From ETH Zurich –Why global warming is taking a break
The average temperature on Earth has barely risen over the past 16 years. ETH researchers have now found out why. And they believe that global warming is likely to continue again soon.
Global warming is currently taking a break: whereas global temperatures rose drastically into the late 1990s, the global average temperature has risen only slightly since 1998 – surprising, considering scientific climate models predicted considerable warming due to rising greenhouse gas emissions.
Climate sceptics used this apparent contradiction to question climate change per se – or at least the harm potential caused by greenhouse gases – as well as the validity of the climate models. Meanwhile, the majority of climate researchers continued to emphasise that the short-term ‘warming hiatus’ could largely be explained on the basis of current scientific understanding and did not contradict longer term warming.
Researchers have been looking into the possible causes of the warming hiatus over the past few years. For the first time, Reto Knutti, Professor of Climate Physics at ETH Zurich, has systematically examined all current hypotheses together with a colleague. In a study published in the latest issue of the journal Nature Geoscience, the researchers conclude that two important factors are equally responsible for the hiatus.
El Niño warmed the Earth
One of the important reasons is natural climate fluctuations, of which the weather phenomena El Niño and La Niña in the Pacific are the most important and well known. “1998 was a strong El Niño year, which is why it was so warm that year,” says Knutti. In contrast, the counter-phenomenon La Niña has made the past few years cooler than they would otherwise have been.
Although climate models generally take such fluctuations into account, it is impossible to predict the year in which these phenomena will emerge, says the climate physicist. To clarify, he uses the stock market as an analogy: “When pension funds invest the pension capital in shares, they expect to generate a profit in the long term.” At the same time, they are aware that their investments are exposed to price fluctuations and that performance can also be negative in the short term. However, what finance specialists and climate scientists and their models are not able to predict is when exactly a short-term economic downturn or a La Niña year will occur.
Longer solar cycles
According to the study, the second important reason for the warming hiatus is that solar irradiance has been weaker than predicted in the past few years. This is because the identified fluctuations in the intensity of solar irradiance are unusual at present: whereas the so-called sunspot cycles each lasted eleven years in the past, for unknown reasons the last period of weak solar irradiance lasted 13 years. Furthermore, several volcanic eruptions, such as Eyjafjallajökull in Iceland in 2010, have increased the concentration of floating particles (aerosol) in the atmosphere, which has further weakened the solar irradiance arriving at the Earth’s surface.
The scientists drew their conclusions from corrective calculations of climate models. In all climate simulations, they looked for periods in which the El Niño/La Niña patterns corresponded to the measured data from the years 1997 to 2012. With a combination of over 20 periods found, they were able to arrive at a realistic estimate of the influence of El Niño and La Niña. They also retroactively applied in the model calculations the actual measured values for solar activity and aerosol concentration in the Earth’s atmosphere. Model calculations corrected in this way match the measured temperature data much more closely.
Incomplete measured data
The discrepancy between the climate models and measured data over the past 16 years cannot solely be attributed to the fact that these models predict too much warming, says Knutti. The interpretation of the official measured data should also be critically scrutinised. According to Knutti, measured data is likely to be too low, since the global average temperature is only estimated using values obtained from weather stations on the ground, and these do not exist everywhere on Earth. From satellite data, for example, scientists know that the Arctic region in particular has become warmer over the past years, but because there are no weather stations in that area, there are measurements that show strong upward fluctuations. As a result, the specified average temperature is too low.
Last year, British and Canadian researchers proposed an alternative temperature curve with higher values, in which they incorporated estimated temperatures from satellite data for regions with no weather stations. If the model data is corrected downwards, as suggested by the ETH researchers, and the measurement data is corrected upwards, as suggested by the British and Canadian researchers, then the model and actual observations are very similar.
Warming to recommence
Despite the warming hiatus, Knutti is convinced there is no reason to doubt either the existing calculations for the climate activity of greenhouse gases or the latest climate models. “Short-term climate fluctuations can easily be explained. They do not alter the fact that the climate will become considerably warmer in the long term as a result of greenhouse gas emissions,” says Knutti. He believes that global warming will recommence as soon as solar activity, aerosol concentrations in the atmosphere and weather phenomena such as El Niño naturally start returning to the values of previous decades.
Literature reference
Huber M, Knutti R: Natural variability, radiative forcing and climate response in the recent hiatus reconciled. Nature Geoscience, online publication 17 August 2014, doi: 10.1038/ngeo2228
Think the clue was in the authors name…..
I would love someone to explain to me, with explicit reference to the laws of thermodynamics, how the heat firstly is transported to the deep ocean without perturbing the climate, and secondly is trapped there in a fluid, again without making any measurable perturbations to the climate.
rogerthesurf says:
August 19, 2014 at 11:32 pm
So much BS. If El Nino returns and sunspots become numerous again there will be warming.
Are you talking about this?
Region Number of
sunspots Class
Magn. Class
Spot
2139 5 β CAO
2141 9 β ESI
2143 5 β DRI
2144 2 β DAO
2146 1 α HSX
2147 2 α HAX
http://www.spaceweatherlive.com/en
OK. Let me get this straight.
CO2 drives the climate unless there are natural influences at work like El Niño and La Niña, sunspot cycles, concentration of floating particles, PDO cycles and AMO cycles. Lets not forget other natural influences such as cloud cover and electro magnetic activity. While we are at it, we can throw in the tilt and wobble, plus unknown natural influences on our planet. Heck, as far as I know fish communicating could have a greater influence than CO2.
“He believes that global warming will recommence as soon as solar activity, aerosol concentrations in the atmosphere and weather phenomena such as El Niño naturally start returning to the values of previous decades.”
How do you know the previous decades are the “normal?” Maybe they are abnormal and the present is normal. Or maybe there is no ‘normal’ because they are always changing.
“According to Knutti, measured data is likely to be too low, since the global average temperature is only estimated using values obtained from weather stations on the ground, and these do not exist everywhere on Earth”
Weather stations and satellites agree. No statistically significant warming in over a decade. C’mon you can invent a smarter excuse than that.
“According to the study, the second important reason for the warming hiatus is that solar irradiance has been weaker than predicted in the past few years.”
So now you are admitting solar irradiance has greater influence than greenhouse gases.
“what finance specialists and climate scientists and their models are not able to predict is when exactly a short-term economic downturn or a La Niña year will occur.”
Natural variability is short term and long term. PDO has 30-year cycle. THC has 1,000-year cycle. AGW is believed to have occurred in the last 60 years. The timescale overlaps with natural cycles. Hence it’s not easy to distinguish one from the other.
The painful lack of universal training for scientists in the elements of logic shows all too clearly in this spectacularly Knutti paper. The climate scare – with the billion a day that the profiteers of doom are making out of it – is based upon predictions by models. No predictions, no scare. The predictions have proven spectacularly wrong since 1988, when Knutti’s long-time co-author and climate campaigner James Hansen predicted 0.5 K/decade warming (and was trumped in the same year by Margaret Thatcher, who predicted 1 k/decade warming).
IPCC in 1990 predicted 1 K warming by 2025. Result after 25 of the 35 years: just one-third of a Kelvin. To reach even the 0.7 K lower bound of IPCC’s 1990 prediction, there would need to be at least another one-third of a Kelvin in just ten years. And that would be the fastest decadal rate of warming since the global temperature record began in 1850. It would be nearly twice as fast as the fastest rate observed since 1850. Since the Sun is becoming less active, that rate of warming is improbable.
My best guess, based on an irreducibly simple climate model, is that by 2025 less than 0.5 K warming will have occurred since 1990. No amount of jiggery-pokery or hokey-stickery will be able to conceal, fudge or airbrush out that massive discrepancy between overheated prediction and lukewarming reality.
Expect to see more Knonsensical papers over the coming year, as the F. of D. make their last big effort to bully intellectually feeble-minded and scientifically-illiterate governments into adopting a binding world-government treaty even nastier than the one that deservedly failed at Copenhagen five years ago. If they fail in Lima this December and fail again in Paris next December, that will be the end of the scare. For by then – allowing for an el Nino and then a la Nina – there will have been no global warming for close to 20 years, even though CO2 emissions in those 20 years were higher than at any previous period in the past 810,000 years.
In the meantime, hold fast to the data. Even the data are to some extent suspect and prone to endless revision, but the predictions – however the usual suspects slice them and dice them – are entirely worthless. There is not yet any scientific basis for rushing to act on the climate. However, since the models relied upon by IPCC have failed, they and the IPCC itself should be de-funded.
Knutti would have a leg to stand on if in the late 90s or early 00s he was proclaiming that the warming was predominantly due to El Nino. Then invoking La Nina would make sense since he would be an ENSO-ist. Other wise he is, at best, like any market fluctuation prognosticator or dare I say Bernie Madoff.
Well, this paper is no different from the ol’ joke ” If my aunt had b******s she’d be my uncle “
Clouds over Europe.
http://www.sat24.com/pl/eu
http://cosmicrays.oulu.fi/webform/query.cgi?startday=20&startmonth=07&startyear=2014&starttime=00%3A00&endday=20&endmonth=08&endyear=2014&endtime=23%3A30&resolution=Automatic+choice&picture=on
Richard says I’ve lost the pea, and somebody else thinks I have given a nod to solar cycles. Say what? Disregarding direct daytime heating for a moment, heat is stored in the oceans and is not substantially released until evaporation sends it into the air. When evaporation turns water vapor into rain, that stored heat is released which in turn causes air temperatures to rise. If oceans were significantly replenished with heat under clearer skies somewhere in our recent past, but the oceans are now in evaporation mode, we will warm up in jagged fits and starts. That stored and now released heating is mixed with direct solar heating. Solar cycles and all the parts therein create such a small blip it can be ignored. Why? Our sensors are not that sensitive and our variable planet buries the solar signal in Earth’s own noise.
I don’t have a dog in the fight over terminology but here is my elevator speech. Global warming is strictly a temperature sensor phenomenon. Nothing else. The term is agnostic to cause. Anthropogenic global warming commonly refers to increased temperatures being caused by human influence. I would admit to urban heat island and rural backyard BBQ heating as being human related thus is anthropogenic warming and is measurable. The additional fossil fuel CO2 molecules do not increase temperatures to the degree that our sensors would notice. On a global scale, natural intrinsic processes, primarily by variously absorbing and expelling heat from the oceans into our greenhouse-like atmosphere, create warming and cooling temperature trends calculated from our temperature sensors. The trends can be short or long term and when measured by our current sensors are jagged-like steps up and down with pauses here and there.
Responses related to terminological gnat hairs (heating versus temperature versus energy, etc) are funny to read but I don’t care seriously about that kind of argument. Not on my payscale.
Meanwhile, the majority of climate researchers continued to emphasise that the short-term ‘warming hiatus’ could largely be explained on the basis of current scientific understanding and did not contradict longer term warming.
If they can post-facto “explain” it via current scientific understanding, why, pray tell, was that scientific understanding not included into at least one of the many GCMs? Hmmm?
Pamela Gray:
At August 20, 2014 at 7:14 am you assert
You could not be more wrong!
The issue is anthropogenic (i.e. man-made) global warming (AGW) and its probable effects. Vast expenditures of time, money and effort have been spent and are being spent to determine AGW, to avoid it, and to mitigate its effects.
Those expenditures are already killing people.
AGW is – and always has been – about increase to global average surface temperature anomaly (GASTA). But GASTA has not risen as proponents of AGW predicted. This should be a matter of rejoicing because it provides doubt to the need for the actions which are killing people.
The response of AGW-advocates such as Knutti is to make excuses for the cessation of AGW, and warmunists such as dp to pretend that global warming has not stopped so AGW has not stopped. Thus they attempt to sustain the AGW-scare and its induced expenditure which a\re killing people.
And you claim that objections to their excuses and pretenses “are funny to read but {you} don’t care seriously about that kind of argument”.
OK. You say you “don’t care seriously”. Be assured that some of us do care seriously about campaigns which are successfully killing people, and we don’t think those campaigns “are funny to read”. We care to the degree of real anger.
Richard
Pamela Gray where is warm?
http://earth.nullschool.net/#current/wind/surface/level/overlay=misery_index/equirectangular
RGB says: “Nobody (rational) doubts that increasing CO_2 will have a net positive effect on the average temperature.”
=====
Since, no evidence has been presented that shows the “net positive effect on the average temperature” and the models used to predict this have proven wrong, then I don’t think it is irrational to doubt the ability of CO2 to have a “net positive effect”.
Those ‘scientists’ are going to correct themselves to death – and their incompetent models, too.
My favorite part is this quote “Short-term climate fluctuations can easily be explained. They do not alter the fact that the climate will become considerably warmer in the long term as a result of greenhouse gas emissions,” says Knutti.
Oh short term climate fluctuations can EASILY be explained?!! We are up to at least 31 excuses for the so-called pause and counting. By their own admission they are not certain why warming stopped,but its easily explained? HUH?
The temperature at the altitude of about 3500 m. Click on the map and check.
http://earth.nullschool.net/#current/wind/isobaric/700hPa/overlay=temp/equirectangular
You have misread my question. Your answer applies to places on Earth, but not the totality of Earth. My question was regards global warming, not regional warming. Your response describes a process that does nothing to change the average (global) temperature of the Earth (all of it). You have moved money between pockets and not changed your wealth in the process.
rgbatduke says:
August 19, 2014 at 9:18 am
Well said and argued. Maybe I’m not rational, but IMO the GHE of CO2 observed in the lab might not obtain in the actual atmosphere.
Sorry for the digression. High pressure building over the lower Mississippi Valley will bring strong rains on the west side.
http://earth.nullschool.net/#2014/08/24/1200Z/wind/isobaric/850hPa/overlay=total_cloud_water/orthographic=-96.20,38.70,1198
Richard Courtney
http://wattsupwiththat.com/2014/08/19/excuse-31-for-the-pause-el-nino-and-longer-solar-cycles/#comment-1713156
henry said
good argument!
note my comment:
there is no [measureable] AGW and there is no [measureable] UHI either, when looking at a reasonably sized global sample of weather stations.
Namely, both would [mainly] affect minimum temperatures or at least seriously enhance them. Yet minima are falling and I find a natural curve…
http://blogs.24.com/henryp/files/2013/02/henryspooltableNEWc.pdf
last table, on the bottom
All results are showing that in nature there is no pause or halt
It either warming or it is cooling.
It is now globally cooling.
dp:
At August 20, 2014 at 11:11 am you say to me
No. You have misrepresented my answer.
My answer applies to GLOBAL temperature, and I wonder what part of the phrase “global warming” you are pretending to not understand. I said at August 20, 2014 at 12:00 am
I will ‘spell it out’ by using simple arithmetic and two hypothetical planets.
The planets heated from space (e.g. by a Sun) with the same radiative heat flux of Es. They each have the same global average surface temperature (GASTA) and they are identical except for one difference. They must each radiate energy equal to Es to maintain radiative balance: failure to radiate at a rate equal to Es results in GASTA adjusting until radiative balance is re-established.
Planet 1.
It has a uniform temperature of 290K over its entire surface.
Its GASTA is T1 and is equal to 290K.
Planet 2.
It has a night side (i.e. hemisphere) with uniform temperature of 240K, and a day side with uniform temperature of 340K.
Its GASTA is T2 and is equal to 290K.
Please note that they have the same average temperature of 290K
But they do NOT radiate heat back to space at the same rate because heat is radiated in proportion to the fourth power of the temperature of the radiating surface.
Planet 1 radiates heat at a rate (E1) proportional to
(290^4)K = 7,070,281,000 radiative units.
Planet 2 radiates heat at a rate (E2) proportional to
{(240^4/2) + (340^4/2)} = 1,692,057,600 radiative units
Clearly, Planet 1 radiates much more heat than Planet 2.
Let Planet 1 be in radiative balance and its temperature stays at 290K.
Redistribute its surface temperature (by moving heat from one side to the other) so it becomes like Planet 2, and it radiates less heat than it receives. Therefore, its GASTA rises until radiative balance is re-established.
Richard
jimmaine says:
August 19, 2014 at 3:08 pm
Warmers: Because the temperature tracks with the climbing C02 levels, so that’s the reason, period.
========================================================================
In a recent argument with a warmist that person had to resort to saying that temperature does not track co2. The reason for that was I posed this question, ” Between 1750 to 1997/98 co2 rose by 87ppm. So in 247 year co2 rises by 88 ppm and there is warming. Why then is there no further warming from a co2 rise of 33 ppm in 17 years?”. His answer was that co2 does not always track with higher temperature. This person claims to be a scientist. Homer Simpson shows more logical ability than many of these warmists.
Here’s the real “Money Shot”, as Hollywood likes to say:
“He believes that global warming will recommence as soon as solar activity, aerosol concentrations in the atmosphere and weather phenomena such as El Niño naturally start returning to the values of previous decades.”
In other words, everything has a greater modifying influence on GW than burning fossil fuels and and the attendant rise in CO2 levels. QED.
AGW, RIP!
Bob Ferdinand:
Thanks for your very fine post at August 20, 2014 at 4:36 pm. You say
Yes! The paper proclaims that many things have “a greater modifying influence on GW than burning fossil fuels and and the attendant rise in CO2 levels”.
And that is why it is important to ensure the paper is publicised and its assertions are not allowed to be distorted.
Richard
To return to the model I mentioned above, given the Beers-Lambert Law (which is not terribly difficult to derive and which has been more than amply experimentally verified), doubting the ability of increasing CO_2 to have a net positive effect on average temperatures is like having a mass on a spring, pulling it away from equilibrium, and having it either not move at all or worse, move the other way.
, it is pretty certain that the sign of this term is everywhere positive. That doesn’t mean that the temperature necessarily has to actually go up with CO_2 at all, certainly not in any short-run observation of a particularly initialized dynamical evolution and forcing scheme. It does make it difficult to see how on average (averaging, in particular, over all initial conditions and some given range of forcings) the response is going to be zero or negative.
I agree that the net systematic effect of CO_2 can easily be lost against the much larger variations driven by natural phenomena, non-Markovian dynamics and prior state, chaotic nonlinear dynamics and feedbacks. However, in terms of the partial derivative of global average surface temperature one expects for CO_2 increases,
So sure, I’ll grant that one can probably invent trigger-pulling highly nonlinear models where one does indeed pull a trigger a bit one way only to release a powerful spring that drives it the other as a transient, one shot affair corresponding to a very special initial state (one with a powerful cocked spring waiting to be triggered with a weak pull). However, these special systems and initial conditions are comparatively unlikely and even more unlikely to be generalizable or to represent suitably averaged behavior in the long term.
Does that mean CO_2 can rescue us from an impending glacial episode? Possibly — it might be just enough to prevent the right conditions from forming that lead to strong negative feedback from e.g. growing ice sheets. Possibly not — we have evidence that glacial episodes can occur when CO_2 levels are over an order of magnitude higher than they are today, although we cannot explain them. Or, as I said, the straight-up Beers-Lambert warming one “expects”, on the order of 1 C per doubling (not very precisely known because of many approximations and assumptions in the models), when mixed with nonlinear feedbacks from e.g. water vapor, could either increase or decrease the expected warming, with — IMO — decrease being physically a lot more plausible given the observed general stability of the climate system. So perhaps it might lead to only 0.1, or 0.3 C warming per doubling, suitably averaged over initial conditions, state, forcings, etc. And for any given initial condition, prior state, and forcing dynamic, the natural nonlinear variation of the system could easily swamp this relative effect to replace it with absolute cooling, much stronger warming (but not forced by CO_2) or anything in between.
After all, that’s basically what is being asserted for the 1997-1998 ENSO. It was basically a great big spring, being gradually cocked by Mr. Sun dumping comparatively strong sunlight through comparatively clear skies into comparatively mixed ocean waters, and eventually something — almost certainly not CO_2-related in any way, as Pamela Grey has noted — pulled the trigger. Did increased CO_2 contribute to the observed huge burst of warming? Maybe, sure, why not, possibly. It is nearly impossible to say. Once can perhaps say probably in the strict sense that it probably had a small net warming effect as it increased over that time frame as opposed to, say, a net cooling or net neutral effect. We just have no possible way too separate that warming from warming due to ENSO, the phase of the NAO, the accidental state of the global thermohaline circulation, the effect of anti-smog regulations that comparatively rapidly were cleaning up anthropogenic aerosols over continental sized tracts over the preceding decade or two, what the sun was doing (either way), what the infamous Brazillian butterfly’s wings were doing the year before.
rgb