"as we have established time and time again that although the concentration of trace gases is small their effect is large."


Not when we bring the oceans into the equation it isn't.

"as we have established time and time again that although the concentration of trace gases is small their effect is large."


Not when we bring the oceans into the equation it isn't.

Are you saying that if we had the oceans but not GHGs the Earth would be about as warm as it is now?

Are you saying that without CO2 there would be no water vapour and no oceans ?

I'd like to resolve that issue because I saw it suggested elsewhere but not explained.

Are you saying that without CO2 there would be no water vapour and no oceans ?

I'd like to resolve that issue because I saw it suggested elsewhere but not explained.

Yeah I was having a protracted discussion about that with a few other commenters on Deltoid, not sure if that's what you saw or not.

My stance is that yes, there would still be water vapour if there was no CO2 (or to be more holistic, no non-condesable greenhouse gases) - just much less of it because the planet would be colder.

Here's a link you might find interesting. Not too sure myself about the title, but the content is good:

http://www.terradaily.com/reports/Carbon_Dioxide_Controls_Earth_Temperature_999.html

"However, it is the 25 percent non-condensing greenhouse gas component, which includes carbon dioxide, that is the key factor in sustaining Earth's greenhouse effect. By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth's greenhouse effect.

The climate forcing experiment described in Science was simple in design and concept - all of the non-condensing greenhouse gases and aerosols were zeroed out, and the global climate model was run forward in time to see what would happen to the greenhouse effect.

Without the sustaining support by the non-condensing greenhouse gases, Earth's greenhouse effect collapsed as water vapor quickly precipitated from the atmosphere, plunging the model Earth into an icebound state - a clear demonstration that water vapor, although contributing 50 percent of the total greenhouse warming, acts as a feedback process, and as such, cannot by itself uphold the Earth's greenhouse effect." [emphasis mine]

Essentially, it's saying that non-condensible GHGs are needed to kick start the greenhouse effect, and without them the amount of water vapour is so low that the temperature of the planet would not be much above what it would be if there were no greenhouse gases at all.

I started to think about the logarithmic radiative forcing effect of GHGs, i.e. that even a very small amount of WV could have a decent warming effect, but then I figured this is hampered by the fact WV is not even close to well mixed with most of it in the lowest few km of the atmosphere, and also in this cold Earth environment there would be very little convection so you would have even less vertical mixing of WV. A thin layer of GHGs is much less effective at warming the surface than the present situation with GHGs (bar WV) being well-mixed up to ~100km

 

 

I can see why AGW requires such a proposition but I just can't see how it could be so out in the real world.

Certainly without CO2 in the air there would be less energy in the air (colder) and as a result the water cycle would slow down but with all that solar shortwave still being absorbed by the oceans before re-release to the air on variable timescales there would be plenty of energy still in the system to maintain an active water cycle.

Furthermore we have lots of oxygen and nitrogen which whilst not having the thermal powers of GHGs do acquire and hold energy by conduction and hence the warmed oceans would keep those gases warm even without GHGs.

Their 'experiment' doesn't seem to deal with solar shortwave into the oceans or our non GHG gases at all.

However it's a bit of a distraction from the real issue. The issue really is as to what would happen if we stripped out all the anthropogenic GHGs and the scale of the effect. The answer in my view is practically nothing compared to natural variability.

They may be right in asserting that with zero GHGs the greenhouse effect as we know it would collapse but we would still have my much more dominant Hot Water Bottle Effect.

I can see why AGW requires such a proposition but I just can't see how it could be so out in the real world.

Certainly without CO2 in the air there would be less energy in the air (colder) and as a result the water cycle would slow down but with all that solar shortwave still being absorbed by the oceans before re-release to the air on variable timescales there would be plenty of energy still in the system to maintain an active water cycle.

Furthermore we have lots of oxygen and nitrogen which whilst not having the thermal powers of GHGs do acquire and hold energy by conduction and hence the warmed oceans would keep those gases warm even without GHGs.

Their 'experiment' doesn't seem to deal with solar shortwave into the oceans or our non GHG gases at all.

The experiment is run on a climate model which of course includes absorption of solar radiation by the oceans and has the atmosphere maintaining a real temperature; no GHGs does not mean that there is no energy transfer to the atmosphere. You're making pretend that climate models only include GHGs and leave out lots of other important stuff, which is simply not true.

The water cycle would not go completely inactive but just much less active.

However it's a bit of a distraction from the real issue. The issue really is as to what would happen if we stripped out all the anthropogenic GHGs and the scale of the effect. The answer in my view is practically nothing compared to natural variability.

Yes this is the issue and not one easily resolved. Various lines of evidence point to about 1.4C equilibrium warming since the start of the industrial revolution, of which we've seen about half so far. Your view relies on several assertions that I don't think are backed up by science, but we've discussed them ad nauseam elsewhere.

They may be right in asserting that with zero GHGs the greenhouse effect as we know it would collapse but we would still have my much more dominant Hot Water Bottle Effect.

The oceans are not magically able to prevent ice ages, in which we still have significant greenhouse effect with 180ppm CO2 and a pretty active hydrological cycle with the cooling at the equator being much less. The scenario with no greenhouse effect results in an even colder Earth. The oceans can only do so much to stabilise global temperature, as even they have to obey the laws of thermodynamics and cool down if they absorb less energy than they emit (if more of the surface is frozen or the overlying air is much colder, for example).

I can see why AGW requires such a proposition but I just can't see how it could be so out in the real world.

I don't see it as having anything to do with AGW.  

But it does have important implications with regards Snowball Earth scenarios: if atmospheric CO2 drops below a critical level, we freeze.  Then, like a stalled engine, the atmosphere needs a kick-start with a boost of fresh CO2 to get it working again and warm us back up.   Which is exactly what appears to have happened and thus, regardless of whether Earth was a snowball or just an icy slushball, we have a mechanism which explains observations.  Neat!

 

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"The oceans are not magically able to prevent ice ages."

I don't suggest that they could.However, even during ice ages there is lots of solar shortwave entering the oceans around the equator and the oxygen and nitrogen still gets warmed by conduction.

There would still be enough energy for a water cycle and thus convection and evaporation as long as the solar shortwave input is enough to keep surface temperature nearer the equator above freezing.

If the model being used included such aspects I don't see how they could come to the result given. Even by your account there would still be a water cycle and not a sudden freezing up of everything which is what they propose.

As for Essan's comment I fail to see where an injection of fresh CO2 would come from once we have the snowball or slushball. Indeed, what would have made the CO2 go away in the first place ?

"The oceans are not magically able to prevent ice ages."

I don't suggest that they could.However, even during ice ages there is lots of solar shortwave entering the oceans around the equator and the oxygen and nitrogen still gets warmed by conduction.

Even in an ice age the non-IR-active gases are still warmed much more by collisions with GHGs and latent heat release than they are by direct conduction from the surface, which is always a very small quantity. Indeed even with no non-condensible GHGs the small amount of water vapour would warm the O2/N2 much more effectively than direct heat transfer from the surface.

Anyway, the point is that even though we have oceans, they didn't stop the Earth plunging into an ice/slushball state when prevailing conditions allowed.

"Anyway, the point is that even though we have oceans, they didn't stop the Earth plunging into an ice/slushball state when prevailing conditions allowed."

Nor did GHGs apparently.

What matters is solar shortwave input to the oceans.

And the continuation of water oceans despite the iciness is what pulled the Earth out of the situation again. It certainly wasn't an increase in GHGs. The sun drilling into the available liquid surfaces comes first and the GHG increase later.

I fail to see where an injection of fresh CO2 would come from once we have the snowball or slushball. Indeed, what would have made the CO2 go away in the first place ?

An upsurge in volcanic activity?  perhaps triggered by the crustal pressure of a growing ice sheet?

As to why it went away, what happens when you introduce something into an ecosystem which removes and essential component of that ecosystem?

What happened when stromatolites first appeared on Earth?  Did the first advanced life forms nearly end it all for everyone?

(no doubt any geologist specialising in the era will point out the errors in that scenario, but it cvertainly seems a possibility)

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I fail to see where an injection of fresh CO2 would come from once we have the snowball or slushball. Indeed, what would have made the CO2 go away in the first place ?

And upsurge in volcanic activity?  perhaps triggered by the crustal pressure of a growing ice sheet?

As to why it went away, maybe something as simple as an decrease in volcanic activity due to plate tectonics?  Or an increase in stromatolite population (the most advanced life on the planet at the time)  removing more CO2 from the atmosphere?   Or perhaps a combination of both?  Though I'm sure geologists specialising in the era have better answers.  None of which have anything to do with AGW.

http://www.nature.com/nature/journal/v429/n6992/abs/nature02640.html 

That link also says this:

"In my simulations, the system remains far short of deglaciation even at atmospheric carbon dioxide concentrations of 550 times the present levels (0.2 bar of CO2). I find that at much higher carbon dioxide levels, deglaciation is unlikely unless unknown feedback cycles that are not captured in the model come into effect."


So there is lots of doubt.

Even the concept of 'snowball Earth' is somewhat speculative.

That link also says this:

"In my simulations, the system remains far short of deglaciation even at atmospheric carbon dioxide concentrations of 550 times the present levels (0.2 bar of CO2). I find that at much higher carbon dioxide levels, deglaciation is unlikely unless unknown feedback cycles that are not captured in the model come into effect."


So there is lots of doubt.

Even the concept of 'snowball Earth' is somewhat speculative.

Of course Stephen, I never meant to imply otherwise

But it's certainly an interesting area of research.

"Anyway, the point is that even though we have oceans, they didn't stop the Earth plunging into an ice/slushball state when prevailing conditions allowed."

Nor did GHGs apparently.

What matters is solar shortwave input to the oceans.

And the continuation of water oceans despite the iciness is what pulled the Earth out of the situation again. It certainly wasn't an increase in GHGs. The sun drilling into the available liquid surfaces comes first and the GHG increase later.

You keep making these bold statements Stephen but we are still waiting for anything resembling data to support them.

Your statement is just too simplistic to be taken seriously.  If there were liquid surfaces then by what mechanism did the ice form and extend to cover much of the oceans away from the tropics?  Something else was going on - as Stu comments.

 

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"Anyway, the point is that even though we have oceans, they didn't stop the Earth plunging into an ice/slushball state when prevailing conditions allowed."

Nor did GHGs apparently.

What matters is solar shortwave input to the oceans.

And the continuation of water oceans despite the iciness is what pulled the Earth out of the situation again. It certainly wasn't an increase in GHGs. The sun drilling into the available liquid surfaces comes first and the GHG increase later.

You keep making these bold statements Stephen but we are still waiting for anything resembling data to support them.

Your statement is just too simplistic to be taken seriously.  If there were liquid surfaces then by what mechanism did the ice form and extend to cover much of the oceans away from the tropics?  Something else was going on - as Stu comments.

 

Yes I agree Gandalf and I had actually missed this earlier statement from Stephen. How would it get into an icebound state if Stephen's hypothesis is correct? You need more than just the fact that there is some open ocean absorbing some solar radiation.

"Anyway, the point is that even though we have oceans, they didn't stop the Earth plunging into an ice/slushball state when prevailing conditions allowed."

Nor did GHGs apparently.

What matters is solar shortwave input to the oceans.

And the continuation of water oceans despite the iciness is what pulled the Earth out of the situation again. It certainly wasn't an increase in GHGs. The sun drilling into the available liquid surfaces comes first and the GHG increase later.

You keep making these bold statements Stephen but we are still waiting for anything resembling data to support them.

Your statement is just too simplistic to be taken seriously.  If there were liquid surfaces then by what mechanism did the ice form and extend to cover much of the oceans away from the tropics?  Something else was going on - as Stu comments.

 

Yes I agree Gandalf and I had actually missed this earlier statement from Stephen. How would it get into an icebound state if Stephen's hypothesis is correct? You need more than just the fact that there is some open ocean absorbing some solar radiation.

Yes, Stu.  What troubles me is that we have guests visiting this site and reading these threads and Stephen holds himself up to be some sort of guru of climate science who has these penetrating insights into how the climate system works.  Superficially sometimes it looks quite persuasive but he keeps making these statements that just don't reflect any sort of scientific reality as I, even with my limited understanding, recognise.

This does rather reflect the comments on the Horizon programme about the proliferation of 'opinion' on the Internet and the fact that it is difficult to differentiate this from proper peer-reviewed scientific study.

Lest Stephen respond with further comments about 'playing the man' this is purely about style and content, whether it be Stephen or anybody else.

 

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Yes, Stu.  What troubles me is that we have guests visiting this site and reading these threads and Stephen holds himself up to be some sort of guru of climate science who has these penetrating insights into how the climate system works.  Superficially sometimes it looks quite persuasive but he keeps making these statements that just don't reflect any sort of scientific reality as I, even with my limited understanding, recognise.

This does rather reflect the comments on the Horizon programme about the proliferation of 'opinion' on the Internet and the fact that it is difficult to differentiate this from proper peer-reviewed scientific study.

We are all guests visiting this site! We are all entitled to our opinions, and raise questions resulting from the incomplete knowledge of our climate system - and that doesn't trouble me. It is actually very easy to differentiate between this forum and 'proper peer-reviewed scientific study' (is there a definition of what counts as that?!). Belittling those making a genuine attempt to understand the science and, through debate, discussion and argument, helping to advance the knowedge of many of us interested non-specialists is not very constructive. Many of today's climate scientists are in highly specialized disciplines: who is there left entitled and qualified to give us a comprehensive overview of climate science, AGW and climate prediction?

Thanks Marcus.

The fact is that I've never held myself out as some sort of guru. Everyone knows I am not a professional scientist or can easily find out.

What I do is spot inconsistencies between observations and established theory. There are so many that that is not difficult. I then formulate a scenario that could account for the observations and put it up for challenge. Sometimes I make incorrect assertions which if pointed out then results in an adaptation of the scenario but I will persist until such adaptations become untenable and thereupon I withdraw or approach the issue from another angle.

I am actually using the other participants here as a quality control service for a climate description that is steadily increasing in precision and scope.

It has been surprising how little of substance there really is behind the assumptions of AGW.

I think that the reason I irritate Gandalf and some others is that I present a challenge to their pretensions of AGW guruhood.

StuN asked:

"How would it get into an icebound state if Stephen's hypothesis is correct? You need more than just the fact that there is some open ocean absorbing some solar radiation."

Well there is a lot of doubt that it ever did achieve an icebound state just because of the problem of closing the gap at the equator. That is why the slushball Earth was proposed as a compromise.

Even if the gap at the equator did close then periods of high solar insolation would create a liquid surface skin on the ice from time to time and the melt process would get under way.

The first suggestion that an icebound state ever existed arose from evidence that all the landmasses have been under ice from time to time but the easiest explanation for that is continental drift.

Unless someone can point to evidence that aspecific land mass was covered in ice at sea level at the equator that is. If that had been found I'm sure I would know about it but if I missed it please now show me.