Sentences with phrase «co2 feedback effect»

Undoubtedly there was a CO2 feedback effect.

Only when we have an INDEPENDENT method of calculating the the marginal CO2 effect on global T can we assign a value to the glacial - interglacial CO2 feedback effect.

Not exact matches

First that CO2 is the main climate driver, second that in calculating climate sensitivity the GHE due to water vapour should be added to that of CO2 as a feed back effect and third that the GHE of water vapour is always positive.As to the last point the feedbacks can not be positive otherwise we wouldn't be here to talk about it.

When I, with some colleagues at NASA, attempted to determine how clouds behave under varying temperatures, we discovered what we called an «Iris Effect,» wherein upper - level cirrus clouds contracted with increased temperature, providing a very strong negative climate feedback sufficient to greatly reduce the response to increasing CO2.

This means the global effect of Arctic melting, which in itself constitutes a feedback from CO2 - driven global warming, is close to the warming effect of the rise in atmospheric CO2 from 280 ppm to 407 ppm since the onset of the industrial age.»

I'm not even an amateur climate scientist, but my logic tells me that if clouds have a stronger negative feedback in the Arctic, and I know (from news) the Arctic is warming faster than other areas, then it seems «forcing GHGs» (CO2, etc) may have a strong sensitivity than suggested, but this is suppressed by the cloud effect.

Remember that direct greenhouse effect from CO2 is quite small; the predictions rely on positive feedback from other effects (particularly water vapour feedbacks, a far more significant greenhouse gas) to cause substantial warming.

The direct warming effect of CO2 is relatively small, and only becomes dominant through positive feedbacks in computer models.

The point is: it's widely recognized that CO2 levels in the atmosphere increase as a result of temperature increases, a positive feedback effect.

This effect is probably significant but it's slow - acting and the CO2 self - feedback would only be fully realized when very little of the original CO2 pulse was left in the atmosphere.

But if our interest is in the effect of * anthropogenic * CO2 only, which is a real forcing, then the feedback CO2 could be tremendously additive.

«Also, if the atmosphere isn't accumulating heat at the rate forecast by the models, then the theoretical positive climate feedbacks which were expected to amplify the CO2 effect won't be as large,» McNider said.

This 2006 study found that the effect of amplifying feedbacks in the climate system — where global warming boosts atmospheric CO2 levels — «will promote warming by an extra 15 percent to 78 percent on a century - scale» compared to typical estimates by the U.N.'s Intergovernmental Panel on Climate Change.

Note also that going back to the ice ages, the glacial - interglacial temperature swing can not be explained without full water vapour feedback on top of both the ice sheet albedo and CO2 effects.

So while it may be true that «uptake of CO2 by natural sinks scales proportional with the CO2 concentration», this feedback effect is not large enough to offset emissions.

I think what Alastair is alluding to is the fact that, say by 2050 when the arctic ocean will conceivably be ice - free in the summer, the atmosphere will have a much higher relative humidity than it has currently because of the open air = water interface, so this will have a magnifying effect beyond just the feedback from increased CO2.

CO2 ppm effects a radiative forcing in W / m ^ 2 and temperature response to forcing in K is mediated by a host of feedbacks and heat capacities.

Additionally, we have Anderson's computations showing that ~ 10 % CO2 emissions reduction per annum is required for years to stay within a (dangerous) 2 C ceiling target, and these numbers don't include the adverse effects of major carbon cycle feedbacks.

It's possible that CO2 contributes about a.6 C increase in temperature and that the effects of clouds acts as a negative feedback to moderate further increases.

These generally show a postive feedback on CO2 levels in a warming climate, though the magnitude of the effect is rather uncertain.

# 27 CCPO It's possible that CO2 contributes about a.6 C increase in temperature and that the effects of clouds acts as a negative feedback to moderate further increases.

For instance, the effect of soot making snow and sea ice darker has a higher efficacy than an equivalent change in CO2 with the same forcing, mainly because there is a more important ice - albedo feedback in the soot case.

Now, if warming also causes increased CO2, then we may be talking about a positive feedback loop in which the warming spirals upwards, which amplifies the warming effect of whatever CO2 we humans contribute to the atmosphere.

The effects of CO2 are a feedback.

As you point out, many of the negative feedback effects that have been proposed would tend to decrease not only the effect of increased CO2, but also of whatever natural variability there may be.

Warming must occur below the tropopause to increase the net LW flux out of the tropopause to balance the tropopause - level forcing; there is some feedback at that point as the stratosphere is «forced» by the fraction of that increase which it absorbs, and a fraction of that is transfered back to the tropopause level — for an optically thick stratosphere that could be significant, but I think it may be minor for the Earth as it is (while CO2 optical thickness of the stratosphere alone is large near the center of the band, most of the wavelengths in which the stratosphere is not transparent have a more moderate optical thickness on the order of 1 (mainly from stratospheric water vapor; stratospheric ozone makes a contribution over a narrow wavelength band, reaching somewhat larger optical thickness than stratospheric water vapor)(in the limit of an optically thin stratosphere at most wavelengths where the stratosphere is not transparent, changes in the net flux out of the stratosphere caused by stratospheric warming or cooling will tend to be evenly split between upward at TOA and downward at the tropopause; with greater optically thickness over a larger fraction of optically - significant wavelengths, the distribution of warming or cooling within the stratosphere will affect how such a change is distributed, and it would even be possible for stratospheric adjustment to have opposite effects on the downward flux at the tropopause and the upward flux at TOA).

VICTOR @ 23 — CO2 increases lead to temperature increases only after a lag, probably 20 - 30 years, due to feedback effects, mainly from the ocean.

The regression simply looks at the outcome of adding more CO2, net of feedbacks and not including the direct effect of other forcings.

First, for changing just CO2 forcing (or CH4, etc, or for a non-GHE forcing, such as a change in incident solar radiation, volcanic aerosols, etc.), there will be other GHE radiative «forcings» (feedbacks, though in the context of measuring their radiative effect, they can be described as having radiative forcings of x W / m2 per change in surface T), such as water vapor feedback, LW cloud feedback, and also, because GHE depends on the vertical temperature distribution, the lapse rate feedback (this generally refers to the tropospheric lapse rate, though changes in the position of the tropopause and changes in the stratospheric temperature could also be considered lapse - rate feedbacks for forcing at TOA; forcing at the tropopause with stratospheric adjustment takes some of that into account; sensitivity to forcing at the tropopause with stratospheric adjustment will generally be different from sensitivity to forcing without stratospheric adjustment and both will generally be different from forcing at TOA before stratospheric adjustment; forcing at TOA after stratospehric adjustment is identical to forcing at the tropopause after stratospheric adjustment).

So feedbacks like reduced ocean capacity, changes due to landuse etc. might effect our ability to predict future CO2 levels for a given anthropogenic input, but they are irrelevant to the sensitivity of T to actual CO2 concentration.

But the CO2 rising does enhance the effect of rising temperature — a positive feedback.

However, the greenhouse effect from water vapour is due to a (positive) feedback from the temperature and so any warming caused by CO2 is amplified by water vapour.

It might be that serious authorities such as Hansen and the head of the UNFCCC secretariat are wrong to declare that goal of a 2.0 C ceiling of warming poses unacceptably dangerous climate destabilization, but it seems widely accepted that a peak of 450ppmv CO2 would allow a near - even chance of staying below 2.0 C and thereby avoiding the feedbacks taking off with catastrophic effects.

In itself I do nt think the positive feedback can be disputed as it is just based on the effect of CO2 on solar radiation coming in and radiation from the earth going back out.

The feedback effect is mentioned only in a comment on the expected change in the atmospheric constitution assuming that the CO2 concentration is increased, but the numbers are given for the present atmosphere, not for the hypothetical modified one.

A negative feedback not on the effect of CO2 but working to decrease CO2 concentration and thus CO2 effect.

After all, the theory is that CO2 is a well mixed gas, and subject differences in humidity (water vapour feedback), the effect of CO2 should be similar wherever it is measured.

The theories for CO2 with feedbacks and aerosols are no doubt good ones to be put forth, but the practical considerations of the effects of these theories must be couched in the magnitudes of the effects and the uncertainties of those magnitudes.

Much of the warming feared by the alarmists relies upon a positive feedback involving increased water vapour exaggerating any CO2 warming effect.

Steve is an admitted lukewarmer (as Jan says a better description is required) and adamant anti-AGW catastrophist who believes the Miscolczian - like - ve feedback of blooms in their various configurations not only mitigate CO2 effect but have causal correlation with ENSO.

Is it the long - awaited, predicted and scientifically reasonable CO2 fertilization feedback effect on the oceans» vast biomass of CO2 - consuming cyanobacteria, albeit also driven by the (literally) «shit - loads» of nitrogen compounds the human race is also pumping into the oceans — thereby shifting sea surface albedos, reducing evaporation rates and troposphere relative humidities (ringing any bells here, bros)?

@David: You write: «If the beneficial aspect of CO2 increases in a lineal manner and the warming effect of CO2 decreases logarithmically, then does it not makes sense that at some point CO2 itself becomes a negative feedback?»

If, for instance, CO2 concentrations are doubled, then the absorption would increase by 4 W / m2, but once the water vapor and clouds react, the absorption increases by almost 20 W / m2 — demonstrating that (in the GISS climate model, at least) the «feedbacks» are amplifying the effects of the initial radiative forcing from CO2 alone.

I already incorporated the weak positive feedback effect that CO2 would have in this model: http://theoilconundrum.blogspot.ch/2012/03/co2-outgassing-model.html

The equation seems to be from Mann 1998, and is for the warming effect from CO2 without feedbacks.

Now many people have calculated the effect of doubling CO2 in the atmosphere and all agree that this would have the same effect as a 1.3 % increase in solar flux and without any feedbacks would lead to about a 1 degree K increase in global average temperature.

Re: The Single Most Important Point: yes, the ASSUMED positive feedback effect is DOUBLE the effect of CO2 alone, giving rise to a predicted warming 3 times that due to CO2 alone.

In most all of the climate models, the warming effect from feedback is actually much larger than the warming effect from CO2 alone.

The evidence supports a higher sensitivity to CO2 in the cryosphere, suggesting a negative feedback by H2O, that prevents CO2 from having the same effect elsewhere.

A substantial reduction in water vapor (shown below, from Lacis et al (2010) as well as increase in the surface albedo are important feedbacks here, showing that removing the non-condensing greenhouse gases (mostly CO2) in the atmosphere can collapse nearly the entire terrestrial greenhouse effect.