Suricat, I said

quote:

But we'd only expect models to be used that reflect reality so you're not allowed both up and down

The quantity I'm talking about (average amount of radiation from the sun reaching the earth) is a one dimensional quantity. So it can either go up, go down or not change.

The climate models are meant to model the atmosphere but some say it goes up, some say it goes down. My contention is only some of these can possibly be correct , so only those that get this right should be used to predict climate as the others are clearly flawed.

quote:

The climate models are meant to model the atmosphere but some say it goes up, some say it goes down. My contention is only some of these can possibly be correct , so only those that get this right should be used to predict climate as the others are clearly flawed.

Well all models are flawed in some way. But to know how to fix them, you need some idea of reality. Maybe the "wrong" models are very accurate for 90% of the earth and badly wrong for 10% whereas the "correct" models are wrong in one way for half of the earth and wrong in the opposite way for the other half.

My understanding is that detailed observations of clouds are currently in a too early stage to know whether they go up or down (maybe that's my next topic for more detailed reading). Presumably all the model cloud responses are within the bounds of the observational knowledge.

The point I was making was that the models have, not too surprisingly, a correlation that says more clouds mean less sun getting through, but more infrared kept in, and vice versa. And when the atmosphere warms, which ever way the cloud amount goes their warming effect overrides their albedo cooling effect.

quote:

Originally posted by suricat:
Steve_M,

The tec level implied by the editor is a lot lower than the level I've encountered!

I've previously tried to express the 'refrigeration' effect of H2O used in an 'Earth atmosphere model' from both ends at the same time together with the 'diffusion pump effect' in CO2 recycling within the 'H2O refrigeration region'. I'm not surprised that this was confusing! I didn't know quite how to express it myself without math (and math doesn't paste well into the dialogue box of this site [even all my underscores disappear])!

I would respectfully suggest that strong consideration should be made for the 'varying "average" altitude of precipitation of H2O' as the primary radiative altitude for the Earth (including towards the planet) and that the surface of the Earth (including cloud, aerosol and particulates with their local effect) be regarded only for its albedo in any model (even the IPCC haven't come to an effective resolution where water vapour is concerned).

Steve, some of the sceptics including me, have been waiting for this I suspect. Following your threads with Son of Mulder has me tetering on the brink of crossover to your camp (I particularly liked the layed PPM analogy). If you now apply your rigourous scientific approach to searching for counter balances to the AGW effect and genuinely find them coming up short that will help your cause (at least in my eyes).

Steve,

quote:

The point I was making was that the models have, not too surprisingly, a correlation that says more clouds mean less sun getting through, but more infrared kept in, and vice versa. And when the atmosphere warms, which ever way the cloud amount goes their warming effect overrides their albedo cooling effect.

My basic understanding is at this stage

Clouds near the equator keep more sun radiation out than radiation in. Clouds during the day keep more radiation out than radiation in. Clouds at night keep more radiation in than no clouds at night.

But I've no knowledge of how to quantify the overall balance but my instinct says the battle is around the tropics between the various cloud forcings.

There it must be directly tied in with rainfall as it cools in the evening, sky clears, loss of heat due to evaporation of the rain when the sun comes up.

Hellishly complex - I'm very grateful for the research you are doing. I don't know where to begin on this topic.

But another Houghton type diagram would be helpful if there is one relating to this battle of the clouds.

Son of Mulder

The reply I've just prepared seems to align in places with your last comment.

Just had a chat to a real climate scientist. This is a bit of a brain dump of what he said.

(SW=Shortwave (ie. sunlight, LW=long wave ie. infrared emissions from the earth or the atmosphere).

Tropical clouds - high tropical clouds are good at reflecting SW, but really poor at keeping in LW, but the outgoing radiation emitted by them is very small since they are so cold (190K). Because the sun is strong here, presence of such clouds has a strong cooling effect. He did talk about some models being described as "bright" because they produced more tropical high clouds with warming.

Low clouds have a lot more moisture in them, so are much better at keeping in LW.

Where the clouds are is important - high clouds at the poles obviously don't have much sun to reflect, low clouds in cold places don't have much heat to keep in.

The sort of studies I was looking at (classification of feedbacks) aren't aiming to have the detail in them to tease apart the different effects of these different cloud changes. Presumably someone is busy on work at this moment to look at these different feedbacks in a lot more detail.

On the effect of 1K warming on evapotranspiration he said it was "reeeeaaally complicated". An instantaneous change would have the effect of speeding this up, and thus producing a large increase to the 78W in this diagram:

oceanworld.tamu.edu/resources/oceanography-book/radiationbalance.htm

but as the temperature and humidity profile comes back into equilibrium he suspects that the net increase would be just a bit higher (1W or so). So there is a bit more evaporation and a bit more precipitation. But again, it depends on where you are in the planet (you won't get much change in deserts or very cold places).

So scores on the doors so far: if CO2 increases to such a level that surface temperatures warm 1K, and the system comes to equilibrium:

- the surface will emit an additional 5.5W/m^2
- evapotranspiration rises by about 1W/m^2 which adds to warming of the atmosphere;
- theres an increase in back radiation (the greenhouse effect) of about 3W/m^2 (* but see below) because there is more water vapour and because the atmosphere is warmer;
- theres an increase of 3.2W/m^2 in LW emissions at the top of the atmosphere, of which up to 0.5W is directly from the surface (not absorbed by greenhouse gases).

(all figures averaged over the earth. Effects on surface albedo ignored)

*There are also less well understood effects related to whether more or less SW gets through the clouds, but these seem to be correlated with the back radiation such that low clouds stop SW getting in, but the back radiation increases at these places too.

(incidentally my understanding is that while the rise so far is less than 1C, if CO2 emissions stopped today, the earth system won't reach equilibrium for some time do to the slow response of the ocean, and a further 0.5C rise would be expected).

‘We're stuck with our production of CO2 for many years and scientists have suggested that 560 ppm of CO2 should be our target to enable a migration from fossil to other energy sources.
So I'd suggest 280-560 ppm as the window’ Son of Mulder
---------------------------------------------
Sorry about jumping into your modelling discussion, but I was thinking about ‘the ideal level of CO2 ppm’ question from yesterday.

Perhaps another way of asking the question is what is the ideal temperature for life on Earth?

The big questions are what would a rise of 1 degrees C mean? What would a rise of 2 degrees C mean? What would a rise of 3 degrees C mean? What would a rise of 4 degrees C mean?

The first book I’ve seen (based on peer reviewed papers) that tries to answer these questions is *Six Degrees by Mark Lynas. [2007] It also tries to match CO2 levels with temperatures increases and impacts. (I’ve heard that at least one more on a similar theme is in production.)
http://www.amazon.co.uk/Six-Degrees-Future-Hotter-Plane...id=1176739761&sr=8-1

The figure of 560 ppm is being out forward not as one that is most desirable, but as one that ‘may’ be achievable. (Let’s face it Kyoto wasn’t a raging success even amongst signatories.) The UK’s current target is of a 60% cut in CO2 emissions below 1990 levels by 2050 and is consistent with what’s required to stabilise CO2 at 550 ppm, IF other countries follow suit and hit their targets. And that’s asking a lot.

Lynas estimates that 560 ppm would produce a temperature rise of 3 – 4 degrees C above today’s levels.

Lynas thinks that if CO2 can be stabilized at 400 ppm (currently 382 ppm) then it should result in a further temperature rise of ‘just’1 – 2 degrees C. (Even if all CO2 output ceased today there’d probably be another 0.5 degree C temperature rise in the pipeline as it were before the planet reaches its thermal equilibrium. It’s a little like slowing and stopping an oil tanker. And in looking at ppm other greenhouse gasses e.g. methane should be included as CO2 equivalents.)

Is stabilisation possible? Someone else has already posted a link earlier to the strategy of using existing technology as ‘Stabilisation Wedges’.
[There’s a slightly more accessible version here.]
http://www.stabilisation2005.com/Robert_Socolow.pdf

Lynas estimates (Lynas gives 75% confidence) that a doubling of CO2 from pre industrial levels [to 560 ppm] would result in a further global temperature rise of 3 to 4 degrees C.

There are problems; as the world warms then more carbon is released from forest fires etc and more feedbacks kick in. Methane from thawing permafrost in subpolar regions and as the Arctic ice cap melts less solar energy is reflected from the white ice and is absorbed into the oceans etc. (There is a very good chance that we will see an Arctic totally free of sea ice during summers in our lifetimes.) The big problem is that a warmer world is more likely to release more CO2/CH4 into the atmosphere leading to an upward spiral.

I no longer think of climate change in terms of hotter/cooler. It’s more important to think ‘does it mean dryer or wetter?’

As an example, during the medieval period 900 AD – 1400 western north America was afflicted by massive droughts of great length and severity.
http://www.ldeo.columbia.edu/res/div/ocp/drought/medieval.shtml

If repeated today, and there are signs that western America is currently becoming dryer, it would have profound implications for the future as well over 100 million people live in the region.
Drought In The West Linked To Warmer Temperatures
http://www.sciencedaily.com/releases/2004/10/041008030315.htm

And that applies also to Australia, East Africa, the Mediterranean region, the Middle East and so on.

So what is the ideal temperature for life on Earth, if it could be controlled?

Interesting post Shefftim

quote:

Lynas estimates (Lynas gives 75% confidence) that a doubling of CO2 from pre industrial levels [to 560 ppm] would result in a further global temperature rise of 3 to 4 degrees C.

Just one observation on the above. As I understand CO2 forced temperature is rising at 0.1 deg C per decade (although it seems to have gone a bit flat since 1998). So Lynas's 3-4 degs will take 300-400 years. I'd suggest that gives plenty of time for the develpment of new technologies (eg Fusion???) as well as implementation of current technologies (Socolow) to counter the upward rise of CO2. The industrial revolution only started 250 years ago and it's fair to say that technology development growth since then has been somewhat exponential, why should the next 250 be any different technology wise?

I've just read papertiger's description of the heat on Venus. There are a few points to correct.

Venus is further from the Sun than Mercury, yet it is hotter. Venus has an average temperature of 740 K, and Mercury has an average temperature of about 400 K and it's peak midday temp. is only 700 K (obviously cooler than 740K !).

Because of the added distance from the Sun, Venus recieves considerably less energy from the Sun compared to Mercury. The inverse square law will tell you this. A second point is that Venus is shrouded by dense white clouds. Clouds which reflect about 60 % of the Sun's energy into space. Mercury reflects 11% of it's energy form the Sun into space. From these data, it should be obvious that Venus recieves considerably less energy than Mercury. These are the data you have to try and explain and that need to be fitted into any hypothesis. So, where is the 'extra' energy on Venus coming from, the energy that causes its temperature to be higher than Mercury's?

Is it the Sun? How exactly would that be possible? As explained more solar energy arrives at Mercury than Venus, so unless the laws of thermodynamics have gone totally loopy it can be explained by something unique to Venus, or Mercury.

Is it something unique to Mercury? Apparently not. If you examine the energy arriving at an analogous object in the solar system, like the Moon, then you see the same temperature response to incoming solar energy ie. a temperature response that can be described solely with Stefan-Boltzmann thermodynamics. The oddity appears to be Venus, a simple S-B treatment simply doesn't work.

Well, what's special about Venus? It is covered in acid clouds and it has an atmosphere of 90 bar CO2. That's a very high pressure. What do we know about CO2 from a multitude of laboratory studies? It absorbs IR. What emits IR? Anything that's hot. That would include the surface of Venus which is about 500oC. It is going to be one raging IR emitter. Now, unless you have a theory that explains why CO2 isn't going to absorb the IR emitted by the heated surface of Venus you've got to concede that the dense CO2 atmosphere of Venus is going to be preventing heat from leaving the planet system. This is in essence the greenhouse effect. Observations of Venus and models of its atmosphere are in total agreement that Venus is hot because of it's carbon dioxide atmosphere.

Venus has very long days because of its dense atmosphere. The dense atmosphere causes tidal friction which dissapates the rotaional energy of the planet. This decay in day length occurred after the changes which cause Venus to have such a hot atmosphere.

Venus has a 90 bar CO2 atmosphere not because of some mythical combustion episode but because of the decomposition of carbon containing rocks in the planet's crust. Venus' atmosphere has virtually no water because all the liquid water boiled into the atmosphere where it was destroyed by intense sunlight to yield hydrogen. Hydrogen being so light escapes the gravitational influence of the planet in the upper atmosphere.

I hope that helps. The long day length is a product of the hot dense atmosphere and not its cause.

quote:

Originally posted by podbod:
I hope that helps.

Where is the disagreement? No one is saying CO2 is not a GHG. There is a matter of degree. To compare Venus with Earth is absurd.

quote:

Originally posted by phlipper:

quote:

Originally posted by podbod:
I hope that helps.

Where is the disagreement? No one is saying CO2 is not a GHG. There is a matter of degree. To compare Venus with Earth is absurd.

I thought so to but am not now so sure.

Podbod, what is the essential difference between Venus and Earth that has prevented such catastrophic warming before now. I assume its life (the entropy reduction agent?). Why will this mechanism not protect us in the future. Is it really simply the case that Gaia is vulnerable to the burning of fossil fuels? If so how did it ever reduce CO2 levels in the first place?

quote:

what is the essential difference between Venus and Earth that has prevented such catastrophic warming before now. I assume its life (the entropy reduction agent?).

Venus receives about twice as much sunlight (per unit area) as the earth. A simple model has been used to calculate that if the sun's strength went up by one-third it would produce a runaway effect on the earth too. Even 10 times the amount of CO2 doesn't get near to the warming required for this.

The sun is gradually warming up, and is expected to reach the levels required to produce a runaway effect in a billion years or so.

To Phlipper,

Papertiger claimed, in an earlier post, that Venus is incredibly hot, not due to CO2, but due to its very long day length. This is wrong.

I wasn't trying to draw any parallel with the Earth. I was giving a discussion of Venus in comparison to Mercury. There are still people (layman) out there who deny that CO2 is a greenhouse ags and that it will have any warming. Venus is an example to show that CO2 is a greenhouse gas. It is a confirmation of theory extended out of the laboratory.

quote:

Originally posted by Steve_M:

quote:

what is the essential difference between Venus and Earth that has prevented such catastrophic warming before now. I assume its life (the entropy reduction agent?).

Venus receives about twice as much sunlight (per unit area) as the earth. A simple model has been used to calculate that if the sun's strength went up by one-third it would produce a runaway effect on the earth too. Even 10 times the amount of CO2 doesn't get near to the warming required for this.

The sun is gradually warming up, and is expected to reach the levels required to produce a runaway effect in a billion years or so.

Sorry Steve, maybe I am getting too old for this ! Are we in imminient danger of catastrophic warming thru our use of fossil fuels (as I thought the Venus analogy was meant to convey)? Is the earths maintenance of a dynamic but relatively stable environment suitable for life nothing to do with life itself?

Seskinreay and Steve,

Steve you are right on the money again. The extra solar energy was enough to trigger the runaway greenhouse effect.

The key processes were increased evaporation of water to intensify the greenhouse effect, rising heat causing rocks to decompose and release CO2, destruction of water vapour by harsh UV resulting in all the free oxygen being bound up with carbon to form more CO2. As a result of this final process, Venus is the driest place in the solar system. The 'clouds' are mostly sulphuric acid.

quote:

Sorry Steve, maybe I am getting too old for this ! Are we in imminient danger of catastrophic warming thru our use of fossil fuels (as I thought the Venus analogy was meant to convey)? Is the earths maintenance of a dynamic but relatively stable environment suitable for life nothing to do with life itself?

It is (beyond) highly unlikely that we are facing this kind of scenario. The issue with global warming is one of rapid change at a pace beyond which human society and the biosphere and food webs can adapt. Examples: predicted water shortages due to re-distribution of rainfall patterns and melted glaciers; 1/3 of all species are predicted to become extinct not via runaway warming but just due to pace of the changes that are being discussed.

I haven't looked at it yet, but this is the latest offering from the IPCC which discusses the impacts:

http://news.bbc.co.uk/1/shared/bsp/hi/pdfs/06_04_05_climate.pdf

quote:

Originally posted by Son of Mulder:

quote:

If this is "the range of CO2 levels within which the human race can continue to generate the greatest good for humanity" would it be acceptable to choose 420ppm as being the average optimum, if a single figure is insisted upon - with allowance for some safe movement in either direction from this figure?

I disagree - if the objective is to turn around the use of fossil fuels then we need a realistic achievable and safe target, not one we'll change when the going gets tough. Because of the enormity of the task we should give ourselves as much space as possible.

To get back to our 1m sq glass analogy Son of Mulder. I like this analogy for for CO2 and if I can understand it, it could be a good way of presenting the AGW case to a world as confused by the complexities of the science as I am.

I can see that the obstacle to the analogy being set up (in a way that everyone can - more or less - agree on) is that the focus keeps getting shifted - prematurely - to how and what can act upon and influence it.

The analogy would be most useful to me purely as a 'SNAP-SHOT' - something which can be used as an agreed-upon ideal representation of a climate in which "the human race can continue to generate the greatest good for humanity".

The 1 sq m sheet of glass is a good starting point, but it seems to me that the glass, if it is to meet our goal, must be neither 100% opaque or 0% opaque (that is, purely transparent) - as this would not support life in accordance with our ideal.

Our pre-industrial glass sheet had a 0.028% opacity (representing 280ppm of CO2). And it seems to be accepted that this opacity was not man-made - and that it was NOT the ideal opacity for our glass to be considered ideal.

Dr Ian B suggests an opacity of 0.031% (310ppm) as a "'natural' level for a comfortable climate".
You suggest somewhere between 0.028 - 0.056% opacity (280-560ppm), of which I took the mean to be 0.042% (420ppm) as you don't give a definite figure.

If we take Dr Ian B's figure and say our glass sheet must be 0.031% opaque for it to function at its optimum (in letting the optimum amount of heat out and keeping the optimum amount in) and compare this to its current real state (which is the state causing concern) of 0.038% opacity, we can see that the glass sheet is away from its optimum by only 0.007% (70ppm of CO2). And that the glass sheet in pre-industrial days was away from its optimum by the higher value of 0.010% (100ppm of CO2).

So can we arrive at the conclusion that a snap-shot of the real glass sheet we have it today - whilst not at its stated optimum - is CLOSER to that optimum than it was in its pre-industrial days?

In all this, I have based the analogy on your original suggestion of the ad-mixed opaque parts being 100% opaque (ie solid black). I'm not sure how the analogy is affected by understanding the opaque parts as being LESS than 100% opaque by some degree (as we later agreed they are).

quote:

Originally posted by Roger58:
If we take Dr Ian B's figure and say our glass sheet must be 0.031% opaque for it to function at its optimum (in letting the optimum amount of heat out and keeping the optimum amount in) and compare this to its current real state (which is the state causing concern) of 0.038% opacity, we can see that the glass sheet is away from its optimum by only 0.007% (70ppm of CO2). And that the glass sheet in pre-industrial days was away from its optimum by the higher value of 0.010% (100ppm of CO2).

No, I'm wrong here.
The glass sheet in pre-industrial days was away from its optimum by the value of 0.003% (30ppm of CO2) - less than it is today.

As I understand CO2 forced temperature is rising at 0.1 deg C per decade (although it seems to have gone a bit flat since 1998). ‘So Lynas's 3-4 degs will take 300-400 years.’ Son of Mulder

Depends upon what you see as a bit flat. 1998 was a hell of an El Nino year (probably the strongest of the 20th century) and that amplified temperatures a full .2 degrees C higher than the previous record year –1997! Temperatures matched, if not surpassed last year.
But 2001, 2002, 2003, 2004, and 2005 all saw warmer temperatures than any year preceding 1998. (Climatic Research Unit.)
Give me a decade of cold, hard winters and cool summers and I might believe that those hot summers were an aberration.
Climate is about looking at a number of years (even taking into account exceptional events) not just one year. A reason why I also don’t expect every year to be hotter than the previous year. (In the next few years we’ll also enter a solar minimum period that the Max Planck Institute thinks is likely to cause a drop in global temperatures by 0.2 degrees Celsius. So this will have to be factored into interpreting overall temperature trends too.)

I’ve also read that temperatures have been rising at 0.2 degrees per decade not 0.1 degrees, but I take your point about timescale. (Something sceptics usually seem to find difficult to grasp by the way. i.e. ‘It’s cold today = what global warming?’)
As for rate of temperature rise, I’d expect amplification and feedback mechanisms to kick in that could accelerate it.

As for the 300-400 years I think climate change can occur with even small changes to temperature and that even current temperatures are having an impact. Hence ‘What is the ideal temperature for life on Earth?’ A small increase on today’s values will have a greater impact and so on. I don’t think we have nothing to worry about until we reach 3-4 degrees.

To expand on my point that changes to precipitation and atmospheric patterns are key to understanding the impacts of climate change; it’s possible from trends to recognise when a region’s climate zone is changing.

Over the past 50 years, the USA’s southwest region has warmed by 1.4 degrees F. Also over the past 50 years there has been a decline in the average snowfall, if the trend continues 50 more years Western US snow packs could be reduced by up to 60 percent reducing the flow into rivers. That would have major impacts on California, Colorado etc. The American West and southwest is already experiencing droughts.

‘Permanent drought predicted for Southwest.’
Los Angeles Times. April 6th 2007
http://www.latimes.com/news/science/la-sci-swdrought6ap...ll=la-home-headlines
Also: Nat. Geographic. April 5th 2007
http://news.nationalgeographic.com/news/2007/04/070405-us-drought.html

Just as El Ninos/La Ninas can cause drought in one region and flooding in another (Often drought in the US SW means heavier precipitation in the US NE as the jet streams shift position.); so a warming atmosphere could produce dryer conditions in one region, but wetter, possibly stormier, conditions in others. The moisture is still in the atmosphere, just being directed elsewhere. For both the regions affected that equals climate change.

Two more examples: Tropical savannahs are a transitional stage between an arid climate and those of a tropical rainforest.
If a savannah receives less and less rainfall then it begins to take on the characteristics of an arid area. When its rainfall, over a period of years, matches the amount found in an arid area then the vegetation and landscape will also begin to match those already found in an arid area.
(If savannah receives more rainfall than usual over a period of years then vegetation from neighbouring rainforest will take the opportunity to expand and colonise the grassland, which would now able to support forest.)
Studies suggest that the tropics have expanded by 2 degrees latitude, or 140 miles, over the past 26 years. (Science. May 06.) Amongst other tings this would mean that subtropical deserts would begin expanding into more heavily populated mid-latitude regions.

Almost all mountain glaciers in non-polar regions retreated during the 20th century. The overall volume of glaciers in Switzerland decreased by two-thirds.
The reason that this is a concern is that many major rivers arise from glacial runoff and if river flow decreases that will impact water available for irrigation and supplies to towns and cities. This will cause major problems in some South American countries for example where towns and cities have grown up along rivers. (It may cause problems for southern Europe as well.)

People expect climate change to show itself in some big spectacular way, but there is much evidence that it’s already happening. It’s how temperature affects atmospheric patterns, does it reduce or increase precipitation, is snowmelt happening earlier and so on. It may not take much more warming to cause incremental changes that could affect a many more peoples. Will it mean wetter or dryer? If wetter

Fusion energy: I have hopes for it (I’m pro nuclear) but the last report I saw showed that tho’ they have produced fusion, they have to switch the reactor off after a second or two as it starts to melt the reactor walls. Be interesting to see how they overcome that.

Venus’ atmosphere.
Venus and Earth were formed at around the same time, Venus is slightly closer to the Sun than the Earth so its HO2 never liquified and remained in the atmosphere to start the greenhouse heating; the CO2 mainly comes from rocks cooked at high temperatures. Life never had a chance to get going, Venus was warming from the get-go. Try these pages:
http://www.astronomynotes.com/solarsys/s9.htm#evem
http://www.astro.virginia.edu/class/oconnell/astr121/guide19-s04.html