As oceans warm, they release more CO2 into the atmosphere. This has always been true.
Natural warming is initiated by some forcing other than CO2. Most major climate change is initiated by astronomical events such as the Milankovitch Cycles. Ice ages are triggered when solar insolation is minimal during summer along the 65th parallel north; insolation has to be so low that it does not melt the ice cover during summer and ice plates begin to grow.
In natural warming, CO2 is a feedback. Once an initial forcing causes a little warming, the oceans start to warm and throw-off more CO2. The ice records show that the lag between initial warming and CO2 increase is about 800 years. As the amount of CO2 increases in the atmosphere, the atmosphere retains more heat and warming is accelerated. That is, CO2 is a feedback: it is caused by a forcing and amplifies changes in the same direction as as the forcing.
The American Institute of Physics has an interesting history of the discovery of how climatolgists came to understand this feedback loop. They were baffled about how ice ages came and went. Milankovitch Clycles corellated well with the timing of ice ages but scientists could not understand how such small astrominical changes made such big differences in earth's climate until the realised the strength of the CO2 feedback look.
http://www.aip.org/history/climate/co2.h...
Right now, there is no known forcing other than CO2 to be causing the warming of the past century. CO2 is causing warming as it always does, CO2 is increasing in the atmosphere, and the CO2 increase is known to be from human sources (in part because the oceans are now gaining carbon as they warm which never happens during natural warming, and in part because the isotopes of the carbon in the atmosphere more increasingly those from plants and animals, i.e. fossil and wood fuels).
Right now, CO is the cause of the warming, the forcing. During natural warming it is a feedback, caused by a forcing and amplifying the change.
If CO2 did have have this greenhouse effect, the earth would be too cold for life. If the oceans did change change the amount of carbon they absorb or thow-off with different temperature the earth would not have gone through the major climate changes it has.
With CO2 as an initial forcing, the warming is much faster than natural warming which depends on CO2 as a feedback.
CO? reduces the rate at which Earth transmits energy to space, by absorbing some of the infrared that would otherwise be transmitted through the atmosphere. This effect may be termed 'radiative forcing'. The most reasonable surmised implication of increased atmospheric CO? concentration is global warming. However, this is not the only implication.
'Feedack' refers to radiative forcings ensuing from global warming itself; or more precisely, from changes in surface temperature. These include reduced surface albedo resulting from ice melt, likely methane release from former permafrost areas such as Siberia (methane is a very powerful greenhouse gas) and increased atmospheric H?O vapour concentration (H?O vapour is, like CO?, a powerful greenhouse gas).
Contrary to some misconceptions, feedbacks do not only occur in closed systems. A feedback will operate whether the system is a 'closed loop' or otherwise. Just for the record, a 'premise' is something on which an argument is based, as opposed to, say, a passing observation. Another misconception (how widespread it is among climate change deniers is hard to say, but it is certainly a powerful aid to reality-denial generally) is that one counterexample (should it be produced) is sufficient to to refute a hypothesis which is not general.
Interesting question.
Possibly dangerous, though, because you might not get a good answer. What then? Will you modify your belief?
Things to ponder:
? Is the level of manmade CO2 emissions noticably larger than the uncertainty with which we know the perentage of H2O in the atmosphere? If not then any manmade effecrs will be insignificant.
? If CO2 levels follow temperatures at all timescales, in practical terms, why would any alleged CO2 feedback matter? Temperature is always in control.
? Can we expect a scientific answer, i.e. with numbers and formulas, rather than the usual hand waving?
EDIT: Sorry, Jeff M if I wasn't clear. My introduction to feedbacks and forcings goes back to the mid-seventies when we learnt about stability, Nyquist, Bode, Whitely, s-plane and z-plane plots. The use of Laplace transforms was standard and all forcings and feedbacks were derived against frequency. So I always hope for something better than: this is bigger than we thought so we call it positive feedback.
"Now, you might be surprised to learn that the amount of warming directly caused by the extra CO2 is, by itself, relatively weak. It has been calculated theoretically that, if there are no other changes in the climate system, a doubling of the atmospheric CO2 concentration would cause less than 1 deg C of surface warming (about 1 deg. F). This is NOT a controversial statement…it is well understood by climate scientists. (As of 2008, we were about 40% to 45% of the way toward a doubling of atmospheric CO2.)
BUT…everything this else in the climate system probably WON’T stay the same! For instance, clouds, water vapor, and precipitation systems can all be expected to respond to the warming tendency in some way, which could either amplify or reduce the manmade warming. These other changes are called “feedbacks,” and the sum of all the feedbacks in the climate system determines what is called ‘climate sensitivity’. Negative feedbacks (low climate sensitivity) would mean that manmade global warming might not even be measurable, lost in the noise of natural climate variability. But if feedbacks are sufficiently positive (high climate sensitivity), then manmade global warming could be catastrophic."
A confusion between forcing and feedback (loosely speaking, cause and effect) when observing cloud behavior has led to the illusion of a sensitive climate system, when in fact our best satellite observations (when carefully and properly interpreted) suggest an IN-sensitive climate system. If the climate system is insensitive, this means that the extra carbon dioxide we pump into the atmosphere is not enough to cause the observed warming over the last 100 years ― some natural mechanism must be involved.
Courtesy of Dr. Roy Spencer - Premier Climate Scientist
Baccheus - There is no amplification. There has been many 0.5C changes from one year to the next and they happen in both directions (warming and cooling). The forced warming of CO2 has always been negated with naturally variable forcings which keep things 'in balance'. If there was an amplification of warming over time due to CO2 emissions, then we would have burned up by now.
The Earth's climate will always maintain its own energy budget. It is hundreds of billions times the size of all humans put together and the Sun is another 1,300,000 times the size of Earth. You can take off those blinders any time now. :-)
Ya sure, CO2 releases CH4 which releases CO2 which releases CH4. A lot of Alarmist don't or can't visualize the numerous possibilities that exists in natural world. If we took their version literally...which I hope none are. The world would be mass hysteria, without rectification. In other words all CO2 would have a detrimental consequence. Nobody believes that so what's your point?
"A lot of denialists seem confused about how feedbacks work.
Your premise is just wrong. We are not confused. Take the case of a simple electric closed loop controlled motor, for instance. You set the speed at 1000 RPM. That happens first. Then the motor turns causing the tack feedback generator to turn. Then based upon the signal of the tack feedback generator the controller will adjust the speed signal to 1000 rpm.
A feedback system only works in a closed loop system. In the environment, man has not discovered the mathematical formula for this feedback as evidenced by the failure of the climate models. With all the scientific knowledge that we have, at this time, it is an open loop system with the Sun being the only speed signal.
You and your group admit that you don't understand the feedback signal theory. You say that CO2 is a feedback. Yet you claim a run away temperature when CO2 reaches some mythical saturation point. That is like that same tack feedback generator sending a signal back to the controller that it is going 2000 RPM and the controller increasing the speed.
Warning causes outgassing of CO2 from the oceans, and that CO2 causes further warming, except that warming, is incredibly small because CO2 is saturated, and the only warming is from the shoulders of it's radiation bandwidth, an amount so small as to be insignificant.
A more accurate statement than CO2 is both a feedback and a forcing would be to say that it could be either a feedback or a forcing. However, for any gas to be either, it would have to either reflect or absorb infrared energy. Carbon dioxide absorbs infrared at wavelengths which are emitted by Earth.
Now, getting back to how it could be either a feedback or a forcing; it depends on how the carbon dioxide is added to the atmosphere.
Up to the industrial age, humans added little carbon dioxide to the atmosphere. The main reason why carbon dioxide concentration in the atmosphere changed in that time was temperature. When Earth warmed, carbon dioxide dissolved in the ocean became less soluble in the water and some of it entered the atmosphere. When Earth cooled, the opposite happened. But, since carbon dioxide is a greenhouse gas, carbon dioxide and temperature had a two way interaction called feedback. Since higher temperature led to more carbon dioxide and carbon dioxide leads to higher temperatures, the feedback was a positive feedback. The warming is not runaway warming, because the additional warming caused by the carbon dioxide is less than the warming which introduced carbon dioxide into the atmosphere.
Now, humans are burning billions of tons of hydrocarbons each year. This is adding carbon dioxide to the atmosphere, not because of a rising temperature, but because of us. Because it is not being added because of temperature, it is now a forcing.
When scientists acting as activists or their supporters decide to declare global warming is a problem because of X, and we need to implement certain policies, that is a forcing. When their followers repeat the stories at blogs, that is feedback.
Increases in atmospheric water vapour are due to warming and increased evaporation. This creates what is known as a negative forcing at the surface. The energy is contained within that vapour as it rises and cools as it is taken away from the surface of the planet. As the surface warms more cooling of the surface will occur due to increased evaporation. When water vapour enters the atmosphere it is a greenhouse gas which is excited by specific wavelengths of radiation causing the molecule to gain momentum and energy. When the vapour cools enough, as it rises through the atmosphere, condensation will occur and that heat energy will be expelled, the droplets will form clouds and rain out. If a volcanic eruption occurs (The forcing) spewing far more water vapour into the atmosphere this effect will increase. Therefor, water vapour can be a both a negative and positive feedback as well as a forcing all in one go.
And Maxx is forgetting to include a timescale by which natural processes react to forcings with his water vapour/CO2 comparison.
And if graphiconception wants equations and mathematics he should actually try and learn them himself before asking others.
https://www.coursera.org/course/globalwa...
And to those denialists complaining that they understand how feedbacks work... perhaps you should re-look at a recent question here where someone asked if a feedback was positive or negative. At least two of you gave the wrong answer where you stated it was a negative feedback when the feedback was clearly positive, that being that it heightened the effects of the original perturbation. Sagebrush, you are one of them. And graphic conception, you seem to have much the same misunderstanding.
Graphicconception wrote "This is bigger than we thought so we call it a positive feedback"
Once again, you seem to have a misunderstanding of what a positive and negative feedback are. A positive feedback is one that heightens the effect of an original perturbation. A negative feedback is one that brings it back to a state of equilibrium and acts against the original forcing. There are no mathematics involved.
A lot of denialists seem confused about how feedbacks work. In particular, they seem to think that because CO2 increases followed solar-based temperature increases in the past, CO2 can't be causing warming now.
So, I was hoping for either an explanation at a for-dummies level on how CO2 is both a feedback and a forcing, or an analogy to something routinely encountered and generally understood that acts more or less the same way (or, of course, both, if you have 'em).
Very simple. CO2 causes plants to grow faster. This means tree rings are bigger. I then conclude from that that temperatures are obviously warming and that the MWP was a local event confined to 300 miles of Greenland coast and was actually .002377149 degrees cooler than it is now.
CO2 is no more a feedback and a forcing than water vapor is Chem. CO2 does not have any magical properties that allow it to have greater influence than other gases in the atmosphere that absorb solar radiation. And all the gases in the atmosphere absorb solar radiation.
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Climate Realist - Even if there was ZERO CO2 in the atmosphere, warming will still cause more evaporation and thus more water vapor in the air. And water vapor absorbs more solar radiation on a molecule to molecule basis than CO2.
So if water vapor by itself doesn't cause run away warming, and it doesn't, then a little additional CO2 isn't going to do it either.
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graphicconception says: "If CO2 levels follow temperatures at all timescales, in practical terms, why would any alleged CO2 feedback matter? Temperature is always in control."
EXACTLY!!!!!!!
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