Global Warming

[Guest Viking141]

I'm going to change the subject a bit. Not that the discussions of Wilson's graphs isn't interesting, but I've spent much of the past twelve hours looking at an important site which was new to me: The Arctic system in a Changing World; Second International Conference on Arctic Research Planning. You can find it on http://www.icarp.dk/

Particularly relevant to a discussion of GW is the material from Working group 9; modelling and predicting Arctic weather and climate.

The conference took place last November and the proceedings were published this year, so its about as up-to-date as we can hope for.

There are discussions about the NAO/AO and PNA, the thermohaline circulation, natural vs. anthropogenic forcings. The focus is on first order feedback and forcing mechanisms over the coming 100 years. Much of this relates directly to discussions of GW scenarios and GCMs.

I hate to admit it, but it demonstrates that, in my case at least, a little knowledge is a dangerous thing. I am now less sure about several of the observations I have made here about thermohaline circulation shutoff in particular, and more aware of the plausibilty of a rapid 'switch' in conditions. It is a bit dry in parts, but worth persevering with.

Excellent site Parmenides, thankyou for flagging this up. I shall now be spending a fair bit of time reading and digesting what it says, particularly some of the subjects you mentioned which are dear to my heart re consequences of a thermohaline shutoff and rapid 'switch' of conditions. Fascinating stuff.

[parmenides3]

Excellent site Parmenides, thankyou for flagging this up. I shall now be spending a fair bit of time reading and digesting what it says, particularly some of the subjects you mentioned which are dear to my heart re consequences of a thermohaline shutoff and rapid 'switch' of conditions. Fascinating stuff.

B) You're welcome. Off topic: have you got your waterproof handy? I've just been looking at the GFS...

[VillagePlank]

But, the 'hockey stick' doesn't compare aginst running 30 year means, indeed I can't think of any graph anywhere that does? Not against running means? I just think comparing aginst running mean adds confusion (I'm certainly getting confused B) ), because you're not comparing years to the same base line.

Of course I'm not comparing years to the same baseline I am using a running mean.

I accept that the average of today's climate is different from the average of the last centuries climate. Why would you pick any period for a mean? Let's look at the 1970-2000 mean. Why use that range. Primarily, I presume, it's because it's close enough to today to be of use If that is the case then when you look at temperatures for 1900 why do we not use the same standard? Use a mean that is close enough to the date so it's useful

I understand that it's more complex to understand, and extrapolate useful information from; but, in my opinion, complexity should never prevent the production of such entities.

Edited August 8, 2006 by Wilson

[Guest Viking141]

You're welcome. Off topic: have you got your waterproof handy? I've just been looking at the GFS...

Well quite! Looks like some hefty rain headed my way for this evening and overnight. Its also very chilly and overcast so shouldnt be too far away!

[parmenides3]

Back to the subject of the graphs.

So, I still don't really get what this graph shows that's helpful?

A couple of suggestions (which may be wrong) about what might be got out of Wilson's graphs:

Historically, it looks like years which are unusually anomalous positively are normally followed by unusually anomalous negative years and vice-versa. As the graph is based on a rolling mean, this is to be expected, as the previous year's anomaly is incorporated into the rolling mean. Both the positive and negative anomalies, as Wilson says, tend to cycle towards zero over time; you can 'read' three 'humps' and three 'depressions' on the chart (the first one). But this is not happening over the most recent series; there is no negative response to the adaptation of the mean. What this could show us is the degree to which the climate tends to diverge from the (ongoing) norm ('deviationness', if you like). As such, it could be said to be supporting the notion that warming is accelerating exponentially. I think that's right.

Still no idea about the groups of three, though.

B)

[Methuselah]

So, I still don't really get what this graph shows that's helpful?

I think that it highlights the short-term variance as opposed to long-term trend. Again, I think that it eliminates the long-term trend altogether??? B)

It's not the sort of graph I'm used to reading, but I do think it's useful...My only idea about the triplets, is that they could be a reflection of negative-feedback mechanisms' natural tendencies to 'overshoot'...Homeodynamism as opposed to homeostasis??

Other than that, Wilson - my brain hurts!

[The Penguin]

I think that it highlights the short-term variance as opposed to long-term trend. Again, I think that it eliminates the long-term trend altogether??? B)

It's not the sort of graph I'm used to reading, but I do think it's useful...My only idea about the triplets, is that they could be a reflection of negative-feedback mechanisms' natural tendencies to 'overshoot'...Homeodynamism as opposed to homeostasis??

Other than that, Wilson - my brain hurts!

Oh, Peter.

Peter, Peter, Peter, Peter.

It’s just a graph. An interesting expression of an idea, but still only a visual representation of statistics. The content, duration, frequency, amplitude, scale and notation, (or lack of,) are chosen to prove a point – right or wrong doesn’t matter, as it’ll never truly be either.

What matters is that it’s pretty. Just enjoy it and absolve yourself from the responsibility of critical analysis. And the headache will go away.

For instance, below is an extended version that includes the same data, which might suggest a different interpretation.

[parmenides3]

Just picked this up from the Boulder, Colorado local paper. On the SOCC (State of the Canadian Cryosphere) site, they have announced that the sea ice extent (not cover) is the lowest ever recorded (100 yr record).

Record retreat of Arctic sea ice

This year's melting of Arctic summer sea ice is on track to be the most extreme since satellites began to track the polar ice cap in 1979, scientists at the National Snow and Ice Data Center on the University of Colorado campus say.

I'll post the same info on the SSTA/sea ice strand.

No GW? Yeah, right.

[VillagePlank]

Oh, Peter.

Peter, Peter, Peter, Peter.

It’s just a graph. An interesting expression of an idea, but still only a visual representation of statistics. The content, duration, frequency, amplitude, scale and notation, (or lack of,) are chosen to prove a point – right or wrong doesn’t matter, as it’ll never truly be either.

What matters is that it’s pretty. Just enjoy it and absolve yourself from the responsibility of critical analysis. And the headache will go away.

For instance, below is an extended version that includes the same data, which might suggest a different interpretation.

What's the scale on the left? (the y axis)

[The Penguin]

As far as I can tell, it is degrees C (edit: as a variation). But it kind of illustrates the point – why for instance is the Zero line where it is?

Edited August 9, 2006 by The Penguin

[The Penguin]

Sorry, the above is wrong. The graph only relates to December - February CET’s and therefore the scale is actual temperature in deg.C.

[parmenides3]

Hang your head...

[The Penguin]

Yes I will. Again.

[parmenides3]

That's alright, I like penguins. B)

Especially for Viking141, but also for other interested parties, another intriguing paper: 'Assessing the Risk of a Collapse of the Atlantic Thermohaline Circulation', by Schlesinger et.al., University of Illinois at Urbana-Champagne, 2005.

http://www.stabilisation2005.com/Schlesing...hermohaline.pdf

Fifty percent !!! I kid you not. Enjoy.

[johnholmes]

I rather think not just me but no one on this forum will still be around in 2205!

[parmenides3]

I rather think not just me but no one on this forum will still be around in 2205!

Point taken. Perhaps that post was a little provocative. B)

[Devonian]

I rather think not just me but no one on this forum will still be around in 2205!

But the consequences of what we do or don't do this century will....

[BLAST FROM THE PAST]

Point taken. Perhaps that post was a little provocative. B)

Still a very good link and read.

BFTP

[VillagePlank]

But the consequences of what we do or don't do this century will....

Indeed.

I rather think not just me but no one on this forum will still be around in 2205!

. . . but graphs will . . . B)

[Guest Viking141]

TY Parmenides excellent read!

For what its worth I think theres a chance we might be further down this road than anyone fully realises and a collapse could be not too far away. Just my opinion.

B)

[parmenides3]

TY Parmenides excellent read!

For what its worth I think theres a chance we might be further down this road than anyone fully realises and a collapse could be not too far away. Just my opinion.

B)

Funnily enough, I was wondering the same myself. However, there are a hell of a lot of monitoring programmes ongoing all round the world, and nobody yet has 'pushed the button'. If I read the material right, it will be the Winter-Spring situation which will determine whether they think we have passed a threshhold.

[summer blizzard]

From looking at data and drawing some conclusions, i must agree with Viking 141, i believe that there will be a severe change in ocean patterns sometime between 2020 and 2050.

[kippure]

From looking at data and drawing some conclusions, i must agree with Viking 141, i believe that there will be a severe change in ocean patterns sometime between 2020 and 2050.

Its already happening , fishermen in the north sea, North atlantic are increasingly losing nets to mud. This mud is been washed down from the land and rivers. Its a simple point. Its one of natures signs i think that something is happening ie theres alot of fresh water flowing into our sea,s.

[parmenides3]

From looking at data and drawing some conclusions, i must agree with Viking 141, i believe that there will be a severe change in ocean patterns sometime between 2020 and 2050.

'Cos I had some questions that the scientific papers didn't exactly answer, i've emailed someone who should know; as & when, I'll update you.

If we're talking about the THC shutting down, (I think we are), the thing to watch out for (the necessary condition) is the amount of 'freshwater' getting into the Atlantic from the Arctic. There are other elements to consider, but the evidence is fairly strong that this is what caused the rapid cooling in the Younger Dryas (about 11,500 years ago). Thing is, the amount of freshwater influx needed to cross the 'threshhold' is hugely mega-ginormous; about 0.6 Sv is the estimate based on recent modelling. (1 Sv = 10,000,000 m3/sec). The average freshwater contribution from the Arctic to the Atlantic is about 5000 km3/year. Glaciers have contributed about 600 km3/year on average.

In the models, the current intensity of the THC is estimated at 17.5 Sv at 15o N. irreversible decline kicks in when it drops to around 10 Sv. There is discussion of a change, historically, of freshwater perturbation between 50oN and 70oN of around 0.2 Sv over 1000 years.

Another analysis considered the key event to be the freshwater outflow over the Greenland/Scotland 'Nordic overflow'. I have figures for this one, too, but basically, both scenarios ended up with a similar result; given the current state of climate change, it is reasonable to believe in the possibility of a slowing of the THC in around 100 years, or a shutdown in around 200.

What gobsmacks me (apart from the complexity of dealing with such disparate measures) is the sheer scale of the whole process.

As I said, I haven't yet bought either of these two conclusions yet, but the kinds of numbers they are bandying about as critical to the THC are much, much greater than the current freshwater additon, by an order or two of magnitude. The verdict from the blue corner at the moment for a shift in thirty years or so is still 'unlikely, but definitely not beyond the realms of imagination'.

[BLAST FROM THE PAST]

Freshwater wise there are many contributory factors. Meltwater from glaciers, ice cover, snowcover melt, river deposit, very high precipitation levels. One quote from the horizon programme was that there would be Armadas of icebergs flowing into the North Atlantic due to the Greenland 'meltdown'. Someone forgot to mention that up til recently Greenland had been cooling for wee while I found that report posted by Permanides3 very intriguing but do not see that as an option in our lifetimes...but of course is possible.

Re the change in ocean patterns I believe solar variance can cause/affect that so a shutdown is not necessary for this to occur.

BFTP

Edited August 11, 2006 by BLAST FROM THE PAST