Feedback Assumptions Finally Being Challenged

When asked what one thing I would want to tell laymen about catastrophic man-made global warming theory, it is the following:  That this theory is in fact a two-part theory.  Greenhouse gas theory alone only gives us incremental warming and no catastrophe.  It is a second theory that Earth’s climate is dominated by strong positive feedbacks that multiplies warming of perhaps a degree over the next century from CO2 to 3,5, or more degrees of warming.  And while it is fairly well accepted by all that CO2 will cause a bit of warming alone, this second theory is not at all settled and in fact may even the the sign of the feedback wrong.

Two stories came out this week undercutting to of the largest sources of feedback.

1.  Water Vapor Feedback

Water vapor is a highly variable gas and has long been recognized as an important player in the cocktail of greenhouse gases—carbon dioxide, methane, halocarbons, nitrous oxide, and others—that affect climate.

“Current climate models do a remarkable job on water vapor near the surface. But this is different — it’s a thin wedge of the upper atmosphere that packs a wallop from one decade to the next in a way we didn’t expect,” says Susan Solomon, NOAA senior scientist and first author of the study.

Since 2000, water vapor in the stratosphere decreased by about 10 percent. The reason for the recent decline in water vapor is unknown. The new study used calculations and models to show that the cooling from this change caused surface temperatures to increase about 25 percent more slowly than they would have otherwise, due only to the increases in carbon dioxide and other greenhouse gases.

An increase in stratospheric water vapor in the 1990s likely had the opposite effect of increasing the rate of warming observed during that time by about 30 percent, the authors found.

2.  CO2  (outgassing from oceans) Feedback

The most alarming forecasts of natural systems amplifying the human-induced greenhouse effect may be too high, according to a new report.

The study in Nature confirms that as the planet warms, oceans and forests will absorb proportionally less CO2.

It says this will increase the effects of man-made warming – but much less than recent research has suggested….

The most likely value among their estimates suggests that for every degree Celsius of warming, natural ecosystems tend to release an extra 7.7 parts per million of CO2 to the atmosphere (the full range of their estimate was between 1.7 and 21.4 parts per million).

This stands in sharp contrast to the recent estimates of positive feedback models, which suggest a release of 40 parts per million per degree; the team say with 95% certainty that value is an overestimate.

OK readers, let’s see how close you have been paying attention.  The models have over-estimated this important feedback by a factor of 5 (40 to 7.7). As I have shown time and time again, the vast majority of the warming in climate forecasts is from feedback — about 1C per century is directly from CO2, the rest is from feedback multipliers.  Have a forecast that says 5C warming in the next century, then about 4C of that is probably due to feedback.

But remember this post, where I said

…there is a very strong social cost in academia to challenging global warming, so that even when findings in certain studies seem to undercut key pieces of the argument, the researches always add something like “but of course this does not refute the basic theory of global warming” at the end of the paper.

So what do this study’s author’s say?

The authors warn, though, that their research will not reduce projections of future temperature rises.

Further, they say their concern about man-made climate change remains high.

Of course, because if this factor goes down, they will just shore up their forecasts and keep them them high with some other plug variable.  Because no one is funding scientists (or quoting them in newspapers) whose models call for just 1C of warming over the next century.

14 thoughts on “Feedback Assumptions Finally Being Challenged”

  1. “And while it is fairly well accepted by all that CO2 will cause a bit of warming alone..”: a better phrasing might be “And while it is fairly well accepted by all that, OTHER THINGS BEING EQUAL, CO2 will cause a bit of warming alone…”.

  2. Perhaps my fault for not reviewing your source links, but something seems amiss here.
    How can forests absorb less or give off more CO2? (#2, lines 2 and 4) If by warming, we extend the growing season, would not forests (and oceanic fauna as well) absorb more CO2? As I recall, forests don’t make CO2, they convert CO2 plus H2O to sugar and oxygen. So, how can forests contribute more CO2 as a by-product of atmospheric warming except perhaps through decay or the occasional fire? My other point of confusion comes from “as the planet warms, oceans…” Is there not an inference that planet and oceans respond the same? Does it seem like conflicting science is declaring the same outcome?

  3. Again, I think that you’re a bit two-faced here. You correctly point out that there is a great deal of science to be done on climate feedbacks. You, however, do a fairly poor job in recognizing that this is still true despite the fact that these two papers support your position. Nothing is more proven now than before these two papers were published. I think this work is important and it makes it easier for researchers to further question the validity of assuming that these feedbacks will creating more warming rather than other outcomes. But it doesn’t mean that their conclusions are ‘right’. You need to be a little more careful in the argument you’re making.

  4. …also, do you have a source for the assertion that CO2 only forced warming will be small? I have seen similar assertions made, but I can’t seem to find a calculation that proves it. Thanks.

  5. re: Restiches.

    Plants use photosynthesis to store energy, as sugars and starches, a process which absorbs carbon dioxide.

    Plants respire to use the stored energy, a process which emits carbon dioxide.

    The stored energy is used for tissue and cell growth.

  6. The number they came up with for CO2 release against temperature has been obvious for a long time.

    Vostock Ice cores show a temperature range of -8C to +2C between ice-age and warm period (roughly).

    CO2 range is 180ppmv to 280ppmv. So 100 ppmv difference for 10C means a multiplier of 10ppmv per degree C.

    Can I have my Nobel Prize now please?

  7. Can someone please explain to me how the authors get around the whole problem of correlation doesn’t mean causation? There might have been forces driving CO2 and warming together, thus CO2 may not drive temperature, and any multiplier is not causal but just a correlation factor. For example, the front wheels of my car always lead the back wheels while in drive, but the front wheels are not actually providing the energy to move the back wheels forward. Its actually the engine in my car driving both sets of wheels, there is just a positional lag (distance between) the front and the back wheels.

  8. In response to Wally:

    Some data I picked up surfing the internet:

    For a number of reasons, the volume of glacial ice near the poles
    waxes and wanes over time. As a result, water is alternately taken from or added to the world oceans. This can result in sea-level oscillations of up to 200 meters. For example, modern continental glaciers are 1.5 to 2.5 km thick and have a total estimated volume of 33 million km3. If we assume the maximum volume of Pleistocene glaciers to have been 71.3 million km3, Flint, 1971 then the difference is 38 million km3. Using the assumption that glacial water volume is 91.7% of the volume of sea water from which it is derived, a sea-level drop of 106 m can be accounted for by Pleistocene glaciation. Melting of the present Greenland and Antarctic glaciers would produce a sea-level rise of approximately 60 meters.

    The specific latent heat of fusion of ice at 0 ºC, for example, is 334 This means that to convert 1 kg of ice at 0 ºC to 1 kg of water at 0 ºC, 334 kJ of heat must be absorbed by the ice. Conversely, when 1 kg of water at 0 ºC freezes to give 1 kg of ice at 0 ºC, 334 kJ of heat will be released to the surroundings.

    “The total mean mass of the atmosphere is 5.1480×1018 kg with an
    annual range due to water vapor of 1.2 or 1.5×1015 kg depending on
    whether surface pressure or water vapor data are used; somewhat
    smaller than the previous estimate. The mean mass of water vapor is
    estimated as 1.27×1016 kg and the dry air mass as 5.1352

    A 4C rise or higher this century would see the world warm almost as
    much in 100 years as it did during the 15,000 years since the end of
    the last ice age.”

    Putting it all together, 71.3 million k3 ice *0.917 vol ice/vol
    water= 65.3821 million cubic kilometers of water.

    1 cubic meter= 1000 kg.
    1 cubic km = 10^12 kg
    65.3821 million cubic km= 65.3821*10^18 kg

    Total heat to melt glaciers =65.3821 *10^18 *1000*334 kj=2.18*10^25

    Cp air= 1.012 joules/gram K
    1012 Joules/kg K * 5.148^10^18 =5.209776 *10^21 joules

    4degree increase=2.0839 *10^22 joules

    So about 1000 times as much heat went into melting the glaciers at
    the end of the Pleistocene as went into heating the atmosphere. Figure that the ice had to start melting before temperatures went up, and that there would be positive feedbacks due to changes in Earth’s albedo after the continental glaciers melted, CO2 must have had only a negligible feedback effect. Tilde Guillemet and Hans Erren have demonstrated that the AGWers who originally hypothesized a 1C increase for a 10 ppm increase were incompetent pseudoscientists- A. McIntire

    – A. McIntire

  9. Restiches,

    “How can forests absorb less or give off more CO2? ”

    At some point trees become heat stressed and die off, of course their rotting corpses give off ‘green house’ gas.
    There have been differing studies on this. There was a study just today that East Coast trees are loving the new environment, there has also been a study that west coast trees hate it.

    Orginal Topic
    “Of course, because if this factor goes down, they will just shore up their forecasts and keep them them high with some other plug variable.”

    I think there is a scramble to identify ‘why it’s not warming as much’ at the moment. Better to toss out of few papers ‘correcting’ the trend then let the trend completely falsify the ‘previous’ research.

  10. Maxwell – If nothing changes other than temperature, the response is straightforward. Emissions in general are proportional to the fourth power of temperature, and on Earth, with surface temperatures of about 288K and emissions to space of about 240 W/m2, we get about 0.3C for each W/m2 forcing. You can nail that down more carefully, but it does correspond closely to what you get with a radiation transfer calculation. It’s called the “Planck response” in climate science. Converting forcing units, this corresponds to about 1.1C per doubling of CO2.
    Recent periods of greater warming than present, the Medieval Warm Period (800 to 1300 AD) being the most recent, did not trigger out-of-control warming. On the contrary, the Medieval Warm Period was followed by the Little Ice Age (1300 to 1850 AD), following the pattern of alternating warming and cooling observed several times since the end of the Ice Age just over 10,000 years ago. In none of these temperature fluctuations was CO2 a factor, and if anything, the feedbacks to rising temperature apparently were net effect negative, not positive. The proof? No runaway warming.
    In terms of catastrophes, the warm periods exhibited the greatest advances in human civilization, and the cold (best documented: the Little Ice Age and, to a lesser extent, the Dark Ages) were characterized by crop failures, famine, violent storms, disease and pestilence, glaciation, and other adverse effects of cooling to vex mankind.
    The greater warming experienced during the Medieval Warm Period requires no examination of tree rings or ice cores, only the observation of natural phenomena: Vineyards flourished in England where they can’t today. Greenland Viking farms are still in permafrost today. Tree lines were 1,000 feet higher. Glaciers were less extensive. The Little Ice Age reversed all that.
    Hundreds of climate studies by thousands of researchers in over 40 countries and on all continents have also established the Medieval Warm Period as global and as warmer than the present. They just confirm what Mother Nature so abundantly and clearly demonstates – climate change is natural, and the peer review is all around us.

  11. Putting the CO2 effect by itself into context:

    Doubling CO2 has about the same effect (in average temperature) as moving from Boston, MA to New York City, NY. And that is using the high end of the estimate for CO2 doubling (1.5 C).

    CO2 doubling has about half the effect of moving from Boston to Washington, DC.

    The rest of the bogeyman is feedback and its net sign.

  12. Maj. Combs, where does the forcing due to one CO2 molecule come from? I get the use of Steffan-Boltzmann equation, but how does one calculate the forcing due to CO2 molecule by molecule? I’m not asking to be nit-picky, I’m just curious. From a molecular perspective, it seems like something that is hard to quantify because it depends on the density of other molecules, inter-molecular collision rates and even chemistry if it’s happening. Thanks.

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