Testing the Core of AGW Theory

[skierinvermont]

1. the physics of AGW accurately predict the temperature of other celestial bodies.

This is now standard practice in astronomy. The temperature of other planets is predicted using incoming solar radiation and GHG concentrations.

2. increasing opacity of the atmosphere to outgoing longwave radiation specifically in the CO2 absorption spectrum is a direct empirical test of AGW.

Theory has long predicted that increasing CO2 concentrations would cause the atmosphere to become more opaque to outgoing longwave radiation in the CO2 spectrum. The amount of energy that is blocked is predictable and testable. Modern measurements have corroborated this prediction which can be dated back to Arrhenius at the turn of the 20th century.

3. AGW theory predicted the temperature increases of the latter 20th century.

4. models using these physics accurately simulate temperature of the last 100 years

5. models using these physics simulate temperature of the last 1,000 years to a reasonable degree

6. when combined with Milankovich theory accurately simulates the periodic ice ages of the last 3 million years

7. our existing understanding of climate can explain the varying temperatures of the earth for the last 600 million+ years

[WeatherRusty]

1. the physics of AGW accurately predict the temperature of other celestial bodies.

This is now standard practice in astronomy. The temperature of other planets is predicted using incoming solar radiation and GHG concentrations.

2. increasing opacity of the atmosphere to outgoing longwave radiation specifically in the CO2 absorption spectrum is a direct empirical test of AGW.

Theory has long predicted that increasing CO2 concentrations would cause the atmosphere to become more opaque to outgoing longwave radiation in the CO2 spectrum. The amount of energy that is blocked is predictable and testable. Modern measurements have corroborated this prediction which can be dated back to Arrhenius at the turn of the 20th century.

3. AGW theory predicted the temperature increases of the latter 20th century.

4. models using these physics accurately simulate temperature of the last 100 years

5. models using these physics simulate temperature of the last 1,000 years to a reasonable degree

6. when combined with Milankovich theory accurately simulates the periodic ice ages of the last 3 million years

7. our existing understanding of climate can explain the varying temperatures of the earth for the last 600 million+ years

Those who are aware of the powerful implications given by points 1. and 2. will have very little trouble accepting the physical basis for AGW theory.

I will add to point 1. one crucial component which Skier left out, that of a planet's albedo which must be known to calculate a planet's effective temperature as seen from space. Knowing greenhouse gas composition and surface pressure are required to determine the surface temperature which will necessarily be higher than the effective temperature.

SEE:

Effective Temperature

Stephan-Boltmann Law

[tacoman25]

1. the physics of AGW accurately predict the temperature of other celestial bodies.

This is now standard practice in astronomy. The temperature of other planets is predicted using incoming solar radiation and GHG concentrations.

2. increasing opacity of the atmosphere to outgoing longwave radiation specifically in the CO2 absorption spectrum is a direct empirical test of AGW.

Theory has long predicted that increasing CO2 concentrations would cause the atmosphere to become more opaque to outgoing longwave radiation in the CO2 spectrum. The amount of energy that is blocked is predictable and testable. Modern measurements have corroborated this prediction which can be dated back to Arrhenius at the turn of the 20th century.

3. AGW theory predicted the temperature increases of the latter 20th century.

4. models using these physics accurately simulate temperature of the last 100 years

5. models using these physics simulate temperature of the last 1,000 years to a reasonable degree

6. when combined with Milankovich theory accurately simulates the periodic ice ages of the last 3 million years

7. our existing understanding of climate can explain the varying temperatures of the earth for the last 600 million+ years

1. What planets are we able to measure the GHG concentrations and surface temperatures?

3. The rate of warming from 1976 on was enabled in part by the +PDO phase, which climate science was completely unaware of at the time. How can you say AGW science accurately predicted temperature rise over such a short period of time, when natural variability clearly played a rather large role in the amount of warming that occurred over that period?

[skierinvermont]

1. What planets are we able to measure the GHG concentrations and surface temperatures?

3. The rate of warming from 1976 on was enabled in part by the +PDO phase, which climate science was completely unaware of at the time. How can you say AGW science accurately predicted temperature rise over such a short period of time, when natural variability clearly played a rather large role in the amount of warming that occurred over that period?

Provide me one study which attempts to quantify the effect of the PDO over that period.

Changes in the PDO didn't single handedly cause all of the worlds oceans to gain massive quantities of heat and expand. Do you really comprehend just how much heat the earth has gained in the last 40 years?

[tacoman25]

Provide me one study which attempts to quantify the effect of the PDO over that period.

Changes in the PDO didn't single handedly cause all of the worlds oceans to gain massive quantities of heat and expand. Do you really comprehend just how much heat the earth has gained in the last 40 years?

1. You didn't answer my planet question.

2. There are different ways of measuring heat/energy content on earth. From your statement, it sounded like you were talking about surface temperature. We now know that surface temperature trends over such periods (the "latter half of the 20th century") are significantly effected by natural climate cycles like the PDO. This was not known previously. Therefore, how did AGW science accurately predict the temperature increase seen over that period?

[WeatherRusty]

1. You didn't answer my planet question.

2. There are different ways of measuring heat/energy content on earth. From your statement, it sounded like you were talking about surface temperature. We now know that surface temperature trends over such periods (the "latter half of the 20th century") are significantly effected by natural climate cycles like the PDO. This was not known previously. Therefore, how did AGW science accurately predict the temperature increase seen over that period?

1. Venus and Mars. Titan (Moon of Saturn).

2. AGW is about the total climate, oceans, atmosphere and land. Not just the atmosphere. The signatures of a warming world will be found throughout, from the bottom of the seas to the top of the atmosphere.

The only way the total system can warm is for a lesser energy to be lost from the system than is entering the system. All something like the PDO, ESO, AMO etc. will do is move more or less energy between regions. It can not add energy to the system.

Look at a chart of global temps ranging over 120 years. You will note that the peaks and troughs of ENSO are clearly visible and that the overall trend in the peaks and troughs is toward warmer on both ends as is the mean value.

[tacoman25]

2. AGW is about the total climate, oceans, atmosphere and land. Not just the atmosphere. The signatures of a warming world will be found throughout, from the bottom of the seas to the top of the atmosphere.

The only way the total system can warm is for a lesser energy to be lost from the system than is entering the system. All something like the PDO, ESO, AMO etc. will do is move more or less energy between regions. It can not add energy to the system.

Look at a chart of global temps ranging over 120 years. You will note that the peaks and troughs of ENSO are clearly visible and that the overall trend in the peaks and troughs is toward warmer on both ends as is the mean value.

It was not clear what measurement skiier was referring to, but I have seen that argument used for surface temperature, which ignores the fact that natural cycles favored a warming trend in the latter half of the 20th century (due to transition from -PDO phase to +PDO phase).

[WeatherRusty]

It was not clear what measurement skiier was referring to, but I have seen that argument used for surface temperature, which ignores the fact that natural cycles favored a warming trend in the latter half of the 20th century (due to transition from -PDO phase to +PDO phase).

Do you mean that the models could not have predicted the past 100 years accurately without knowledge of PDO. If so, that would be true except that the models are hind-casting rather than forecasting.

[skierinvermont]

2. There are different ways of measuring heat/energy content on earth. From your statement, it sounded like you were talking about surface temperature. We now know that surface temperature trends over such periods (the "latter half of the 20th century") are significantly effected by natural climate cycles like the PDO. This was not known previously. Therefore, how did AGW science accurately predict the temperature increase seen over that period?

I know of no study which indicates the PDO has had a significant effect on GLOBAL surface temperatures. No doubt it has had some small effect, but it is mostly regional. Show me a study.

Or better yet propose one remotely plausible mechanism whereby the PDO causes significant surface warming of the globe. The only mechanism I can think of is that the pacific ocean releases heat to the atmosphere. Except it hasn't. The Pacific ocean has absorbed a tremendous amount of heat.

[tacoman25]

I know of no study which indicates the PDO has had a significant effect on GLOBAL surface temperatures. No doubt it has had some small effect, but it is mostly regional. Show me a study.

Or better yet propose one remotely plausible mechanism whereby the PDO causes significant surface warming of the globe. The only mechanism I can think of is that the pacific ocean releases heat to the atmosphere. Except it hasn't. The Pacific ocean has absorbed a tremendous amount of heat.

1. Just looking at global surface temperature trends, it's rather obvious. They were mostly flat in the 1950s/1960s/early 1970s during the -PDO phase, and then began rising rapidly right after the +PDO phase set in.

2. The -PDO phase is correlated with significantly more -ENSO events, which cause surface cooling while the ocean absorbs more heat. There's probably more to it than that, but so much is unknown about the PDO and other natural climate cycles still.

[tacoman25]

Do you mean that the models could not have predicted the past 100 years accurately without knowledge of PDO. If so, that would be true except that the models are hind-casting rather than forecasting.

Skiier's claim was that AGW science correctly predicted the temperature trends over the last half of the 20th century. Ususally when one says "predicted", it's not in hindsight, but again I'm not sure exactly what he's claiming.

[skierinvermont]

Skiier's claim was that AGW science correctly predicted the temperature trends over the last half of the 20th century. Ususally when one says "predicted", it's not in hindsight, but again I'm not sure exactly what he's claiming.

There were scientists back in the 50s saying that human GHGs would cause warming. The only question back in the 50s was whether GHGs or human aerosol emissions would be the dominant factor.

I believe Arrhenius might have even suggested that increasing CO2 concentrations in the atmosphere would cause warming.

[skierinvermont]

1. Just looking at global surface temperature trends, it's rather obvious. They were mostly flat in the 1950s/1960s/early 1970s during the -PDO phase, and then began rising rapidly right after the +PDO phase set in.

2. The -PDO phase is correlated with significantly more -ENSO events, which cause surface cooling while the ocean absorbs more heat. There's probably more to it than that, but so much is unknown about the PDO and other natural climate cycles still.

1. There a millions of "obvious" correlations in nature. Very few of them are causative.

2. This hypothesis of yours is easily testable. If a +PDO causes warming by releasing heat and a -PDO causes cooling via absorbing heat via changes in ENSO frequency, then we should see the Pac ocean gain heat in -PDO and release heat in +PDO. We don't. The Pac ocean absorbs heat in the +PDO directly contrary to your hypothesis. The anthropogenic contribution completely dominates on timescales of 30+ years even when we isolate to the Pacific ocean alone where the PDO effect would originate.

[tacoman25]

1. There a millions of "obvious" correlations in nature. Very few of them are causative.

2. This hypothesis of yours is easily testable. If a +PDO causes warming by releasing heat and a -PDO causes cooling via absorbing heat via changes in ENSO frequency, then we should see the Pac ocean gain heat in -PDO and release heat in +PDO. We don't. The Pac ocean absorbs heat in the +PDO directly contrary to your hypothesis. The anthropogenic contribution completely dominates on timescales of 30+ years even when we isolate to the Pacific ocean alone where the PDO effect would originate.

1. So why do you think there is a correlation between global temps and PDO, and what would suggest is a more likely cause?

2. Not for surface temperatures. Just look at the trends over the past 10+ years as we have transitioned to a -PDO/-ENSO dominated regime. You are making absolute statements that cannot be supported, i.e. "the anthropogenic contribution completely dominates on timescales of 30+ years".

[tacoman25]

PDO reconstruction is sketchy once you get more than 75 years or so back. But we do know that there was a +PDO phase from about 1925-1945, a -PDO phase from 1946-1975, and then a +PDO phase from 1976-2006ish. Looking back to the early 1900s, it's clear that global temperatures rose rapidly during the two +PDO phases and were relatively flat during -PDO phases. There is no stronger explanation for these trend variations other than the PDO phases.

[skierinvermont]

1. So why do you think there is a correlation between global temps and PDO, and what would suggest is a more likely cause?

2. Not for surface temperatures. Just look at the trends over the past 10+ years as we have transitioned to a -PDO/-ENSO dominated regime. You are making absolute statements that cannot be supported, i.e. "the anthropogenic contribution completely dominates on timescales of 30+ years".

1. uhh chance? why does global temperature correlate with a million other natural variables that are unrelated? correlation != causation.. does this really need to be repeated?

2. Yes but I asked you what the mechanism was and you said OHC transfers. I went looking for signs of this OHC transfer. There is none. Your hypothesis is easily testable.. and it fails. The PAC ocean has GAINED heat not released it. If the PDO was causing warming, the Pac ocean would be RELEASING heat not ABSORBING it.

[skierinvermont]

global temperatures of the last 100+ years are explained without the PDO just fine. Primarily by solar activity, GHG trends, and aerosols.

[tacoman25]

1. uhh chance? why does global temperature correlate with a million other natural variables that are unrelated? correlation != causation.. does this really need to be repeated?

2. Yes but I asked you what the mechanism was and you said OHC transfers. I went looking for signs of this OHC transfer. There is none. Your hypothesis is easily testable.. and it fails. The PAC ocean has GAINED heat not released it. If the PDO was causing warming, the Pac ocean would be RELEASING heat not ABSORBING it.

1. That is a silly answer. There is an obvious correlation and no other reasonable explanation. Isn't that the argument for longterm AGW warming? I could just as easily say that it's just "chance" that we have warmed over the past 100 years while GHGs have increased.

2. OHC release plays a large role in surface temperatures. During +ENSO, huge quantities of OHC are released into the atmosphere, causing surface warming. During -ENSO, OHC is retained, causing surface temperatures to cool. We don't know how deep oceanic circulation works exactly or how heat/energy is stored in the oceans, but the relationship between ENSO and surface temperatures is plain as day. And that is directly related to PDO phases, which is why PDO phases have a signficant effect on global surface temperature trends.

[tacoman25]

global temperatures of the last 100+ years are explained without the PDO just fine. Primarily by solar activity, GHG trends, and aerosols.

Not the variation. Aerosols were the explanation for the flat trend in the 50s, 60s, 70s before the PDO phase was known. That is an outdated theory that doesn't hold water any more.

And you didn't say the past 100 years originally. You said the second half of the 20th century.

Why are we regressing here? I know you have acknowledged the PDO's effect on decadal trends before, why are you suddenly acting like it's not a factor? Content to follow the IPCC blindly now?

[skierinvermont]

Not the variation. Aerosols were the explanation for the flat trend in the 50s, 60s, 70s before the PDO phase was known. That is an outdated theory that doesn't hold water any more.

And you didn't say the past 100 years originally. You said the second half of the 20th century.

Why are we regressing here? I know you have acknowledged the PDO's effect on decadal trends before, why are you suddenly acting like it's not a factor? Content to follow the IPCC blindly now?

Really? Aerosols are an outdated theory? News to me.

1 link please. Just one remotely credible study will do. Should be pretty easy!

[skierinvermont]

1. That is a silly answer. There is an obvious correlation and no other reasonable explanation. Isn't that the argument for longterm AGW warming? I could just as easily say that it's just "chance" that we have warmed over the past 100 years while GHGs have increased.

2. OHC release plays a large role in surface temperatures. During +ENSO, huge quantities of OHC are released into the atmosphere, causing surface warming. During -ENSO, OHC is retained, causing surface temperatures to cool. We don't know how deep oceanic circulation works exactly or how heat/energy is stored in the oceans, but the relationship between ENSO and surface temperatures is plain as day. And that is directly related to PDO phases, which is why PDO phases have a signficant effect on global surface temperature trends.

1. There is an alternate reasonable explanation.. which is why climate models are able to simulate 20th century temps without the PDO using solar, aerosols, the sun, etc.

2. Yes I understand that.. during a 1 year period of +ENSO the pacific ocean probably loses energy to the atmosphere. But in order for your theory to hold any water, the Pac Ocean would have to lose energy during the +PDO phase as a whole. Which it simply does not. It has gained a tremendous amount of energy.

The +PDO has not caused a net release of energy from the Pacific ocean and thus it has not had a net warming effect on the atmosphere.

[tacoman25]

1. There is an alternate reasonable explanation.. which is why climate models are able to simulate 20th century temps without the PDO using solar, aerosols, the sun, etc.

2. Yes I understand that.. during a 1 year period of +ENSO the pacific ocean probably loses energy to the atmosphere. But in order for your theory to hold any water, the Pac Ocean would have to lose energy during the +PDO phase as a whole. Which it simply does not. It has gained a tremendous amount of energy.

The +PDO has not caused a net release of energy from the Pacific ocean and thus it has not had a net warming effect on the atmosphere.

1. Wait a second...you have claimed before that climate models do incorporate PDO phases. Now you are saying they don't?

2. How exactly do we measure the entire energy the Pacific Ocean is storing/losing? I'm curious.

The +PDO phase (more +ENSO) caused more heat to be released into the atmospere, causing surface temperatures to be warmer than they would have otherwise. -PDO phases (more -ENSO) release less heat from the ocean into the atmosphere, which results in less surface warming. This isn't rocket science. And it is directly supportable by surface temperature trends as far back as we have reliable PDO records.

None of this contradicts the core of AGW theory, so I'm not sure why you are so adamantly opposed to the idea that natural ocean climate cycles can have significant effects on multi-decadal global temperature trends.

[skierinvermont]

1. Wait a second...you have claimed before that climate models do incorporate PDO phases. Now you are saying they don't?

2. How exactly do we measure the entire energy the Pacific Ocean is storing/losing? I'm curious.

The +PDO phase (more +ENSO) caused more heat to be released into the atmospere, causing surface temperatures to be warmer than they would have otherwise. -PDO phases (more -ENSO) release less heat from the ocean into the atmosphere, which results in less surface warming. This isn't rocket science. And it is directly supportable by surface temperature trends as far back as we have reliable PDO records.

None of this contradicts the core of AGW theory, so I'm not sure why you are so adamantly opposed to the idea that natural ocean climate cycles can have significant effects on multi-decadal global temperature trends.

it is measured by buoys, tide guages, and satellite altimetry

If a +PDO releases heat to the atmosphere, why did the Pac Ocean gain an absurd amount of heat during a +PDO?

Perhaps it absorbed less heat than it would otherwise have absorbed. However, the effect is clearly very small given it had almost no dampening effect on the gain in OHC caused by AGW.

Your hypothesis is easy to test. During a +PDO the pac ocean should release heat. During a -PDO it should absorb heat. This is not observed... the Pac ocean absorbs heat at a fairly linear rate, as have the global oceans.

So yes, as I have said before, the PDO may play a small role in regulating decadal ocean-atmosphere heat transfer and thus surface temperature. But the effect is clearly small or else we would observe a much larger footprint on OHC. So there could be some small effect, which is supported by the correlation observed (although global temperature also correlates with other variables like solar+GHG+aerosol). But if the effect were large, we would see the oceans absorbing much more heat in -PDO than +PDO.

[skierinvermont]

Ok here is a little way too overly simplistic thought experiment on the PDO.

Lets say ignoring the PDO the earth gains 10 units of heat. 9 to the ocean 1 to the atmosphere. For every 10 units of heat the atmosphere gains, the temperature rises .15C.

Now let's say in a +PDO the earth still gains 10 units, but 8.5 to the ocean 1.5 to the atmosphere. Surface warming after 30 years: .67C

And during a -PDO the earth still gains 10 units, but 9.5 to the oceans and .5 to the to atmosphere. Surface warming after 30 years: .22C

We'd expect the ocean to warm slightly slower during a +PDO than a -PDO.

But this is the opposite of what is observed. OHC has risen during +PDOs and dropped during -PDOs. This indicates that the warming and cooling were externally forced, not due to internal variability such as the PDO.

And guess what? The above OHC changes correlate perfectly with EXTERNAL radiative forcing (not internal variability).

[skierinvermont]

In short, the PDO cannot explain why the global oceans cooled from 1945-1970. Radiative forcing explains why both the oceans and surface cooled during that period.

The cooling 1945-1970 was very likely externally forced. It is the only way both the oceans and the atmosphere could cool simultaneously.

[WeatherRusty]

What would be the amplitude of the PDO be on the global warming trend? We can see the ENSO signal quit clearly, but what of the PDO.

Let's look at it from a forcing perspective.

The Planck Response to radiative power is 0.3C/watt.

Since 1850 or so solar absorption at the surface has increased about 0.25W so we can say about 0.1C attributed to increased solar.

CO2 radiative forcing has increased by about 1.6 watts so we can attribute about 0.5C to growing CO2 concentration.

The net of other factored forcing agents positive + negative = 0

Global surface temp has risen about 0.8C

So we are left with about 0.2C to account for. Some of that will be feedback related (water vapor) (ice albedo) etc.

Where does the PDO fit in? By how much?

[The_Global_Warmer]

Question:

the PDO like the AMO is just he measure of surface temps compared to an average.

this in itself shows nothing in the way of direct forcing.

So how can the PDO "do anything"?

[WeatherRusty]

Question:

the PDO like the AMO is just he measure of surface temps compared to an average.

this in itself shows nothing in the way of direct forcing.

So how can the PDO "do anything"?

You are correct that the PDO is not a forcing. However, since surface temperature is directly involved in heating the lower atmosphere, the PDO will affect atmospheric temperature. I ask by how much?

ENSO has a stronger effect on global temps because it occurs deep in the tropics where most of the energy received from the Sun is accumulated. The PDO is spread out over a much larger geographical area and is more of a rearrangement in where the warm and cool SST reside. So how much affect on global temps does it have at it's max in both phases.

[tacoman25]

it is measured by buoys, tide guages, and satellite altimetry

If a +PDO releases heat to the atmosphere, why did the Pac Ocean gain an absurd amount of heat during a +PDO?

Perhaps it absorbed less heat than it would otherwise have absorbed. However, the effect is clearly very small given it had almost no dampening effect on the gain in OHC caused by AGW.

Your hypothesis is easy to test. During a +PDO the pac ocean should release heat. During a -PDO it should absorb heat. This is not observed... the Pac ocean absorbs heat at a fairly linear rate, as have the global oceans.

So yes, as I have said before, the PDO may play a small role in regulating decadal ocean-atmosphere heat transfer and thus surface temperature. But the effect is clearly small or else we would observe a much larger footprint on OHC. So there could be some small effect, which is supported by the correlation observed (although global temperature also correlates with other variables like solar+GHG+aerosol). But if the effect were large, we would see the oceans absorbing much more heat in -PDO than +PDO.

The oceans have massive depths with no temperature sensors in them. We only have a historical records of SSTs. We can see how much heat is being stored/released near the surface, but that is it. So while the ocean may be absorbing heat/energy at a fairly linear rate overall, the amount that is released at the surface is determined largely by ENSO fluctuations. Which is ENSO plays a big role in surface temperatures, and since ENSO is closely related to PDO phases, over the course of decades a +PDO phase will release a lot more heat into the atmosphere than a -PDO phase.

[tacoman25]

You are correct that the PDO is not a forcing. However, since surface temperature is directly involved in heating the lower atmosphere, the PDO will affect atmospheric temperature. I ask by how much?

ENSO has a stronger effect on global temps because it occurs deep in the tropics where most of the energy received from the Sun is accumulated. The PDO is spread out over a much larger geographical area and is more of a rearrangement in where the warm and cool SST reside. So how much affect on global temps does it have at it's max in both phases.

Right, but it would appear it's mainly the ENSO/PDO relationship that causes the temperature correlation with PDO phases.