Playing Devil's advocate on climate

sylas

Quote by Xnn

Consider the 3C/CO2 doubling most likely value.

CO2 levels are going up about 0.5% per year.
That works out to 0.015C/year of warming.

Now; look at the amount of observed global warming over the last 30 years.

It's about 0.016C/year.

In other words, observations are tending to support the most likely value.

That's technically incorrect on many levels.

First, the doubling value of 3 C/2xCO2 is an equilibrium response; not the transient response.

There's a lot more changing than just CO₂. Taken in isolation, CO₂ is the largest forcing, but there are a number of other forcings, both positive and negative, and they make a difference.

An increase of 0.5% per year is log₂(1.005) of a doubling, and this is 0.0072. At 3 degrees per doubling you would have 3*0.0072 = 0.021 C/year.

As it turns out, observations are consistent with the estimates of sensitivity, but the argument is a bit different. It is not sufficient to give a strong constraint on the sensitivity estimate. If you look at the section of the technical summary you quoted previously, the next paragraph deals with "transient response" as opposed to "equilibrium sensitivity". Chapter 10 deals with the difference between these concepts in more detail. Here's the extract (page 88, technical summary)

The transient climate response is better constrained than the equilibrium climate sensitivity. It is very likely larger than 1°C and very unlikely greater than 3°C. {10.5}

With a transient response 2°C per doubling, and with an increase of 0.5% per year CO₂, and in the absence of all other forcings, you should expect a temperature increase trend of about 2*log₂(1.005) = 0.0144 C/year. Of course, there are other forcings as well; but all told this is why transient response is better constrained. The available data for the immediate present allows you to constrain it, where equilibrium response requires an additional level of indirection to get from observations to a number.

Also relevant is a recent thread with a discussion of the cummulative carbon emissions response (CCR), which tends to reflect transient climate response rather than equilibrium climate response. There were two recent papers on this, which are discussed in msg #83 and following of thread "Estimating the impact of CO2 on global mean temperature".

Cheers -- sylas

Xnn

Thanks sylas;

So, doing this in natural logs, the calculation is 0.016/0.0072 = 2.2 C/CO2 doubling; using the last 30 years of global observational data if other forcings are ignored.

Not sure if how significant other forcings are.

sylas

Quote by Xnn

Not sure if how significant other forcings are.

Neither is anyone else; there are significant uncertainties in other forcings. CO₂ is the simplest forcing to evaluate and is known to quite high accuracy. Other forcings are known, but with larger bounds of accuracy. The bounds are sufficient to conclude with strong confidence that greenhouse effects are the largest forcing, and that CO₂ is the largest contributor to that. But the lack of certainty in other forcings still means a large spread of uncertainty about total forcing.

I've given a widely repeated diagram in msg #66 of thread "Estimating the impact of CO2 on global mean temperature", outlining estimates and uncertainties for forcings. It can be found also as figure 2.20, on page 203 (chapter 2) of the 4th AR. The estimates are quantified, with 90% confidence bounds, in table 2.12, page 204.

Felicitations -- sylas

PS. As an added wrinkle... a forcing is a change from one time to another. The table I've shown is giving the forcings from 1750 to the present. But if you want to look at the last 30 years, then the picture changes again, generally making the greenhouse effects and CO₂ in particular even more significant for the immediate rate of change. The immediate rate of change also is affected by changes in heat uptake in the ocean, which will impact rates of change in much the same way as a forcing.

*Saul*

The other explanation for the 20th century warming is a decrease in planetary clouds rather than AWG, in particular CO2.

The observations do not show a steady increase in the base line planetary temperature about which planetary temperature oscillates. Planetary temperature has in fact cooled slightly post 1998.

http://www.woodfortrees.org/plot/had...09.8/normalise

http://wattsupwiththat.com/2009/09/0...of-0-4%C2%B0c/

As I noted further up in the this thread planetary temperature in the 20th century has strongly correlated with geomagnetic field change measured by the parameter Ak that is in turn modulated by solar wind bursts. The solar wind burst remove cloud forming ions by a process called electroscavenging. The sudden warming events in planetary temperature records and the longer term warming and cooling trends correlate with Ak.

http://www.atmos-chem-phys.org/5/172...1721-2005.html

Analysis of the decrease in the tropical mean outgoing shortwave radiation at the top of atmosphere for the period 1984–2000

All cloud types show a linearly decreasing trend over the study period, with the low-level clouds having the largest trend, equal to −3.9±0.3% in absolute values or −9.9±0.8% per decade in relative terms. Of course, there are still some uncertainties, since the changes in low-level clouds derived from the ISCCP-D2 data, are not necessarily consistent with changes derived from the second Stratospheric Aerosols and Gas Experiment (SAGE II, Wang et al., 2002) and synoptic observations (Norris, 1999). Nevertheless, note that SAGE II tropical clouds refer to uppermost opaque clouds (with vertical optical depth greater than 0.025 at 1.02μm), while the aforementioned synoptic cloud observations are taken over oceans only. The midlevel clouds decreased by 1.4±0.2% in absolute values or by 6.6±0.8% per decade in relative terms, while the high-level ones also decreased by 1.2±0.4% or 3±0.9% per decade in relative terms, i.e. less than low and middle clouds. Thus, the VIS/IR mean tropical (30_ S–30_ N) low-level clouds are found to have undergone the greatest decrease during the period 1984–2000, in agreement with the findings of Chen et al. (2002) and Lin et al. (2004).

http://news.yahoo.com/s/mcclatchy/20...latchy/3295216

WASHINGTON — Has Earth's fever broken?
Official government measurements show that the world's temperature has cooled a bit since reaching its most recent peak in 1998.

"It's entirely possible to have a period as long as a decade or two of cooling superimposed on the long-term warming trend," said David Easterling , chief of scientific services at NOAA's National Climatic Data Center in Asheville, N.C.

So far this year, the high has been 0.42 degrees Celsius (0.76 degrees Fahrenheit), above the 20-year average, clearly cooler than before.

vanesch

Quote by Saul

As I noted further up in the this thread planetary temperature in the 20th century has strongly correlated with geomagnetic field change measured by the parameter Ak that is in turn modulated by solar wind bursts. The solar wind burst remove cloud forming ions by a process called electroscavenging. The sudden warming events in planetary temperature records and the longer term warming and cooling trends correlate with Ak.

The problem is that the planetary temperature in the 20th century also correlates with the logarithm of the average number of transistors on an Intel processor chip...

*Saul*

Quote by vanesch

The problem is that the planetary temperature in the 20th century also correlates with the logarithm of the average number of transistors on an Intel processor chip...

Do you have a paper to show the correlation?

Please explain the cooling post 1998.

I provided papers that shows the correlation, papers that provide a cause to explain the observations, and papers to explain the mechanism.

What is your point? Or problem?

*Saul*

Galteeth's comment was:

This is a fascinating forum, and these climate discussions are very interesting and educational. I couldn't help but notice however that it seems posters tend to line up along sides on the issue of AGW (or perhaps the degree to which they are skeptical of the consensus). I think it would be interesting to see people play devil's advocate and argue for the other position, or rather acknowledge data that does not support their view (on both sides).

There are most definitely basic observations that do not support the AWG hypothesis. There have been a series of papers that have been written concerning the discrepancy between prediction and observations.

The science is interesting. A pointless sarcastic monologue is not.

Because there currently appears to be a deep solar magnetic cycle minimum, there should be observational evidence and papers to clarify the problem situation. We can have some fun reading and discussing those papers and discussing the observational evidence.

The competing scientific explanation for the 20th century warming is solar modulation of planetary cloud cover. As noted in the past cosmogenic isotopes changes correlate with abrupt planetary temperature change. There is smoking gun evidence at each of the cyclic abrupt climate change events.

vanesch

Quote by Saul

What is your point? Or problem?

The point is that finding a correlation doesn't indicate a causal relationship, and even if so, it doesn't even indicate which way. Now, there can (I didn't check) be a correlation with solar activity, why not. The mechanism you mention can be active.

However, you are not going to convince me that the mechanism of cloud formation through solar activity is simpler physics, which is less prone to modelling errors, and to which there are less complex feedback factors working, than the heat transport problem of an atmosphere containing some gases that interact with IR radiation, which is based upon rather elementary thermodynamics, and of which several basic aspects are easily checked and known for tens of years (like the lapse rate, or the black body properties of gases).

In other words, the warming of the last century can be for sure find its origins in many elements, but the CO2 is definitely a part in it, and it is probably the easiest part to calculate, because at least the forcing due to it is easy to estimate.

The point is that even if you had a straight-forward model that no-body can doubt because based upon very elementary physics for your solar activity stuff that gives you the expected change in cloud cover as function of the solar activity, calculated from first principles only, and not using any climate data, still you would be faced with exactly the same problem as the one with CO2: the climate sensitivity. Even if you had the perfect model that gives you without an ounce of doubt, from first principles, the cloud cover as a function of solar activity, the only thing you would be able to get from that, is a forcing (so many watts per square meter). The question of how temperature is dependent on that is exactly the same as for the CO2 forcing: the sensitivity.

Now, at least the forcing is easy to calculate with CO2, because for that there DOES exist a simple and straightforward physics model based upon first principles.

So it might very well be that your mechanism ALSO exists, and is ALSO a significant drive - I don't know. But to say that it is a *more straightforward* explanation than CO2 seems to me to push things, no ?

*Skyhunter*

Quote by Saul

Do you have a paper to show the correlation?

Please explain the cooling post 1998.

I provided papers that shows the correlation, papers that provide a cause to explain the observations, and papers to explain the mechanism.

What is your point? Or problem?

Denier blogs are not scientific papers. Therefore you have failed to meet the standards of this forum.

There is no cooling trend since 1998. 1998 was an anomalous year, influenced by a very strong el nino event. The long term trend did plateau slightly, but has remained positive.

*Saul*

Quote by vanesch

The point is that finding a correlation doesn't indicate a causal relationship, and even if so, it doesn't even indicate which way. Now, there can (I didn't check) be a correlation with solar activity, why not. The mechanism you mention can be active.

However, you are not going to convince me that the mechanism of cloud formation through solar activity is simpler physics, which is less prone to modelling errors, and to which there are less complex feedback factors working, than the heat transport problem of an atmosphere containing some gases that interact with IR radiation, which is based upon rather elementary thermodynamics, and of which several basic aspects are easily checked and known for tens of years (like the lapse rate, or the black body properties of gases).

In other words, the warming of the last century can be for sure find its origins in many elements, but the CO2 is definitely a part in it, and it is probably the easiest part to calculate, because at least the forcing due to it is easy to estimate.

The point is that even if you had a straight-forward model that no-body can doubt because based upon very elementary physics for your solar activity stuff that gives you the expected change in cloud cover as function of the solar activity, calculated from first principles only, and not using any climate data, still you would be faced with exactly the same problem as the one with CO2: the climate sensitivity. Even if you had the perfect model that gives you without an ounce of doubt, from first principles, the cloud cover as a function of solar activity, the only thing you would be able to get from that, is a forcing (so many watts per square meter). The question of how temperature is dependent on that is exactly the same as for the CO2 forcing: the sensitivity.

Now, at least the forcing is easy to calculate with CO2, because for that there DOES exist a simple and straightforward physics model based upon first principles.

So it might very well be that your mechanism ALSO exists, and is ALSO a significant drive - I don't know. But to say that it is a *more straightforward* explanation than CO2 seems to me to push things, no ?

vanesch,

I am not trying to convince you of anything. I am trying explain these observations.

Those advocating the AWG position (AWG caused 90% of the 20th century warming. Deny the cooling occurred or attribute cooling to satellite problems.) in this forum have not acknowledge the most basic fact which is that the 20th planetary temperature changes did not correlate with the CO2 changes. Changes in planetary cloud cover do correlate with the 20th century temperature rise.

A scientific mind ask why, is interesting in a scientific explanation. You and the other AWG supports in the forum do not acknowledge that there is a problem situation. Something that requires explanation.

The point is you write in capital letters. I do not understand the emotion. Science is science. The truth is the truth. What will happen will happen.

The are multiple observations (for example the current cooling trend and the increase in sea ice in the arctic and antarctic) and papers that do not support the AWG hypothesis.

http://www.woodfortrees.org/plot/had...09.8/normalise

http://wattsupwiththat.com/2009/09/0...of-0-4%C2%B0c/

http://www.atmos-chem-phys.org/5/172...1721-2005.html

Analysis of the decrease in the tropical mean outgoing shortwave radiation at the top of atmosphere for the period 1984–2000

All cloud types show a linearly decreasing trend over the study period, with the low-level clouds having the largest trend, equal to −3.9±0.3% in absolute values or −9.9±0.8% per decade in relative terms. Of course, there are still some uncertainties, since the changes in low-level clouds derived from the ISCCP-D2 data, are not necessarily consistent with changes derived from the second Stratospheric Aerosols and Gas Experiment (SAGE II, Wang et al., 2002) and synoptic observations (Norris, 1999). Nevertheless, note that SAGE II tropical clouds refer to uppermost opaque clouds (with vertical optical depth greater than 0.025 at 1.02μm), while the aforementioned synoptic cloud observations are taken over oceans only. The midlevel clouds decreased by 1.4±0.2% in absolute values or by 6.6±0.8% per decade in relative terms, while the high-level ones also decreased by 1.2±0.4% or 3±0.9% per decade in relative terms, i.e. less than low and middle clouds. Thus, the VIS/IR mean tropical (30_ S–30_ N) low-level clouds are found to have undergone the greatest decrease during the period 1984–2000, in agreement with the findings of Chen et al. (2002) and Lin et al. (2004).

*Saul*

Quote by Skyhunter

Denier blogs are not scientific papers. Therefore you have failed to meet the standards of this forum.

There is no cooling trend since 1998. 1998 was an anomalous year, influenced by a very strong el nino event. The long term trend did plateau slightly, but has remained positive.

Skyhunter,
Science is the discussion of observations. Planetary temperature is dropping. Antarctic and Arctic Sea ice is increasing.

Name calling "denier blogs" is a sign that you are not interesting in the problem situation from a scientific standpoint. Why the emotion? The observations do not support the AWG hypothesis.

http://news.yahoo.com/s/mcclatchy/20...latchy/3295216

http://www.woodfortrees.org/plot/had...09.8/normalise

WASHINGTON — Has Earth's fever broken?
Official government measurements show that the world's temperature has cooled a bit since reaching its most recent peak in 1998.

vanesch

Quote by Saul

Those advocating the AWG position (AWG caused 90% of the 20th century warming. Deny the cooling occurred or attribute cooling to satellite problems.)

This is not what I would call the defining position of AGW. AGW means, at least, that's how I understand it, that human emissions of greenhouse gasses are significant enough to cause an observable extra warming on top of all the other forcings that there might be, in the coming centuries. Then the scientific debate goes about how much exactly.

And then the non-scientific AGW debate goes about what this is going to do to humanity and the biosphere, and whether that is a bad thing in the first place, and if so, what, if anything, we should/can do about it.

*Saul*

Quote by vanesch

This is not what I would call the defining position of AGW. AGW means, at least, that's how I understand it, that human emissions of greenhouse gasses are significant enough to cause an observable extra warming on top of all the other forcings that there might be, in the coming centuries. Then the scientific debate goes about how much exactly.

And then the non-scientific AGW debate goes about what this is going to do to humanity and the biosphere, and whether that is a bad thing in the first place, and if so, what, if anything, we should/can do about it.

The AWG position is that a doubling of from 280 ppm to 560 ppm will cause the planet to warm 3C to 5C.

The AWG position is not that an increase in CO2 from 280 ppm to 560 ppm will cause 0.75C increase in planetary temperature.

The scientific formula for CO2 forcing is logarithmic. The current increase (from 280 ppm to 380 ppm) will if the formula matches reality result in an increase in forcing of around 2.7 w/m^2 of the total calculated 3.7 w/m^2 that the formula predicts will result from a doubling from 280 ppm to 560 ppm.

Rather than discuss the recent planetary cooling, it is denied. There cannot be a long term cooling trend if there was an increase in forcing that never goes away of 2.7 w/m^2.

That is the problem situation from the AWG position. The CO2 must warm the planet every day if the mechanism exists as hypothesized.

What it appears based on the shape of planetary temperature change, is CO2 saturates or at least partially saturates from a perspective of the mechanism. The why and what will happen next due to the abrupt solar magnetic cycle change, is an interesting question.

The key question is the magnitude of up coming planetary temperature change.

*Skyhunter*

Quote by Saul

Skyhunter,
Science is the discussion of observations. Planetary temperature is dropping. Antarctic and Arctic Sea ice is increasing.

Name calling "denier blogs" is a sign that you are not interesting in the problem situation from a scientific standpoint. Why the emotion? The observations do not support the AWG hypothesis.

http://news.yahoo.com/s/mcclatchy/20...latchy/3295216

http://www.woodfortrees.org/plot/had...09.8/normalise

Denier blogs or fellowship for scientific truth, it doesn't matter what you call them. They are not credible sources and therefore against forum rules.

*Saul*

Quote by Skyhunter

Denier blogs or fellowship for scientific truth, it doesn't matter what you call them. They are not credible sources and therefore against forum rules.

Skyhunter what is your point or problem? You appear not to want to discuss the science and instead try to stop anyone else from discussing the science, the problem situation.

The AWG position is that a doubling of CO2 from 280 ppm to 560 ppm will cause the planet to warm 3C to 5C. Based on the AWG formula the increase from 280 ppm to 380 ppm should have resulted in an increase in forcing of 2.7 w/m^2 of the total 3.7 w/m^2, 24 hours a day, seven days a week.

The AWG forcing mechanism cannot appear in January and then disappear in June.

There is no evidence in the planetary temperature changes of a steady increase in of 2.7 w/m^2.

The other explanation for the 20th century warming is a change in planetary clouds. The forcing mechanism that increases and decreases planetary clouds can change and hence can explain the observations.

http://www.atmos-chem-phys.org/5/172...1721-2005.html

Analysis of the decrease in the tropical mean outgoing shortwave radiation at the top of atmosphere for the period 1984–2000

All cloud types show a linearly decreasing trend over the study period, with the low-level clouds having the largest trend, equal to −3.9±0.3% in absolute values or −9.9±0.8% per decade in relative terms. Of course, there are still some uncertainties, since the changes in low-level clouds derived from the ISCCP-D2 data, are not necessarily consistent with changes derived from the second Stratospheric Aerosols and Gas Experiment (SAGE II, Wang et al., 2002) and synoptic observations (Norris, 1999). Nevertheless, note that SAGE II tropical clouds refer to uppermost opaque clouds (with vertical optical depth greater than 0.025 at 1.02μm), while the aforementioned synoptic cloud observations are taken over oceans only. The midlevel clouds decreased by 1.4±0.2% in absolute values or by 6.6±0.8% per decade in relative terms, while the high-level ones also decreased by 1.2±0.4% or 3±0.9% per decade in relative terms, i.e. less than low and middle clouds. Thus, the VIS/IR mean tropical (30_ S–30_ N) low-level clouds are found to have undergone the greatest decrease during the period 1984–2000, in agreement with the findings of Chen et al. (2002) and Lin et al. (2004).

http://news.yahoo.com/s/mcclatchy/20...latchy/3295216

WASHINGTON — Has Earth's fever broken?
Official government measurements show that the world's temperature has cooled a bit since reaching its most recent peak in 1998.

"It's entirely possible to have a period as long as a decade or two of cooling superimposed on the long-term warming trend," said David Easterling , chief of scientific services at NOAA's National Climatic Data Center in Asheville, N.C.

So far this year, the high has been 0.42 degrees Celsius (0.76 degrees Fahrenheit), above the 20-year average, clearly cooler than before.

*Skyhunter*

The Earth is not cooling.

Short term trends are flat, not negative. As the current el nino event develops global temperatures are once again on the rise.

Quote by Saul

The CO2 must warm the planet every day if the mechanism exists as hypothesized.

This is a strawman argument.

There is nothing in the AGW theory that requires temperatures to rise everyday.

*Skyhunter*

Saul,

If you want to discuss science, then provide a scientific source.

We are not allowed to discuss psuedo-science on this forum.

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Xnn Blog Entries: 2	Thanks sylas; So, doing this in natural logs, the calculation is 0.016/0.0072 = 2.2 C/CO2 doubling; using the last 30 years of global observational data if other forcings are ignored. Not sure if how significant other forcings are.

Skyhunter	Saul, If you want to discuss science, then provide a scientific source. We are not allowed to discuss psuedo-science on this forum.