As a long-standing member of the APS, I think it's the *duty* of us as scientists to issue a warning message when there's enough evidence (and consensus). I don't want to argue for or against the climate change here; the point is that even if most climate scientists were completely wrong and there would be no global warming, we should of course reduce pollution and production of greenhouse gases (and consumption of fossile fuels) as a matter of principle - it would be stupid not to. There's nothing to lose but the huge profits of oil-based industries by following APS's advice.

As a long-standing member of the APS, I think it's the *duty* of us as scientists to issue a warning message when there's enough evidence (and consensus). I don't want to argue for or against the climate change here; the point is that even if most climate scientists were completely wrong and there would be no global warming, we should of course reduce pollution and production of greenhouse gases (and consumption of fossile fuels) as a matter of principle - it would be stupid not to. There's nothing to lose but the huge profits of oil-based industries by following APS's advice.

But more than just global warming, the emerging idea is that there is global climate change. After all, it may not be possible to, I quote " measure the average temperature of the whole earth for a whole year", but climate change is observable.

Colder winters, hotter summers, shift in rain cycles and the like, those are observable, track-able data that has shown change that is arguably linked changes that humans have made to the environment.

But perhaps the statement "The evidence is incontrovertible: Global warming is occurring." is the one that draws the most ire. In any case, to argue that our actions (landscaping, creation of cities, etc.) has no effect on the environment is irresponsible. This should be self explanatory and I don't think I need to give any evidence for this.

So instead, we should be asking what effects do our actions collectively have on the environment?

Perhaps a strong stand on global warming has resulted in some hurt but accepting that human actions have an effect on the environment is, in my opinion, the necessarily responsible thing to do.

@Tapio

I understand your argument based on "nothing to lose by doing it"

There are at least two things I think may be on the line.

1) Policy statements in the APS are reasonably aimed at scientists. Scientists who may not be work on climate change, but are smart enough to observe asymmetries, and variations in standards. Scientists don't base their opinion policy statements from APS, but on arguments that makes sense to them. The relative upside of the policy statement (should it make a few scientists change their mind) may be countered by the observation that climate science is a special kind of science with lower standards on evidence, making other scientists uneasy of whether they should treat climate science evidence as confident as they treat evidence in their own field. The downside is reduced reliability on the concept of "science"

2)

In the western world, there is basically no real downside with higher energy prices, we cut back on flying, driving, wasting and such. But considering that there is starvation in the world, and that some only use energy for food, there is certainly a downside to them. If we are to reduce emissions, ultimately we need to leave fossil fuels in the ground, as the climate does not care whether we or developing countries pollute. Some calculations (that I couldn't find, sorry) indicate that every calorie of food uses 2-10 calories of oil.

These people will starve in a changing climate as well, there is clearly a downside to some. They would pay the price for saving hypothetical people in the future.

Andre, I fully agree that this is a complex, multifaceted issue. Concerning point 1), I think there's enough evidence & consensus to issue a warning message - I don't work on climate physics, but I'm a theorist and I think that the models they have are pretty good by now. In this I have to trust my esteemed colleagues working in this field. A lot of confusion in the issue of climate change seems to be deliberately created to cloud the issues and give the appearance that there's a legitimate scientific dispute going on there.

Concerning point 2) my research group works on alternative energy ideas, too. My view is that a massive effort in this field would not only slow down (or cancel) possible adverse climate effects, but offer unprecedented opportunity to economic wealth in the developed countries, and solve most of the energy problems in the undeveloped parts of the world, too. It's a simple fact that traditional energy solutions cannot provide enough energy and nutrition to satisfy the needs of > 7 billion people.

Http://www.newscientist.com/special/living-in-denial

Neither "supporters" nor "deniers" can be "scientists". Science requires perpetual skepticism and uncertainty, which in this case is attacked from both sides. There are claims on both sides that are incontrovertible, but they are always mixed into a soup of unsupported personal opinions and political agendas, in an intentional effort to legitimize said opinions and agendas by association with said incontrovertible facts. Sadly, science has no place in this process except to add credibility to one political faction or the other. That does not mean the issue is less urgent or the consequences of wrong decisions less monumental; but don't try to invoke "Scientific tests prove..." in your propaganda.

There are quite a few scientific facts (theoretically and empirically proven) that many people deny. There are, of course, many genuinely controversial topics as well, where there's good reason for doubt and skepticism. As you say, sometimes it's difficult even for the professionals to decide what's "proven" and what's not.

I am delighted to see the recent public debate shift from a "global warming" to a "global climate change" debate. This simple change in terminology shifts the discussion from a narrow view of global surface air temperature, that Ivar Giaever properly describes as a difficult metric to measure (i.e different methods of analysis may result in different results). Other metrics indicating a change in regional climates (that sum up to global climate change) are more relevant to society, primarily the regional society that must adapt with the regional climatic changes (drought, floods, lack of snow cover,..). Historically societies were more diverse and adaptable because regional societies depended on regional resources and traditions. But with globalization, societies are tied to other regions and the other regional climatic changes. A shift from dependence on fossil fuels extracted and transported great distances, to local renewable sources would free regional societies from the need to adapt to other regional climatic disturbances. This may be the best method to adapt to global climate change regardless of the debate of whether the current climate change is anthropogenic or part of a natural cycle.

To get back to the original question, does the opinion of a journal or Nobel laureate help or hinder the debate. In this instance the journal may have taken into account the many other metrics of global change (I admittedly don't know if the journal did), but Ivar Giaever has apparently based his opinion on a single metric that is not the most relevant metric to society (surface atmospheric air temperature). I think making a determination about global climate change on a single metric does a disservice to the scientific debate by attempting to reduce climate to only one variable, further confusing the public.

A scientific society should publish its opinion on issues of which the public has a poor understanding, especially on points which have strong public policy implications, and so have well funded PR groups pushing a counter-scientific view on the subject.

And while scientists in their 80s, even renowned ones, might have an understanding of the subject that is incomplete, and while one scientist of the 50,000 APS membership may drop out, and while the denialist blogosphere might hammer the story until many people remember the one and not the 49,999, it is still important that the world's scientific organizations do their part for public education.

The point that the APS, the AAAS, the ACS, the AIP, the AGU, the AMQUA, and the AIBS have all issued statements supporting the basic findings of the IPCC, is a strong one, and public understanding of the depth of the consensus would be damaged if one of the major American scientific societies withdrew their statements for fear of giving publicity to one or two denialists.

@Robin

Although we probably have the same take on the actual issue of climate change, I believe that education in form of policy statements are like preaching to the quire. People who already believed will continue to do so, while people who don't would be quite irrational to change their mind as well.

In the meantime people working with simulations and models in other fields (well, I guess I can only speak for myself really), who know rather well from their own history in conceptually simpler fields that they are wrong quite often, wonder how the wizards in climate science finally managed to make models and simulations that were incontrovertible.

But it is an infected topic, this idea makes me somewhat of a hillbilly to my sophisticated peers, on both sides of the argument actually.

@Andre

It's not about convincing people who already believe, it's about showing what the position of the scientific community is.

The APS statement does not talk about climate models, it says that "[t]he evidence is incontrovertible: Global warming is occurring." The evidence is incontrovertible with or without considering climate models.

I'm not sure what you mean about an incontrovertible climate model. All the papers I've read that include data from climate models have also included an estimate of error. Do you have a particular paper in mind?

I don't think that there are "both sides of the argument" when you look at scientific understanding. There are no scientific organisations like the APS that take any other side. And Giaever is one Physicist of 50,000.

I smell a troll: This ill-written question seems aimed simply to invite controversy over politics.

"[B]oth human health and happiness have definitely improved"

Where's the data to support this? And what does it have to do with GW?

Have the ecosytem and biosphere similarly "improved"?

Let's keep "research gate" concerned with research.

@Robin

To me it seems obvious that you need a model to connect the first section about pollution and Green house gases with the second that claims that global warming is going on. The idea that the first causes the other needs a model.

Error estimates are great, but they only offers statistical evidence based on the assumption that the model is qualitatively correct. In principle, error estimates do not show you that your model is correct.

But my intention is not to argue that (man caused) climate change isn't going on, I do believe that too. I was merely curious of how such controversial policy statements were interpreted by you guys, and if you too see the point Mr Giaever makes on double standards, illustrated by the open-mindedness on far fetched things like changing proton mass, versus the relative narrow-mindedness on climate change.

And as it seems (by sampling this thread), this is not an issue for most scientists. Fair enough then.

@ Simon

Your comment is off topic, misses the point, and makes unsupported accusations, seemingly based on "smell".

That is a textbook example of trolling, please do it somewhere else.

Whatever may be the policy.the goal should be always to save the environment.

What is "incontrovertible" is that complex, far-from-equilibrium phenomena and systems --- like the one under discussion --- are a reality: life is a beautiful manifestation of complexity and holism. The new science of complex holism calls for a renovation of the way science is done: “We are in a revolutionary period but are using the inadequate tools of normal science” according to one distinguished commentator. It would be misleading to suppose that the undeniable perception of Global warming/Climate change are isolated instances of something gone horribly wrong. Add to this the state of the global economy having gone berserk without much of a clue of the identity of the villain, and you get the interconnectedness of complexity.

Science of the last 400 years has essentially evolved by the reductionist tools of linear mathematics in which a composite whole is regarded as the sum of its component parts. Increasingly, however, a realization has grown that most of the important manifestations of nature in such diverse fields as ecology, biology, social, economic and the management sciences, be­side physics and cosmology, display holistic behaviour which simply put, is the philosophy that parts of any whole cannot exist and be understood except in their relation to the whole. These complex self-organizing systems evolve on emergent feedback mechanisms and processes that “interact with themselves and produce themselves from themselves”: they are “more than the sum of their parts”. Thus society is more than a collection of individuals, life is more than a mere conglomeration of organs as much as human interactions are rarely dispassionate.

We have here therefore a definite case of dispassionate appraisal of the APS call; indications tend to corroborate the perception.

@Andre. You don't need a model to show that increasing the concentration of greenhouse gasses will increase the greenhouse effect. That's a known result from optics.

The amount of increase in global mean surface temperature due to a given change in radiative forcing can be calculated by observational evidence, or by historical reconstructions.

There's a much more vast body of recsearch, following different lines of evidence, that show global warming is anthropogenic, than that shows the mass of a proton is a conserved under translations in time. And, more significantly, the published scholarly papers speak with one voice. (On the subject of the existence and anthropogenic origin of the current global warming). The APS should trust the result more.

But as someone who finds it impossible to believe that models can be accurate to within their stated error, I assume you avoid tall buildings, bridges, aeroplanes and trains?

Climate models are qualitatively correct with respect to global mean surface temperature, because that parameter is robust to different monsoon patterns, different ocean currents, and different states of the NAO and the ENSO. It reduces the whole think to an energy balance with space. But they're qualitatively correct in other ways too. They reproduce the ENSO, not on the correct year, but the phenominon of the oscillation. They reproduce Hadley cells. They reproduce monsoons, and ocean currents.

And they reproduce the global mean surface temperature with disturbing accuracy.

And while climate science has lots of methods of investigation, and certainly hinges on optics, not modelling, it is also not true that climate models do not reproduce important aspects of the climate very well.

@Robin

I strongly disagree on the no model needed idea. To me this is just as odd as believing that just because it is a fact that concrete is so hard that you can walk on it, all buildings using it automatically becomes stable and safe to be in. Or thinking that you know anything about the input/output in an electrical system without having to know anything about the feedback circuit. And on this, I think climate scientists agree with me.

"it is also not true that climate models do not reproduce important aspects of the climate very well."

Who said that? I get the feeling that you think I said that? Well, I did not say anything like it.

If the warming is unprecedented (http://www.clim-past.net/8/227/2012/cp-8-227-2012.html) it might be incontrovertible to say so....

@Filippo

I missed your comment, and personally I think that a slight softening like that would have made me fine with the statement. The essence is of course the same, but I guess they were making an extra statement just by using the extra bold formulation.

@Andre

re:"I strongly disagree on the no model needed idea."

We know from optics that greenhouse gasses cause the greenhouse effect.

There are many ways that you can estimate or at least constrain the effect of this on temperature without using a GCM. For a few examples:

You can calculate it from Earth Radiation Budget data:

The Climate Sensitivity and Its Components Diagnosed from Earth Radiation Budget Data:

http://journals.ametsoc.org/doi/full/10.1175/JCLI3611.1

You can derive it from temperature and CO₂ historical reconstructions:

Climate sensitivity constrained by CO₂ concentrations over the past 420 million years.

http://droyer.web.wesleyan.edu/climate_sensitivity.pdf

You can abandon all assumptions and do something completely different:

Probabilistic climate change projections using neural networks

http://www.climate.unibe.ch/~plattner/papers/knutti03cd.pdf

Or you can make observational based estimates:

An Observationally Based Estimate of the Climate Sensitivity

http://journals.ametsoc.org/doi/full/10.1175/1520-0442%282002%29015%3C3117%3AAOBEOT%3E2.0.CO%3B2

There's also observational data that allows independent verification of models, such as the work that has been done on volcanic effects on climate over the instrumental period.

So models are not needed. There are other lines of evidence.

@Robin

They seem to use several models in your articles, they also assume several things (assumptions that I am sure are fair approximations, or they wouldn't have been published), neither do they ever state that climate change is incontrovertible, they seem to have pretty balanced conclusions.

Philosophically I am not sure if you can preform science without models. Science is more or less about testing and improving determinism through various models (or to try to falsify models and hypotheses, if you like Popper).

@Andre

re:"They seem to use several models in your articles"

Not general circulation models. The work done in these papers does not depend on climate models.

re:"neither do they ever state that climate change is incontrovertible"

They're not literature reviews of the evidence of climate change. They're papers that show how much warming an amount of CO2 produces. If you want to know if climate change is incontrovertible, and you're not in the field, you should look at what the scientific societies are saying, rather than any individual paper. The APS says "The evidence is incontrovertible: Global warming is occurring", for instance.

re:"Philosophically I am not sure if you can preform science without models."

Most science is performed without models. The reason models are used a lot in climate science is that you can't run an experiment with a control on the earth's climate, because we don't have another earth to use as the control.

You reiterate the nonsense du jour of the climate science denial industry when you claim that models "are wrong quite often", and by extension, so is science.

In reality, the science does not hinge on models alone, and the models, in turn, are disturbingly accurate with respect to global mean surface temperature.

@Robin

Well I think you are horribly wrong on the "no models needed in most science" comment as well.

The fact that I have stated my position in the matter several times in this thread doesn't seem to get through to you, all you see "is climate science denial industry".

I am a little curious to know what kind of science you do, which doesn't involve models.

@Andre

The fact is that the current warming is anthropogenic does not require a GCM to establish. There are other lines of evidence.

Broadening the discussion to all kinds of models, be they an atmospheric radiative transfer model, or GEOCARBSULF isn't relevant to that point.

Your comment "[I] wonder how the wizards in climate science finally managed to make models and simulations that were incontrovertible" is anti-scientific, and unhelpful.

Given that we have about zero chance of avoiding 2°C of warming now, and depending what the climate sensitivity is, could quite possibly be seeing 4°C of warming over the next 50 years, it is depressing and annoying to see the low brow politics of the denial industry represented in this forum.

My field is mathematics.

@Robin

You were the one who introduced GCM to the discussion, i always meant models in a much broader sense.

I disagree that my question is anti-scientific, but am not sure what you mean with unhelpful, it was an inquiry.

The "low brow" smear campaign of yours is immature, uncalled for since it is off topic, and unnecessary since I disclosed my position. Frankly, I also think it is counterproductive, as it reveals glimpses that are less than flattering of the people that form the consensus. As part of the consensus, i must ask you to keep these bully tendencies to yourself. If you manage to brand the rest of us as ordinary bullies, it will be much harder for the rest of us to convince "the other side".

@Andre

re:"You were the one who introduced GCM to the discussion, i always meant models in a much broader sense. "

Really. You think all models are "wrong quite often"?

How do you feel about tall buildings, bridges, planes, trains and cars?

I don't notice them failing catastrophically very often myself. I assume you avoid them?

@Robin

Yes, they are all wrong, but they may serve as nice and critical tools anyway, or as your fellow mathematics colleague George Box put it:

"essentially, all models are wrong, but some are useful"

Why do I then fly planes?: The engineers that built the plane have the same take on models as Mr. Box

When designing the electronic system in airplanes, Engineers choose the model that gets the job done, which is a non-chrashing plane. During this process they use various models that they feel are good enough in a very specific context. They use Ohms model (known as Ohms law outside Electrical Engineering) for designing the entertainment system. For systems where the circuit has the same length as the signal wavelength, they refine the model to include voltage phase and amplitude. For critical systems, they refine the model to include electromagnetic interference. For the transistors in the hardware, the engineers in the transistor factory refined their models to include gate quantum tunneling.

Which of the models are wrong? All of them, and they provide the wrong result every time they are used in the "wrong" context. But they are all useful, when used by an experienced engineer. Even though they still don't let me use my electronic equipment during take off and landing, I thrust that they know a thing or two about when their models are useful, and when they are wrong. Therefore, I fly.

But isn't this solved by error bars, you might ask? No, when using Ohms model, there is zero percent chance of having tunneling electrons through the gate at DC voltage, and no margin for other outcomes in any error bar. Still in reality, you will have a leaking current through the gate. This is because the model you used to calculate the error bar is wrong (or used in the wrong context, if you prefer). The error bars will only fool you to believe your safe, and your transistor may cause hardware malfunction still.

Edit:

I found an ever greater quote from professor Box:

"Remember that all models are wrong; the practical question is how wrong do they have to be to not be useful."

@ Andre

Your argument for why models used in climate science (be they GCMs or radiative transfer models, or reconstructions of past atmosphere and climate, or the movement of ice within an ice sheet), are wrong enough to be not useful so far has been that all models are "often wrong".

This argument doesn't establish that they are particularly wrong models, but only that they are no better than the best models in the world.

But you trust the model that produces the maintenance schedule of an aircraft enough to fly in an aircraft. You can trust a climate model to produce the global mean surface temperature. You can certainly trust a radiative transfer model to produce a good estimate of the heat transfer through the atmosphere by radiation.

https://www.aps.org/policy/statements/07_1.cfm