Through two new studies in Nature, the weakening of the Gulf Stream System is back in the scientific headlines. But even before that, interesting new papers have been published – high time for an update on this topic.
Let’s start with tomorrow’s issue of Nature, which besides the two new studies (one of which I was involved in) also includes a News&Views commentary. Everything revolves around the question of whether the Gulf Stream System has already weakened. Climate models predict this will be one consequence of global warming – alongside other problems such as rising sea levels and increasing heat waves, droughts and extreme precipitation. But is such a slowdown already underway today? This question is easier asked than answered. The Atlantic Meridional Overturning Circulation (AMOC, also known as Gulf Stream System) is a huge, three-dimensional flow system throughout the Atlantic, which fluctuates on different time scales. It is therefore by no means enough to put a current meter in the water at one or two points.
Since 2004 there has been a major British-American observation project, called RAPID, which tries to measure the total flow at a particularly suitable latitude (26.5° North) with 226 moored measuring instruments. This provides good results and shows a notable slowdown – but only since 2004, and probably the change over such a short period of time is mainly due to natural fluctuations and in itself hardly reveals anything about the possible effects of climate change.
If you want to look further back in time, you have to look for other sources of evidence. In my view, it is the ocean temperatures that are most likely to solve the mystery – because firstly, there is a lot of good data and, secondly, the AMOC has a dominant influence on sea temperatures in large parts of the North Atlantic. In our study – together with colleagues from Princeton and the University of Madrid – we therefore compare all available measurement data sets since the late 19th century with a simulation of a climate model in which the ocean currents are computed in very high resolution. Here is a cool animation:
This model simulation took six months on 11,000 processors (9,000 of them for the ocean alone) of the high-performance computer at NOAA’s Geophysical Fluid Dynamics Laboratory in Princeton. The central result is shown in Fig. 1 (left).
Fig. 1 Trends in sea surface temperatures. Left: in the climate model CM2.6 in a scenario with a doubling of the amount of CO2 in the air. Right: in the observation data from 1870 to the present day. In order to make the trends comparable despite the different periods and CO2 increases, they were divided by the globally averaged warming trend, i.e. all values above 1 show an above-average warming (orange-red), values below 1 a below-average warming, negative values a cooling. Due to the limited availability of ship measurements, the measurement data are much more “blurred” than the high-resolution model data. Graph: Levke Caesar
In the North Atlantic, the measured values differ markedly from the average global warming: the subpolar Atlantic (an area about half the size of the USA, south of Greenland) has hardly warmed up and in some cases even cooled down, contrary to the global warming trend. In contrast, a wide area along the American east coast has warmed up at an excessive rate. Both can be attributed to a weakening of the AMOC in the model simulation. The cooling is simply due to the reduced heat input from the AMOC. The excessive warming, on the other hand, is based on a somewhat more nerdy mechanism that has been known to experts for some time: if the AMOC weakens, the Gulf Stream shifts closer to the coast. (This has to do with conservation of angular momentum on the rotating globe.)
The model thus shows a fairly characteristic “fingerprint” of sea surface temperatures as the AMOC weakens. We now wanted to know what temperature changes the observational data show since the late 19th century. My doctoral student Levke Caesar evaluated the various data sets. They show a very similar pattern – see the right globe in Figure 1 – and the annual cycle of change – more cooling in winter – also corresponds to that of the model simulation. I know of no other mechanism that could explain this spatial and temporal pattern than a weakening of the AMOC. Such a slowdown as a result of our greenhouse gas emissions has long been predicted by climate models – these data show that it is already underway.
Weaker than for over a thousand years
Another new study (Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years by David Thornalley and colleagues) was published in the same issue of Nature, which supports this finding and places it in a longer climate history context. The authors used two types of data from cores in sediments at the seabed – so-called ‘proxy data’. These deposits gradually accumulate over thousands of years and tell us what happened in the ocean in the past. Naturally fuzzier than modern observations – but reaching much further back in time, in this case 1600 years.
The first data series – from calcareous shells of marine organisms that live 50 to 200 metres below the sea surface in the northern Atlantic – shows the temperature conditions there. From these, the strength of the heat transport and thus the flow can be deduced, similar as in our study. A second data series is based on the grain size of the sediments at two points at a depth of 1700 and 2000 metres – where part of the water brought northwards by the Gulf Stream flows back towards the south as a cold deep current. The neat thing is that the current sorts the sediment. Coarse grain size of the sediments indicates a strong flow, finer grain size indicates a weaker flow, to put it as a simple rule of thumb.
The authors conclude from their data that the AMOC has never been as weak in all those previous centuries as in the last hundred years. This supports an earlier conclusion of a study I led in 2015, where we had already concluded this for the last 1100 years – based on a completely different, independent database.
A look at the time evolution
What changes in the AMOC do the data show? The time series from the two new and some earlier studies are shown in Fig. 2. Each of the six curves is based on a different data type and methodology, but they show a largely consistent picture. The green curve shows changes in water mass based on deep sea coral data, the blue curve shows the grain sizes mentioned and the yellow curve shows the RAPID measurements discussed above. The three remaining curves are based on temperature changes – but also on three different methods. The curve from Rahmstorf et al. 2015 was based on a network of land-based proxy data such as tree rings and ice cores, while the new red curve from Thornalley et al. was based on sediment data. And the new curve from our study (dark blue) uses measured sea surface temperatures, as shown in Fig. 1.
Fig. 2 Time evolution of the Atlantic overturning circulation reconstructed from different data types since 1700. The scales on the left and right indicate the units of the different data types. The blue curve was shifted to the right by 12 years since Thornalley found the best correlation with temperature with this lag. Makes sense: it takes a while until a change in currents alters the temperatures. Graph: Levke Caesar.
The curves all show a long-term slowdown that is accelerating. The red curve is so smooth because these particular sediment data have too low a time resolution to show shorter fluctuations. The blue curve shows an early decrease already in the 19th century, which Thornalley and colleagues attribute to an earlier warming at the end of the so-called ‘Little Ice Age’, when the inflow of meltwater could have slowed the formation of deep water in the Labrador Sea. This is not necessarily a contradiction to the other data series, because the two sediment cores used are located in the area of the deep outflow of Labrador Sea Water – but this is only one of two deep currents that together make up the southward part of the overturning circulation of the Atlantic, and thus the heat transport to the north. Therefore, the time evolution of ocean temperatures does not always have to coincide with that of the Labrador Sea Water.
In our study we conclude that the AMOC has weakened by about 15% since the middle of the 20th century. In absolute figures, this is a weakening of the current by 3 million cubic metres per second – a figure that corresponds to around fifteen times the flow of the Amazon, and thus three times the outflow of all rivers on earth combined. Using a whole suite of climate models (the CMIP5 models), we have tested how well our temperature-based estimate can reflect the actual trend of the AMOC, and have arrived at an uncertainty of plus or minus one million cubic metres per second.
Some other studies
There are a number of other studies worth reporting on the subject, which I can only briefly mention here. Moore et al 2015 found in Nature Climate Change that convection (the deep mixing of seawater closely linked to the AMOC) in the Greenland and Iceland Seas has weakened and is likely to exceed a critical point as global warming continues, where it will become limited in the depth reached. Sevellec et al 2017 argue in the same journal that the weakening of the circulation could be caused mainly by the shrinkage of sea ice in the Arctic. Oltmanns et al (2018, again in Nature Climate Change) recently found signs of a growing risk that convection in the Irminger Sea could shut down. Sgubin et al. (2017, Nature Communications) analyse the occurrence of abrupt cooling in the North Atlantic in various climate models. And finally, Smeed et al. 2018 recently reported in Geophysical Research Letters on the latest measurements in the RAPID project, which are also included as a linear trend in Fig. 2. At the annual gathering of the European Geosciences Union (14,000 geoscientists are meeting in Vienna), which I am currently attending, the changes in the North Atlantic are also an intensively discussed topic.
What effects could the slowdown have?
It sounds paradoxical when one thinks of the shock-freeze scenario of the Hollywood film The Day After Tomorrow: a study by Duchez et al. (2016) shows that cold in the North Atlantic correlates with summer heat in Europe. This is due to the fact that the heat transport in the Atlantic has not yet decreased strongly enough to cause cooling also over the adjacent land areas – but the cold of the sea surface is sufficient to influence the air pressure distribution. It does that in such a way that an influx of warm air from the south into Europe is encouraged. In summer 2015, the subpolar Atlantic was colder than ever since records began in the 19th century – associated with a heat wave in Europe. Haarsma et al (2015) argue on the basis of model calculations that the weakening of the AMOC will be the main cause of changes in the summer circulation of the atmosphere over Europe in the future. Jackson et al (2015) found that the slowdown could lead to increased storm activity in Central Europe. And a number of studies suggest that if the AMOC weakens, sea levels on the US coast will rise more sharply (e.g. Yin et al. 2009). The impacts are currently being further researched, but a further AMOC slowdown cannot be considered good news. Yet, although the oscillations seen in Fig. 2 suggest the AMOC may well swing up again for a while, a long-term further weakening is what we have to expect if we let global warming continue for much longer.
Postscript (18 April)
Several articles by so-called “climate skeptics” (e.g. James Delingpole on Breitbart) have dismissed our findings by pointing to previous studies that supposedly contradict these. This is based on apples-to-oranges comparisons, in that these studies consider different aspects of the ocean circulation and most importantly look at short time periods dominated by natural variability.
For 1994-2013, Rossby et al. (2013) found a decrease in the upper 2000m transport of the Gulf Stream by -0.8 Sv.
Also for 1994-2013, Roessler et al. (2015) found an increase of 1.6 Sv in the transport of the North Atlantic Current. For this period, our reconstruction yields an AMOC increase by 1.3 Sv.
For 1994-2009, using sea-level data, Willis et al. (2010) reconstructed an increase in the upper AMOC limb at 41°N by 2.8 Sv. For this period, our reconstruction yields an AMOC increase by 2.1 Sv.
There is thus no contradiction there, and anyone who has looked at the time series in Fig. 6 of our paper or Fig. 2 above should have seen this right away. These articles illustrate once again how “climate sceptics” are not interested in an understanding of science, but in confusing the public with misleading claims.
Weblinks
German version of this blog article: Stärkere Belege für ein schwächeres Golfstromsystem
Nature editorial on the two new studies: Ocean circulation is changing, and we need to know why
The Conversation: Climate change is slowing Atlantic currents that help keep Europe warm (by one of the authors of the Thornalley paper)
Washington Post: The oceans’ circulation hasn’t been this sluggish in 1,000 years. That’s bad news.
Carbon Brief: Atlantic ‘conveyor belt’ has slowed by 15% since mid-20th century
AP in Spanish: Cambio climático debilita corriente oceánica: estudio
Washington Post: The fast-melting Arctic is already messing with the ocean’s circulation, scientists say (about the Oltmanns paper)
Interesting that DDS@48 can “recreate” past climate from his kitchen sink germs, presumably by scaling those numbers(supposedly random, but presumably autoregressive and some of them probably actually related to climate) appropriately with respect to the climate data. He would be doing so retrospectively, fitting a curve by scaling without any strictures on the amplitudes of the scaling, and probably varying the weighting along the way. This would be a bit like making a fourier description of a time series using a set of sinusoids, but using the “random” numbers as the sinusoids. But really very, very unlike the much more constrained operation of a climate model, which has to relate to the scalings of real physical processes. DDS wants to believe that climate models fit the climate record that way, so he believes it. This illustrates his talent for believing what he wants to believe; OK, just don’t expect us to tag along!
DDS — look on the right sidebar.
See the heading Science?
Start with the first link there.
You’re reposting frequently answered questions here.
It’s an invitation to recreational typing, and that won’t get you the best answers.
Dan De Silva @40, thanks for the video link, and you summarised M Manns comments on models ok, however the consensus that agw is 100% human caused doesn’t come from climate modelling alone. The agw consensus is based largely on numerous studies of natural casues, solar irradiance patterns, volcanic activity, the nature of the greenhouse effect etc. The modelling simply adds further information that helps rule out natural causes.
Like Killian says climate models aren’t broken. And don’t get obsessed with the way models are used to hindcast past climate trends. Models developed in the early 1990s have successfully predicted things in subsequent decades like the cooling stratosphere.This is successful forwards prediction spanning a couple of decades now.
#48 Dan DaSilva said
“recreate past climate”?
Give me variables totally unrelated to climate and even I can recreate past climate temperature record (or a lot of other past records).
Bull. Only if you manipulate the data. We are not talking manipulation of data, only inputting data into honestly made programs.
I not sure what creating past climate means.
I do not believe you.
#50 Kevin McKinney said DDS, #48– Dan, I can’t help but wonder: how is it that I–a musician by training, and undoubtedly someone whose mathematical background is far weaker than yours–knows this, but you don’t?
What a strange assumption that his statements are innocently made and questions innocently asked. Perhaps it was rhetorical. Do you think it humanly possible to engage on a climate website for an extended period and still try to imply or claim seasonal weather equals 30-year climate analyses? Or that any data can be fed into a climate model and get back correct past climate simulations? Or those reasonable questions for even the least informed climate activists, of any persuasion?
Engage these people if you like, but it does no good to pretend they are not what they are; it feeds false equivalence.
It is not a question of will the slowing occur but what is the rate of the occurrence. If it is decades then we are all finished but if it is centuries then we have time to pull up our socks and work on it. We may have to implement a program worldwide that studies and monitors all projects and consumer products for their impact on global warming in a manner not unlike the method used for measuring the economics and market abilities of present day consumer products and activities. All activities form the use of fossil fuels to the lifestyle expectations of everyone worldwide will have to be rated based on the consumption of fossil fuels and then find ways to reduce the same consumption to a bare minimum. This is achievable but not with the present system of governments in charge throughout the world.
Killian @55,
At face value, the examples provided by Dan DaSilva for his three-variable function f(x,y,z) clearly demonstrate his failure to see that the variables need to bear some significant connectivity to the “past record” being investigated. Given that requirement, I’m pretty sure the levels of opium smuggling from Afganistan, the cleanliness of Dan DaSliva’s kitchen sink and the number of whores in the Bois de Boulogne have no significant connectivity to any “past climate temperature record” either individually or collectively.
Yet it could he is trying to humorously (& carelessly) mirror the words presented by another person with dodgy climate credentials, no less than one of the Gentlemen Who Prefer Fantasy, ex-physicist turned AGW-denier Freeman Dyson. It was Dyson who provided the world with the anecdote attributing von Neumann to the quote in which Fermi tells Dyson “I remember my friend Johnny von Neumann used to say, with four parameters I can fit an elephant, and with five I can make him wiggle his trunk.” (Apparently, such an ‘elephant fit’ has been <a href="https://www.johndcook.com/blog/2011/06/21/how-to-fit-an-elephant/"shown to be possible by employing complex numbers although this does also require some big relaxations on the precision of ‘elephant fit’.)
Dodgy link in above comment is here
I realize that this is off topic, but DDS’s ignorant comments seem to stem at least in part from a failure to understand scientific modeling. He doesn’t even seem to understand that there are many types of scientific models, and that overfitting will only be an issue for some types (e.g. statistical models) whereas one can include as many factors as one can into a physical model with the only downside being that it slows down computation. It makes me wonder whether some of the other lay readers might benefit from a general discussion of scientific modeling. Thoughts?
#56, Killian–
I’ve learned by repeated observation that people, when ‘engaged’ in adversarial mode, have a truly amazing ability not to hear what their interlocutor is actually attempting to communicate, even as they mine that interlocutor’s words for rhetorical advantage.
So, short answer: yes.
It’s perhaps not one of our more admirable human abilities, but there it is. I’d add that such perceptual filtering can and does occur even when folks are acting basically in good faith (at least by some definitions.) I’d opine further that the result generally is that someone makes themself idiotic*, as when our friend Victor painted himself into a position where he was unable to acknowledge, or perhaps even to see, that a ‘lack’ of air conditioning can indeed be determinative of a warmer room under some circumstances.
Of course, bad faith is, as you point out, also something that exists.
*Sic–the idiocy is voluntary and temporary (or at least reversible in principle), but not merely a matter of appearance.
Ray, I think you’ve hit on something important.
A lot of deniers seem to think climate models are looking for something to fit to warming–these straw men see the Keeling curve, say, “Hey, that looks like it!” and declare that CO2 is the cause.
In reality, of course, anthropogenic global warming was predicted (in 1896) on the basis of radiation physics. Given that CO2 is a greenhouse gas (Tyndall 1858), and given that burning coal produces more of it, the Earth should warm up. The match between the Keeling curve and the warming is only confirmation, not the source of the hypothesis.
As I recall realclimate did do a simple climate model at one point. Perhaps they could do both a climate model (based on physics) and a statistical model (a multiple regression, say), to contrast the two.
Killian @56
“Do you think it humanly possible to engage on a climate website for an extended period and still try to imply or claim seasonal weather equals 30-year climate analyses?”
I think in some cases the denialists know climate is not weather but deliberately promote deceit with malice and intent to spread doubt and to protect business interests.
However I think with most denialists something slightly different is going on, a bit more subtle but still inexcusable. They come to genuinely believe weather equals climate, and all the usual climate myths, because they think AGW is a giant liberal conspiracy, so none of the data can be trusted and you dont need to apply logical analysis because its all a conspiracy and fake data and equations anyway. This is best characterised as a mass delusion, and a self brainwashing exercise.
#63 nigelj said think in some cases the denialists know climate is not weather but deliberately promote deceit with malice and intent to spread doubt and to protect business interests.
However I think with most denialists …come to genuinely believe weather equals climate, and all the usual climate myths, because they think AGW is a giant liberal conspiracy…
You seem to be, imo, conflating climate denial pawns or dupes, your typical Trump voter, e.g., and active denialist activists, often paid.
Killian @64
“You seem to be, imo, conflating climate denial pawns or dupes, your typical Trump voter, e.g., and active denialist activists, often paid.”
I hope I’m not conflating it. For me the question is are the paid denialists you mention fully are aware weather is not climate, (and that agw is real in general) or do they believe weather is actually climate, because agw is a liberal scam by definition, so don’t believe anyone who tries to tell you weather and climate are different.
It would be easy to assume the paid denialists are smart enough to know perfectly well weather is not climate, but I have a hunch its a 50 / 50 split. Humans are complicated.
The same 50 / 50 split might apply to the climate pawns and dupes, although conspiracy theories and ignorance would probably be reasonably widespread in this crowd.
However its equally indefensible either way, whatever the truth is. I tried to find some relevant research polling motives but nothing came up and people would hardly admit they were deliberately spreading lies about agw.
But what interests me is once people embrace a conspiracy theory they have an excuse to stop thinking and tackling evidence, and its easy to rationalise anything. For example they dismiss any inconvenient data or research as fake and part of the conspiracy. I suspect conspiracy theory ideation is a root cause of the climate denial problem driven mainly by a dislike of liberals, environmental groups and so called elites.
https://text.npr.org/s.php?sId=602847565
How much phytoplankton activity is there at the areas where surface water sinks?
62: I think it is worse than that, more like setting up a counter-argument (logical or not) which enables them to never be convinced.
If the climate models don’t replicate past climate well, they are flawed and unreliable.
If the climate models do replicate past climate well, it is because they have been fudged to fit the data.
You can’t convince anyone who reasons like that, it is clearly agenda driven.
You can’t convince anyone on the truth of a matter when their personal identity/ego depends on it being false.
In almost all cases the only people who think the weather is climate are straw men.
Climate models use a time slice which is short (weather), but they get weather wrong. If you model an electric motor for example and the time slice (or the tick) results are wrong it is a bad model.
But climate models can not even predict “past weather”. (The use of the phrase predicting the past is strange). This is just curve fitting, so why not curve fit until both the weather and climate are right? (bad idea, and a waste of CPU time)
If you want to model something understand it first. Modeling it first will give you overconfidence and confirm your bias. (I have done this, not good)
#68, DDS–
I do not think that phrase means what you think it means.
Climate is not determinate, practically, in the same way that an electric motor is.
More deeply, climate is an abstraction of weather, not a object in the same sense. Weather parameters have measurable values at particular places and times. Climatic conditions are always an aggregation derived therefrom, and often reduced to some sort of mean, specified usefully. (For example, mean daily high temperature for a particular place and a particular day of the year.)
Illustratively, there can be–are, mathematically speaking–infinitely numerous data sets for any given mean. However, it may well be that what we need to know is that value of the mean. If a model gives us that reliably, its use need not be debarred by some amount of mismatch in the specifics of the modeled data field.
No, I don’t think it’s ‘curve fitting’ at all.
“Curve fitting is the process of constructing a curve, or mathematical function, that has the best fit to a series of data points, possibly subject to constraints.”
https://en.wikipedia.org/wiki/Curve_fitting
By contrast, a climate model (like an operational forecast model) numerically represents processes and relationships, not just outcomes.
As to “why not curve fit until both the weather and climate are right,” it’s because that is not possible–certainly not given computational realities today, nor observational realities today (and probably ever). The models are quantized much more coarsely than reality is. As stated, in combination with the nonlinear ‘chaotic’ math involved, that’s a fundamental reason why weather forecasting has limited forward visibility in time.
In other words, if we could do what you so blithely suggest, we’d also be able to perfectly forecast weather arbitrarily far into the future.
I don’t know what you mean by this. To me, understanding something means precisely that you have in some way constructed some sort of mental model of it. And the modeling process seems to me to be one that leads to understanding, in that to build an accurate model you have to cross-compare time and again between model and observation(s). You’re constantly asking, “OK, is this bit right? This bit?” In practical terms, it seems to me that model-building is a prime learning strategy, employed repeatedly throughout history.
I expect you mean something quite definite in your mind, but as you stated it, I frankly don’t get it.
67 Adam Lea says: You can’t convince anyone on the truth of a matter when their personal identity/ego depends on it being false.
True. Fits climate scientists and renewable energy fanatics as easily as it fits young earth creationists plus political parties and their voters and of course corporate boards and shareholders.
Fits all humans because the subject matter is irrelevant. confirmation bias, false beliefs, societal beliefs, religious beliefs and so on do run deep and affect how the mind works across domains in the frontal cortex and in other areas.
This is science speaking about the known evidence. Don’t believe me. People and climate scientists included can look it up in a multitude of papers and connect the dots. If they wanted to but do they.
Truth is you can’t convince anyone to go look up the truth of a matter when their personal identity/ego depends on not going and looking it up only to discover they’re wrong. The very low % of people who do prove the majority don’t.
Remaining ego friendly means not being motivated to go look something up in a scientific field where the ego is not the expert. Tell them a truth a thousand times even and it will make no difference. Proof is all around. Some people even believe that climate science and climate scientists will save the world from the looming disasters of climate change. Like how dumb is that?
65 nigelj after a few moments wondering about the equivalent of how many angels could fit on a pin head, says people would hardly admit they were deliberately spreading lies about agw.
True. Nor would they admit they were deliberately spreading lies about the solutions to it. And yet it happens here and across multiple climate change forums all the time.
No less by the very people (climate scientists included) who hide behind their claims they accept the science of climate change and the urgent need for immediate actions which must include changes to Laws and Regulations directly related to energy production and use.
Deniers are everywhere denying the overwhelming evidence of all kinds of things. Foolish beliefs driven by ego always override inconvenient truths.
@68
Based on your reply in #68, I would have to say your expertise regarding modeling knows no bounds.
Which is a problem.
Hank, 66 – “How much phytoplankton activity is there at the areas where surface water sinks?”
Why? The link you include is about zooplankton … But if it is not a typo – then it depends on the time scale – if you are talking annual average productivity then high lats are quite productive.
But if you mean at the time of deepwater formation (your “sinking”?) – then the answer is probably very little – the traditional thinking (Sverdrup’s critical depth concept) has the bloom requiring stratification (otherwise algae moved up and down by mixing spend too little time in the illuminated part of the water column). But stratification means – no more deep convection …
Piotr
@70
False equivalence warning…
Carrie greatly misunderstands how the scientific method works. In particular, an individual scientist’s views are not the point. It is how peers judge those views that is the point.
Of course any particular individual is going to miss something through insufficient observation/data/bias/whatever. But the whole point is to present them for the examination by others with DIFFERENT personal biases, often different data, usually somewhat to greatly different analyses, etc., etc., etc. and to convince THEM.
The beauty of the scientific method is that it _harnesses_ the various personal foibles Carrie correctly sees in individual workers in the service of coming up with a better version of reality across the field.
Unless, of course there is a conspiracy going on such that scientists of all stripes in every country in the world must toe some specific line. Actually, there are in fact many such “conspiracies”: These are generally otherwise described as generally accepted findings or scientific laws.
Deniers lack such a feedback mechanism. They are not equivalent.
DDS 68: This is just curve fitting
BPL: No. Fundamental wrong assumption. Climate models are not curve fits. Go look up how climate models actually work.
Carrie’s fallen prey to the “mighty oak” fallacy, the notion that all of a field of science depends on some one fundamental early piece of work and if problems are found with it, the entire structure fails. You see attacks on Darwin by people who think his occasional errors somehow undermine evolution. Nope. Science is more like kudzu, it grows in every possible direction from wherever it first takes root, and flourishes wherever there’s more useful material to develop.
Peter Watts put that quite well a while ago, during the email tskandal: http://www.rifters.com/crawl/?p=886
Word.
74 & 76 greatly misunderstand what Carrie wrote and what it means.
76 Hank Roberts (quote), 74 jgnfld (in general)
“Science is so powerful that it drags us kicking and screaming towards the truth despite our best efforts to avoid it.”
On longer time frame, I would agree. All bad science tends to be found out. (To use a climate/weather analogy the climate debate we have now is the weather.) Sometime in the future, more and more truth will come out. Just do not expect science to never go down a rat hole. It will go down rat holes (and has) but it will return.
Why does it take so long in this case? The facts cannot be easily tested, this is a very complex chaotic system and the ratio noise/signal is high. Also, the science is also polluted on both sides by politics.
70, 71 Carrie:
Well said, we are all only human and the best we can do is be self-aware.
Climate Models:
As far as models I was pointing out why they should be treated with skepticism, not that the climate scientists are abusing them as badly as my example. If you want an area of actual abuse, look at aerosols and their role in climate sensitivity.
Carrie @77
“74 & 76 greatly misunderstand what Carrie wrote and what it means.”
With respect “Carrie” its because you are mostly never clear with what you are saying.
Dan De Silva @78
“Also, the science (climate science) is also polluted on both sides by politics.”
No matter how many times you say this, it doesn’t make it true. You appear to be really suggesting scientists tamper with data or come up with fake equations for political reasons, so because its a serious accusation, you have a duty to show explicit proof. Which you don’t.
You give no specific evidence, and not even a plausible detailed mechanism. It’s hard to see a plausible motivation because its hard to see what climate scientists would have to gain personally from catastrophic climate change, or how it would advance political views.
You probably think liberals all want carbon taxes or something just for the sake of having a tax, but I can assure you liberals don’t like taxes any more than anyone else, and only propose them for good reasons if all else has failed.They accept a role for taxes (just as the USA constitution does by the way) it doesn’t mean they have some weird agenda.
I think you are likely a strongly politically driven person so just assume this must somehow taint all scientists, but assumptions are nothing.
The climate denialists obviously have a range of motives including vested interests to some level of natural scepticism, but a lot of their motives are clearly political. You see this in how they talk about so called UN conspiracies to redistribute wealth and false accusations equating environmentalism and communism and fears about so called big government, all political and all paranoid and disproportionate views.
Individual scientists might make mistakes or have some ideological bias, however the scientific method forces people to look at data, experiments, logic etc and this is very merciless on their beliefs, politics and gut instincts.
Peer review helps identify bias and errors. Competition in science is fierce and exposes bad science. None of this is perfect, but its actually really good and like most critics you FAIL to provide a sensible improvement.
80 nigelj quote:
“Peer review helps identify bias and errors. Competition in science is fierce and exposes bad science. None of this is perfect, but its actually really good and like most critics you FAIL to provide a sensible improvement.”
I AGREE with you! It is GOOD, but DEFINITELY not always perfect and here is my sensible improvement:
When the point used against your opinion is that there is a consensus in science, do not stop thinking and blindly accept the consensus.
When what is said is that a crisis causing unprecedented for the last 1000 years warming is taking place but you also notice a very very similar warming (determined using thermometers and not by proxy about 100 years ago a time when the IPCC says it could not be AGW). You point this out, for science should not be treated as a sacred religion.
When you learn that models do not know how to treat areosols and clouds, but those models are used to support the statement that 100 percent of the warming is caused by man, take notice. For you are not sure that 100 percent is true and maybe 50 percent is.
When you know that the benefits of carbon fuels are helping poor people survive and even thrive and that cutting back will hurt these people badly (but not the people who want to cut), you notice and say something.
So my solution is voice your opinion and let others do the same even if you do not like their opinion. Do this and hope that we can forever live in a country where we are allowed our opinions.
I thank RealClimate for giving me that voice.
Dan De Silva @81
You haven’t answered my question and suggested any better way to do science, and have just posted fallacies about the science and propoganda. Thats clearly all you have to contribute.
You aren’t thinking about the warming period early last century, because we know it was a relatively brief period, and so lacked huge significance, and was caused by a combination of CO2 emissions, high solar activity and low volcanic activity and the later two factors haven’t been apparent since the 1970’s modern warming period. Were you actually unaware of this really basic information easily googled?
You provide no evidence cutting back on fossil fuels has to harm poor people. In fact parts of Africa are already moving to solar power.
So no you haven’t contributed anything at all except to spread more ignorance.
stefan, I know this thread is moving far from the original subject but let me ask one last question before moving on.
To all who have used the term “denier” in this thread, what does it mean to you?
Does it mean I do not your like an opinion?
Does it mean your estimate of climate sensitivity is too low?
Does it mean you are politically in the wrong camp?
Does it mean you are someone who is morally in the group of people who deny the holocaust?
A question related to the suggested (by one) analogy of climate models and curve fitting. I can appreciate that curve fitting doesn’t really make sense when talking about running climate models initialised on historical data and comparing the output to observations. My question is, are there paramaterizations in the climate models which can be tweaked so that model hindcasts can replicate historical climate change? Climate models cannot resolve all scales and so must use parameterizations to take into account sub grid scale processes which are non-negligable. I’m thinking something analogous to numerically solving the Reynolds averaged Navier Stokes equations for turbulent flow. The turbulance closure problem means that the 2nd or 3rd order turbulence parameters need to be expressed in terms of lower order known turbulence parameters or the mean flow, in order to close the equations. Some of these closure schemes have constants which can be specified according to the type of turbulence simulation being modelled. Does anything similar happen with climate models. I appreciate the modelling is at the extreme other end of the scale of atmospheric motion.
Dan DaSilva:
“When what is said is that a crisis causing unprecedented for the last 1000 years warming is taking place but you also notice a very very similar warming (determined using thermometers and not by proxy about 100 years ago a time when the IPCC says it could not be AGW)”
…you’d be deceiving yourself. The IPCC has an explanation for the early 20th century warming that includes increasing greenhouse gases (guess the source), increased solar output (doesn’t apply today) and a volcanic hiatus (reduction in aerosols, doesn’t apply today). Moreover, you’d be focusing on a 30 year period where we actually have less reliable data (global coverage was less), and ignore that the current warming isn’t stopping, is already going on for at least 40 years (10 years more), is actually faster, and isn’t likely to stop anywhere soon.
“When you learn that models do not know how to treat areosols and clouds, but those models are used to support the statement that 100 percent of the warming is caused by man, take notice. For you are not sure that 100 percent is true and maybe 50 percent is.”
…and you’d be deceiving yourself again, by only letting uncertainty go in one direction without proper explanation as to why this would be the case. Moreover, you’d forget that a major part of those aerosols are anthropogenic in nature, too. Moreover, the uncertainty as such doesn’t negate that climate change over the last many decades is 100% anthropogenic in nature – unless you can point to some non-anthropogenic factor that causes cloud cover to change in a way that would cause warming. With aerosols you also get little out of proposing a less negative climate feedback of aerosols. Still doesn’t change much in the attribution of warming to anthropogenic factors.
“When you know that the benefits of carbon fuels are helping poor people survive and even thrive and that cutting back will hurt these people badly (but not the people who want to cut), you notice and say something.”
…you’d actually be admitting that your supposed concerns about the science is actually supposed concerns about the perceived potential societal impact of actions to reduce AGW. And you’d also be deceiving yourself once again, by ignoring that scientific studies indicate that those most affected by AGW would be those same poor people. That is, they would be most impacted whether we would do something or not.
Dan DaSilva,
I have not used the term “denier” in this thread, but can answer none the less: to me it is someone who selectively shops in scientific knowledge and only accepts those parts that fit with his/her ideological stance.
Or more general, as the Cambridge dictionary quite aptly states: “a person who says that something did not happen or that a situation does not exist, especially something that most people agree did happen or does exist”.
Dan DaSilva (#81) said:
You might want to deploy some skepticism anent that idea.
For instance:
https://cleantechnica.com/2018/04/24/bids-called-to-replace-2-gigawatt-coal-with-solar-wind-in-india/
http://www.irena.org/-/media/Files/IRENA/Agency/Publication/2018/Jan/IRENA_2017_Power_Costs_2018_summary.pdf?la=en&hash=6A74B8D3F7931DEF00AB88BD3B339CAE180D11C3
Got that? It’s a direct replacement of coal capacity by solar for the primary reason that it is now often cheaper.
And it’s not just India, or just solar.
So the perception that clean renewable energy is ‘too expensive’ and will therefore hurt the world’s poor by restricting their access to energy is no longer true. (Moreover, the modular nature of both wind and solar, with much of the fabrication taking place at the factory level, typically leads to rapid project development. That means in turn that capacity can be added faster, alleviating energy poverty sooner. That is especially true of remote locations.)
On the cost side of the ledger, RE also provides significant benefits in terms of toxic air pollution reduction (and in many cases, national energy security.)
For instance:
https://www.cnbc.com/2016/02/11/pollution-crisis-is-choking-the-chinese-economy.html
And the problem is likely worse in India, albeit less well-documented, since Indian cities frequently have air quality measurements even more appalling than their Chinese counterparts.
Thus, shifting to RE is not only a no-regrets climate mitigation strategy, it’s likely a net win in terms of energy access, economics, and public health. That’s why we are increasingly seeing outcomes like this:
https://cleantechnica.com/2018/04/24/india-beats-north-america-europe-japan-in-2017-solar-additions/
China easily remains the solar champion, though, adding a rather incredible 53 GW of capacity in 2017–out of a global total of 93.7 GW.
I’d say that’s transformational–and it is–but it’s still not enough in terms of mitigation needs, considering that global installed generation capacity is ~5.25 *tera*watts, and remembering what a tight timeline we face if we are not to utterly blow the carbon budget.
Still, it’s a far more favorable picture in that regard than anyone dared to dream a decade ago. And we’re clearly in a ‘virtuous circle’, with increased RE deployments driving economies of scale that deliver consistent and rapid price drops (most markedly in the case of solar PV)–and with real-world cases of RE displacing thermal capacity directly on purely economic grounds already happening now (as noted above.) It’s clear that dynamic is going to be continuing for a while, and we are consequently going to be seeing a *lot* more renewable energy coming online–Trump or no Trump.
http://mecometer.com/topic/electricity-installed-generating-capacity/
(If we want to discuss this further, it would be a natural topic for the Forced Variations thread.)
DDS 83: To all who have used the term “denier” in this thread, what does it mean to you?
Does it mean I do not your like an opinion?
Does it mean your estimate of climate sensitivity is too low?
Does it mean you are politically in the wrong camp?
Does it mean you are someone who is morally in the group of people who deny the holocaust?
BPL: It means you deny that global warming is real, man-made, or dangerous. Duh.
DDS: “When the point used against your opinion is that there is a consensus in science, do not stop thinking and blindly accept the consensus.”
So, Dan, I am curious. What precisely do you think “scientific consensus” is? It does not about an “agreed upon” opinion of scientists, but rather an overwhelming preponderance of evidence in support of a theory, fact, technique or approach. I don’t know if you’ve realized this, but we scientists are not an agreeable lot. When we reach a consensus, it is because our field of study cannot make sense without that aspect of the field.
The other thing is that it is not a democratic process. The scientists who know the field the best (e.g. those who have published the most and most influential papers) have the largest voice. You don’t get a vote. I don’t get a vote. Donald Trump and Barrack Obama and even Al Gore don’t get votes.
The scientist who publish get a vote in proportion to their contribution to the understanding of the field–and the evidence gets a veto.
@83
Oddly enough, “denier” on a climate science site normally refers to someone who denies the accepted findings of climate science and climate scientists.
Kevin McKinney @87, and all that progess on getting costs of solar and wind power down and spreading deployment has been made despite the efforts of the denialists to impede the process every way they can. Just imagine the progress if the denialists got out of the way.
#91, Nigel–
Yes. Denialist opposition to renewable energy is an interesting case. For a long time, it was almost non-existent, I suspect because RE didn’t seem like a viable threat to the energy status quo. But as deployment expanded exponentially, so did attacks on the ‘apparent viability’ of the technologies, along with serious political opposition funded by the usual suspects (prominently the Koch donor network) and delivered via the usual organizations (notably ALEC, the ‘legislative counsel’ existing to deliver pre-made legislation to legislators who are receptive–or captive–to the oligarchy.)
Now we’re starting to see inter-corporate struggles between RE companies and the fossils. An example I witnessed personally (in part) was the recent skirmish over the 2% cap on rooftop solar here in South Carolina. There was a rally ‘for solar jobs’ at the Statehouse, and it was classic astroturf–a few hundred employees of Sunrun (a large solar PV leasing/installation company) and smaller solar firms, plus a smattering of actual energy activists. At the conclusion of the rally, the Sunrun folks headed inside to buttonhole representatives.
(Just to finish the story–for now–the measure passed second reading easily, but failed on third reading because opponents managed to have it ruled a tax measure, due to a fairly incidental tax exemption provision–and tax measures require a 2/3 majority vote. So rooftop PV is capped at 2%, for now.)
I think the biggest difference-maker has probably been the indifferent progress of measures to put a price on carbon–complete national-level failure in the US, and with EU measures less than effective. Tony Abbott, of course, killed Australia’s plan while it was still in the cradle, and Canada is just now about to have a new national scheme; we’ll see how that works.
(Particularly in that Ontario, the nation’s largest province, could potentially have a ‘Trump turn’ with Conservative policy vandal Doug Ford currently in very good position to become the next Premier in the upcoming election. Barring a miracle, he’ll become a center of opposition to Federal climate policy. And Ontario’s climate-friendly policies of the last decade or so may well be reversed or blunted.)
But anyway, I think that, had the story generally been one of widespread effective carbon price measures, we’d be quite a bit further along today with our energy transition.
DDS:
Yes. The metaphorical ‘Devil’ is in the wide range of ‘wariness’ values available, and the extent your level of wariness is epistemically justified.
The lopsided consensus of working (i.e. publishing in peer-reviewed specialist venues) climate scientists for AGW is justified by the established methods of the Earth Sciences, on a firm foundation of basic Physics. You OTOH, while professing only a basic understanding of physics, evidently feel competent to contradict the peer-reviewed claims of full-time climate specialists, and aren’t persuaded by their strong consensus. You don’t appear to recognize the role of expert consensus in science, and you seem deeply suspicious of the motives of climate experts in particular. You’ve even invoked the name of a notoriously ‘liberal’ politician to represent the scientific consensus for AGW, implying thereby that the research agenda of climate science is set by your straw cultural enemies, and the consensus established by extraordinary political influence.
It seems, IOW, that your understanding of AGW is largely informed by unwarranted confidence in your own ability to evaluate multiple consilient lines of evidence, together with reflexive hostility toward anyone who tells you something you don’t want to hear. In my irredeemably mediocre opinion (IMIMO) you are a pseudo-skeptic. A genuine skeptic, who is not himself a expert on a topic, is humble enough to acknowledge there may nonetheless be genuine experts, i.e. scientific specialists on the topic, who have earned their expertise by putting the freakin’ time and effort in, and who continually and unsparingly scrutinize each other’s work. It follows that the experts are best able to judge who their peers are, that their aggregate expertise is greater than any individual’s, and that peer consensus is essential to scientific progress. Of course, even genuine experts are human beings, so scientific knowledge can never be more than tentative and provisional. Be that as it may, Science is the only method we’ve evolved for understanding and predicting ‘objective’ (i.e. inter-subjectively verifiable) reality that’s more successful than divination with offal, because it’s a way of trying really hard not to fool yourself, and because peers don’t let their peers get away with fooling themselves.
Climate science is no different from other Earth Sciences. The challenge for the genuine skeptic can’t (or won’t) make the effort to become an expert himself, is to achieve scientific meta-literacy adequate to distinguish genuine from fake climate expertise. Failing that, he has no way to know when he’s fooling himself. He thus remains a metaphorical ‘sitting duck’ for professionally crafted bespoke disinformation, commissioned by those who have the most to lose when the world stops burning fossil carbon for energy. Some ‘skeptic’, huh?
If it’s not obvious, that’s “The challenge for the genuine skeptic who can’t (or won’t) make the effort to become an expert himself, is to achieve scientific meta-literacy adequate to distinguish genuine from fake climate expertise”.
Oh, and in case he still hasn’t caught on: “Hey Dan DaSilva, you’re an AGW denier!”
It’s so boring to stay away from sites like this for a few months and come back to find that you are *still* giving major air space to wastes of space like DaSilva and Carrie.
What’s boring is having to scroll past reams of posts spouting nonsense that’s been heard ad nauseum before, posts refuting such nonsense using arguments that needn’t be given because they’re talking to the denier’s hand, and others talking about the knowledge, mind sets and motives of the deniers.
What’s frustrating is how, in finding the comments that are about the science, so much time can be wasted in recognising and dismissing the comments offering non-science, and even more wasted on the ones which offer good science but are all about countering the nonsciense, and are thus a needless read.
It’s a law of human nature that not all people can resist a troll. Identifying, deleting and banning Denialists at the earliest opportunity will lead to shorter comments sections with a corresponding higher relevance to the issues. Nobody will complain about not getting to read troll exchanges and meta-comments (such as this one) about the ongoing troll exchanges and about Denialist trolls in general.
Perhaps a better way to moderate comments on scientific matters would be to stop a comment at the first false statement, show why the statement is false, and delete the rest of the comment.
It would drastically reduce the amount of denier garbage readers would have to scroll past and would moreover be educational for the readers, if not the deniers.
96 Occasional, I agree with much that you say and not with other parts. There’s an Art to living well. I hope you find what that is for you, so you don’t get so easily bored and critical of things you do not fully understand as well as you imagine that you do.
recovering a narrative of place – stories in the time of climate change
“In a material sense, the group is as marginalised as it gets. To an outsider they may appear powerless, perhaps inarticulate. They are neither. They have a story to tell, a story that they happily share. To love country and to be loved by it is the basis of their survival, and ours.
https://theconversation.com/friday-essay-recovering-a-narrative-of-place-stories-in-the-time-of-climate-change-95067
I think denialist comments should be deleted if they are just spamming, utter crap, or make huge claims without a link to published research, or some fact based website.
But I would feel uneasy if all sceptical opinion was banned, as scepticism of the intelligent sort is part of science.
And its important to rebut these denialist comments, in case politicians and the like start to think theres a grain of truth in them. Its a frustrating exercise of course.