My belief in Global Warming is getting shaky

[engineerdude]

Many models work, but no models work perfectly for every scenario. It's simply unrealistic to expect that we can model such a chaotic system with 100% accuracy.

 

That said, here's a good read on climate models and why they are efficient and useful.

 

 

 

Global Warming : Feature Articles

 

So why are the IPCC models and projections always off by so much, and nothing is done to correct them?

 

In addition, the information you cited concerned a climate model and the eruption of Mount Pinatubo. Obviously, not every climate model are stupidly wrong - just the global warming ones. :)

[engineerdude]

Many models work, but no models work perfectly for every scenario. It's simply unrealistic to expect that we can model such a chaotic system with 100% accuracy.

 

That said, here's a good read on climate models and why they are efficient and useful.

 

 

 

Global Warming : Feature Articles

 

Oh, my God. The NASA Goddard people are really off base.

 

As a result of the quoted post I decided to actually look at the climate models the NASA Goddard people are using. An extensive description of their models can be found here:

http://pubs.giss.nasa.gov/docs/2008/2008_Bader_etal.pdf

 

THESE MODELS IGNORE OVERALL CHANGES IN SUNLIGHT

 

These models assume that the amount of energy zooming to us through space never ever changes. For this assumption to be valid Earth's orbit would have to be perfectly symmetrical, and the sun could never be a little brighter or dimmer.

 

In addition, even though the report I linked above was published in July 2008, all the charts shown end in 2000. That was the year all the IPCC and NASA climate models stopped working, even with the IPCC's exaggerated data.

 

How can no one have ever actually looked at these models outside of Goddard, and pointed out the problems which make the results totally invalid?

[Michaelangelica]

An intersting article

Ice coverage has been decreasing since the 1960s. In 2007 the trend line fell out of bed. There was a small recovery in 2008, as there was in 2006 from the then record low of 2005.

 

We need to keep in mind that “ice coverage” is defined at 15% coverage or more, quite a low standard. Also the ice is thinning rapidly.

Science, denialism or unconscionable fraud? at Larvatus Prodeo

 

and

http://larvatusprodeo.net/2009/01/13/more-polar-bears-are-going-hungry-but-is-that-the-biggest-concern/

[freeztar]

Oh, my God. The NASA Goddard people are really off base.

 

As a result of the quoted post I decided to actually look at the climate models the NASA Goddard people are using. An extensive description of their models can be found here:

http://pubs.giss.nasa.gov/docs/2008/2008_Bader_etal.pdf

 

THESE MODELS IGNORE OVERALL CHANGES IN SUNLIGHT

 

These models assume that the amount of energy zooming to us through space never ever changes.

 

Goddard does not ignore the sun.

 

http://www.yale.edu/yibs/Solar%20Variability%20Program/2008_Yale_solar_Shindell.pdf

[engineerdude]

Goddard does not ignore the sun.

 

http://www.yale.edu/yibs/Solar%20Variability%20Program/2008_Yale_solar_Shindell.pdf

 

This document you link is only for regional stuff - there is nothing I can find in the overall climate models that reflects this. And the overall models are what everyone looks at, talks about.

[freeztar]

How long (in seconds, minutes, hours) after the sun goes down does it take for a co2 molecule to begin shedding its warmth?

 

Co2 does not "store" heat as far as I know. The IR energy is received and transmitted in a very short period of time (much less than a second).

 

How long before it is not retaining the (alleged) heat its absorbed in the day? Its not like CO2 is plutonium or uranium and self heating.

 

Indeed. CO2 does not act as a storage or generation of heat. Even in the dead of the night the atmosphere is absorbing/emitting IR. Remember, heat is not as accurate as IR in this sense.

 

These are teeny little things that are insignificant in the total of the atmospheric makeup. 38-39 of them floating around per 100,000 pieces of atmospheric stuff.

This is a common misconception. The amount is insignificant compared to the effect.

Would you think it was insignificant if I added 38 drops of anthrax per one thousand drops of your drinking water and asked you to drink it? What about 3 drops? :)

 

In actuality, the current CO2 content in the atmosphere is somewhere around 385ppm which corresponds to 0.000385 parts to each part atmosphere. Insignificant in quantity, but proven significant in effect.

Dont you at least kinda wonder if whats being fed to us may be tainted, with or without intent?

 

All the time. :)

[freeztar]

This document you link is only for regional stuff - there is nothing I can find in the overall climate models that reflects this. And the overall models are what everyone looks at, talks about.

 

Is it that far of a stretch to assume that the same is applied to global climate models?

The folks at NASA know a thing or two about the sun. :)

 

Why not seek the source though? From the link you posted:

 

Time-dependent climate-forcing simulations

are the most realistic, especially for eras in

which climate forcing is changing rapidly, such

as the 20th and 21st centuries. Input for 20th Century

simulations includes observed time-varying

values of solar energy output, atmospheric

carbon dioxide, and other climate-relevant gases

and aerosols, including those produced in volcanic

eruptions. Each modeling group uses its

own best estimate of these factors. Significant

uncertainties occur in many of them, especially

atmospheric aerosols, so different models use

different input for their 20th Century simulations.

We discuss uncertainties in climateforcing

factors in Chapter 4 and 20th Century

simulations in Chapter 5 after comparing control

runs with observations.

 

http://pubs.giss.nasa.gov/docs/2008/2008_Bader_etal.pdf

[Biochemist]

If carbon dioxide made up a significant portion of our atmosphere then it's likely earth would be like Venus with average temps well above the melting point of aluminum or lead. Compared to that—I'd say it's the little changes we're interested in.

There is a limit to the amount of heat that can be trapped by CO2, since it only absorbs a narrow portion of the spectrum. That is why a 50% increase in CO2 over the last 100 years is associated with only a 0.5 to 1 degree rise. Realistically, even if you think CO2 is casual, it would probably not be the ONLY reason for the rise. Further, the main greenhouse gas, water vapor (90% of GG is water vapor, 4% is CO2) absorbs in an overlapping spectrum. Once that spectrum is absorbed, there is not more retention.

 

The estimates that I saw for an incremental doubling of CO2 predicted a range of 2 to 4 degrees for increased absorption. It is pretty unlikely that CO2 could ever raise us another 10 degrees.

 

Most of Venus' incremental heat is because it is closer to the sun.

[freeztar]

The estimates that I saw for an incremental doubling of CO2 predicted a range of 2 to 4 degrees for increased absorption. It is pretty unlikely that CO2 could ever raise us another 10 degrees.

 

Ten degrees is extreme. Who is predicting this?

Most of Venus' incremental heat is because it is closer to the sun.

 

Care to back this up?

Venus is HOT! Not necessarily because it's close to the sun though.

Mercury is hot, but it is closer to the sun. Venus is hot because it is close to the sun and because of its atmosphere. Proximity to the sun is not the reason that Venus arises in such discussions. Type "Venus atmosphere" in google to see.

 

The enormously CO2-rich atmosphere, along with thick clouds of sulfur dioxide, generates the strongest greenhouse effect in the solar system, creating surface temperatures of over 460 °C.[21] This makes Venus's surface hotter than Mercury's which has a minimum surface temperature of -220 °C and maximum surface temperature of 420 °C, even though Venus is nearly twice Mercury's distance from the Sun and receives only 25% of Mercury's solar irradiance. Because of the lack of any moisture on Venus, there is almost no relative humidity (no more than 1%) on the surface, creating a heat index of 450 °C to 480 °C.

Venus - Wikipedia, the free encyclopedia

[modest]

Fig 5 shows the medieval warm period as warmer than today.

For central Greenland.

So you didnt make it past page 8?

I didn’t read the paper you linked. I started to, but gave up about half way through the abstract when it said something that I knew for a fact was untrue. I assumed the author was an idiot and decided not to read further.

 

I specifically went to your reference of figure 5. I found it on page 6, but it didn’t appear to be anything like what you were talking about which confused me until I found another figure 5 on page 8. There are, in fact, 2 figures labeled “Figure 5”. The fact that the author was unable to successfully count to six reinforced my presumptuous opinion that he was an idiot.

 

I noticed the figure said “in central Greenland” and the description of the figure had the name Alley. I then recognized the data came from the Greenland Ice Core Project (GRIP), and, in particular, its analysis done by Richard Alley. This was a surprise to me because your description “Fig 5 shows the medieval warm period as warmer than today.” led me to believe that the figure showed average global surface temperatures greater than today. This is not what the figure shows.

 

I posted the words “For central Greenland” in my reply to your post thinking it would prevent others from making the same incorrect conclusion I made.

 

I'm not very familiar with climate models. Can you point out a link to one that shows a temperature (any temperature) predicted for 2007 or 2008?

Your not familiar with climate models??

That’s almost what I said.

I said I know of no climate model that predicted 2007/2008. You surely have that source as a proponent of AGW correct?

No. I don’t. The very few papers reporting climate models / simulations that I’ve looked at give probable projections over decades given different possible scenarios and uncertainties in the models themselves. Even the Hadley Centre which runs continuous simulations for weakly regional weather and seasonal projections doesn’t seem to give individual yearly predictions in the way you say. I thought you might know something I didn’t. Apparently not.

 

Well that might be the answer to some question. But its not an answer to mine.

 

How long (in seconds, minutes, hours) after the sun goes down does it take for a co2 molecule to begin shedding its warmth?

 

I didn’t want to be rude. Your question shows a gigantic misunderstanding of what the greenhouse effect is. Freeztar was nice enough to address the problem while I’ve been away from the computer. To answer your question directly:

CO2 molecules start shedding their energy immediately (as in, instantly). It might bump into an O2 molecule (or some other atom or molecule) and pass some kinetic energy off to it. Or it might radiate a photon either back to the ground, or off to another CO2 molecule, or off into space. It could do all that immediately or it might hold on to the energy for a while.

 

The point of the greenhouse effect is that there is any interaction. When the surface radiates infrared heat upward it can be (and it would be) radiated out into space and lost to the earth. Temperature declines only when energy is lost to the system (assuming the system maintains volume and mass, which is a good assumption for the earth). So, if the earth shoots off an IR photon upward and it *immediately* gets reflected right back to the ground then the greenhouse effect worked. It effectively rose the surface temperature.

 

Here's a good google book source explaining gas molecules that are opaque to IR light and the mechanism:

 

Environmental chemistry - Google Book Search

 

[on Venus]Here we go with the NON-comparison.

 

CO2 doesnt make up a significant portion of our atmosphere. Even with the increases noted its STILL not a significant portion of our atmosphere.

 

I am always disappointed when someone tosses around venus as an example to be compared with earth, when the moon is oh so much closer. :doh:

 

Computer models can only do only so much. If you want to know what surface conditions on earth would be like were our atmosphere composed primarily of carbon dioxide then our sister planet out there is a great place to look. Your post commented on the small amount of carbon dioxide and small changes to temperature.

 

This is compared to a large amount of carbon dioxide and large temperatures on Venus. Had Venus no CO2 with its current albedo then it would be colder than earth. We've measured its emission temperature and it is indeed less than earth's. So, the comparison is appropriate if only to show the temperatures possible on earth.

 

I should tell you I am neither a proponent or opponent of AGW. I have little interest in debating the issue, and even if I did—I don't consider myself knowledgeable enough to advocate a political position on the issue. My interest is mostly in understanding the science involved. Your response above seems like you want to debate the topic.

 

Shall I point out posts where I've supported "anti-AGW" papers so we can have an accord? Probably wouldn't help...

 

~modest

[modest]

There is a limit to the amount of heat that can be trapped by CO2, since it only absorbs a narrow portion of the spectrum.

 

I see your line of thought. It assumes the amount of IR radiated from the surface over any given frequency range is constant. It is not. As earth warms, so then does the amount of IR emitted in the frequency range of CO2's absorption. More heat is then retained.

 

A limit to spectrum does not in any way equal a limit to temperature or "heat that can be trapped". Your further statements are based on this mistaken assumption.

 

~modest

[freeztar]

That is why a 50% increase in CO2 over the last 100 years is associated with only a 0.5 to 1 degree rise.

 

50%?

0.5-1.0?

 

Source? Rise?

Realistically, even if you think CO2 is casual, it would probably not be the ONLY reason for the rise.

 

Indeed. CO2 is not the ONLY reason for temp increase. No one serious is claiming otherwise.

 

Further, the main greenhouse gas, water vapor (90% of GG is water vapor, 4% is CO2) absorbs in an overlapping spectrum. Once that spectrum is absorbed, there is not more retention.

 

Overlapping does not mean equal! Furthermore, H2O is much more complicated for reasons that we don't need to go into in this thread.

[modest]

THESE MODELS IGNORE OVERALL CHANGES IN SUNLIGHT

 

Please don't shout.

 

Solar irradiance is a forcing.

 

Pubs.GISS: Abstract of Hansen et al. 2002

 

~modest

[freeztar]

Please don't shout.

 

Solar irradiance is a forcing.

 

Pubs.GISS: Abstract of Hansen et al. 2002

 

~modest

 

:doh:

 

Solar forcing is included in the models!

[Biochemist]

I see your line of thought. It assumes the amount of IR radiated from the surface over any given frequency range is constant. It is not.

Help me with this, Mod. I was not assuming anything about IR from the surface. I was assuming only that the quantity of energy initially sequestered by the troposphere from sunlight is limited (in any bandwidth range) to the quantity of energy in that bandwidth range.

 

Ergo, once you have sequestered the majority of the energy in the CO2 absorption spectrum, incremental CO2 causes little or no incremental retention.

 

Per:Cold Facts on Global Warming

 

The arithmetic of absorption of infrared radiation also works to decrease the linearity. Absorption of light follows a logarithmic curve (Figure 1) as the amount of absorbing substance increases. It is generally accepted that the concentration of carbon dioxide in the atmosphere is already high enough to absorb almost all the infrared radiation in the main carbon dioxide absorption bands over a distance of only a few km. Thus, even if the atmosphere were heavily laden with carbon dioxide, it would still only cause an incremental increase in the amount of infrared absorption over current levels. This means that a situation like Venus could not happen here. The atmosphere of Venus is 90 times thicker than Earth's and is 96% carbon dioxide, making the atmospheric carbon dioxide concentration on Venus 300,000 times higher than on Earth. Even so, the high temperatures on Venus are only partially caused by carbon dioxide; a major contributor is the thick bank of clouds containing sulfuric acid [7]. Although these clouds give Venus a high reflectivity in the visible region, the Galileo probe showed that the clouds appear black at infrared wavelengths of 2.3 microns due to strong infrared absorption [8]. Thus, Venus's high temperature might be entirely explainable by direct absorption of incident light, rather than by any greenhouse effect. The infrared absorption lines by carbon dioxide are also broadened by the high pressure on Venus [9], making any comparison with Earth invalid.

 

Correct my understanding, Mod.

[Biochemist]

Ten degrees is extreme. Who is predicting this?

Agreed. I was responding to Mod's post in #1185 about earth being like Venus if CO2 rose.

[modest]

Help me with this, Mod. I was not assuming anything about IR form the surface. I was assuming only that the quantity of energy initially sequestered by the troposphere from sunlight is limited (in any bandwidth range) to the quantity of energy in that bandwidth range.

 

Ergo, once you have sequestered the majority of the energy in the CO2 absorption spectrum, incremental CO2 causes little or no incremental retention.

 

Per:Cold Facts on Global Warming

 

 

 

Correct my understanding, Mod.

 

There are two very real problems I see with this thinking.

 

The first is the frequency range itself. The range falls off parabolic-like. Increasing the amount then *does* increase the range. A photon of about 13 or 14 micrometers might currently have a very good chance of escaping the atmosphere. Increasing the amount of CO2 would decrease that probability.

 

The other thing, which I commented on already is the intensity (or brightness) of the radiation itself. As the temperature of the surface increases then the amount of radiation at any given wavelength also increases. This is wine's displacement law. Looking at measured intensity vs. wavelength diagrams:

 

-source

 

-source

 

Increasing the amount of CO2 would both broaden the CO2 depressions and raise the entire intensity line. So, of course, further heating can happen due to CO2 increase. What your link points out about Venus (thatCO2 doesn't act alone) is true, and it's also true that CO2 does not act alone in warming our planet above its emission temperature.

 

But, this is well-known. CO2 is one factor in many. This doesn't discount the effects of CO2 as a greenhouse gas—it just makes modeling our climate that much more difficult.

 

~modest