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Discussion > CO2 and OHC

Talking to lapogus, I said:

Increased back radiation from CO2 does not warm the oceans.It prevents them from cooling.

Obviously solar SW warms the upper 30m ocean layer with most energy transfer in the top 1m. The energy absorbed is then radiated in the LW spectrum.

OHC will rise if LW radiation to the atmosphere is inhibited.

This happens when atmospheric CO2 re-radiates enough LW to 'get in the way' of LW energy loss from the ocean surface.

This causes OHC to rise.

Lapogus responded:

I am intrigued by this inhibition. Do photons about to depart from over excited oceanic H2O molecules suddenly stop and check what the atmospheric CO2 concentration is before they decide to set off for space?

CO2 is responsible for about 5% of the 'greenhouse effect'? We have increased atmospheric CO2 concentration from 0.028 to 0.039%. By far most of the OLW is already being bounced back and scattered by water vapour. I just don't buy this idea that 2 extra CO2 molecules for every 10,000 in the atmosphere (or to be fair an extra 30% of 5%) can either significantly warm or inhibit the oceans from cooling. Whereas even a 1 or 2% decrease in cloud cover over the tropics will easily provide the extra energy input to explain the increase in OHC. It is the oceans which moderate the atmospheric temperatures, not the other way round.

It's very interesting. How does increased LW radiation from CO2 cause OHC to rise?

Aug 5, 2011 at 7:57 PM | Unregistered CommenterBBD

lapogus

Looks like no takers ;-)

So, to your original comment:

[Your paragraph 1:]

It all depends on the thermal gradient across the ocean skin layer - the top 1mm:

The existence of the temperature gradient is explained by the way heat is transferred: within the bulk waters, heat transfer occurs due to turbulence, but as the surface is approached, viscous forces dominate and molecular processes prevail. Because heat transfer by molecular conduction is less efficient than by turbulence, a strong temperature gradient is established across the boundary layer.

Ward & Minnett (2001). This article is about an instrument (SkinDeEP) that is designed to provide high resolution measurements of the top 6m of the sea surface. Measurements.

Minnet goes into further detail in a post at Realclimate:

Reducing the size of the temperature gradient through the skin layer reduces the flux. Thus, if the absorption of the infrared emission from atmospheric greenhouse gases reduces the gradient through the skin layer, the flow of heat from the ocean beneath will be reduced, leaving more of the heat introduced into the bulk of the upper oceanic layer by the absorption of sunlight to remain there to increase water temperature. Experimental evidence for this mechanism can be seen in at-sea measurements of the ocean skin and bulk temperatures.

So:

- The temperature at the skin surface affects the thermal gradient across the skin layer.

- The thermal gradient across the ocean skin layer determines the rate of heat loss from the ocean to the atmosphere.

- Increased DLR caused by re-radiation of LR by atmospheric CO2 raises the temperature of the skin surface.

- This increases the thermal gradient across the skin layer and decreases the rate of conductive energy transfer through the skin layer.

- Energy from solar SW is held in the mixed layer for longer, and OHC rises.


[Your paragraph 2:]

If you do not accept the hypothesis that increased RF from increased CO2 causes energy to accumulate in the climate system, then just pretend for the sake of discussion.

Aug 6, 2011 at 11:38 PM | Unregistered CommenterBBD

Eh?

Sep 14, 2011 at 7:37 PM | Unregistered CommenterBBD

Hmm, let's play word associations shall we.

'Spam, 'finance', fraud, PCeU.'

Your go.

Sep 18, 2011 at 4:31 PM | Unregistered CommenterBBD

A not very bright spammer posting a link to a non resolving website

Sep 23, 2011 at 4:25 AM | Unregistered Commenterbreath of fresh

I need the effects of long wave re-radiation from atmospheric CO2 to be explained in a little more detail. With an emissivity of less than 0.01 at atmospheric concentration, how can re-radiation from CO2 be of significance?

Sep 23, 2011 at 7:53 AM | Unregistered CommenterWannabe Scientist

Wannabe Scientist

So there's no greenhouse effect then? File under 'time-waster'.

Sep 23, 2011 at 1:32 PM | Unregistered CommenterBBD

So there's no greenhouse effect then? File under 'time-waster'.
Sep 23, 2011 at 1:32 PM | Unregistered CommenterBBD

as a non scientist I asked a serious question.

Is my emissivity stat wrong? if so, enlighten me.

If not, it doesn't seem a very high figure compared to a black body.

Water vapour, with an emissivity of 0.04 wuold appear to be a better radiator though still not very efficient.

You guys seem to educated in the subject so why not explain this apparent conundrum to a comparative novice like myself.

Or is this blog just a cosy clique for the initiated?

Sep 23, 2011 at 3:54 PM | Unregistered CommenterWannabe Scientist

With an emissivity of less than 0.01 at atmospheric concentration, how can re-radiation from CO2 be of significance?
Sep 23, 2011 at 7:53 AM | Unregistered CommenterWannabe Scientist

So there's no greenhouse effect then? File under 'time-waster'.
Sep 23, 2011 at 1:32 PM | Unregistered CommenterBBD

I don't think Wannabe was wasting time deliberately.

Let's try to rephrase his question.

Compared to conduction and convection, what is the significance of LW radiation emitted by atmospheric CO2 on the undisputed greenhouse effect. Bearing in mind that whilst CO2 is efficient at absorbing LW radiation, it is, by it's emissivity rating, a pretty poor radiator.

I'd be very interested in those comparative figures myself.

Sep 23, 2011 at 5:06 PM | Unregistered CommenterRKS

Wannabe Scientist

You sound to me as though you've been reading Marohasy and Biocab or similar. Hence this 'emissivity' stuff.

It's yet more sceptical red herring, and I'm not going to deal with it here. I will discuss the way in which increased atmospheric temperatures immediately above the ocean skin layer reduce the rate of ocean cooling, and so increase OHC over time. Nothing else.

Sep 23, 2011 at 5:07 PM | Unregistered CommenterBBD

Connected to the above, I'm quite keen to find out more about "heat in the pipeline".

Where is it and how do we detect it?

I asked over at Climate Etc a few days ago to no avail...?

Jan 7, 2012 at 2:41 AM | Unregistered Commenterwoodentop

woodentop

Apologies - I have only now noticed that you posted a comment here.

And it's a horrible question ;-) 'Heating in the pipeline' is complicated. The grossly over-simplified version is something like this:

There are two things to consider: anthropogenic CO2 in the atmosphere and ocean heat content (OHC).

The argument goes that even if we stabilised CO2 tomorrow at 390ppmv, the climate system is not currently in energetic equilibrium. The radiative forcing from the ~115 ppmv anthropogenic CO2 accumulated during the Industrial era has not yet raised surface temperatures to the level at which energy in (solar short wave) = energy out (long wave) as measured at the top of the atmosphere.

Of course the oceans constitute 70% of the planetary surface. Energy mainly accumulates in the oceans as heat (mechanism discussed above). Ultimately, rising OHC will increase sea surface temperatures until the total planetary surface LW emissivity is sufficient to cause the climate system to reach energetic equilibrium at the top of the atmosphere. At this point, the oceans would cease warming.

All this takes time, hence warming 'in the pipeline'.

I strongly advise you to hunt for good, detailed treatments of this online. It's long and complicated and my sketch is too simplistic to be much real use. Google is your friend, etc.

Jan 8, 2012 at 7:08 PM | Unregistered CommenterBBD

For those interested in "heat in the pipeline", this posting over at Climate Etc seems apposite, with lots of related links and discussion.

I've just found it so still working through it...

http://judithcurry.com/2011/01/07/wheres-the-missing-heat/

Jan 12, 2012 at 1:12 AM | Unregistered Commenterwoodentop