The Great Climate Change Debate- Continued

[Iceberg]

It is an interesting question maybe to help why don't people post up a graph of the PDO, solar activity over the last 30 years ?. I am more than happy to try and post something later but when I am at work at not on a dial up line.

To be fair this has been answered several times in the last couple of months but we can answer it again.

The Thompson graph re corrected ENSO has also been put on here. Anybody can post a corrective graph, but it depends how much you trust the person that corrected it, what methods did they use, was the method double checked etc. I don't believe the thompson graph answers well to these questions.

[Pennine Ten Foot Drifts]

Again, I ask: what are the strong negative natural forcings that would cause a flat temperature trend the past 8-10 years? Solar activity was only slightly lower with Cycle 23 than the previous two cycles, and the PDO remained mostly positive until 2007.

These are questions that AGWers have not been able to answer. If the AGW signal is so strong, then it should take significant negative natural forcings to cancel it out. And yet we have seen temperatures level off with very little regression of positive natural forcings.

Two days since you asked this,Smithers,and still no takers. Whilst no natural 'cooling' forcings at work,there's been no let up of CO2 emissions. I've nothing to say,don't need to,but 'supporters' of AGW certainly need to pipe up. LG,awaiting more pseudo science gobbledygook to uphold something which simply does not exist.

Not a defender or a sceptic personally, but all I would say is that any 8-10 year period when used in an argument like this is almost irrelevant. I would have thought when anyone is discussing such things as global temperature trends the minimum time period for any meaningful trend data is going to be around 30 years, and probably nearer fifty, or maybe nearer a hundred (?). As such, in this type of discussion the only graphs which could significantly swing the debate one way or the other are those based on such timescales.

As such personally I only find trend data based on long term data to be useful, and as far as I know the long term trends, (i.e. the 30, 50 and 100 year graphs), all still show significant increases, so at present I am still more inclined to the idea the earth is warming. However, if the 1990-2020 graph shows flat-lining, or even a reduction, then I'll be the first to accept that as strong proof to the contrary.

That is of course why much of the argument on here is borderline pointless because the evidence being posited from both sides naturally very often includes data which, whilst to our 'human' perspective appears perfectly legitimate, is actually using timescales which are far too short.

I would suggest that there will be no decent resolutions to the questions posted by both sides until long after we've gone.

[johnholmes]

a very sensible post, nice to see a balanced constructive comment about time scales.

[laserguy]

I would suggest that there will be no decent resolutions to the questions posted by both sides until long after we've gone.

True,so very true. The problem is,no one has a clue what will be in ten years from now (or even one!),due entirely to things beyond our control - that's assuming for the sake of this argument that our CO2 does have an effect. It doesn't,but I digress.

However,the ptb have already decided the road they're going down regardless. That's science? That's exhibiting the approach of wait and see? They don't need to wait X many years to decipher a trend - they 'know' what's going down from now into the great blue yonder and are acting accordingly. In the here and now,and in the absence of natural known cooling events but in the presence of rocketing CO2 emissions,temps have all but flatlined for nigh on a decade.

Once all the schemes are in place to reduce emissions - and the alleged attendant warming - what's going to happen when climate inevitably plunges into the cold side? Because it surely will do just that at some point,whether it's for a long time or just a 50 year blip which means nothing in the grand scheme of things. When we are dependant on wind farms and the like and have no industry or effective transport left,those short- or otherwise- lean years would be our ruination.

Iceberg - I'd a feeling you'd see Smithers' graph as faulty,howd'I guess? Of course it would have been perfectly legit had it shown warming,however slight. Me? I trust no-one but especially the likes of Gore,Hansen,Mann etc.

[Devonian]

But look at ENSO-corrected temperatures. Still a flat or slightly cooling trend since around 2000. And that's with the GISS temps dominating the picture...if satellite temperatures were used, the trend would most definitely be more downwards.

Again, I ask: what are the strong negative natural forcings that would cause a flat temperature trend the past 8-10 years? Solar activity was only slightly lower with Cycle 23 than the previous two cycles, and the PDO remained mostly positive until 2007.

These are questions that AGWers have not been able to answer. If the AGW signal is so strong, then it should take significant negative natural forcings to cancel it out. And yet we have seen temperatures level off with very little regression of positive natural forcings.

The 1998 El Nino caused a huge spike up in temperatures, perhaps it's surprising the recent La Nina has only caused a 'levelling off'?

I don't think you can refute AGW using a ten year period of time. If you could there are probably several ten year periods from the last century that could be said to refute AGW only for warming to resume later on - see the more extended graph in the RC article your graph comes from.

I'm not confident this present time isn't just somewhat of a pause - and besides over thirty years (the minimum time professionals would use) the trend is still a warming one. I'd expect renewed warming unless some other -ve forcing equally as strong cancels out AGW. It's possible that might happen (a real drop in solar output, perhaps SE Asian aerosols, or a really big volcano) but unlikely - imo.

Whatever we'll, know in a few years. I would expect renewed warming in the next few years ans some reason to be apparent if that doesn't happen.

Edited August 11, 2008 by Devonian

[Gray-Wolf]

If we were to take away ALL naturally occurring variation within the global climate we would still surely still be looking at a period of flat-lining/pan evaporation rates falling wouldn't we?

The first 'globally dimmed' period ,when the First world and USSR seemingly went hell for leather to 're-build' post WW2 (and in a very i 'dirty/unregulated/unrestricted' kind of way must've been similar to the mess that the 'brown coal/lignite' (which is powering the Chinese mega-drive into 'first world' status .....India aside) is putting up into the atmosphere.

We know ,from past experience, that once folk 'clean up their acts' that there is a rapid acceleration in the rate of change in global temperature up to the point that global temps would have attained were it not for the period of 'dimming'.

Add back in the natural, cyclical, climate variations and we have what we see globally today (even though global temps are still historically 'high' and on a rising trend over the past 100yrs). I worry (as you all know) about us breaching various 'tipping points' and any that any complacency ,within any temporary period temperature stability , would lead to a rapid breaching of many of these 'tipping points' once the 'normal' global rates of warming are resumed (as the first world helps the developing nations to 'clean up' their acts).

[Iceberg]

This is a graph of Thompson's reconstructions which (I wonder why) doesn't seem to get the same exposure. He's applied a very simplified basis for the correction and as we know every Enso event has a different outcome depending on a variety of factors, was a short sharp ENSO spike, what was the prevailing PDO signal etc.

So you pay your money and take you pick. I still don't think much of his work except as an exercise however the trend is still very very obvious.

Going back to the question of why temperatures have leveled off over the last decade.

I've put in the enso index the PDO index and the solar index all of which have an effect on temperature. Now with me thinking that the AGW theory is right my view would be that CO2 leads per se to an increase in tempertures, however we all know that per se is not correct in the real world. We have natural climate forcings from Natural cycles such as the ENSO and PDO, from sulphur, from volcanic activity and from solar forcings. (I am leaving out GWO's theories for now! ).

Going for the ones that are easier to read in a graph ENSO, PDO and Solar.

Basically you can see for yourselves we have the 1999 to 2008 period has seen a marked reduction in PDO since the 70's, a marked reduction in the ENSO index and more recently we are entering a low point of the solar cycle. All three have not been in such a negative forcing state since the 70's.

This has had a holding effect on the global temperatures reached but has barely brought them down from the heights they have achieved.

Cycle 23, by and large coincided with a much more positive ENSO and PDO which is not the case now.

I can turn the answer on it's head, if we have a triple wammy of negative forcing at the moment, why are temperatures not a lot lower than they are now ?. I might have believed the theory of delayed action but when matching the major forcings against temperatures previously this delayed action has not been evident......

[JRMcLeod]

Sorry its slightly off topic but would i be right in saying that i read recently that because a government agency have recovered and studied shipping data all the way back to the back to the eary 1600's, they are now suggesting that these temperature changes, extreme weather etc etc etc have all occurred before, even more seriously than they are now but minus the pollution factor that we have now?

[Iceberg]

I think the answer is that an academic went through the old naval logs and discovered what he believed to still be extreme events. He then went on to say that he thought that AGW was still occuring, just that not every extreme event should be attributable to it. Something I broadly agree with, although I do not agree with some of his analysis of the naval logs.

[Thundery wintry showers]

Well, I would argue that adopting a "wait and see" approach whenever something's uncertain is actually a dangerous route to go down. If my CPU temperature shows 75C, is it a good idea to just wait and see if it fries my CPU, since it could just be a natural cycle (it could drop to 60C tomorrow you know!) and my CPU might be capable of handling the temperature? Or do I play it safe and take action to get the temperature reduced to a more sensible 55C?

I'd also argue that the premise that we have no control over what happens is presupposing that CO2 isn't having an effect, not the opposite. I say these things, btw, as someone who is not convinced that we can say for definite that CO2 is the main cause of the recent warming, so I don't want anyone labelling me as a strongly biased pro-warmist.

Iceberg's posts above add a fair amount of evidence for the assertion that natural forcings may well be causing the stalling of the trend, and not necessarily signifying zero anthropogenic forcing (e.g. 0.2C of anthropogenic forcing - 0.3C of natural cooling = -0.1C change). We don't know these things, but we can make educated guesses- thus, guesses that have an above average chance of being near the mark.

[beng]

I've put in the enso index the PDO index and the solar index all of which have an effect on temperature. Now with me thinking that the AGW theory is right my view would be that CO2 leads per se to an increase in tempertures, however we all know that per se is not correct in the real world. We have natural climate forcings from Natural cycles such as the ENSO and PDO, from sulphur, from volcanic activity and from solar forcings. (I am leaving out GWO's theories for now! ).

Going for the ones that are easier to read in a graph ENSO, PDO and Solar.

Basically you can see for yourselves we have the 1999 to 2008 period has seen a marked reduction in PDO since the 70's, a marked reduction in the ENSO index and more recently we are entering a low point of the solar cycle. All three have not been in such a negative forcing state since the 70's.

This has had a holding effect on the global temperatures reached but has barely brought them down from the heights they have achieved.

Well looking at your graphs I'd say Enso has averaged out close to neutral over the last 10 years as has the PDO. If these signals are neutral over that timespan then it means there's no forcing on global temperature (averaged over the period) - however we should still have seen the AGW signal and hence a rise in global temperatures corresponding to the strength of that signal (this excludes any effect from solar forcing of course) - but that seems to be missing. I'm not arguing for no AGW, only that it seems to be rather small.

If we see the PDO and Enso average 'negative' over the next 10 years and then leaving aside effects from AGW, then you'd expect the cooling to show itself.

[VillagePlank]

Kept away for a couple of weeks (after losing me rag) but I still see nothing has changed. Same old same old.

The mathematics do not support any theory that global warming has ended (I've left out the anthropological bit on purpose) Indeed, to claim such a case is tantamount to claiming that Princess Diana did not die, she was actually abducted by aliens.

The simple truth (and it is simple) is that not enough time has elapsed to debunk a 30 year old trend. On really, really, simple terms, you'd need another 30 years to be confident of a 50/50 or (or 50%) chance of you being right, and, given that the high point, recent, seems to be 1998 (I am, for brevity conveniently ignoring the 1998 spike) that'll put you on even terms about 2028, some twenty years hence.

It really is quite simple.

I can understand predictions, within that twenty years, of severe winters, and of real problems, but can you really say that this is the tune to hum for the future? The 'agreed' AGW signal is 0.2C; it is very clear and very apparent that the natural signals mask this - at an extreme end of the spectrum, I can see some of you arguing that, "hey! look it get's 5C colder every night - of course there's no global warming!"

There is a middle ground, and that middle ground is that, short-term, it's going to cool. EVERYBODY believes that, including the very pro-AGW MetO. To use that as evidence in a mire of misunderstaning, in my opinion, is erroneous.

To search for the truth, in this case, is to look at the mathematics. There's nowhere else to look, and if you are looking elsewhere, you might as well be looking at your feet.

[jethro]

Kept away for a couple of weeks (after losing me rag) but I still see nothing has changed. Same old same old.

The mathematics do not support any theory that global warming has ended (I've left out the anthropological bit on purpose) Indeed, to claim such a case is tantamount to claiming that Princess Diana did not die, she was actually abducted by aliens.

The simple truth (and it is simple) is that not enough time has elapsed to debunk a 30 year old trend. On really, really, simple terms, you'd need another 30 years to be confident of a 50/50 or (or 50%) chance of you being right, and, given that the high point, recent, seems to be 1998 (I am, for brevity conveniently ignoring the 1998 spike) that'll put you on even terms about 2028, some twenty years hence.

It really is quite simple.

I can understand predictions, within that twenty years, of severe winters, and of real problems, but can you really say that this is the tune to hum for the future? The 'agreed' AGW signal is 0.2C; it is very clear and very apparent that the natural signals mask this - at an extreme end of the spectrum, I can see some of you arguing that, "hey! look it get's 5C colder every night - of course there's no global warming!"

There is a middle ground, and that middle ground is that, short-term, it's going to cool. EVERYBODY believes that, including the very pro-AGW MetO. To use that as evidence in a mire of misunderstaning, in my opinion, is erroneous.

To search for the truth, in this case, is to look at the mathematics. There's nowhere else to look, and if you are looking elsewhere, you might as well be looking at your feet.

It's all well and good saying this VP and I pretty much agree that short time spans are meaningless for large scale predictions, but both the 3rd and 4th IPCC reports, use terms of five years to present their evidence as compelling proof that CO2 is the culprit. Their five year periods are even more meaningless than using the past ten years, or even just the 21st century to date. Yet it is ok for them but not those who disagree with the AGW theory - where's the sense in that?

Given that ocean cycles such as the PDO oscillate in 20-30 year time spans, would it not make more sense to compare like with like? The last 30 year positive phase ended in 1947, if we compare the run up to this period with today, then climate signals deriving from this particular driver should be more obvious. We've flat lined in temps for the last 8-10 years, so if we compare to a similar period of positive PDO, did we flat-line in temps during 1937-47? Did temperatures escalate in a way similar to today during the late 1920's-mid 30's?

I know the past in no definite indicator of the future, but it would give us some idea of the level of impact these individual cycles have upon global climate.

[Devonian]

It's all well and good saying this VP and I pretty much agree that short time spans are meaningless for large scale predictions, but both the 3rd and 4th IPCC reports, use terms of five years to present their evidence as compelling proof that CO2 is the culprit. ...

My italics.

I can't remember them doing this so what do you have in mind, and proof of being the culprit for what?

Btw, I think VP is pretty much right.

[VillagePlank]

It's all well and good saying this VP and I pretty much agree that short time spans are meaningless for large scale predictions, but both the 3rd and 4th IPCC reports, use terms of five years to present their evidence as compelling proof that CO2 is the culprit. Their five year periods are even more meaningless than using the past ten years, or even just the 21st century to date. Yet it is ok for them but not those who disagree with the AGW theory - where's the sense in that?

Given that ocean cycles such as the PDO oscillate in 20-30 year time spans, would it not make more sense to compare like with like? The last 30 year positive phase ended in 1947, if we compare the run up to this period with today, then climate signals deriving from this particular driver should be more obvious. We've flat lined in temps for the last 8-10 years, so if we compare to a similar period of positive PDO, did we flat-line in temps during 1937-47? Did temperatures escalate in a way similar to today during the late 1920's-mid 30's?

I know the past in no definite indicator of the future, but it would give us some idea of the level of impact these individual cycles have upon global climate.

Hi Jethro. I avoided Co2 on purpose, and I think I virtually said that. I am coming from a completely agnostic point of view, and from that stance, I stand by what I said. Indeed, from what I have been saying it might well be the case that Co2 is a misleading issue, but, from my PoV, it'll take quite some time to show that.

[jethro]

Hi Jethro. I avoided Co2 on purpose, and I think I virtually said that. I am coming from a completely agnostic point of view, and from that stance, I stand by what I said. Indeed, from what I have been saying it might well be the case that Co2 is a misleading issue, but, from my PoV, it'll take quite some time to show that.

I appreciate that VP, CO2 was my addition, perhaps what I should have said is "anything other than natural cycles".

Climate cycles up and down, with or without influence from us, choosing the time scale to gauge this seems to have become an arbitrary 30 years but that doesn't make much sense to me. Ocean oscillations make large differences to climate, they oscillate on 20-35 year cycles (depending upon which one) so to take a 30 year period where a cycle has been in a positive phase as a measure of "our impact" upon climate is ludicrous. A positive phase PDO leads to warming, if we compare today's temperatures to a similar period during the last positive phase, would that not give a clearer indication of how much warmer we are now, than then?

In 1905 the PDO switched to positive mode, 1946 to negative, 1977 to positive and now again it has switched back to negative. We are now being told to expect cooler temperatures - a natural driver has kicked in which should lead to cooling. Can anyone please tell me how it is perfectly acceptable to predict and expect cooler temps due to this and yet the same scientists, using the same knowledge and expertise can and do say the previous positive phase had no impact upon the warming we have experienced? It doesn't make any sense.

To measure the difference in temps, roughly calculating to mitigate the influence of a positive PDO we should compare today to 1936/37 - a time comparable with today, after 30-31 years of positive PDO influence.

Dev: you've asked me this before, the last time I trawled through pages and pages to provide the evidence for you, I'm sure if you scroll back through this thread, you'll find it.

[laserguy]

I can't remember them doing this so what do you have in mind, and proof of being the culprit for what?

Hmm... but everyone concerned and able to change policy are doing so on the basis of the IPCC's statement that they are 95% certain that we are responsible for warming. Action and policy so far is assuming that warming will proceed indefinitely (even though it's stopped,certainly for the time being),and no concession whatsover is entertained wrt to the possibility of long term cooling. Judging by all the clamour to reduce CO2 emissions,they see nothing else as being culpable and,erronously,that the only way is up - long term of course.

[Iceberg]

Your not being told that Jethro.

" Can anyone please tell me how it is perfectly acceptable to predict and expect cooler temps due to this and yet the same scientists, using the same knowledge and expertise can and do say the previous positive phase had no impact upon the warming we have experienced? It doesn't make any sense"

Scientists say that of the warming that occured during the last 30 years x% is natural and y%is Not. They argue over what the percentages are. But the consensus is around x=30 y = 70 or x - 40 y = 60.

This is largely being born out by the effect of brief negative PDO around 2000 and the the negative PDO again now(see my double wammy post). Nobody can be certain but the theory's and evidence are there.

[Devonian]

Hmm... but everyone concerned and able to change policy are doing so on the basis of the IPCC's statement that they are 95% certain that we are responsible for warming.

Well " Most of the observed increase in global average temperatures since the mid 20th century is very likely due to the observed increase in anthropogenic ghg concentrations" so close. But, I can't remember the IPCC claiming anything is proven over a five year period (but, I've yet to check all the posts of this thread - obviously...).

Action and policy so far is assuming that warming will proceed indefinitely (even though it's stopped,certainly for the time being),and no concession whatsover is entertained wrt to the possibility of long term cooling. Judging by all the clamour to reduce CO2 emissions,they see nothing else as being culpable and,erronously,that the only way is up - long term of course.

Sorry, but no one is assuming or predicting indefinite anthropogenic warming.

[jethro]

Your not being told that Jethro.

" Can anyone please tell me how it is perfectly acceptable to predict and expect cooler temps due to this and yet the same scientists, using the same knowledge and expertise can and do say the previous positive phase had no impact upon the warming we have experienced? It doesn't make any sense"

Scientists say that of the warming that occured during the last 30 years x% is natural and y%is Not. They argue over what the percentages are. But the consensus is around x=30 y = 70 or x - 40 y = 60.

This is largely being born out by the effect of brief negative PDO around 2000 and the the negative PDO again now(see my double wammy post). Nobody can be certain but the theory's and evidence are there.

I've yet to see anything which states in percentage terms how much is natural/manmade. I have also not seen anything which accepts the last thirty odd years of a positive PDO have contributed to warming temps. Brief ups and downs are not the issue here, we're talking phase shifts. Google climate shift 1976, there's loads of info, too many links to list here.

Which theory and evidence do you mean?

[Android]

Again, I ask: what are the strong negative natural forcings that would cause a flat temperature trend the past 8-10 years?

Perhaps it's not forcings at all but internal variation, ie climate noise. ENSO is only one component of that so the ENSO-corrected graph still contains such noise.

It's possible that the rise to 2001-2002 temp levels was aided by positive contribution from internal variation. It was rather higher than 90s levels afterall and got there fairly quickly. In which case the drop/flatness since then has been largely due to that dropping out, perhaps even being followed by a bout of negative contribution in the last few years. Id like at least another 10 years of not much changing before concluding warming has ended.

[Rob]

didnt the Met Office publish a report a little while ago that showed that the world's temperatures have cooled and not warmed?

[Thundery wintry showers]

The MetO published a report showing no warming in global temps over the period 1998-2007 but stressed that there have been natural forcings over the period that have tended towards cooling, which would negate any anthropogenic forcing over the period. So elements for both sides of the argument really.

[Rob]

The MetO published a report showing no warming in global temps over the period 1998-2007 but stressed that there have been natural forcings over the period that have tended towards cooling, which would negate any anthropogenic forcing over the period. So elements for both sides of the argument really.

i dont know what to believe anymore! so many stories, i don't believe any of it, ill wait and see what happens.

[jethro]

The MetO published a report showing no warming in global temps over the period 1998-2007 but stressed that there have been natural forcings over the period that have tended towards cooling, which would negate any anthropogenic forcing over the period. So elements for both sides of the argument really.

Did they say which natural forcings? As far as I'm aware, there have been no natural drivers in a negative/cooling phase over the last ten years.