Overhype on global warming

[Bobby]

How about everyone else? Does our recent hot summers and warm winters make the AGW case more believable?

Of course it does. When our temperatures keep going up and up, then that is evidence backing the AGW case. We have had I believe 14 months all above average in a row, imagine if we had 14 months below average in a row. Probably everyone would be believing an ice age was imminent.

[noggin]

Is that a forecast? When do you expect temperatures to fall? And to what level, where, and why?

Ah, Dev........I'll show you mine if you show me yours!

Do you expect temperatures to rise? And to what level, where and why?

Without a crystal ball or any sort of ability to look into the future of course I cannot say that on such and such a date the temperature in such and such a place will fall to so and so.

What I am saying is that warming and cooling are natural cycles. I'm getting a bit bored with having to repeat the same old things all the time, but I believe the heat peaked about 3 years ago. We have reached the "top" and are teetering along on a plateau. Yes there will be a few wobbles, but I believe (it's that word again!) than in a few years time we will be able to look back and say "ah, yes.......we can see now that this current cooldown started in the early 2000s".

Of course it does. When our temperatures keep going up and up, then that is evidence backing the AGW case. We have had I believe 14 months all above average in a row, imagine if we had 14 months below average in a row. Probably everyone would be believing an ice age was imminent.

I thought that July 2007 was below average.

Edited August 8, 2007 by noggin

[jethro]

Thanks Eddie, I'm sure you're not alone in thinking the two are connected; the endless media coverage certainly paints that picture.

Noggin; I too think natural cycles play a much larger part than AGW in the weather over recent years, trouble is it's hard to distinguish the two when so much weather be it hot, cold, dry or wet is attributed to climate change. How can you not believe in AGW when it's clear our climate has changed; appears to be the over-riding message. It will be interesting to see what happens when natural drivers deliver a downturn in temps, I expect though, the correct information about synoptics will then be publicised but their connection to the past few years of warming will be convieniently forgotten.

Of course it does. When our temperatures keep going up and up, then that is evidence backing the AGW case. We have had I believe 14 months all above average in a row, imagine if we had 14 months below average in a row. Probably everyone would be believing an ice age was imminent.

Precisely Magpie but weather and more importantly weather in a tiny country like ours does not reflect climate change; our increased temperatures are not an accurate correlation of global climate change. It's weather. The correlation of the two is a direct measurement of hype, nothing more.

[Bobby]

I thought that July 2007 was below average. huh.gif

I mean from April 2006-June 2007. Some have August 2006 being slightly below, others just above. 13 out of 14 at least, which is something.

Precisely Magpie but weather and more importantly weather in a tiny country like ours does not reflect climate change; our increased temperatures are not an accurate correlation of global climate change. It's weather. The correlation of the two is a direct measurement of hype, nothing more.

True, climate warming here doesn't mean climate warming globally, but the globe itself is warming steadily also...

Edited August 8, 2007 by Magpie

[jethro]

I mean from April 2006-June 2007. Some have August 2006 being slightly below, others just above. 13 out of 14 at least, which is something.

True, climate warming here doesn't mean climate warming globally, but the globe itself is warming steadily also...

Oh I know, and I'm not disbuting that, but our weather isn't an accurate portrayal of that. I'm just wondering how much our weather has influenced the belief in AGW in this country. Take out the recent warm summers and mild winters, replace with more traditional British weather which we will experience again and I'm not so sure the wholesale belief in AGW would be quite so profound. I know you post regularly in the model/weather threads and in those there are many posts, particularly in winter or the run up to it, which state almost catagorically that the snowy winters of old are impossible to achieve nowadays and that summer will be hot; it's always struck me as an odd stance to take.

[Bobby]

Oh I know, and I'm not disbuting that, but our weather isn't an accurate portrayal of that. I'm just wondering how much our weather has influenced the belief in AGW in this country. Take out the recent warm summers and mild winters, replace with more traditional British weather which we will experience again and I'm not so sure the wholesale belief in AGW would be quite so profound. I know you post regularly in the model/weather threads and in those there are many posts, particularly in winter or the run up to it, which state almost catagorically that the snowy winters of old are impossible to achieve nowadays and that summer will be hot; it's always struck me as an odd stance to take.

True. No doubt our recent above average conditions does affect people's beliefs on the global climate and where it's going, but that's not really a logical stance for them to take. One can only make judgements on the global climate based on global measurements, but I suppose people aren't like that. I've already noticed some people laughing off AGW just because of this cool summer, ignoring the astonishing warmth previous. People have short memories and narrow outlooks.

As for the winters of old being impossible... well, more and more unlikely definitely, but not impossible. There's a still a chance we could have a winter similar to 62-63 or more realistically something like 1981-1982. In fact I do believe we will see a winter like that again, even if just once before the warming blasts much hope away. A 1995 sort of winter is also likely again in the future I think, our climate hasn't warmed that much. The last year or so of warmth has been exceptional taking into account warming and it's not sustainabile, we were due a cool period eventually.

And as for summers always being hot... well, this one has certainly proved that idea wrong.

In fact, there is of course the possibility that warming globally will trigger a cool down here in the UK, by whatever process. We could return to a much cooler climate, perhaps even to a little ice age climate. No particular evidence for that, but it is possible.

[eddie]

I do think there is a tendency to gloss over some of the more 'complicated' parts of our climate history to make the AGW theory seem less vulnerable to the 'climate has changed this fast before so it must be natural' argument. I think this is the wrong attitude to take because it can lead to accusations that the past is being manipulated to support the AGW theory.

It doesn't necessarily follow that just because climate has changed quickly before due to natural cycles that the current warming is caused by natural cycles. For example it could be quite possible that the warming in the medieval warm period was caused by the sun and the warming now is caused by C02.

[jethro]

True. No doubt our recent above average conditions does affect people's beliefs on the global climate and where it's going, but that's not really a logical stance for them to take. One can only make judgements on the global climate based on global measurements, but I suppose people aren't like that. I've already noticed some people laughing off AGW just because of this cool summer, ignoring the astonishing warmth previous. People have short memories and narrow outlooks.

As for the winters of old being impossible... well, more and more unlikely definitely, but not impossible. There's a still a chance we could have a winter similar to 62-63 or more realistically something like 1981-1982. In fact I do believe we will see a winter like that again, even if just once before the warming blasts much hope away. A 1995 sort of winter is also likely again in the future I think, our climate hasn't warmed that much. The last year or so of warmth has been exceptional taking into account warming and it's not sustainabile, we were due a cool period eventually.

And as for summers always being hot... well, this one has certainly proved that idea wrong.

In fact, there is of course the possibility that warming globally will trigger a cool down here in the UK, by whatever process. We could return to a much cooler climate, perhaps even to a little ice age climate. No particular evidence for that, but it is possible.

Agreed. Interesting times ahead. I wonder if the government has kind of missed the boat a bit, I'm pretty certain taxation of some sort will come into play in order to reduce Co2 emissions. Increased or new taxes always raise discontent, remember the poll tax demo's, if those taxes were introduced at the height of our warm summers/mild winters I'm sure they would receive more backing, attract less controversy, if however they delay and natural climate drivers begin to regularly deliver more traditional weather, I think they may run into a few problems. As you say, folk have short memories and it will only take a year or two for climate change to be discounted in our part of the world. It may be a global problem but if it's not in our backyard, affecting us then to a lot of people, it either isn't happening or is not our problem.

[jethro]

I do think there is a tendency to gloss over some of the more 'complicated' parts of our climate history to make the AGW theory seem less vulnerable to the 'climate has changed this fast before so it must be natural' argument. I think this is the wrong attitude to take because it can lead to accusations that the past is being manipulated to support the AGW theory.

It doesn't necessarily follow that just because climate has changed quickly before due to natural cycles that the current warming is caused by natural cycles. For example it could be quite possible that the warming in the medieval warm period was caused by the sun and the warming now is caused by C02.

No arguement from me on that Eddie. Old warmer periods may well have been caused by the Sun, I certainly wouldn't say current warming is all natural either. However, if natural cycles are in a warming phase it may be amplifying the increase in temperatures or perceived idea that climate change as we know it, is down to increased Co2 emissions. A prime example which springs to mind is Arctic ice loss, the general perception is that it is down to warmer air melting ice, yet there is a large body of evidence from reputable sources which say this is not the case, warmer ocean currents are to blame and these are entirely unconnected to AGW, and that is a natural, synoptical pattern. I do believe that all the hype and spin that climate change has attracted will eventually bite the AGW side firmly on the backside. When natural drivers deliver different synoptics and temps either decrease or stop rising in our part of the world, getting backing for their message and drive to reduce Co2 will be much much harder. It's easy to say, look at record levels of ice loss, those poor Polar Bears will have nowhere to live, we must stop this now. A few years down the line, it will be a different story trying to convince folk if the ice loss is in recovery. Spin and hype is a short-sighted, dangerous line to tread

[Devonian]

Ah, Dev........I'll show you mine if you show me yours!

Do you expect temperatures to rise? And to what level, where and why?

Without a crystal ball or any sort of ability to look into the future of course I cannot say that on such and such a date the temperature in such and such a place will fall to so and so.

What I am saying is that warming and cooling are natural cycles. I'm getting a bit bored with having to repeat the same old things all the time, but I believe the heat peaked about 3 years ago. We have reached the "top" and are teetering along on a plateau. Yes there will be a few wobbles, but I believe (it's that word again!) than in a few years time we will be able to look back and say "ah, yes.......we can see now that this current cooldown started in the early 2000s".

I'm old enough to be able to say that people have been saying a cool down is just around the corner for shaking on for two decades...

I'll be utterly amazed if global temps don't continue to warm on trend, and surprised if warming doesn't accelerate. Short of the Sun cooling markedly or a huge volcanic something or other I can't see cooling happening. I do, though, expect to hear people say 'a cool down is imminent' for some time to come .

This (which includes the odd 'fall') is warming on trend.

Edited August 8, 2007 by Devonian

[jethro]

Thank you for those kind words of encouragement Tamara; it's reassuring to know not everyone thinks I spout rubbish. I'm still in the early learning stages of synoptics and how they all fit together but even to my untrained, novice eye and the limited research I've done to date, it's clear to me they have played a MUCH greater role in our weather of recent years than AGW. Interesting times ahead.

[Devonian]

Thank you for those kind words of encouragement Tamara; it's reassuring to know not everyone thinks I spout rubbish. I'm still in the early learning stages of synoptics and how they all fit together but even to my untrained, novice eye and the limited research I've done to date, it's clear to me they have played a MUCH greater role in our weather of recent years than AGW. Interesting times ahead.

So, synoptics are a cause not an effect?

[Devonian]

Hi - no problem! :lol: What you say here works both ways - I find it equally reassuring that there are like minds who possibly express it better 'under fire' such as you clearly have been on here!

Some posters need to remember that the synoptical shift to this milder period which began abruptly back around 1988 is coming up for twenty years, which comprises up to approx, say, a quarter (on average) perhaps, of one's one lifetime but is actually very short in historical weather cycle terms . On the basis of measurement in the former period, it is understandable how people's belief in the correlation between milder weather and AGW has been influenced in our modern age of spin, but in reality it is very small change in terms of meaning anything much at all for the future. I'm genuinely surprised though that so many people do not appear to try and read between the lines more like this.

Tamara, I guess we're just not as smart as you? You know, we've taken in by spin, you haven't? Nothing to do with us having spent years studying the issue and coming to a differing conclusion? Nothing to do with looking at the global context, or over longer periods? Nah, nothing like that, we've just been taken in! To think sometimes people here accuse ME of being dismissive...

It is neither scientific nor rocket science - and such a qualification isn't necessary either. Much fuss is made about many consecutive months of above average CET, such as in the last year, but even though that impacts on minds in the relative immediate term, it still means very little indeed IMO in the bigger picture historical context of climate patterns and cycles.

The trouble is, that when as you have repeatedly said, the drivers do start to deliver different cooler synoptics and weather patterns and the PFJ returns south again (as will happen sooner or later) these perceptions, assumptions and associations will be truly bitten on the proverbial bum! It is merely a case of how much older we will all be, or whether the next generation sees it.

Tamara

Good to see you know so much better than all those experts at places like Hadley

Looking at the CET - I can't see a step change in 1988?

Edited August 8, 2007 by Devonian

[parmenides3]

Going back to jethro's unanswered question of yesterday: yes. People tend to believe what they can experience for themselves, and tend to be uncertain about what they are told, unless is already conforms to their existing prejudices. It is much easier to believe in global warming when the weather is warm. It is also easier to believe in the impacts of GW when the weather around the world seems to be going haywire. It is human nature to accept the evidence our own experience over all other evidence. Unfortunately, it isn't necessarily accurate.

Take GW, for example. Living in the UK in 2007, where the annual temperature anomaly so far this year is a round +1.5C, we might be inclined to think this is about what others are experiencing. Whilst some places on the planet may be having the same kind of anomalous warmth, many, if not most others, are undergoing more extreme differences, whilst, when the ocean temperatures are taken into account, the annual anomaly so far this year is only around +0.5C. Our experience is a limiting factor in our understanding of what is really going on.

Look at the SSTAs for example: between 70 and 80N, the SSTA is running at about +5C, with patches greather than +7C (see the Unisys graphic in the data files). If the UK was currently running at this kind of anomaly, there'd probably be no discussion at all about whether the planet was warming or not; average temperatures would be around 22C by the CET, with regular daytime maxima around 34C.

It's important to distinguish between synoptics, weather and climate. Climate Change is the generic term for the shifts in patterns of weather which are otherwise, within a measurable range, predictable, even when they go through cycles. Synoptics are (correct me if I'm wrong) the descriptions of those patterns of weather, and the postulated knock-on effects they have. Where Global Warming comes in is the way in which longer term, semi-permanent changes in the entire system effect the patterns we are used to.

Take ENSO as an example. As things stand, ENSO events, when they are positive or negative, have a knock-on event about six-nine months down the line in the North Atlantic. Taking the definition of El Nino as a persistent anomalous warmth in the E Pacific of +0.5C over five consecutive months or more, if global warming results in El Nino becoming a semi-permanent state sometime in the near future, then here in the UK, whatever knock-on effect that has will also become semi-permanent; it will become a background synoptic against which other factors have to be considered.Likewise with the Azores High (though this one is trickier to suss out; if a warming Mid-Atlantic helps to stimulate a larger, longer-lasting or more Northward Azores high, then we will face a different set of standard synoptic to the ones we are used to.

Then there's the potentially more alarming THC issue; if the Labrador and Norwegian/GIS sea areas become freshened enough by influx of Arctic waters, and if such a freshening contributes to a change in the amount of warmth reaching us via the gulfstream, then we would face a whole set of different synoptics and weather patterns for a time.

But none of this would have an impact on the background state of the system; the continuing warming of the atmosphere and oceans. In the long run, none of these will have so great an impact as that persistent warming. In the UK, it may be that the impact will be moderate, only a couple of degrees of warming, but globally, the effects will be such that we will have to face economic, geographical and political changes - if not disasters - however hot or cool it is in London or Manchester.

So, while we are having an exeptionally 'bad' year around the world in terms of weather impacts, we cannot say 'this is because of GW'; as far as we understand it, the system hasn't changed so much, yet, that such impacts might be expected regularly. However the media, and many of us, will persist with the delusion that this year is 'proof' of GW, and 'the shape of things to come'. It might, possibly, be the latter; it is not the former. The proof of GW is in the numbers, the measurements which show how much warmer this year is than the average, globally, and the persistence of a trend which is more rapid than can be accounted for by 'natural cycles'. And don't be fooled by that argument either; if it's all 'natural', what's causing it?

That'll do for now.

:)P

[jethro]

So, synoptics are a cause not an effect?

Synoptics and natural drivers have existed since time immemorial, loooooooooong before AGW. They haven't suddenly appeared as a result of AGW nor have they been over-ridden by AGW. My point AGAIN is that WEATHER in this country in recent years is more a result of synoptics NOT AGW. The resulting weather is not an accurate portrayal of any AGW but our own personal experience of it may well colour our opinion on AGW, especially given the constant linkage of ANY kind of weather event as being a result of AGW. Weather and climate change are two COMPLETELY different things as I'm sure you yourself would remind everyone if we took this summer to be a clear indication that AGW was not happening. Hype is the point here, hence hype thread.

Just read your post; agreed P3. Wow! A sceptic and a believer in agreement, what will folk say. There'll be gossip...

Edited August 8, 2007 by jethro

[parmenides3]

Tamara, i'm not about to claim that the future is set in stone, nor that the 'whole package' (as presented by the media, the government, or the scientists, BTW?) is a given. But I will point out that, unless we have evidence to the contrary, and excepting a mammoth volcanoe or asteroid impact, the trend of warming is set to continue, and to accelerate, for another 40-80 years. As things stand, I don't know of any reason why this projection might be argued to be unlikely, as the factors which are causing the warming are not going to change in that timespan.

Respectfully,

:)P

ps; I'll come back after walking the dog. :)P

[Bobby]

Tamara, i'm not about to claim that the future is set in stone, nor that the 'whole package' (as presented by the media, the government, or the scientists, BTW?) is a given. But I will point out that, unless we have evidence to the contrary, and excepting a mammoth volcanoe or asteroid impact, the trend of warming is set to continue, and to accelerate, for another 40-80 years. As things stand, I don't know of any reason why this projection might be argued to be unlikely, as the factors which are causing the warming are not going to change in that timespan.

Respectfully,

:)P

ps; I'll come back after walking the dog. :)P

I too think that it's likely that worldwide warming will continue and accelerate way off into the future, but there is certainly the possibility of something unknown happening that may trigger a slowing of the warming or even a reversal. Not a meteorite of volcano or nuclear winter or anything, but perhaps an unexpected shift in ocean currents, or some feedback mechanism will be triggered. But yes, until there is evidence to suggest this, there isn't any reason to think that anything other than a warming future is going o happen.

Also no certainty that Britain will continue to warm of course, gulf stream could slow, synoptics could shift due to warming elsewhere. A warming future looks likely though.

[parmenides3]

If the whole package isn't a given then I'm not sure how one can be confident about the outcome over the next 40 to 80 years. If there is acceptance that natural drivers may induce a change in global weather patterns with cooler synoptics, and some concession that the type of assumptions that Jethro has been talking about may indeed be clouding perceptions and exaggerating the hype over the extent of the trend then why do we have to feel compelled to believe such expressed confidence about a further accelerated warming trend over the next several decades?

The media and government can be taken with a pinch of salt anyway but I'm sorry if I appear disrespectful to so many scientists. However, how do we know without a crystal ball what mother nature is likely to do over the next several decades and more? - and it doesn't have to be as unsubtle as an asteroid or mammoth volcano. :lol:

Tamara

It depends what you want 'confident' to mean. Most climate models, (which are the only means of doing the huge numbers of calculations necessary), work on the basis that some elements of the system play an important role in changing patterns, whilst others have a less significant effect. The elements which have the major effects are quite well understood, measured and defined. Yes, there are 'uncertainties' associated with modelling, and scientists are constantly striving to improve the accuracy and reliability of the models, but there is very little uncertainty about the warming trend; the main arguments revolve around the degree to which the warming will be ameliorated by changes in cloud cover, or worsened by deforestation, and the like. If your demand is for absolute certainty, you'll never get it, I'm afraid. But most scientists agree with the basics and most of them, when they do experiments or analysis, end up with a continuing warming trend.

I don't know about the natural drivers assumption, though. Are you thinking about solar variability, or something similar? If Solar, once again, the principal patterns of variability are well understood, and the amount of difference they would make in their normal range wouldn't be enough to do more than temporarily suppress the dominant trend for a short period, by fractions of a degree, for a few years, during which time, the background trend continues because its cause is still present. If not Solar, what other drivers might have a cooling effect?

Of course the hype exaggerates the trends; that's what hype is. It's also B****hit. My expressed confidence about the future extent of the trend is based on the science, not the hype; for this reason, you may or may not choose to accept that such a projection is likely; that's up to you, but if you do so, it is a choice which runs counter to the reasoned conclusions of a large number of reasonable people, who generally need to have good reasons to believe anything, being by nature sceptics. By all means disbelieve the media and the government, and all of the hype, but I would encourage you to view the science dispassionately, and see whether it matches with my suggestions or not.

We don't have crystal balls, but we do have climate models, physics and a lot of good minds working on the problem. This, combined with our own ability to see the observed trends of the last thirty years, even the last century, might be enough to give us cause to accept that we have a fair idea of what 'mother nature' is going to do, in some areas, whilst we know very little about what might happen at the more extreme ends of the projections, beyond a decent guess that it isn't likely to be very good for us.

Respectfully,

:)P

[jethro]

That's all well and good P3 but you are a reasonable person with a quite in-depth interest and knowledge on the subject, you are the exception, not the rule. Research suggests the Enso cycle is in perturbation, time scales and history suggest the AO has cycles lasting 30-40 years; we are reaching the end of its' expected predominately positive phase, the next and possibly following solar cycle are predicted to be quieter, less intense; all these will have an impact on our weather and it is that which will influence Joe Bloggs in the street, not what scientists may or may not know. And with the greatest of respect, you attribute far more faith to the outcomes of the models used by the IPCC than even their own scientists possess.

[Admiral_Bobski]

Hi P3 - long time no debate!

As things stand, I don't know of any reason why this projection might be argued to be unlikely, as the factors which are causing the warming are not going to change in that timespan.

Would it not be fairer to say that "the factors to which the warming is attributed are not going to change in that timespan"?

If the current warming trend is, indeed, being caused by the factors and forcings we think are causing it, then yes there is unlikely to be a change, but what if the cause of warming is being wrongly attributed?

CB

[parmenides3]

Just to clear up a couple of misunderstandings: The ENSO index is cyclical, as historically observed. For there to be a semi-permanent El Nino, there would have to be substantially more heat in the oceans than there is at the moment, or a change in the way in which upwelling occurs in the Pacific; this is probably a few years away yet. This is not a part of my argument that the warming trend will continue; it was an example of the nature of the relationship between climate change and synoptics - possibly a bad one, I don't know.

The AO cycle is problematic at the moment. I read a paper recently which suggested that the negative phase 'should' have started between 1995-2005, but there has been no clear indication of this yet. The future solar cycles are expected to be quiet, yes, but the variability is quite small. How much effect solar cycles have on weather is an open question at the moment. All in all, though there may well be a combination of natural phenomena which conspire to produce an overall cooling signal, the sum of these parts is unlikely to exceed even the existing warming signal, never mind any future warmth.

I'd take issue with only one thing; the suggestion that my 'faith' in the outcome of the global climate models is unusual. There is always the element of uncertainty, but you'll be hard stretched to find a scentist who will commit to the idea that the current warming is natural or that the trend is likely to stop any time soon. My own research suggest that less than 5% will admit to thinking this.

I don't wish to sound overconfident - you know that's not my style - but in this case, the global average temperature trend, there's not much around to counter the conclusion of the majority, that this is set to continue for some time to come, irrespective of any efforts we make now to slow down warming later in the century. Of course, I could be wrong, as could many scientists, and of course, there may be something which hasn't been thought of yet, but, on the basis of what we know now, and on the best available information, the prognosis remains the same; global temperatures will, on average, continue to rise, at least by another 0.5C in the next 40 years, more likely by 3C over the coming century.

:)P

PS: yes, C-Bob, it would be fairer, and probably more accurate. Attribution is slightly trickier than other elements, though the role of CO2 is sure enough, and the claims for the extent of its impact are fairly strong now, there is still enough uncertainty to give us some slack in the rope.

Edited August 8, 2007 by parmenides3

[noggin]

and of course, there may be something which hasn't been thought of yet....

Whenever I've said that, it's been pooh-poohed.

Not by your goodself, P3, I hasten to add.

It will be interesting to see if a poster of your eminence gets the same sort of response as I have had!

[parmenides3]

Whenever I've said that, it's been pooh-poohed.

Not by your goodself, P3, I hasten to add.

It will be interesting to see if a poster of your eminence gets the same sort of response as I have had!

I have found that being a prominent figure in the Church adds a certain gravitas, but I'm quite willing to be criticised, argued with, or whatever. It's all about how you say it, not necessarily what you say, noggers old chum.

:)p

[HighPressure]

MODELS:

I don't have a problem with using models as tools but they do nothing magical simply do man's calculations for him, they really only provide a mirror image of what's gone before plus or minus any factors they are told to include in their calculations for a future point in time. Obvious maybe but many people think that these models think for themselves which they cannot. One good test I would be interested in, is if the IPCC have run their models to recreate the past, say 1920-1970 in theory without changing its parameters is should be able to recreate the temp trend from this period quite accurately? Not a criticism but a genuine question I have.

I really have a problem with statements like "we understand the main factors involved in climate change but don't really understand some of the lesser factors" Simply if you do not understand something how can you know it is a lesser factor, and how can you model it correctly? What is worse for me is that the IPCC then go and attach an accuracy statement to their findings. I have no problem with providing model results and saying this is our current understanding but cannot accept as logical that projected model result(s) can be put forward as 95% accurate, when there is no previous record of 95% accuracy?

[parmenides3]

MODELS:

I don't have a problem with using models as tools but they do nothing magical simply do man's calculations for him, they really only provide a mirror image of what's gone before plus or minus any factors they are told to include in their calculations for a future point in time. Obvious maybe but many people think that these models think for themselves which they cannot. One good test I would be interested in, is if the IPCC have run their models to recreate the past, say 1920-1970 in theory without changing its parameters is should be able to recreate the temp trend from this period quite accurately? Not a criticism but a genuine question I have.

I really have a problem with statements like "we understand the main factors involved in climate change but don't really understand some of the lesser factors" Simply if you do not understand something how can you know it is a lesser factor, and how can you model it correctly? What is worse for me is that the IPCC then go and attach an accuracy statement to their findings. I have no problem with providing model results and saying this is our current understanding but cannot accept as logical that projected model result(s) can be put forward as 95% accurate, when there is no previous record of 95% accuracy?

HP: the process you are describing, of going back in time and comparing the models' output for a period in the past with the observed data is an essential part of the process of modelling. Generally, they use runs of up to 150 years wherever possibe, to allow for the least chance of random similarities, and then they spend a long time comparing the output of the model runs to the observations. This is one of the tools which give climate scientists some confidence in saying that temperature changes are likely to continue; whilst the models have historically not been very succesful in replicating the details of some tropical climate patterns, they have been much more successful at matching the pattern of the temperature record. Whilst this might be chance on one or two occasions, the reason that they believe they understand the main factors affecting GW is that, even when some of the variables are changed, the results come out in predictable ways. And the results are replicated in more than a dozen different major papers.

I won't complain that your paraphrase is slightly unfair, but will point out that the ways in which the influence of some factors change the model outputs (or, in many cases, fail to), shows that these are not as critical, hence the descrption of them as 'lesser' factors. It isn't about not understanding it; this itself is a misunderstanding; it's about not being absolutely precise about the details of the processes; aerosol effects is an example of this, where a great deal of work is continuing on the variations in size, composition, chemistry and location of aerosols in the atmosphere, and how this changes the earth's radiative balance.

The IPCC, to which I think you are referring, does not claim that the models are 95% accurate; what they say is that the likelihood of CO2 being the principal forcing behind GW is at the 95% confidence level; IOW, they are pretty much sure its that.

I think that if the models were measurable as being 95% accurate, there wouldn't be much argument; but how do you measure this? The acid test must be to compare historical model projections with subsequent temperatures. The only meaningful one of these we have at the moment is Hansen's 1979 GISS projection, which, when you compare the 'main line' estimated global warming by 2005 with the actual observed data, you get a match which is about 90% accurate. Bear in mind, too, that this was with one of the early models, with very outdated computer technology; we can at least suggest that subsequent models are plausibly likely to be at least as, if not more accurate than this.

None of this is to say that climate models, or their output, is 'the last word' on climate projections. The IPCC certainly isn't; it is probably still quite conservative in its estimates of climate changes and the speed of these changes. But we have nothing else, apart from seaweed or guesswork.

The IPCC was formed because there was a widespread concern among many governments that the climate was changing, but the evidence supporting how, why, how much and when, was a bit thin. It was (is) an attempt to synthesise the most reliable and best tested findings into one document, and provide estimates under certain scenarios of what might plausibly happen in the future. By and large, this is still what it does; it does none of the science, though its lead authors often do, and makes up none of the material; it really is a genuine attempt to provide a genuine best estimate (or at least, uncontroversial estimate) of present and future conditions and changes.

So what is left? Nobody yet has come up with a scientifically sound idea why the current trend will change. Nobody has yet shown that the current warming is part of a natural cycle and nothing more; they've pretty much ruled this option out completely, now. Of course, the entire scientific effort at understanding climate change could be wrong or misdirected, it could even be missing some key ingredient, but what are the odds? What are the odds that all this effort has missed something critical which will make everything all right again. They aren't nil, but they aren't great, either.

:)P