Remember the 400+ anti-gw report ?

[jethro]

This looks a little circular to me. See IPCC thread for greater clarification.

[Roo]

This looks a little circular to me. See IPCC thread for greater clarification.

Doesn't at all to me: and you still haven't answered my question!

1) I believe that the consensus is one of the majority of the scientific community, NOT just the IPCC. Therefore to use my name with an assumption that it was just the IPCC consensus I was referring to, was incorrect.

2) By referring only to the IPCC consensus, you were suggesting the rest of the scientific community did not agree: I wanted to check that was what you meant. Was it?

[jethro]

I was replying to Diessoli, not you. I mentioned your name, my mistake, won't do it again. For clarification of anything else please read the IPCC thread.

Again, apologies for mentioning your name whilst replying to someone else, won't do it again.

Edited January 25, 2008 by jethro

[Roo]

I was replying to Diessoli, not you. I mentioned your name, my mistake, won't do it again. For clarification of anything else please read the IPCC thread.

Many thanks for the apology, and sorry to be picky, but I truly am interested, and having looked through the IPCC thread, I still can't find the answer. I'll put it another way, just to be clear: do you believe that AGW is an IPCC created phenomenon not backed up by consensus of the wider scientific community?

[pottyprof]

Many thanks for the apology, and sorry to be picky, but I truly am interested, and having looked through the IPCC thread, I still can't find the answer. I'll put it another way, just to be clear: do you believe that AGW is an IPCC created phenomenon not backed up by consensus of the wider scientific community?

Roo.. In all fairness to Jethro, she has answered that question elsewhere on the forum. AGW is still not a proven fact. It is still just a theory with holes, just not as many holes as other theories..

[Guest diessoli]

Hi Jethro,

No worries about the delay. I've got other things to do as well.

Good morning Diessoli

Sorry for the delay in replying - busy, busy, busy.

So the role of the IPCC is to look for human-induced climate change, it doesn't do research but instead selects research which supports it's mandate of AGW. Seek and ye shall find.

If their mandate was to look at CLIMATE CHANGE as a whole then the report would have more credence.

The role of the IPCC is to assess the information about human-induced climate change, not to look for it. This is because it was realised that humans might change the climate and that we need to know if so and what consequences it might have.

I would say, that the part I've highlighted is purely your interpretation. I also believe that it is an unfair and unjustified allegation (and not backed up by evidence). It is also much too convenient, because once you have such an opinion it gives you a very easy way out of discussing any of the contents of the report - or the referenced material.

I am a wee bit disappointed that you did not reply to any of the points I made, in particular the ones about the Schwartz and Hartmann papers. You have used them as examples of papers that support your doubts, and I would be interested if you still see them that way or not.

Cheers

Hi Pottyprof,

Roo.. In all fairness to Jethro, she has answered that question elsewhere on the forum. AGW is still not a proven fact. It is still just a theory with holes, just not as many holes as other theories..

Makes me wonder what you consider a proven fact. Would you mind to give some examples of theories that you think are proven facts?

The IPCC report (there you go again) for instance just says that it is very likely that the observed trend in global temperatures are not solely due to natural variation.

Anyway, unless you guys point out specific scientific issues that you have with the research used for the reports or with the conclusions that are drawn, there isn't really any basis for a discussion that might get us anywhere.

Cheers

[pottyprof]

Hi Pottyprof,

Makes me wonder what you consider a proven fact. Would you mind to give some examples of theories that you think are proven facts?

The IPCC report (there you go again) for instance just says that it is very likely that the observed trend in global temperatures are not solely due to natural variation.

Just about everything about this subject is based on theory. Most of it is full of holes. The only thing that can be proven at the moment is one of temperature rise and it's observed effects. Prove without doubt that AGW exists and I'll be happy to accept that 100%.. But you can't. I did say AGW theory has less holes than other theories.

Anyway, unless you guys point out specific scientific issues that you have with the research used for the reports or with the conclusions that are drawn, there isn't really any basis for a discussion that might get us anywhere.

Cheers

In your humble opinion.

Perhaps I should just give in and accept without question? Perhaps just hope and pray the recent cooling trend is a short live blip..??

[Guest diessoli]

Just about everything about this subject is based on theory. Most of it is full of holes. The only thing that can be proven at the moment is one of temperature rise and it's observed effects. Prove without doubt that AGW exists and I'll be happy to accept that 100%.. But you can't. I did say AGW theory has less holes than other theories.

In your humble opinion.

Perhaps I should just give in and accept without question? Perhaps just hope and pray the recent cooling trend is a short live blip..??

By no means I am asking you to just "give in and accept". All I wanted to say is that, if you want to question the science it's pretty pointless to make arguments like "it's all just a theorie with holes". It would be much more interesting to talk about what those holes are and what there impact on the general picture is.

We could for example talk about the question if two years of lower temperature anomalies constitute a statistacilly significant trend.

Here is my take: the temperature trend (for any of the global data sets) is still upward, there is no cooling trend as far as climate is concerned.

As for proving without doubt: you're right I can't. Especially given that doubt is a subjective thing.

Cheers

[pottyprof]

By no means I am asking you to just "give in and accept". All I wanted to say is that, if you want to question the science it's pretty pointless to make arguments like "it's all just a theorie with holes". It would be much more interesting to talk about what those holes are and what there impact on the general picture is.

We could for example talk about the question if two years of lower temperature anomalies constitute a statistacilly significant trend.

Here is my take: the temperature trend (for any of the global data sets) is still upward, there is no cooling trend as far as climate is concerned.

As for proving without doubt: you're right I can't. Especially given that doubt is a subjective thing.

Cheers

But it depends on data sets you use to get the results you are looking for. If you use a 30 year average then yep it shows warming.. Try using the last 10 years as a rolling average. That will show a recent trend of levelling. Try looking at real data and it becomes obvious that there is a cooling over recent years though higher temps than 100 years ago...

Until scientists can agree upon a single set of figures as a standard, then there will always be circular arguments.. Holes.. Yep.. and Plenty..

[Guest diessoli]

Hi,

But it depends on data sets you use to get the results you are looking for. If you use a 30 year average then yep it shows warming.. Try using the last 10 years as a rolling average. That will show a recent trend of levelling. Try looking at real data and it becomes obvious that there is a cooling over recent years though higher temps than 100 years ago...

Until scientists can agree upon a single set of figures as a standard, then there will always be circular arguments.. Holes.. Yep.. and Plenty..

Ok, let's look at 10 year averages. Or maybe let's look at 9, 10 and 11 year averages.

We play it simple and just look at some plots and don't worry about testing the significance.

Since we're talking about recent changes I've plotted only the last 17 years, data is from HadCru.

Looking only at the last few points we see warming, cooling and less warming (or levelling as you call it).

What we see is the influene of the 1998 El Nino.

Let's get rid of it by replacing the 1998 value with the average of the 1997 and 1999 values:

Now they all show warming (or levelling).

Simple averages are not robust against outliers, which is a particular issue for small sample sizes.

By just looking at the 9 year averages we can see how easily a "trend" can be poluted.

The 10 and 11 year average are somewhat less affected:

Although in both cases you see noticable differences from 1998 on.

Now let's look at 15, 20 and 25 year averages:

With the El Nino event:

and without it.

Already the 15 year average is much less affected by short term variation.

Now. I have looked at real data (I am not sure what you think I looked at before).

To me it is not obvious that the 10 year average shows a cooling over recent years. If anything, we see that there is less warming. And since there is no rule that says the 10 year averages is more correct than the 11 year ones, I can just as well look the latter and conclude that, compared to the year before, the warming has accelerated.

Since both are too much affected by short term variation it's meaningless to use them to determine long term climate trends.

Also none of the two is statiscally significant. I've probably bored you enough with those plots, but we could go through and do some tests for significance.

If you really want to establish that we are seeing a change in the trend around now you will have to wait for probably another 10 years.

Climate scientists know all that, which is why you will normally not find that they are using simple rolling averages. Usually the data is passed through a low pass filter to remove the short term variability. Applying a 10 year average to that sort of data is a completely different matter.

Holes? There are certainly aspects in climate science (or AGW in particular) that are not understood or uncertain. But as of yet you've not really pointed your finger to any holes.

As for "Until scientists can agree upon a single set of figures as a standard", I have to say that I don't understand what your point is.

Cheers

P.S.

There is something very annoying about posting here. Almost everytime I want to post something I get an error message that I don't have permission and need to log in again, using the "saved post data" text which I than have to reformat. I guess it's because my session has expired?

And attachments seem then to be lost.

Is there anything I Can do about this? Or I am just too stupid to use this s/w properly?

Thanks

Edited January 27, 2008 by diessoli

[Roger J Smith]

Sorry I left a couple of details unanswered in this thread.

The point I was making earlier about large natural variations was not to compare absolute temperatures but relative temperature variations. All of these ups-and-downs have been against a steadily rising global or at least northern hemisphere temperature curve, a fact that itself should cause some skepticism about the AGW theory, since even before this recent warm spell, the supposedly natural peaks of the 20th century were at least on a par with the 18th century and medieval warm spells. In any case, I have already conceded that as much as one-third of the observed warming in recent decades is from greenhouse gases, and I believe this explains the surplus of temperature now relative to, let's say 1921-39 to find a period suitably far removed from the present.

I also mentioned the Alberta oil sands project in a somewhat facetious way, as it was not really up and running in 1994. It is now, however, and critics say it is the largest single source of greenhouse gas emissions of an industrial nature in Canada. The location is near 56 N just west of the Alberta-Saskatchewan border. The predicted overnight low there on Wednesday is about -40, so the local effect is not exactly catastrophic.

This winter has actually demonstrated a lot of weaknesses in the AGW theory, record cold spreading across large parts of southern and eastern Asia, a very cold winter in parts of North America too, and Greenland seeing a return of thick ice to the west coast after an absence of many winters. That open water anomaly closed up very quickly in the western arctic and temperatures across the far north of Canada have been generally 3-5 degrees below normal since New Years.

I sense that there is just as much chance of a reversal of this current regime to a colder natural climate soon, as there might be for a continuation of the warmer regime. We will have to wait and see. The interaction of the greenhouse gas warming with a colder natural regime might be difficult to interpret, once again, we will have to assess that if and when it develops.

People who think that there will now be runaway warming and no return to the degree of cold known in the recent past, may be in a for a big surprise. However, as I've explained elsewhere on NW, Europe would be the last to feel this change, this natural cycle has phased with a shift in the magnetic field to allow for considerably higher jet-stream latitudes in the past 20 years, and it could be a while until Europe gets more than the weak outer edges of any large-scale changes to cold going on elsewhere. Hemispheric natural variations can take 10-20 years at a minimum to affect all continents and even longer to have effects on oceanic temperatures and currents. I suspect that we may now be in the first stages of this cooler natural climate in North America at least. The last decade to register colder than the previous one here was probably 1975-84, and that change began with a very volatile period of large swings above and below normal through much of 1975-77 before it settled into a cold regime for several years.

[Guest diessoli]

Hi,

Sorry I left a couple of details unanswered in this thread.

The point I was making earlier about large natural variations was not to compare absolute temperatures but relative temperature variations. All of these ups-and-downs have been against a steadily rising global or at least northern hemisphere temperature curve, a fact that itself should cause some skepticism about the AGW theory, since even before this recent warm spell, the supposedly natural peaks of the 20th century were at least on a par with the 18th century and medieval warm spells.

I don't know a lot about those, but there is considerable doubt in the scientific community that those where global phenomen.

But even if there had been such warm periods, that is no proof that the underlying cause is the same.

This winter has actually demonstrated a lot of weaknesses in the AGW theory, record cold spreading across large parts of southern and eastern Asia, a very cold winter in parts of North America too, and Greenland seeing a return of thick ice to the west coast after an absence of many winters. That open water anomaly closed up very quickly in the western arctic and temperatures across the far north of Canada have been generally 3-5 degrees below normal since New Years.

Can you explain a bit more what those weaknesses are, in your opinion. Where does AGW say that we can longer have cold winters?

Cheers

Edited January 28, 2008 by diessoli

[Roger J Smith]

Well, I am just referring to the widespread belief among AGW skeptics that there is a tendency to try to sweep up all weather events as "proof" of the theory, as it has already morphed into the easier-to-defend "climate change" theory.

Although I am willing to grant some leeway here, realizing that a warming climate could produce a variety of individual events, there would be some critical point at which the frequency of cold events would no longer sustain credibility for the AGW hypothesis. I don't think we have reached that point, in other words, the AGW hypothesis still remains valid, but it does seem that colder events are increasing in frequency globally since perhaps 2000, and this trend has been noticed by quite a few people, not just myself -- even here on Net-weather, it is hardly a fringe observation.

I am not that strongly moved in either direction on this, frankly, the theory strikes me as plausible but not yet nailed down, and I have reservations about what percentage of the warming we can really ascribe to the human contribution. It would not surprise me as much as it might surprise ardent AGW supporters, if the climate in Europe turned colder at some point, because I have seen this happen over here, at least the runaway warming aspects of the 1990s seem to have slowed to a standstill if not a slight reversal.

And it plays out in public expectations being unmet -- the public, non-weather-buffs that is, were generally led to expect a steady reduction in the duration and intensity of winter, for example, but now this winter we are seeing more snow than usual in quite a few places and the western mountains are generally buried in huge amounts of snow. If these inconsistencies happen frequently enough, public acceptance of the global warming theory, which is surprisingly robust given the usual climate of skepticism of official pronouncements in this continent, may erode.

Climate change to my mind is the essentially Buddhist scientific theory -- it is what it is. People can predict whatever they want, but climate will be whatever it actually is, at any time, and there's no altering that fact with any amount of belief, passion, or concern. So we will just have to wait and see what really happens, although if people want to develop cleaner technology, that will be a good thing. I don't oppose the technology of global warming so much as the intellectual constructs of the theory.