Global Warming

[pjclarke]

And in the reality-based community, climate means longer than the last 18 months....

Here are the IPCC model sea level numbers, baselined 1990 Climate Change 2001: The Scientific Basis

Scenario A1F1 best matches the actual emissions, giving a model average projected sea level rise 1990-2010 of 37mm or 1.85mm / year (upper bound 65mm).

You can see just by eyeballing the graph that the actual rise was greater,




So which measurements and predictions had you in mind, exactly? Not the IPCC, clearly.

[EternalOptimist]

Whose predictions ? well the paper you quoted earlier was coauthored by Hansen

according to him, we should be in runaway temp and sea level rises, in tandem with runaway CO2 rises.

[pjclarke]

Now I am confused. Hansen co-authored a paper with which he disagreed?

[BlasterBates]

Wierd, coulda sworn there was a post here a moment ago saying something about the ice age start date, been Googling? ....



Just wrong. Borehole proxies work by actually measuring the current temperature at various depths and adjusting for upward heat flux (read the paper!), nothing to do with isotopes. Ice cores work by analysing the composition of ice bubbles trapped at various depths. The borehole data goes up to present day, albeit with decadal resolution, the ice cores, well just one more thing that Easterbrook gets wrong:


Here's another Easterbrook special



You'll notice that

- He has 10K years ago warmer than today, as opposed to -2C in the borehole data,

- He has no idea when the MWP was, and

- His 'present day' temps are just nuts.

Apart from that, a perfectly informative graph.

Sure you want to champion this guy?

his historical data matches the rest of the literature try Alley 2000. Is he also nuts?

His present day temps match the peer reviewed paper I showed

http://www2.imm.dtu.dk/~kmos/papers/B7-Science1998.pdf

The CO is 2.5K warmer than the present temperature

and if you don't belueve that checkout the HADCRUT Greenland temperatures.



http://www.cru.uea.ac.uk/cru/data/gr...eenlandave.dat

So you can discredit Easterbrook until you're blue in the face, I'll just cite Dahl-Jensen et al. instead, and state exactly the same conclusions.

There is evidence in the ice core that for most of the last 10 thousand years it was warmer than today.

How did the Vikings keep cattle ?

[pjclarke]

So you can discredit Easterbrook until you're blue in the face, I'll just cite Dahl-Jensen et al. instead, and state exactly the same conclusions.

Well, yes I am sure you will, cherry-picking a single study (how big are the error bars 10K years ago btw?) and ignoring the bigger picture being another 'sceptic' tactic.
There are major discrepencies between Easterbrook and the borehole curve, and a single regional record cannot stand in for the global record — local variability will be higher than the global, plus we have evidence that Antarctic temperatures swing in the opposite direction to Arctic changes.

So the fact that it has been warmer in Greenland is not news. There were regional hotspots all around the North Atlantic c AD1000



But that was then, this is now

[BlasterBates]

There are major discrepencies between Easterbrook and the borehole curve, and a single regional record cannot stand in for the global record — local variability will be higher than the global, plus we have evidence that Antarctic temperatures swing in the opposite direction to Arctic changes.

So the fact that it has been warmer in Greenland is not news. There were regional hotspots all around the North Atlantic c AD1000



But that was then, this is now

Finally you agree with Easterbrook, and admit it was warmer, his basic premise. You do know don't you that the historic graph was taken from the literature, and that the blog was disputing the last 95 years?

Roundabout way of doing things don't you think. So to summarise:

You now agree the paleoclimate data in Greenland shows it was warmer 1000 years ago, and you are not disputing the other paper which shows it was warmer for most of 10000 years.

You've now changed your argument and saying it was a regional hotspot. That's fine so lets move on shall we,

What other evidence from other regions around the world, apart from tree trunks that is.

What about glacial variations, what do you think caused glaciers in North America and Europe to recede at around 1000 AD?

These variations are also backed up with other Paleo-Climate data:

Paleoclimatic interpretations based on shelled invertebrates from four sites in the northwest corner of the Northwest Territories, Canada, during the time interval 14 410–6820 years BP, indicate that the mean annual temperature was about 8.2–11.6 °C higher than at present, and that the annual precipitation was about 55–234 mm greater than at the present time. Based on potential evapotranspiration, it can be computed that the length of the growing season was about 156 days long as compared to between 90 and 135 growing days at the present time for the same area.

http://www.nrcresearchpress.com/doi/abs/10.1139/e77-174

Were these also regional hotspots? A big area don't you think? Looks like half of the Northern hemisphere.

[BlasterBates]

No, I do not agree with Easterbrook in any shape or form. Nor have I changed my argument. His work is profoundly unscientific and the antithesis of true scepticism. You cite Dahl-Jensen (1998) which reported on a single borehole as supporting the soundbite. A true sceptic might be tempted to ask questions about the uncertainty range of that study, whether the data from a single pinprick can possibly be representative of the wider area, never mind the whole globe. A true sceptic might want to look at more recent work, collect more data. Did Dahl-Jensen go on to expand the research? Ah, it seems she did, in 2001 she co-authored a study of 6 arctic ice cores which found:-



Not quite the tidy picture you and Easterbrook strive to paint with your single cherry-picked core but that's science for you. Rather than have you state my position for me, let me be clear ...

Modern global warming - the last 100 years or so, accelerating after the mid-seventies is unprecedented in rate and magnitude for at least the last millenium. The 'Medieval Warm Period' seems to have been warm in Europe and the N Atlantic, but cool in the Pacific and the Southern Ocean.

Data before about 2K years ago is sparse and uncertain, but the planet has certainly been warmer in the past. The fact that natural warming occured millenia ago means modern warming must also be natural is an obvious logical fallacy. In fact large historical swings mean the planet is more sensitive to changes in forcings, which is actually bad news as nobody sensible disputes that increasing greenhouse gas concentrations by 35% is anything other than a substantial positive forcing.

All neatly summarised in IPCC FAQ no 6.2

http://www.ipcc.ch/pdf/assessment-re...4-wg1-faqs.pdf

I like the way you keep changing the argument:

To summarise you argued

1) Greenland was colder.
changed to
2) Greenland was warmer but it was regional.
then changed to
3)The globe was warmer, but this doesn't mean the warming we have now which is natural, even though it was in the past. (see Alley at al. who investigate abrupt climate change globally)

I think those who read this can draw their own conclusions.

[Mich the Tester]

This thread is becoming a borehole.

[BlasterBates]

I agree with Mich. I've better things to do than 'debate' with someone who makes stuff up. (e.g. Point 1)

Or maybe run away rather than debate?

Very typical of those who support AGW, on the one hand banging on about science but refusing to actually debate it. The whole point about science is getting into the "nitty gritty", but you prefer sensationalised statements from blogs who aren't even run by scientists.

I think we'll note that and call it a day.

Have a nice day

[sasguru]

I think those who read this can draw their own conclusions.

Yes. You're not very bright nor very well educated.
Stick to your day job which is a dead cert to be one that does not require a rocket scientist to do it.