[puppypower]

I don't believe the weather models are using liquid state physics. CO2 in air and CO2 in water use two different sets of physics; gas and liquid state physics.   

That belief would be wrong. Also, irrelevant as weather models and climate models are different things.

Yes, thank you. "Two sets of physics," that's rich. The only two "sets of physics" I know are Relativity and Quantum Mechanics, and that's only because they don't play nicely when physicists try to describe things like singularities. Other than that, gauge invariance, symmetry, all that seems to imply that the behavior of mass and energy is predictable in all sorts of environments. One does not have to change to a different set of physics rules just because the local conditions are warm enough to make steam or cool enough to condense it.

Actually, though, isn't it possible to describe both weather and climate using a set of equations to construct a chaotic fluid dynamics model? Weather I would say yes, climate I'm not sure but am tempted to say yes. I'm pretty sure I remember that from James Gleick's book Chaos, but I'd like to hear what you think.

Liquid, solid and gases all use the same laws of physics. However, each phase does so in different ways. For example, gases can't be placed under tension. Gases are defined and modeled exclusively by partial pressure. If I take a gas in a cylinder, like in a shock absorber, and pull the cylinder to elongate the gas, the pressure will drop. I don't create tension in the gas. The gas molecules are still randomly colliding; exerting pressure.

Solids can be placed under pressure or tension. I can push or pull a solid and place it under pressure or tension. What I can't do is push and pull or apply pressure and tension, at the same time, and form a steady state. If I push and pull the object at the same time, the object will move linearly, rotate, or I will create shear stresses.

Liquids are different from both gases and solids, in that they can be placed under tension and pressure, at the same time, and achieve a steady state. A glass of water open to the atmosphere will be under pressure; STP. While the surface contact between the air and liquid will create surface tension. Both pressure and tension can occur at steady state. The properties of that glass of water can measured and will be the same in all labs. They do not keep changing toward a steady state.

The fundamental laws of physics are the same for all three phases. However, each state uses different combinations of the same laws. Anomalies in one state can be the norm in another. Modeling the universe as a liquid allows paradoxical combinations of properties you can't get with solids and gas state models. Life makes use of the paradoxes of the liquid state, because life is mediated by water. There is no such things as gas or solid state life. Even if you argue life can form in other solvents, these will work due to the unique nature of liquid state physics.

Further examples of liquid state physics;

For example, in the discussion of entropy, entropy in liquid state physics, is a state variable. Water at 25C defines a specific amount of entropy that is always the same. It does not increase with time. The entropy of water at 25C will not change 10,000 years from now even wth the second law in affect. If most people associate entropy with disorder and random, then how can a liquid always define an ordered amount of entropy, even with the second law in affect? Gas and solid state analogies, which are more common to physics, don't know this is possible in liquids. This is how I inferred modern physics does not teach liquid state physics but conditioned the young mind for solid and gas state models.

One interesting set of liquid state physics properties are called colligative properties. A colligative property is only dependent on the concentration of the solute; in water for example. These are not dependent on electromagnetic character of the solute; specific atoms and  their arraignment, whether they contain plus to minus ions, single or double ions, or the strength of the ions. We can essentially ignore the  the EM forces in water when dealing with colligative properties in water.

My favorite example of colligative properties is osmosis. Osmosis is critical to the living state. Below is a diagram of an osmotic device. With osmosis one will get the same osmotic pressure exerted by water, regardless of the EM character of the solute that is dissolved in water. It is only dependent on the unit count; concentration, and not the specific EM character of any solute.

Osmosis is driven only by the entropy of the water. This entropy is not dependent on any specific force interaction between solute and water. The same concentration of any solute, will define a specific osmotic pressure; macro-level, based on the randomness; entropy, of the water, at the micro-level. In the liquid state physics of life, entropy both random and ordered at the same time. This may be hard to grasp if you are look at reality only in terms of solid or gas state physics. 

If you look at an osmotic device below, at steady state, a pressure head will build on the left; osmotic pressure. Since pressure is force/area the entropy is exerting a force. I call this force the entropic force. There is a fifth force of nature in liquid state physics. This is inferred since osmosis is not traditional force dependent; EM, but will still generate a force.

If we do reverse osmosis, and apply a physical force to the pressure head, that force will translate into a very specific decrease in water entropy. Conceptually, I can use entropic force to alter the entropy environment around enzymes. This can be used to influence changes of configuration and activity, that rely on entropy.

The pressure head should be exerting a force in the water, that is pushing the water from left to right at steady state. Yet the micro-scale water at the membrane will diffuse in both ways at the same rate, as though the water at the micro-level does not see the pressure head force.

I am not expert at climate models but I would guess nobody is using liquid state physics or else they would have an easier time correlating the randomness to ordered states. They appear to be using solid state analogies than can't form equilibrium.

[alancalverd]

Unless you can disprove the observation that CO2 absorbs IR there's no way round the fact that more CO2 will give rise to more trapped heat.

CWT is on a temporary ban for unparliamentary behaviour.

Everyone knows CO₂ absorbs IR, but physics is about numbers. At some point, when you add more and more absorber to a medium, there's so little absorbate left that adding more absorber doesn't make a ha'porth of difference.  Now the absorption spectrum of CO₂ is very narrow. The effective thickness  of CO₂  (i.e the amount of gas you would have if it was all at 1 atm pressure, not distributed over several kilometers at at 0.0004 atm) in the atmosphere is about 3 meters. The mean absorption coefficient of CO₂ is about 10 cm^-1 at atmospheric pressure, which suggests that the amount of in-band IR reaching the earth's surface (or leaving it) is e^{(-10 x 300)} of the incident intensity.

Now add 33% more CO₂, i.e another meter or so at 1 atm pressure. The difference between e^-3000 and e^-4000 is, to my mind, the difference between buggerall and a gnatscock less than buggerall.

[Bored chemist]

You seem to have tacitly assumed that the absorption bands have infinitely steep sides- they don't.
So, as you say, it's all down to the numbers.

[Tim the Plumber]

Wherever he is, let's try.
There are no perfect records of past temperature or past CO2 content of the atmosphere.

However we can, today, make measurements of the spectroscopic properties of  CO2.
Those properties indicate that it would act in in a way that has become known as the "greenhouse effect".
There is little or no doubt that temperatures are currently rising.
There is no doubt that mankind has added roughly a third to the CO2 concentration in the atmosphere over the last century or two- and much of that addition has been recent.

Setting aside the issue of proving that the temperature rise has been due to the excess CO2.

How could you explain that the additional CO2 would not give rise to a temperature increase?

Unless you can disprove the observation that CO2 absorbs IR there's no way round the fact that more CO2 will give rise to more trapped heat.

Given that thewhole IR absorption/re-emission thing is beyond my science I'll take your and others word for all that.

The IPCC has a figure that they use as the basis for the heatimg from the effect of CO2 which they then add an additional amount to due they say because of feedback effects of additional water vapour.

Since there is already lots of water vapour up there why would this happen and if it does not what fogure of temperature rise would you expect from a doubling of CO2?

[alancalverd]

Given that thewhole IR absorption/re-emission thing is beyond my science I'll take your and others word for all that.

The IPCC has a figure that they use as the basis for the heatimg from the effect of CO2 which they then add an additional amount to due they say because of feedback effects of additional water vapour.

Since there is already lots of water vapour up there why would this happen and if it does not what fogure of temperature rise would you expect from a doubling of CO2?

Water vapor has an enormously wide IR absorption spectrum as a momomer. It also exists in the atmosphere as a dimer, trimer, and probably heaxamer, all with additional IR spectra. Water also exists in the atmosphere as a solid (in several forms) and a liquid (both supercooled and normal). H₂O, quite simply, is capable of absorbing or reflecting practically every wavelength of electromagnetic radiation, which is why we get radar reflections and shadows on the ground from clouds, very little penetration of radio waves under water, and the bottom of the sea is dark and cold.

Warm air can hold more water vapor than cold air, so the water greenhouse effect is inherently self-multiplying, up to the point at which the water condenses into clouds which cut off the heating during the day and prevent heat radiation at night.

And just to make it interesting, all the phase changes of H₂O occur at normal atmospheric temperatures so the specific heat capacity of saturated air is tens of times greater than that of dry air - which is why we get every kind of weather, and the British winter (cool and damp) upsets visiting Americans who find their cold, dry conditions much less chilling! Without water, the atmosphere would be as stable and uniform as that of Mars.   

And for a further complexity, the circulation of atmospheric water is crucially different in the northern and southern hemispheres. There being no land mass in the Southern Ocean, there is a constant westerly wind that determines the mixing of polar (cold, dry) oceanic (warmer, moist) and continental (warm, dry) air. This is quite different from the northern hemisphere where large chunks of land interrupt the circumpolar flow. In consequence, tropical and equatorial climates are inherently unstable as the extremely variable northern flow meets the relatively more constant southern circulation. As a simple example of the medium-term complexity, events in the Weddell Sea have a predictable effect on Argentine crop yields three years later, but North Atlantic storms have no predictable effect beyond a month.   

Adding more CO₂, ven doubling the concentration, would have negligible effect. Whatever you do to the atmosphere is ultimately swamped by the subsequent redistribution of water.

[alancalverd]

You seem to have tacitly assumed that the absorption bands have infinitely steep sides- they don't.
So, as you say, it's all down to the numbers.

That's why I quoted the weighted mean over the entire NIR spectrum. In places it's over 20 cm^-1.

[Bored chemist]

How do you weight it?

[Bored chemist]

The point remains that, since there are bits that are not saturated, more means more.

[agyejy]

I've already linked to an argument debunking the CO2 saturation argument. Here it is again:

http://www.skepticalscience.com/saturated-co2-effect.htm
http://www.skepticalscience.com/saturated-co2-effect-intermediate.htm
http://www.skepticalscience.com/saturated-co2-effect-advanced.htm

At three different levels of complexity.

A particularly important point:

There's one more subtle effect related to increased absorption. Upon increasing CO2 concentration, the layer at which the absorption coefficient at each wavelength is low enough to let the IR light escape will be found higher in the atmosphere. The emitting layer will then have a lower temperature, at least until the tropopause is reached, and hence a lower emitting power.

By moving the layer at which the atmosphere becomes transparent to IR to higher altitudes we've reduced the amount of IR it can radiate because the gas is cooler. Thus even if we ignore the changes in the amount of absorption due to the band edges we've still reduced the ability of the atmosphere to emit heat into space and thus the Earth must warm. Well at least until we put so much CO2 into the air that it is opaque all the way to the tropopause but I think we can all agree that would be a bad idea.

Here is something more generic about CO2 (which I'm fairly certain I have also linked to):

http://www.skepticalscience.com/empirical-evidence-for-co2-enhanced-greenhouse-effect.htm
http://www.skepticalscience.com/empirical-evidence-for-co2-enhanced-greenhouse-effect-intermediate.htm
http://www.skepticalscience.com/empirical-evidence-for-co2-enhanced-greenhouse-effect-advanced.htm

I would appreciate not having to link these again.

[puppypower]

Over 50% of the energy that comes from the sun, that reaches the earth, is in the form of infrared; IR. Since CO2 is sensitive to IR, doesn't that mean the CO2 will also trap heat in space; CO2 will keep some of the solar IR heat out in space?

As an analogy, water is also a very important greenhouse gas.  A cloudy night in the fall will prevent frost, due to the greenhouse affect trapping heat.

If you look at a cloud of water. A cloud can block and reflect solar energy entering the earth, away from the surface. A cloud gives us shade so it feel cooler. Water can also trap heat at night, so there is no frost on cool fall nights.

If we have a dry day, more solar heat will reach the surface, while at night the lower water content in the air allows the heat to escape faster; desert. The greenhouse gas, water, creates a two way affect. I would expect the same of CO2. 

A one way greenhouse assumption of CO2; only traps heat in, could explain why all the computer model predictions are always higher than experimental. They appear to assume CO2 can only trap heat in, but not keep heat out, like water does. If the models are 100-1200% to high in terms of temperature predictions, the trap out affect, appears to be very significant.

The affect should be similar to thermal pane glass. This keeps the heat out in the summer and it also keeps the heat in during the winter. It blocks IR with no direction preferences. It appears the greenhouse affect of CO2 makes use of thermo pane glass.

[alancalverd]

I would appreciate not having to link these again.

By all means save yourself the trouble. A reference that includes graphs of global mean temperature back to 1850 is a work of fiction, not science.

[agyejy]

Over 50% of the energy that comes from the sun, that reaches the earth, is in the form of infrared; IR. Since CO2 is sensitive to IR, doesn't that mean the CO2 will also trap heat in space; CO2 will keep some of the solar IR heat out in space?

As an analogy, water is also a very important greenhouse gas.  A cloudy night in the fall will prevent frost, due to the greenhouse affect trapping heat.

If you look at a cloud of water. A cloud can block and reflect solar energy entering the earth, away from the surface. A cloud gives us shade so it feel cooler. Water can also trap heat at night, so there is no frost on cool fall nights.

If we have a dry day, more solar heat will reach the surface, while at night the lower water content in the air allows the heat to escape faster; desert. The greenhouse gas, water, creates a two way affect. I would expect the same of CO2. 

A one way greenhouse assumption of CO2; only traps heat in, could explain why all the computer model predictions are always higher than experimental. They appear to assume CO2 can only trap heat in, but not keep heat out, like water does. If the models are 100-1200% to high in terms of temperature predictions, the trap out affect, appears to be very significant.

The affect should be similar to thermal pane glass. This keeps the heat out in the summer and it also keeps the heat in during the winter. It blocks IR with no direction preferences. It appears the greenhouse affect of CO2 makes use of thermo pane glass.

https://www3.epa.gov/climatechange/kids/basics/today/greenhouse-effect.html

The most basic of basic things about the greenhouse effect is that visible light from the Sun is absorbed by the surface of the Earth and then reemitted by the surface as infrared light. This is the infrared light that is trapped by clouds and greenhouse gases. No reputable climate scientist would ever make the mistake of assuming that greenhouse gases only absorb IR light coming from the surface.

The reason we call this the greenhouse effect is because this is exactly how greenhouses work. The glass of the greenhouse lets in visible light. The stuff in the greenhouse absorbs the visible light and emits IR light. The IR light is then trapped inside the greenhouse by the glass because the glass is much more reflective to IR than visible light. In short, visible light comes in and is converted to IR light which can't get out.

By all means save yourself the trouble. A reference that includes graphs of global mean temperature back to 1850 is a work of fiction, not science.

You're certainly welcome to have this opinion as long as you recognize it as an opinion that is unsupported by observational evidence and scientific reasoning. As is demonstrated here (which I have also previously linked):

http://www.skepticalscience.com/surface-temperature-measurements.htm
http://www.skepticalscience.com/surface-temperature-measurements-intermediate.htm
http://www.skepticalscience.com/surface-temperature-measurements-advanced.htm

People with absolutely no affiliation to each other and no ulterior motive have analyzed the data using different methodologies and got the same result. Independent temperature records have been analyzed and produced the same result. The temperature records have been analyzed without the corrections people cite as being used to fudge the data and the result doesn't change. Temperature proxies have been measured and produced the same result. Does a perfect data set exist? No of course not because nowhere in any scientific discipline is there ever a perfect data set and that problem is worse when you can't really repeat the experiment easily. However, science can still be done if you get enough independent measures of the same thing and they all give the same result.

Also the trend of increasing temperature is very clear even only going back to 1950-1960. Therefore even if we ignore the data going back to 1850 as you suggest that doesn't actually change the conclusion at all.

[Bored chemist]

I would appreciate not having to link these again.

By all means save yourself the trouble. A reference that includes graphs of global mean temperature back to 1850 is a work of fiction, not science.

ok, if you write off the graphs of temperature vs date because they go back too far (Though in post 407 you were perfectly happy to cite the Vostok cores that go back a lot further) you are left with the spectroscopy.
How do you respond to that?

[jeffreyH]

What happens to plant growth rates when soils become saturated as in flood events? How does this affect plant growth and the carbon cycle? Water water everywhere and not a drop to drink. The water cycle is very important.

[alancalverd]

ok, if you write off the graphs of temperature vs date because they go back too far (Though in post 407 you were perfectly happy to cite the Vostok cores that go back a lot further) you are left with the spectroscopy.
How do you respond to that?

I have never suggested that Vostok or Mauna Loa data gave us the absolute mean global surface temperature. What they provide is utterly credible records at two single points, over a time scale in which they were actually collected. Both sets of data unequivocally show that temperature leads CO2, not the other way around, so CO2 cannot be the controller of temperature.

If I extrapolated my bank account to a time before I was born, would you consider that to be a reasonable proxy for your grandfather's bank balance, never mind the world average?  So how can anyone dare to assert what the mean temperature of the globe was, fifty years before anyone visited the poles and a hundred years before anyone made any accurate measurements on land, let alone at sea?

[alancalverd]

People with absolutely no affiliation to each other and no ulterior motive have analyzed the data using different methodologies and got the same result. Independent temperature records have been analyzed and produced the same result.

Alas, the sources you cite talk about reconstructions, not measurements. If we all use the same hypotheses and extrapolate from the same data set, it would be surprising if we came up with different extrapolations.

We know for a fact that the only actual measurements of mean global surface temperature come from satellites, post-1970. Everything else, whether you call  it proxy, model, or extrapolation from airfield data, is guesswork over the 90% of the planet for which we have no credible previous data.
 
We also know that whenever the satellite data is "corrected", the new curve is a better fit to the CO2 curve, and the "corrections" now exceed the error bars in the original data. Funny, that.   

Beware of the straw man. Only a fool would pretend that the climate hasn't changed, and I'm quite happy to accept that mean global temperature has indeed risen during my lifetime

BUT

Historically and by recent measurement, temperature leads CO2

AND

the discovery of 500-year-old bryophytes under a retreating glacier tells us unequivocally that Canada, at least, was significantly warmer 500 years ago than it is today. 

These rather boring facts get in the way of the prevailing consensus of anthropogenic global warming. Which is a pity, because the consensus implies that we could do something to prevent it, whereas the observation sugests that we need to do something to mitigate its effect.

Not that it matters, as politicians have decided on your behalf to do nothing anyway.

[agyejy]

I have never suggested that Vostok or Mauna Loa data gave us the absolute mean global surface temperature. What they provide is utterly credible records at two single points, over a time scale in which they were actually collected. Both sets of data unequivocally show that temperature leads CO2, not the other way around, so CO2 cannot be the controller of temperature.

Repeating refuted arguments does not in anyway change the fact that they were refuted. In addition to the links given below we've been over quite clearly how the measured seasonal variation of CO2 concentration is perfectly consistent with the combination of seasonal changes in photosynthetic activity, seasonal changes in the temperature of the ocean, and the general resistance of any large system to instantaneous change.

http://www.skepticalscience.com/co2-lags-temperature.htm
http://www.skepticalscience.com/co2-lags-temperature-intermediate.htm

http://www.skepticalscience.com/warming-co2-rise.htm

If I extrapolated my bank account to a time before I was born, would you consider that to be a reasonable proxy for your grandfather's bank balance, never mind the world average?  So how can anyone dare to assert what the mean temperature of the globe was, fifty years before anyone visited the poles and a hundred years before anyone made any accurate measurements on land, let alone at sea?

For starters there is definitely some amount of correlation between your bank account and that of your parents and grandparents. With a large enough sampling of bank accounts and some statistics a reasonable guess and long term trends regarding the wealth of families over generations would become predictable. Beyond that in terms of temperature data we actually have many other temperature proxies beyond straight measurements of temperature that show the same thing. So your analogy grossly mischaracterizes both the amount of data we currently have and the nature of the data that we currently have.

Alas, the sources you cite talk about reconstructions, not measurements. If we all use the same hypotheses and extrapolate from the same data set, it would be surprising if we came up with different extrapolations.

Data processing happens all the time in science. Rarely in science is it possible to directly measure the thing you wish to measure. Scientists have become very good at processing data to get at the relevant quantities without distorting their conclusions. They've also come up with ways of proving that they have not reached false conclusions from their data. This is the entire point of statistical analysis. Unless you can specifically point out how all the different statistical analysis of all the different groups was done incorrectly this line of argument is meaningless. Your claim that somehow the mathematical apparatus that has allowed science to advance for generations and is currently employed in everything from biology to particle physics is flawed or was somehow misapplied in this specific case is an extraordinary claim and requires extraordinary proof on your part.

From here: http://www.skepticalscience.com/surface-temperature-measurements-advanced.htm

The temperature increase is not an artifact of the GHCN adjustment process
Most of the analyses shown above actually use the raw (unadjusted) GHCN data. Zeke Hausfather has done comparisons using both the adjusted and raw versions of the GHCN data set, and as shown in fig. 5, the results are not substantially different at the global scale (though 2008 is a bit of an outlier).

The temperature increase is not an artifact of declining numbers of stations
While it is true that the number of stations in GHCN has decreased since the early 1990s, that has no real effect on the results of spatially weighted global temperature reconstructions. How do we know this?

Comparisons of trends for stations that dropped out versus stations that persisted post-1990 show no difference in the two populations prior to the dropouts (see, e.g., here and here and here).
The spatial weighting processes (e.g., gridding) used in these analyses makes them robust to the loss of stations. In fact, Nick Stokes has shown that it's possible to derive a global temperature reconstruction using just 61 stations worldwide (in this case, all the stations from GISTEMP that are classified as rural, have at least 90 years of data, and have data in 2010).
Other data sets that don't suffer from GHCN's decline in station numbers show the same temperature increase (see below).
One prominent claim (by Joe D'Aleo and Anthony Watts) was that the loss of "cool" stations (at high altitudes, high latitudes, and rural areas) created a warming bias in the temperature trends. But Ron Broberg conclusively disproved this, by comparing trends after removing the categories of stations in question. D'Aleo and Watts are simply wrong.

And you characterization that it is all the same data set is clearly wrong:

The temperature increase is present in other data sets, not just GHCN
All of the above studies rely (mostly or entirely) on monthly station data from the GHCN database. But it turns out that other, independent data sets give very similar results.

What about satellite measurements of temperatures in the lower troposphere? There are two widely cited analyses of temperature trends from the MSU sensor on NOAA's polar orbiting earth observation satellites, one from Remote Sensing Systems (RSS) and one from the University of Alabama-Huntsville (UAH). These data only go back to 1979, but they do provide a good comparison to the surface temperature data over the past three decades. Figure 7 shows a comparison of land, ocean, and global temperature data from the surface reconstructions (averaging the multiple analyses shown in figs. 3 and 4) and from satellites (averaging the results from RSS and UAH):

Reanalysis data sets also show the same warming trend.  A ‘reanalysis’ is a climate or weather model simulation of the past that incorporates data from historical observations.  Reanalysis comparisons by Vose et al. (2012) and Compo et al. (2013) find nearly identical global surface warming trends as in the instrumental record (Figure .

A paper by Anderson et al. (2012) created a new global surface temperature record reconstruction using 173 records with some type of physical or biological link to global surface temperatures (corals, ice cores, speleothems, lake and ocean sediments, and historical documents).  The study compared their reconstruction to the instrumental temperature record and found a strong correlation between the two (0.76; Figure 9).

//////////////

We know for a fact that the only actual measurements of mean global surface temperature come from satellites, post-1970. Everything else, whether you call  it proxy, model, or extrapolation from airfield data, is guesswork over the 90% of the planet for which we have no credible previous data.
 
We also know that whenever the satellite data is "corrected", the new curve is a better fit to the CO2 curve, and the "corrections" now exceed the error bars in the original data. Funny, that.   

Beware of the straw man. Only a fool would pretend that the climate hasn't changed, and I'm quite happy to accept that mean global temperature has indeed risen during my lifetime

BUT

Historically and by recent measurement, temperature leads CO2

AND

the discovery of 500-year-old bryophytes under a retreating glacier tells us unequivocally that Canada, at least, was significantly warmer 500 years ago than it is today. 

These rather boring facts get in the way of the prevailing consensus of anthropogenic global warming. Which is a pity, because the consensus implies that we could do something to prevent it, whereas the observation sugests that we need to do something to mitigate its effect.

Not that it matters, as politicians have decided on your behalf to do nothing anyway.

We've previously covered the ins and outs of why the CO2 and temperature trends are not always exactly as one would naively expect. There are complicating factors that need to be taken into account and once they are a very reasonable and highly predictive theory emerges. To review the complicating scenarios, no system (especially one the size of the planet's atmosphere) can respond infinitely quickly to changes in environmental factors, there is a natural carbon cycle that has seasonal variation (and are subject to the lags of the first point), and there are long term climate variations due to the various ways in which the Earth orbits and its rotation wobbles as well as solar cycles but these changes cannot account for the total temperature changes without the help of CO2 (specifically there is a positive feedback were these changes increase or decrease CO2 concentration due to the feedback which exacerbates the changes). Currently there are no non-anthropomorphic  changes in the Earth or the Sun that can account for the observed warming.

Further, climatologists don't just rely on temperature/CO2 correlation to make their point:

http://www.skepticalscience.com/its-not-us-advanced.htm

There are several different ways one can fingerprint if the changes we are seeing are caused by humans or natural. Here are some selected bits:

Stratospheric Temperature Change
As the lower atmosphere warms due to an enhanced greenhouse effect, the upper atmosphere is expected to cool as a consequence. The simple way to think about this is that greenhouse gases are trapping heat in the lower atmosphere. Since less heat is released into the upper atmosphere (starting with the stratosphere), it cools.

Jones et al. (2003) investigated the changes in temperature over the past 4 decades at both the near surface (troposphere) and stratosphere layers, and compare them to changes predicted by a coupled atmosphere/ocean general circulation model, HadCM3. They concluded as follows.

"Our results strengthen the case for an anthropogenic influence on climate. Unlike previous studies we attribute observed decadal-mean temperature changes both to anthropogenic emissions, and changes in stratospheric volcanic aerosols. The temperature response to change in solar irradiance is also detected but with a lower confidence than the other forcings."

This change in the stratospheric temperature in conjunction with increasing surface temperature is only explained via increased heat trapping of the lower atmosphere.

Precipitation
Zhang et al. (2007) showed that models using natural + anthropogenic forcings do a much better job of matching observed precipitation trends than either natural or anthropogenic alone. The correlation with natural forcings alone is extremely weak - only 0.02. With anthropogenic alone is 0.69, and with both combined is 0.83 over the past 75 years.

"We show that anthropogenic forcing has had a detectable influence on observed changes in average precipitation within latitudinal bands, and that these changes cannot be explained by internal climate variability or natural forcing. We estimate that anthropogenic forcing contributed significantly to observed increases in precipitation in the Northern Hemisphere mid-latitudes, drying in the Northern Hemisphere subtropics and tropics, and moistening in the Southern Hemisphere subtropics and deep tropics. The observed changes, which are larger than estimated from model simulations, may have already had significant effects on ecosystems, agriculture and human health in regions that are sensitive to changes in precipitation"

There are even direct measurements of the changes in IR radiation that match what is expected based on the changes in greenhouse gasses and don't have any other explanation:

Infrared Radiation
Increase in downward longwave radiation
Anthropogenic global warming is caused by an increase in the amount of downward longwave infrared radiation coming from greenhouse gases in the atmosphere. Philipona et al. (2004) measured the changes and trends of radiative fluxes at the surface and their relation to greenhouse gas increases and temperature and humidity changes measured from 1995 to 2002 at eight stations of the Alpine Surface Radiation Budget (ASRB) network. They concluded as follows.

"The resulting uniform increase of longwave downward radiation manifests radiative forcing that is induced by greenhouse gas concentrations and water vapor feedback, and proves the "theory" of greenhouse warming with direct observations."
Evans et al. (2006) took it a step further, performing an analysis of high resolution specral data which allowed them to quantitatively attribute the increase in downward radiation to each of several greenhouse gases. The study went as far as to conclude,

"This experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming."
Decrease in upward longwave radiation
As the concentration of greenhouse gases in the atmosphere increases, we expect to see less infrared radiation escaping at the top of the atmosphere. Satellite observations have confirmed that the decrease in upward longwave radiation matches well with model predictions, including in Harries 2001, Griggs 2004, and Chen 2007, the latter of which concluded:

"Changing spectral signatures in CH4, CO2, and H2O are observed, with the difference signal in the CO2 matching well between observations and modelled spectra."

Those examples are of course not exhaustive. You seem to be under the impression that the only evidence is temperature/CO2 correlation and that pretty much couldn't be further from the truth. In fact framing the argument purely in terms of temperature/CO2 correlation could be considered a strawman as it ignores the fact there is a lot of other evidence that is telling us that the changes we are observing are not natural and must be due to the greenhouse effect.

[Bored chemist]

ok, if you write off the graphs of temperature vs date because they go back too far (Though in post 407 you were perfectly happy to cite the Vostok cores that go back a lot further) you are left with the spectroscopy.
How do you respond to that?

I have never suggested that Vostok or Mauna Loa data gave us the absolute mean global surface temperature. What they provide is utterly credible records at two single points, over a time scale in which they were actually collected. Both sets of data unequivocally show that temperature leads CO2, not the other way around, so CO2 cannot be the controller of temperature.

If I extrapolated my bank account to a time before I was born, would you consider that to be a reasonable proxy for your grandfather's bank balance, never mind the world average?  So how can anyone dare to assert what the mean temperature of the globe was, fifty years before anyone visited the poles and a hundred years before anyone made any accurate measurements on land, let alone at sea?

And, as I said, if you don't like the historic temperature (and/ or CO2) data forget it. Just address the issues about spectroscopy raised by those posts.

[smart]

Beware of the straw man. Only a fool would pretend that the climate hasn't changed, and I'm quite happy to accept that mean global temperature has indeed risen during my lifetime

BUT

Historically and by recent measurement, temperature leads CO2

AND

the discovery of 500-year-old bryophytes under a retreating glacier tells us unequivocally that Canada, at least, was significantly warmer 500 years ago than it is today. 

These rather boring facts get in the way of the prevailing consensus of anthropogenic global warming. Which is a pity, because the consensus implies that we could do something to prevent it, whereas the observation sugests that we need to do something to mitigate its effect.

Not that it matters, as politicians have decided on your behalf to do nothing anyway.

You're forgetting geoengineering. Solar geoengineering may destroy the ozone layer and lower temperature by injecting sulfate aerosol in the troposphere. Ozone and temperature are strongly correlated.

Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will be significantly reduced.

http://iopscience.iop.org/article/10.1088/1748-9326/4/4/045108/meta

[Bored chemist]

You're forgetting geoengineering. Solar geoengineering may destroy the ozone layer and lower temperature by injecting sulfate aerosol in the troposphere. Ozone and temperature are strongly correlated.

Therefore, geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles and cause a significant depletion of the ozone layer even though future halogen concentrations will be significantly reduced.

http://iopscience.iop.org/article/10.1088/1748-9326/4/4/045108/meta

Try to get a grip here; what might happen in the future
"geoengineering by means of sulfate aerosols is predicted to accelerate the hydroxyl catalyzed ozone destruction cycles "
is not the same as what is happening now.
You kept making that mistake in the other thread too.
Please stop.