Naked Science Forum
Life Sciences => The Environment => Topic started by: The Scientist on 26/02/2011 12:55:29
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Please share your views! Thanks!
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The question is odd. It's a bit like saying "I have put another blanket on the bed, and now it's warmer. Did the blanket cause the rise in temperature?"
The answer is obviously yes- the questions are how much and did anything else also have an effect?
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CO2 likely has an effect on the temperature of the planet.
However, there are a number of other things that also effect the temperature including 30/60 year climate cycles, ocean currents, solar cycles, land-use, along with other atmospheric gases including methane and tropospheric ozone.
While there are many mature models, there are some people who believe the forcing effect of CO2 has been overestimated, and many of the projections fail to adequately take into account natural climate variability.
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During the discussions on the “What does Iain Stewart's "CO2 experiment" Demonstrate” thread (http://www.thenakedscientists.com/forum/index.php?topic=38723.25) JP provided a link which took me to an interesting book “Introduction to Atmospheric Chemistry” by Daniel J. Jacob, Princeton University Press, 1999 PDF version (http://acmg.seas.harvard.edu/publications/jacobbook/index.html). It is available for free viewing and CHAPTER 7. THE GREENHOUSE EFFECT is relevant to this question. That chapter, unlike Professor Stewart’s demonstration, makes it quite clear that
.. By far the most important greenhouse gas is water vapor because of its abundance and its extensive IR absorption features ..
It also gives a very even-handed description of that vexed question of feedback effects in Section 7.4 RADIATIVE FORCING.
It’s worth having a look at.
Best regards, Pete Ridley
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"Is Carbon Dioxide the real cause of an increase in Global Warming?"
Here, 'increase' is the key word in the thread's title.
Yes, water vapour can have a stronger absorption effect per se.
Yes, there are several other chemicals common in the atmosphere that heavily influence absorption.
The key issue is which ones are currently drastically changing?
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The question is odd. It's a bit like saying "I have put another blanket on the bed, and now it's warmer. Did the blanket cause the rise in temperature?"
The answer is obviously yes- the questions are how much and did anything else also have an effect?
I was going to says something, but I don't think I can put it any better than this.
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On the thread “What does Iain Stewart's "CO2 experiment" Demonstrate (http://www.thenakedscientists.com/forum/index.php?topic=38723.25) JP and I had a brief chat about a book “Introduction to Atmospheric Chemistry” by Daniel J. Jacob, Princeton University Press, 1999 PDF version (http://acmg.seas.harvard.edu/publications/jacobbook/index.html), which is available for free viewing. CHAPTER 7. THE GREENHOUSE EFFECT (unlike Professor Stewart’s demonstration) makes it quite clear that
.. By far the most important greenhouse gas is water vapor because of its abundance and its extensive IR absorption features ..
. It also gives a very even-handed description of that vexed question of feedback effects in Section 7.4 RADIATIVE FORCING, but this was off topic for that thread. It appears relevant to this one and could help to answer the question.
I have E-mailed Dr. Jacob about it and also suggested that he might be interested in taking a look at the analyses provided by Roger Taguchi on Professor Judith Curry's "Physics of the atmospheric greenhouse(?) effect" thread (http://judithcurry.com/2010/11/30/physics-of-the-atmospheric-greenhouse-effect/#comment-62506), which challenge Dr. Jacob’s analyses. Dr. Jacob has not yet responded but Roger has and here’s his comment .. In general, I agree with most of what's there. The main difference remains in their continued misconception about the atmosphere being able to emit black body radiation (the grey atmosphere model is wrong, what Judith Curry has called "kindergarten science"). It can't.
What the CO2 and other greenhouse gases do is absorb IR emitted BY THE WARM SOLID OR LIQUID SURFACE OF THE EARTH, and transfer by inelastic collision energy to N2 and O2 and Ar, gases, which CANNOT re-emit IR energy to outer space. At steady state, the IR that DOES manage to escape to outer space through the windows where there is no appreciable absorption by greenhouse gases must balance the net incoming Solar radiation which is mainly in the visible and near-IR. I was glad to see that the book quotes an
albedo of 0.28, which happens to be what I calculated after correction for truncation error (the IPCC numbers give an albedo of 0.24, a little on the low side).
The wrong idea that the atmosphere actually absorbs AND THEN RE-EMITS black body radiation (according to the Stefan-Boltzmann T^4 relation) I think results in their wrong factor of 1/2 in the temperature sensitivity
relation. Compare my simple, compact and true derivation of temperature sensitivity by simply differentiating the Stefan-Boltzmann law WHICH APPLIES TO A SOLID OR LIQUID EMITTING SURFACE, NOT THE ATMOSPHERE WHICH IS A GAS which cannot emit a continuous, i.e. black body, spectrum.
Because of a cancellation of errors the book actually got close to predicting the observed 0.7 degree (they call it 0.6 degree) rise in global temperature since about 1850. They got 0.8 degrees. Multiply this by a factor of 2 to correct for their mistake in using f/2 instead of f in the temperature sensitivity formula, and you get 1.6 degrees, which means they are a factor of 2 too high (my contention)
I’m sorry that this is not easy reading but that simply reflects the complexity of the subject itself. Further details are available on Professor Curry’s "Physics of the atmospheric greenhouse(?) effect" thread and in Roger’s revised article “Net Feedback Analysis - revised 2011_04_12”, which I can make available if anyone is interested.
Best regards, Pete Ridley
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Nice of you to provide a link to the other forum in which you slag off the naked scientists. Pete - get off the hobby horse and discuss matters or at least admit that you come to the debate with preconceived notions that you have no intention of changing. The pose that you are only seeking clarification is very hackneyed.
I am moderately undecided on certain areas of anthropogenic climate change; this undecision is caused, to a large extent, by the rabidity and intransigence of proponents of both sides of the discussion. In a forum such as this one (based on rational, honest, and friendly debate) an attitude of barely concealed condescension, prejudice, and combativeness will be counterproductive to say the least.
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This is becoming embarrassing Peter. I agree fully with Imatfaal here.
Please act a little more in the spirit of us discussing, and stop this bombastic attitude you present. You don't seem to want to sit down and study, you don't really want to discuss. You only want to argue your view, refusing to see others.
It doesn't impress.
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Besides, green house gasses are not the major influencing factor of the earth's temperature.
This is why I like to stay out of this issue - all of the people who argue for or against greenhouse gases and their importance in global warming are arguing against a totally false premiss - there is only a slight, short term connection between the two.
In the long run there is NO relationship.
At present, there is undeniably some slight relationship between CO2 & temperature rise which is most important because of the relationships this one feedback system has with all of the other causes of climate change.
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JB that one you will need to explain?
What do you see as the major influence, or are you thinking several influences?
I'm guessing you're looking at it differently :)
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Let's look at the energy budget of the solar system. (The following is generalized - doesn't apply to the moons of the gas giants, etc)
The overwhelming amount of energy is derived from the sun. The energy is more diffuse the further one is from the sun - that is obvious. So why should the three planets that are "sister" planets all have different conditions for life. We live on the Goldilocks planet. Mars and Venus - Papa and Mama bear - are not able to support life as we know it - UNDER PRESENT CONDITIONS. (Mars at one time had an atmosphere but the mechanism that kept it in place has long since vanished. It may still support some form of familiar life forms. We just do not yet know.)
Venus is shrouded in a CO2-rich (95% CO2) Atmosphere and the density of the atmosphere is 9200 kilopascals (kPa), compared to earth's ~101.3 kPa at sea level. Clearly, gravity plays a larger part in the retention of the Venusian atmosphere than it does on earth.
So, Mars has little or no atmosphere left, Earth and Venus do - what is the difference?
A magnetic field. TWO types of magnetic fields to be exact. The Venusian magnetic field is an induced field, the Earth's field is generated within the Earth itself by a process no one understands. Even the induced magnetic field of Venus due to the extremely strong ionosphere of Venus is only partially understood as measurement of the exterior field precludes exact modeling of the interior field, if any.
The climate of Earth is dependent on having an atmosphere. We only have an atmosphere because we have a strong interior magnetic field. Our magnetic field is the only reason we can discuss climate or climate change. Peripheral issues, such as CO2 content, have little to do with climate change over a period of 3-400 years. At the end of the Permian, climate change due to a change in the gaseous content of the earth's atmosphere was probably the dominant reason for climate change. This end-of-Permian event is only an isolated event.
For most of the Earth's history, the magnetic field of the earth is one of several factors that control the Earth's climate. Other factors are the coherence of the continents. Gondwanaland and Pangaea prevented wide variations in temperature differences, the placement and height of mountain ranges cause climate change (the rise of the Himalayas has caused huge deserts to be formed in Central Asia)
AT PRESENT: THE DOMINANT FACTORS CAUSING CLIMATIC VARIATION ARE THE SUN AND THE EARTH'S MAGNETIC FIELD.
The sun has cycles of activity that are predictable and can be seen in the recent temperature record. But inter-dispersed between the predictable sun-produced record are variable periods that can, on occasion, be correlated with magnetic field changes.
MY PERSONAL OPINION is that what we are witnessing at present a break-down in the earth's protective barrier. At present, The North pole is moving towards Russia between 34 and 37 mi a year. And a very large anomaly involving a "second" south pole is forming in the South Atlantic. Are these just normal variations or do they portend something more significant? No one knows. Personally, I suspect they are not normal.
As the earth's magnetic field fluctuates, so does the amount of energy delivered into the earths climate. The lack of the shielding in the South Atlantic is leading to severe drouth conditions in Australia and possible the present lack of rain in many other places of the world as well.
The Earth's magnetic field is like a quasi-potentiometer moderating, only in part, the amount sun's energy that is put into the earth's climatic system. But the suns energy WITH the magnetic moderation of its input is hundreds of times more important than a little bit of CO2.
The coupling of these two forces is the most important consideration for climate change of any sort.
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Nice theory JimBob!
Unfortunately, the Earth's magnetosphere only deflects slow moving ionized particles in the solar wind. This protects our atmosphere and prevents the solar wind from ripping it away from the Earth.
Most of the thermal energy from the Sun arrives on the Earth in the form of photons (electromagnetic radiation) travelling at the speed of light. The magnetosphere does bugger all has no effect on that radiation.
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Interesting JB, I will need to read more about it. My own pet horse is that we live in a non-linear environment. That is, i think there can, and have been, such things as 'tippings' from one 'stable' state to another earlier. Also I think there is a lot to consider more than CO2 although I do believe it to be the worst villain I know, over any longer time period, depending on its ability to conserve heat.
And then we have those giving importance to solar spots. And you discuss magnetic fields which in a way seem interrelated? "The Venusian magnetic field is an induced field, the Earth's field is generated within the Earth itself by a process no one understands. Even the induced magnetic field of Venus due to the extremely strong ionosphere of Venus is only partially understood as measurement of the exterior field precludes exact modeling of the interior field, if any.
In what way is it 'induced'? And Earths not?
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I started a separate topic to discuss a bit more the effect on magnetic field weakening/pole reversal and climate change: http://www.thenakedscientists.com/forum/index.php?topic=39128.0;topicseen
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Nice theory JimBob!
Unfortunately, the Earth's magnetosphere only deflects slow moving ionized particles in the solar wind. This protects our atmosphere and prevents the solar wind from ripping it away from the Earth.
That was precisely the point of bringing in the fact that Mars has no atmosphere. Without an atmosphere, the whole problem would not exist - and neither would we. Sun cycles greatly affect the atmosphere of earth; cycles as short as 11 yaers or so.
Induced field. Venus - http://en.wikipedia.org/wiki/Venus%27_atmosphere - Paragraph 3
I also said above " The Earth's magnetic field is like a quasi-potentiometer moderating, only in part, the amount sun's energy that is put into the earth's climatic system. "
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I started a separate topic to discuss a bit more the effect on magnetic field weakening/pole reversal and climate change: http://www.thenakedscientists.com/forum/index.php?topic=39128.0;topicseen
You may want to rethink the wording of the question. For example - field strength change vs climate change
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I started a separate topic to discuss a bit more the effect on magnetic field weakening/pole reversal and climate change: http://www.thenakedscientists.com/forum/index.php?topic=39128.0;topicseen
You may want to rethink the wording of the question. For example - field strength change vs climate change
Maybe. But we don't have record of field strength changing, do we, while we do have evidence of poles reversing? Either way, any evidence of correlation between changes in the earth's magnetic field and climate change could be interesting.
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Okay saw what you meant by 'induced'. And will look at that other thread.
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Nice theory JimBob!
Unfortunately, the Earth's magnetosphere only deflects slow moving ionized particles in the solar wind. This protects our atmosphere and prevents the solar wind from ripping it away from the Earth.
That was precisely the point of bringing in the fact that Mars has no atmosphere. Without an atmosphere, the whole problem would not exist - and neither would we. Sun cycles greatly affect the atmosphere of earth; cycles as short as 11 yaers or so.
Induced field. Venus - http://en.wikipedia.org/wiki/Venus%27_atmosphere - Paragraph 3
I also said above " The Earth's magnetic field is like a quasi-potentiometer moderating, only in part, the amount sun's energy that is put into the earth's climatic system. "
Ah! So you are saying the amount gas in the Earth's atmosphere can change according to the field strength of the magnetosphere.
If there was a significant change in the mass of the atmosphere, there would be changes in average atmospheric pressure too. Is it possible to determine that from the fossil record?
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The field intensity can be compared but not too well - measurement techniques are just not exact enough.
As for the last question - ????????????????????????????
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It seems to have been a long time since anyone mentioned CO2 or the globe.