.

However, if you look at the global climate maps, the major anomaly drivers are not coming from the Pacific, but from the poles. For this fall saw extreme warming both in the northern and southern polar regions of the world. Today, temperature anomalies in both the Arctic and the Antarctic were 5.84 and 4.19 C above average respectively. A rough average between the two poles of +5 C for these high latitude regions. As we’ve mentioned many times before, such severe warming is an obvious signal of climate change based polar amplification where temperatures at the poles warm faster relative to the rest of the Earth during the first phase of greenhouse gas forced warming.

extreme-polar-amplification-november-4

(Extreme warming of the polar regions continued on November 4 of 2016. This warming is pushing against the La Nina trend which would tend to cool the world temporarily. Image source: Climate Reanalyzer.)

By themselves, these abnormally high temperatures at the poles would be odd enough. But when taking into account that La Nina should still be cooling the globe off, it starts to look like this severe polar warming has jostled the La Nina cooling signal a bit — turning it back toward warming by late fall. And if that is what’s really happening, then it would imply that the natural variability signal that is produced by ENSO is starting to be over-ridden by polar amplification based influences. In other words, there appears to be another signal that’s starting to intrude as a polar amplification based temperature spike.

It’s something that has popped up from time to time as a blip in the observational data over the past few years. But fall of 2016 provides one of the stronger signals so far. And it’s a signal related to a set of feedbacks that have the potential to affect the overall pace of planetary warming. Something to definitely keep an eye on.

Links:

NOAA

Karsten Haustein

Climate Reanalyzer

NOAA El Nino

Hat tip to June

Hat tip to ClimateHawk1

Hat tip to JCH

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Giant Gravity Waves Smashed Key Atmospheric Clock During Winter of 2016 — Possible Climate Change Link

Two [climate change] effects [of Arctic warming] are identified … : 1) weakened zonal winds, and 2) increased [Rossby] wave amplitude. These effects are particularly evident in autumn and winter consistent with sea-ice loss… Slower progression of upper-level waves would cause associated weather patterns in mid-latitudes to be more persistent, which may lead to an increased probability of extreme weather events — Evidence linking Arctic amplification to extreme weather in mid-latitudes, Dr. Jennifer Francis and Dr. Stephen Vavrus, Geophysical Research Letters (emphasis added)

The recent disruption in the quasi-biennial oscillation was not predicted, not even one month ahead. — Dr. Scott Osprey

This unexpected disruption to the climate system switches the cycling of the quasi-biennial oscillation forever. — Professor Adam Scaife

scientists believe that the quasi-biennial oscillation could become more susceptible to similar disruptions as the climate warms. — Physics.org (emphasis added)

jet-stream-crossing-equator-on-february-18-of-2016

(During February of 2016, high-amplitude Jet Stream waves or gravity waves interfered with the upper-level Equatorial Winds. This disruption was so significant that it caused a seasonal upper-level wind pattern near the Equator to change direction, a shift that was unprecedented in modern observation. Note how the upper-level wind flow frequently intersects with and even appears to cross the Equator at some points. Image source: Earth Nullschool global 250 hPa capture for February 18, 2016.)

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I’ve said it before, and I’m going to say it again — loss of predictable seasons, or seasonality, due to human-forced climate change is very big deal. And regardless of how all the scientific details specifically pan out, there are now observed changes to Northern Hemisphere winter, possibly due to human-forced warming, that are apparently starting to undermine its traditional seasonal climate behaviors. As a result, weather patterns appear to be shifting toward greater extremes and lower levels of predictability.

QBO — One of Our Most Predictable Atmospheric Clocks…

For decades now, scientists have been observing a kind of atmospheric clock tick-tocking high above the Equator. Up in the stratosphere, 10 to 13 kilometers above the Earth, winds tend to flow either east to west or west to east. These air flows change direction about every 28 to 29 months. This feature, called the quasi-biennial oscillation or QBO, has never significantly varied. It has always flowed in one direction for a predictable period of time and then switched to flow in the other direction.

Winds flowing at this level of the atmosphere over the Equator have a far-reaching effect, particularly on the winter climate of northern Europe. There, westerly high-level Equatorial winds are known to bring warmer, wetter winters. Easterlies in the stratosphere over the Equator are known to bring cooler, drier winters. The key to remember is that the QBO has always been both amazingly predictable itself, and had equally predictable climate effects. As a result, meteorological observation of the QBO natural-variability pattern enabled forecasters to get an idea of what weather trend to expect for winter — not just during a single year, but also over a longer time horizon.

…and Climate Change May Now Be in the Process of Breaking It

What happens if the QBO becomes less predictable due to influences such as human-forced polar warming? What happens if the big meanders in the Jet Stream produced by this warming dig down all the way to the Equator during Northern Hemisphere winters and start to shove at the upper-level Equatorial wind field, causing the QBO to switch? If that happens, then a major aspect of Northern Hemisphere winter seasonal variability will have been fundamentally altered by climate change. Winter would become less like it is now and more like some strange, difficult-to-predict, climate-change-morphed hybrid of a thing.

Over the past decade, scientists like Dr. Jennifer Francis have observed strange changes to the Northern Hemisphere Jet Stream. In winter, the North Pole has tended to exhibit extreme relative warming versus the rest of the Northern Hemisphere. This warming has created less difference in temperature from north to south during this season. As a result, it appears that the Jet Stream has slowed and is generating very large atmospheric waves, known as gravity waves or Rossby waves. At times, these waves have linked upper-level air flows between the Tropics and the North Pole.

(For years now, Dr. Jennifer Francis has warned that polar amplification could lead to some weird and extreme weather, especially during winter. However, no one initially predicted that the large Jet Stream waves apparently resulting from polar warming would completely disrupt the upper-level Equatorial winds as appears to have happened last February.)

Such strong polar warming during winter is called polar amplification, an effect produced by climate change. Polar amplification happens because greenhouse gasses resulting from fossil-fuel burning (like carbon dioxide and methane) preferentially trap heat during times of darkness. During December through March, large sections of the North Pole are blanketed in the dim of Polar Night. During this time the heat-trapping effects of these gasses really go to work. Additionally, heat from the ocean is transferred through the thinning veil of sea ice over the Arctic Ocean even as local carbon stores add to the overburden of the heat-trapping gasses already in place. The net effect is a much warmer-than-normal Arctic during winter. This warming appears to be doing a serious number on the Jet Stream and, apparently, even Equatorial atmospheric circulation.

Unprecedented QBO Switch in February 2016

During the most recent winter, scientists observed these high-amplitude Jet Stream waves reaching all the way into the Equatorial upper-level wind field with enough oomph to switch an east-west wind pattern to west-east. This switch was entirely unpredicted and unprecedented. No one expected it and it has never before been observed.

The weather pattern for a big swath of Europe was, as a result, flipped from the expected cool and dry to warm and wet. If you had told any atmospheric scientist that such a set of changes would happen, they might have categorically dismissed these claims. But now, some scientists are starting to look at the possibility that the recent QBO flip was due to a climate warming-related influence.

geographical-pattern-of-surface-warming

(Geographic pattern of surface warming as provided by the IPCC. Uneven relative warming of the surface of the Earth may result in some unexpected changes to larger atmospheric circulation patterns. Scientists now indicate that future flips in Equatorial wind patterns, like the big switch that occurred this past winter, may be driven by such atmospheric warming. Image source: IPCC.)

There is a possibility that the recent flip was related to large atmospheric waves which are potentially a result of polar amplification. These waves appear to have impacted the upper-level Equatorial winds, and so are not necessarily related to natural climate variability.

To initiate such a big atmospheric change requires a great deal of force. The equatorial wind field and atmospheric mass is generally the heaviest, is typically the region with the greatest atmospheric inertia. Having an outside influence, like polar warming and associated gravity waves, generating a flip in its flow is about the meteorological equivalent to rivers running up hill. Apparently, due to climate change, atmospheric ‘rivers’ in the Jet Stream may now be capable of doing just that, and that’s pretty disturbing.

Links/Statements/Hat tips:

Scientific hat tip to Dr. Jennifer Francis

Scientific hat tip to Dr. Scott Osprey

Scientific hat tip to Professor Adam Scaife

Evidence linking Arctic amplification to extreme weather in mid-latitudes

Unprecedented atmospheric behavior disrupts one of Earth’s most regular climate cycles

An unexpected disruption of the atmospheric quasi-biennial oscillation

Earth Nullschool

Note: Paul Beckwith again appears to be using this issue as a means self-promotion — bragging about ‘vindication’ and his video ‘that went viral.’ First, this issue is a matter of concern (not petty personal score-keeping). And it is probably one that remains uncertain given that the MET study is the first to touch on it in the peer reviewed science. So any definite claims at this point are both unwarranted and premature. Caution and humility should be the watch-words here. Not active grasping for credit or media attention. Further, I did not work with Paul Beckwith on his first ‘viral’ video — which was an independent response to my initial gravity waves article here. So responsible sources will not conflate my work with that of Paul’s even though he appears to agree with my (admittedly evolving) analysis in some (but not all) instances. For my part, this work is an attempt to open the issue. Not to close it or to support someone attempting to claim credit of first discovery.

Finally, I absolutely respect and admire the work and opinions of scientists like Gavin Schmidt, Stefan Rahmstorf, Jennifer Francis, the IPCC, the MET Office and others who have helped to build a powerful and compelling consensus on climate change as a critical issue for the 21st Century. Sometimes the process of threat identification will highlight instances that are outside of that consensus currently. And such identifications will, at times, result in strong reactions. I understand that this is part of the process and even if views differ, I will endeavor to read, and where I am able, incorporate them into my ongoing study here.

No More ‘Hiatus’ — Human Emission to Completely Overwhelm Nature by 2030

Keep burning fossil fuels at current rates and you can kiss nature’s influence over temperature good-bye. That’s the conclusion of two recent scientific studies.

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Humans are forcing heat trapping substances into the atmosphere at a terrifying pace. We pump out more than 10 billion tons of carbon on the back of about 50 billion tons of CO2 equivalent hothouse gasses into the atmosphere each year. This massive volume is the upshot of an inexorably rising emission starting during the 19th century and continuing to this day. By the end of this century, rates of burning could again increase nearly threefold.

The current, rampant pace of human emission is now at least six times faster than at any time during Earth’s geological past. But on our current path, that rate could exceed 20 times that seen during any of the previous worst hothouse extinction events.

Emission scenarios

(Current rate of annual carbon emissions in gigatons [black dots] compared to IPCC projected scenarios. Note that current human emissions are on the worst case emissions path. Image source: Global Carbon Project.)

This incredible rate of emission was the key factor in two new studies issued this week investigating the possibility of future hiatuses or ‘pauses’ in global warming due to nature-driven variability (see the studies here and here). And what the studies found was that rampant human burning of fossil fuels removed any possibility for hiatus decades driven by natural variability after 2030.

In essence, we are in the process of shutting down nature’s temperature-related influence entirely.

Understanding Natural Cycling Between Warm and Cool Periods

Natural shifts between atmospheric warm and cool spells appear to be primarily driven by how much heat the oceans uptake or expel.

In the Pacific, this rate of heat uptake is driven by the strength or weakness of the trade winds driving across the equator. During periods in which the trade winds are strong, a great volume of air contacts the surface water and more atmospheric heat is driven into the ocean through down-welling. During periods in which the trade winds are weak, the atmosphere-to-ocean heat transfer shuts down even as warmer waters rise from the depths and spread out across the ocean surface. During these times, the ocean is dumping heat back into the atmosphere.

A similar process happens in the Atlantic where salty, warm surface water down-welling transfers atmospheric heat toward the deep ocean. When that process shuts down, more heat piles up at the ocean surface and bleeds back into the atmosphere.

The first of these processes is called Interdecadal Pacific Oscillation (IPO — which is related to ENSO variations) and is thought to be the primary governor of this global natural variability. The second process, Atlantic Multidecadal Oscillation (AMO), is thought to be the lesser of the two forces.

Past Variability in the Global Temperature Record

Even with large-scale human warming proceeding throughout the 20th Century and into the 21st Century, we can see the effects of this natural variability on the global temperature record. During naturally driven warmer periods human-caused warming advances rapidly. During two of the naturally driven cool periods, human forced warming has a set-back, and, during the third, only seems to briefly slow down.

Temps since 1880

(Global temperature record as compiled by NASA. Note how warming has traditionally proceeded in a step-like fashion. Image source: NASA GISS.)

Taking a closer look, we find that the time from 1880 to 1910 saw global surface temperatures falling by 0.2 degrees Celsius as ocean heat uptake increased and IPO went negative. From 1910 to 1940, the IPO driver switched into positive. As the oceans disgorged their heat, the first effects of human greenhouse gas heat forcing became evident as global temperatures jumped by 0.45 degrees Celsius over a 30 year period. From 1945 to 1975, IPO again switched into negative, but this time human forcing was in the driver’s seat and temperatures only fell by around 0.06 degrees Celsius. By 1975, temperatures were again on the rise and through 2002, the heat spike rocketed fully 0.6 degrees C upward.

From about 2002 onward, we enter the current ‘hiatus’ period in which atmospheric warming, during a time when we should have seen cooling, has proceeded slowly despite major natural variability factors pushing for cooler atmospheres and warmer oceans.

Reducing Impacts of Natural Variability

The term ‘global warming hiatus,’ however inaccurate, is a new invention. Its use first cropped up over the past couple of years as human greenhouse gas forced warming seemed to slow somewhat from its rampant upward pace through the 1980s and 1990s. This brief pause in atmospheric warming caused some global warming skeptics to declare an end to human-caused heating. An extraordinary claim in the face of highest ever heat-trapping gas emissions.

But what was really happening was that natural variability, which should have been driving the Earth’s atmosphere to cool, was starting to take a back seat.

For two recent studies, mentioned above, found that natural variability driven temperature change has radically fallen even since the 1980s.

The first study, headed by Masahiro Wantanabe, found that, during the 1980s natural variability was responsible for about 47 percent of the observed global temperature change. By the 1990s, this number had fallen to 37 percent. And as an IPO driven switch should have led to cooler temperatures during the 2000s, Wantanabe finds that the effect of natural variability had again plunged to 27 percent.

The cause for the loss of the temperature driving effect of natural variability, according to global climate model runs, is a stunning rate of human greenhouse gas increase. And a related study led by Nicola Maher found that if greenhouse gas emissions by humans kept rising at ever more rapid rates, the natural variability measure is completely overwhelmed by 2030:

The likelihood of future hiatus periods is found to be sensitive to the rate of change of anthropogenic forcing. Under high rates of greenhouse gas emissions there is little chance of a hiatus decade occurring beyond 2030, even in the event of a large volcanic eruption.

Under the worst case emissions scenario — RCP 8.5 — natural variability is completely subsumed by human warming by 2030. Continuing on this track through 2100 means that the human forcing is so strong that even a volcanic eruption on the scale of Krakatau would not be enough to generate a warming hiatus.

For those considering use of solar radiation mitigation through aerosol inject, this point is a very important one to consider. It is a basis for proof that such mitigation eventually radically fails to reduce greenhouse gas heating effects if levels of emissions are not also drawn down.

Sadly, we are currently on the RCP 8.5 track. But, according to the studies, if humans could somehow rapidly reduce greenhouse gas emissions, the effect of natural variability on climate would be at least somewhat preserved.

Human-Forced Variability

The discussion of natural variability does not include instances in which human heat forcing produces outcomes outside of natural variability. The most obvious of these would be a large glacial outburst event in which enough water is released from Greenland and West Antarctica to raise seas by 1 meter or more this century. Such an event would have a temporary cooling effect that could result in an unnatural hiatus in warming. Such a human-forced variability was not considered in these global climate model studies, but it is worth considering as the strength of the now rampant human heat forcing continues to increase.

Links:

Global Carbon Project

NASA GISS

Contribution of Natural Variability To Global Warming Acceleration and Hiatus

Drivers of Decadal Hiatus in 20th and 21st Centuries

No More Pause — Global Warming Non-Stop From Now On

Hat Tip to Colorado Bob

 

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