Messrs Mastrandrea and Schneider,

"The scientific evidence for a human fingerprint on this global warming is now overwhelming."

What, again, is that evidence? I wish to be overwhelmed.

You say that temperatures have been rising, but that is not to say that man has caused it. You say that our emissions of greenhouse gases have been increasing, but that is not to say they have raised the temperature.

None of the "troubling changes"—the impacts of warming—that you mention have been beyond the historical range of natural variation and some are not in fact occurring, such as "rising seas".

Your long, thoughtful consideration of the next several decades rests on the observed evidence, yet you do not tell us what it is.

Your detailed, intelligent analysis of how to cope with a difficult future depends upon proof of global warming being caused by man's activities, yet you withold it from us.

Do you consider that thinking people will forgive this serious omission, or that they will somehow fail to notice it?

Whichever is true, it is strange indeed that men of your obvious intelligence can be so stupid. For why should we listen to your prescriptions when you offer no evidence that your hypothesis is true?

Who do you think you're speaking to?

Cheers,
Richard Treadgold.

Sirs,

Your article seems to take it for granted that the Earth is warming, and will continue to warm in accordance with IPCC predictions. Yet neither of these facts are true.

Having warmed for a period up to 1998/9, the Earth's temperature then stayed static, and for the last few years has been falling rapidly, in spite of continuing CO2 output. This has meant that ALL the IPCC predictions have proven completely untrue, and effectively disproves the assumed link between temperature and CO2.

Yet you behave as if the last 8 years have not happened. Why is this?

You guys need to go over and debate your predetermined conclusions. The more I read the AGW Hysterics doomsday prophesies, the more disgusted I am convinced they are terminally brain dead.

http://www.dailyexpress.co.uk/posts/view/69623

Excerpt:
At the beginning of this year there was a BBC show with four experts saying: “This is going to be the end of all the ice in the Arctic,” and hypothesising that it was going to be the hottest summer ever. Was it hell! It was very cold and very wet and now we’ve seen evidence that the glaciers in Alaska have started growing rapidly – and they’ve not grown for a long time.

I’ve seen evidence, which I believe, that says there has not been a rise in global temperature since 1998, despite the increase in carbon dioxide being pumped into the atmosphere. This makes me think the global warmers are telling lies – carbon dioxide is not the driver.

The idiot fringe have accused me of being like a Holocaust denier, which is ludicrous. Climate change is all about cycles, it’s a natural thing and has always happened. When the Romans lived in Britain they were growing very good red grapes and making wine on the borders of Scotland. It was evidently a lot warmer.

I agree that the authors don't do a great deal to explain the evidence, but there are plenty of places where you can find that. It doesn't need to be rehashed in every article about climate change. Scientists who for years challenged the growing consensus on climate change have been convinced by the data (see here, for example, which discusses the 1998 fallacy: http://www.reason.com/news/show/125281.html). When the foremost libertarian publications and think tanks are on board, you can bet the data is, at last, overwhelming. I do think it makes sense, however, for authors like these to at least acknowledge that other perspectives persist and then blind them with some science, if I may indulge in a gratuitous pop-culture reference.

If you think the portions of the scientific and policy communities that accept the reality of anthropogenic climate change are steamrolling you, you are not doing your due diligence in educating yourself on the subject. At one point I would have agreed that the "denier" appellation was unscientific and, indeed, offensive, but, at this point, it's apt.

In any case, Mastrandrea and Schneider don't really know what's going to happen, and I think they may occasionally reach farther than prudent caution and into the realm of overreaction, but the scientific debate over climate change does appear to be over. These guys aren't taking warming for granted--they've followed decades of increasingly persuasive research and are now moving on to the next stage: crafting a sound policy.

If anything it is significantly gaining pace.
There is still a mountain of literature available to read on the internet from noted scientists in a number of fields including climate science, and if anything it's the skeptics that are growing in number.
The only place the debate is over is in the mainstream media and politics. The scientific community as a whole certainly don't think it's over.
To pick up on one of the points from the article link in #4. To dimiss the decline in temperatures as natural variation masking CO2 warming is completely absurd. If the cooling is a result of natural variables that the models didn't predict or allow for, how can we be expected to trust our future to these obviously flawed models. That alone is enough to tell me that saying "The debate over evidence is laid to rest" is completely wrong.

To Treadgold, Rowland and Barelysane:

Do you guys remember waiving your hands in front of your little sister's face on long car rides?

"I'm not touching you... I'm not touching you..."

It's a simple question.

Damion Greer - "I agree that the authors don't do a great deal to explain the evidence, but there are plenty of places where you can find that."

You smudge the point, which is not that they have failed to explain the evidence, but to reveal any.

Telling us to find it elsewhere simply avoids responsibility.

"…you can bet the data is, at last, overwhelming." I don't want to bet on the data, I want to see the data. You can't persuade people like that. You must show them the evidence; somebody showed it to you, didn't they? So come on, what is it?

Whistle - I wish I could tell what you're talking about. I hope you're all right. Oh, and check the spelling of wave.

Cheers.

Richard:
That's what I mean when I say I agree with you—they should state which evidence they find persuasive, though I don't think it is their responsibility to explain it in exhaustive detail. After all, this isn't a scientific journal. But you don't have to look there for the evidence either. The data is everywhere. You can, for example, read the IPCC report online. If you truly want to see the data, as you claim you do, you will read that.

Alternatively, the article I linked in my post above points to some other important data in a more accessible format. Boston Review had an article a couple of years ago (which is now a book) by an MIT professor explaining that among the factors scientists have found convincing are the results of computer models. Obviously, real experimentation would be best, but the climate is an arena that doesn't allow for easy experimentation, so computer simulations are the next best thing.

We know that the simulations are useful because they mirror past observations with great accuracy. In other words, we have the equations and parameters necessary to produce a model that comports with observed reality. If we use the same parameters that produced results in accordance with past observations, we find that observations from the late 1960s onward (it depends on the simulation, but they group around that time period), in particular, do not comport with the computer model. There is a strong and consistent divergence: the model predicts consistently lower temperatures than have been observed. But when increased concentrations of human-generated greenhouse gasses are incorporated into the equations, one finds that the new simulation results match observed temperatures very well.

Now, you could argue that the simulations are designed to produce the results the scientists are looking for. The scientists know that there are other factors that could account for the warming trend but they have purposely omitted them from their equations and parameters. This, however, would entail a wide-ranging conspiracy that, one would have to admit, is profoundly unlikely.

More plausible is that there are systematic errors involved in the simulation building process, and surely there are, but would they yield these sorts of results? What kind of error would allow the simulation to accurately mirror past observations (i.e. from the earliest days of comprehensive climate measurements until the late 1960s) but consistently underestimate more recent ones?

The only potentially valid error I can conceive of is that there is some explanation other than greenhouse gasses that, when factored mathematically into the simulation, realigns the curves. However, a rigorous scientist would try out these other variables, and I suspect that many have, although I can't say for sure because I haven't read the journals. I would not be able to understand them if I tried. (Actually, I would appreciate it if a qualified individual would point out what kind of work in this area has been done.) These explanations might include phenomena related to changing earth ecology, certain "celestial" factors that I have no understanding of, subtle changes in the Earth's magnetic field, and I don't know what else. But I am certain that if these factors can be measured and their effects understood and incorporated into the computer models, they have been.

The physical evidence (core samples, decreasing ice mass, etc.) is available ad nauseum in the IPCC report.

All of this involves a great deal of uncertainty, but not so much uncertainty as to be beyond usefulness. That simulations are able to accurately model the climate of bygone days without incorporating human-generated greenhouse gasses tells us that the models are well-calibrated. That there is no way to make the model fit the past forty plus years without introducing the human variable tells us that humanity is having an impact on the climate, just as other forms of life (e.g. everything green on planet Earth) do and always have.

Reliance on computer models does run the real risk of bad science. In response to observations that do not comport with predicted behavior, scientists need to be willing to alter their models to account for new data. And if, after constant tinkering, the model continues to fail, it may need to be scrapped altogether. But existing models have done well at mirroring past climates so, for now, they seem useful. And to the degree that they ARE useful the most rigorous research we have available shows anthropogenic warming.

It's still a simple question.

Damion, you refer to evidence in your first paragraph then spend the rest of your lengthy (and admittedly interesting) post talking about models. But models are not evidence of any kind.

If models match history it's because they are told to do so, not because the modellers understand the climate. They don't understand it.

The IPCC don't believe the models match the future, since they don't pick a 'scenario', they give us a dozen or so and let us choose for ourselves.

The models do not predict that CO2 leads to increased temperatures, they are told that it does. If they match historical temperatures "only" when anthropogenic emissions are included, it is not evidence of an anthropogenic influence. It is evidence the scientists don't know what else it could be. (So it must be man-made.)

The models failed to forecast the last decade or so of flat and falling temperatures, and all El Ninos and La Ninas. If they cannot forecast the first few years of the climate with any skill, what hope can we have they will succeed over 100 years?

There is a readable summary of all this at http://www.climate-skeptic.com/2007/09/chapter-5-skept.html.

I appreciate your level-headedness over a difficult topic, Damion, but my question remains simple. Of course, it was originally directed to the authors of this article.

As to evidence obliquely referred to by you: core samples are not evidence of present warming; decreasing ice mass is determined by reduced precipitation, not air temperature; and, anyway, no evidence of warming speaks to man's involvement in that warming.

To sum up: the atmosphere is not warming, but cooling; the models are not validated; nobody understands the climate perfectly; there is evidence that solar output drives our temperature. We don't want to ruin the economy without better cause!

Only evidence will persuade intelligent hearts and minds of the truth. Indeed, just the mere existence of evidence is required—all else is but a vain flapping of the lips.

That is why I continue to repeat my question: What is the evidence?

Cheers.

This one's going out to Treadgold specially--

I remember pretending that my little sister WASN'T EVEN THERE when she was right in the room with me. It drove her crazy!

Whistle:

Please note the periods of warming and cooling in this graph of lower tropospheric temperature anomalies since 1978. Note especially that in the last seven years, though the temp goes up and down, there is no clear trend until a pronounced descent over the last eighteen months.

Note that there is no evidence of warming while the temperature remains level or descends.

So again, what is the evidence of global warming?

Cheers.

Sorry, no html allowed, it seems. The link I gave did not survive; the graph of lower tropospheric temperature anomalies can be found at http://www.junkscience.com/MSU_Temps/UAHMSUglobe.html.

Cheers.

In regard to the "global warming ceased in 1998" myth, I direct you to the following: http://www.newscientist.com/article/dn14527-climate-myths-global-warming-stopped-in-1998.html

Tammy,

Thank you. The first point to note is that I didn't mention 1998. I was discussing the evidence for man-made global warming. Actually, if one could "ignore" 1998, the UAH record goes right back, with wiggles, to about 1980 with very little trend.

Still, there are some other things to say about El Nino et al.

None of the climate models predicted the giant El Nino of 1998, or any other, or any La Nina. So the models don't do weather all that well, do they? Not as well as many people presume they do. And all that means is that the modellers don't understand climate as well as we wish they did.

It's an interesting article, and everyone should take the point that meteorological issues become more complex the closer one looks. There is much more, for example, to warming the oceans than one might think.

The article says: "Global warming has certainly not stopped, even if average surface temperatures really have fallen slightly as the Hadley figures suggest."

First, the Hadley figures don't suggest, of course, since they are numbers. The author seems to like the Hadley dataset, as he quotes it extensively; let us assume, then, that he believes it. So this statement means that he agrees that average surface temperatures have fallen slightly. That's a bit strange, since he's just gone to some trouble to persuade us that they have not fallen. Definitely ambiguous.

But more importantly, it is an undeniable fact that, in the absence of a rising average temperature, global warming has indeed stopped. You are free to predict a resumption, and if you propose a reasonable hypothesis for that then people will agree with you. But reason could never agree that warming could occur during decreasing temperatures because it's ludicrous—like saying you risk sunburn because snow is falling.

You cannot have them both at the same time; warming and cooling are mutually exclusive. End of story.

The simple fact is, that in the absence of warming for a period of years, people are going to enquire into the facts of the global warming theory. They will want to know why the air is not warming, when it has been firmly predicted.

In any case, temperatures may rise and fall as they always have, but what the article asserted is that humans are responsible for it. They simply failed to show us the evidence.

I'd like to know about that.

Cheers.

"What is the evidence?"

The evidence suggests you wouldn't last three rounds in a cage match with Willard Scott.

You kick enough sand about average global temperature, you just might be the Hero of the Beach!

Still, I wouldn't want to just pick on your rhetorical style: you're actually talking out of both sides of your mouth. In your June 9 article "Why pick on carbon dioxide?" you state it plainly--

"Picking on CO2 is a strange development for two reasons: first, because it is axiomatic that life forms do better where it is warmer.
...
The point is that we have been induced to fear what we actually prefer. What, really, is wrong with a little warming? By a little, I mean perhaps 3°C—a moderate prediction for the end of this century. Three degrees will hardly boil water, will it?"

So which is it, Rick? Are we getting warmer or colder? Or are you hoping to get some use out of that Antarctic time-share?

http://www.climateconversation.wordshine.com/docs/rt001_why_pick_on_carbon_dioxide.htm

Most all scientist conclude that past industrial CO2 output has been helping to overload atmospheric levels. Hence the supposition is that future CO2 injections will do the same.

The sarcastic use of the word "evidence" means some will never be satisfied with an answer. You know, there is no PROOF that tobacco and cigarettes cause cancer - there are only high confident correlations between smoking and cancer. And the confidence is high enough to win court cases and compel warning labels. I don't smoke. And I urge others to believe the science.

Of course a noble experiment would be for humans to radically reduce CO2 output and then observe changes to atmospheric CO2 levels and attendant cooling. I prefer that experiment to continued pollution.

You might want to follow the recent EPA decisions about regulating CO2.

Whistle,

My CO2 article in June attempted to refute the hypothesis that CO2 will be responsible for dangerous warming. It did not say that warming will occur and it does not conflict with my comments above that warming is not occurring right now.

Draw the lines, connect the dots, do whatever you must, but please show us the evidence that man is responsible for warming the planet to a dangerous degree.

Cheers.

RPauli,

We're not talking about smoking.

I know some seem to demand 100%, water-tight, cast-iron, guaranteed 'proof' of dangerous AGW before they're prepared to consider a case for doing something about it. That's not my position.

I would like to know what has convinced you and others to call the emission of CO2 (hitherto the well-known minor atmospheric gas required by plants for growth through photosynthesis) "continued pollution".

That's all. I presume some evidence lies behind your decision, so tell us what it is, please. Not evidence of increased CO2, but of its causal role in dangerous warming.

And of course, I mean evidence, not more polemics, if you don't mind.

Cheers.

RPauli,

A decision by a public servant is not scientific evidence of dangerous man-made global warming.

It may, or may not be, evidence of his adherence to instructions.

CO2 feeds us all, through its nourishment of plants. It is not a pollutant of any kind.

The 'noble experiment' you propose can of course easily be conducted by examining history. As CO2 levels rose, the hypothesis says temperature should have risen, too; so did they?

Say the increase in CO2 is taken as starting in 1750. What correlation do you find between CO2 and temperature until 1800? Or until 1900? Or since 1900? Do you find any correlation at all?

Or is the picture more complex than that, and you acknowledge that other drivers are present? Do let us know. It's fairly important to your theory.

Cheers.

Wether or not the climate is warming and if warming, is caused by man, it is unescapable that we will run out of oil quite soon and coal in a few hundred years. Why don't we concentrate on taking measures which take this into account while at the same time reducing the output of green house gasses just in case anthropogenic climate change is a reality. Such measures would include doing everything we can to generate all of our electricity by renewables, shifting over to electric cars as quickly as possible, making sure that contraception is affordable and in the hands of every woman of the world, even if it has to be free and so forth. If climate change is all nonsense, we still address the problems of overpopulation and disapearing reserves of fossil fuels.
William
http://mtkass.blogspot.com/2009/02/malthus-pyramid-schemes-starvation.html