Medieval Warm period due to NAO

[nigelfr]

Breaking news from Physics.org..."In the April 3rd edition of Science a collaborative group of scientists from Switzerland, California and the UK report that medieval climate over Europe was heated by the North Atlantic Oscillation (NAO). This oscillation pattern, defined as the pressure difference between the Icelandic Low and the Azores High, also influences modern-day weather conditions and has contributed to the recent droughts in North Africa and floods in North-Central Europe."

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

[nelly1]

Medieval you say?

Well I guess that's the Man Made CO2 theory pretty much up the Swanney as well!

[TheEnd]

nigelfr said:

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

Pretty much all heat comes from the sun

[FarleyRusk]

nelly1 said:

Medieval you say?

Well I guess that's the Man Made CO2 theory pretty much up the Swanney as well!

Yeah, but no, but - the population was growing massively and people BREATHE OUT CO2.

[ewenm]

nigelfr said:

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

nelly1 said:

Well I guess that's the Man Made CO2 theory pretty much up the Swanney as well!

So what have we got left?

[ATG]

TheEnd said:

nigelfr said:

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

Pretty much all heat comes from the sun

On that at least everyone agrees. The question is about solar variability

[NiceCupOfTea]

Quick! Hush it up!

[Bing o]

nigelfr said:

Breaking news from Physics.org..."In the April 3rd edition of Science a collaborative group of scientists from Switzerland, California and the UK report that medieval climate over Europe was heated by the North Atlantic Oscillation (NAO). This oscillation pattern, defined as the pressure difference between the Icelandic Low and the Azores High, also influences modern-day weather conditions and has contributed to the recent droughts in North Africa and floods in North-Central Europe."

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

Nigel - you do realise that MMGW proponents point to the recent droughts and floods as being a sign of MMGW don't you??

MMGW is bullst - 1 . . . 0 MMGW

33" Nigelfr (og)

[DocJock]

Do you have a link please nigel? I can't find it anywhere in the 'latest news'.

Alternatively, how were these pressures measured in medieval times and where were they recorded or what is the mechanism for estimating the values from back then?

[voyds9]

nigelfr said:

Breaking news from Physics.org...scientists from Switzerland, California and the UK theorise that medieval climate over Europe was heated by the North Atlantic Oscillation (NAO).

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

Excuse my alteration but that is probably nearer the truth.

Also because one effect is in play it doesn't stop another. The NAO may have had an effect so may the sun.

(If a man has cancer it doesn't stop him getting diabetes.)

[TheLemming]

DocJock said:

Do you have a link please nigel? I can't find it anywhere in the 'latest news'.

Alternatively, how were these pressures measured in medieval times and where were they recorded or what is the mechanism for estimating the values from back then?

The mechanism for nearly all historic atmospheric information (as I understand it) is ice cores. Take a nice old iceflow. Drill down into it, remove ice made back then. Test composition of ice and et voila.

Works back to long before mankind was around.

[Blib]

Nigel...?

Nigel.......?


Where you gone?

[Swilly]

nigelfr said:

Breaking news from Physics.org..."In the April 3rd edition of Science a collaborative group of scientists from Switzerland, California and the UK report that medieval climate over Europe was heated by the North Atlantic Oscillation (NAO). This oscillation pattern, defined as the pressure difference between the Icelandic Low and the Azores High, also influences modern-day weather conditions and has contributed to the recent droughts in North Africa and floods in North-Central Europe."

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

What is the root cause of any weather pressure system, the root cause, without which there would be no weather system ?

[tamore]

ewenm said:

nigelfr said:

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

nelly1 said:

Well I guess that's the Man Made CO2 theory pretty much up the Swanney as well!

So what have we got left?

weather. supposed to be pissing down in london today according the the report of the 6 o'clock news last night. so far, unbroken sunshine. we haven't got a clue when it comes to short, medium or long range predictions.

[Swilly]

ewenm said:

nigelfr said:

So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

nelly1 said:

Well I guess that's the Man Made CO2 theory pretty much up the Swanney as well!

So what have we got left?

A third man in the building behind the grassy knoll !?

[odyssey2200]

opcorn smiley:

[mybrainhurts]

nigelfr said:

Wow, Wee, Bam, Whack....
So I guess that makes a big hole in the "It's the Sun" theory of Global Warming.

Here we go again...

I have this mental picture of our Nige, garbed up like a ninja, bursting through the door, flailing about with a gigantic soggy loofah, screaming Eureka, I've cracked another one, aaaaaaaaargh hahaha haaaaa

...Calm down, Nigel, it's only a dream...

[nigelfr]

Sorry for the delay in replying, DocJock. I haven't seen the paper yet, just the report from
http://www.physorg.com/news157963913.html

You make a valid point about the measurements: I wondered how CRF was measured in that period too. Especially as the CRF/cloud theory requires energies in the 10GeV range according to Shaviv and the Be or C proxies require much lower energies.( <1 GeV IIRC)

Now the responses so far have been interesting: I see some of the ditto bots have turned up and revealed that they haven't learnt anything about the "It's the Sun" theory of GW even though it has been mentioned here a lot by the sceptics as an alternative to AGW.

In brief: some people have compared proxies of sun spot counts against temperature and have used the medieval warm period in Europe to "prove" a correlation. Now there is no proven mechanism to show cause and effect and also Europe is not the world, so a warm Europe doesn't really show global temperature.

Sceptics of this sunspot theory have suggested that an oscillation in the Atlantic (NAO) like the ENSO in the Pacific could explain the MWP. The report as mentioned on Physics.org sounds interesting.

Edited by nigelfr on Saturday 4th April 16:54

[TheEnd]

Right, so that paper suggests that a medieval warm period wasn't caused by an increase in solar activity.

That is as useful as telling someone with a flat tyre that you once drove over a nail.

[odyssey2200]

TheEnd said:

Right, so that paper suggests that a medieval warm period wasn't caused by an increase in solar activity.

That is as useful as telling someone with a flat tyre that you once drove over a nail.

and it certainly was not caused by V8s, 4X4 or Co2.

So there goes that myth