Sentences with phrase «feedbacks on climate sensitivity»

It would be wrong to think that climate scientists have been ignorant of the non-linear nature of feedbacks on climate sensitivity.

Energy from warm GHG in the higher layers of the troposphere can escape more easily into space; if the upper troposphere warms more quickly than the surface as greenouse gases increase, this reduces the overall warming for a given increase in GHG, a negative feedback on climate sensitivity.

Not exact matches

Earlier studies on the sensitivity of tropical cyclones to past climates have only analyzed the effect of changes in the solar radiation from orbital forcing on the formation of tropical cyclones, without considering the feedbacks associated to the consequent greening of the Sahara.

The conclusion that limiting CO2 below 450 ppm will prevent warming beyond two degrees C is based on a conservative definition of climate sensitivity that considers only the so - called fast feedbacks in the climate system, such as changes in clouds, water vapor and melting sea ice.

From the paper...» These results provide enhanced confidence in the range of climate sensitivity in climate simulations, which are based on a positive uppertropospheric water vapor feedback.

Sure, there might be a few papers that take climate sensitivity as a given and somehow try to draw conclusions about the impact on the climate from that... But, I hardly think that these are swamping the number of papers trying to determine what the climate sensitivity is, studying if the water vapor feedback is working as expected, etc., etc..

That's the same value for climate sensitivity I've seen from the string theory physics site and from knowledgeable climate sites as well — it's the number people get this way: calculated in the absence of any feedback, on the hypothetical twinning of each molecule of CO2 in the atmosphere to make two where there were one, instantly, and having nothing else happen.

A 2008 study led by James Hansen found that climate sensitivity to «fast feedback processes» is 3 °C, but when accounting for longer - term feedbacks (such as ice sheet disintegration, vegetation migration, and greenhouse gas release from soils, tundra or ocean), if atmospheric CO2 remains at the doubled level, the sensitivity increases to 6 °C based on paleoclimatic (historical climate) data.

All this discussion of the Schmittner et al paper should not distract from the point that Hansen and others (including RichardC in # 40 and William P in # 24) try to make: that there seems to be a significant risk that climate sensitivity could be on the higher end of the various ranges, especially if we include the slower feedbacks and take into account that these could kick in faster than generally assumed.

So the reference system climate sensitivity parameter is based on a negative feedback due to Stefan's law.

Webb, M.J., et al., 2006: On the contribution of local feedback mechanisms to the range of climate sensitivity in two GCM ensembles.

At its present temperature Earth is on a flat portion of its fast - feedback climate sensitivity curve.

The goal of the paper under review, as I take it, is an attempt to put an upper bound on the Charney climate sensitivity feedback by considering the LCM paleoclimate.

New paper mixing «climate feedback parameter» with climate sensitivity... «climate feedback parameter was estimated to 5.5 ± 0.6 W m − 2 K − 1» «Another issue to be considered in future work should be that the large value of the climate feedback parameter according to this work disagrees with much of the literature on climate sensitivity (Knutti and Hegerl, 2008; Randall et al., 2007; Huber et al., 2011).

The regional climate feedbacks formulation reveals fundamental biases in a widely - used method for diagnosing climate sensitivity, feedbacks and radiative forcing — the regression of the global top - of - atmosphere radiation flux on global surface temperature.

They find a climate feedback parameter of 2.3 ± 1.4 W m — 2 °C — 1, which corresponds to a 5 to 95 % ECS range of 1.0 °C to 4.1 °C if using a prior distribution that puts more emphasis on lower sensitivities as discussed above, and a wider range if the prior distribution is reformulated so that it is uniform in sensitivity (Table 9.3).

Although the strength of this feedback varies somewhat among models, its overall impact on the spread of model climate sensitivities is reduced by lapse rate feedback, which tends to be anti-correlated.

Then on page 9.5 we read «There is very high confidence that the primary factor contributing to the spread in equilibrium climate sensitivity continues to be the cloud feedback.

We'll also dig into some of his peer reviewed work, notably the recent paper by Spencer and Braswell on climate sensitivity, and his paper on tropical clouds which is widely misquoted as supporting Lindzen's IRIS conjecture regarding stabilizing cloud feedback.

Because high latitudes are thought to be most sensitive to greenhouse gas forcing owing to, for example, ice - albedo feedbacks, we focus on the tropical Pacific Ocean to derive a minimum value for long - term climate sensitivity.

It is my understanding that the uncertainties regarding climate sensitivity to a nominal 2XCO2 forcing is primarily a function of the uncertainties in (1) future atmospheric aerosol concentrations; both sulfate - type (cooling) and black carbon - type (warming), (2) feedbacks associated with aerosol effects on the properties of clouds (e.g. will cloud droplets become more reflective?)

Including a temperature feedback on would change the climate sensitivity, but doesn't much change the impact of a small offset in.

I am thinking that the permafrost feedback article we were discussing was refering to a non-runaway feedback, but rather a delayed feedback, which is otherwise just like the fast feedbacks except that it's slow response would make clear that it does feedback on itself according to the climate sensitivity from all other feedbacks (it drives itself, via climate change, to go farther, but it approaches a limit asymptotically).

What about the feedbacks that are not normally well represented by ECS and normally fall into the Earth System Climate Sensitivity, stuff like the Arctic Ice cover, which now has trends over decades closer to what was seen on centuries in paleoclimate:

(but quickly: On the point of paleoclimatic evidence: if there is a threshold below (or above) which a feedback is not activitated, then climate variations staying below (or above) that threshold would not bear on the sensitivity with that feedbackOn the point of paleoclimatic evidence: if there is a threshold below (or above) which a feedback is not activitated, then climate variations staying below (or above) that threshold would not bear on the sensitivity with that feedbackon the sensitivity with that feedback.)

Just to follow - up on John Finn's question (# 10), if one puts in a rough value for the emissivity of the earth (whatever that might be), so one is no longer assuming it is a perfect blackbody, then does the resulting estimate for climate sensitivity correspond to what one would expect in the absence of any feedback effects?

Aslo, regarding climate sensitivity a very key thing to remember, especially if sensitivity turns out to be on the high side, is that the «final» equilibrium temperature (Alexi's concerns about there being such a thing aside) calculated from climate sensitivity does not take into account carbon cycle feedbacks OR ice sheet changes.

David Benson, Based solely on the fact that Earth was 33 degrees warmer than its blackbody temperature, on what was known of the absorption spectrum of CO2 and on the fact that Earth's climate did not exhibit exceptional stability characteristic of systems with negative feedback, I'd probably still go with restricting CO2 sensitivity to 0 to + infinity.

This is enough to matter, but it's no more scary than the uncertainty in cloud feedbacks for example, and whether they could put us on the high end of typical climate sensitivity estimates.

SM, what I am saying is that if you had negative sensitivity, that would imply strong negative feedback, and you wouldn't see much change in the climate system — in contrast to the climate we see on Earth.

And once we're on that positive feedback track for good, it's just a matter of time (which climate sensitivity can help us understand, but only in part) before it gets really really bad.

This paper is nonetheless interesting for the link that they make to the carbon cycle and the potential for feedbacks that may amplify the CO2 concentration in the future that will depend on the warming, and hence on climate sensitivity.

On the real planet, there are multitudes of feedbacks that affect other greenhouse components (ice alebdo, water vapour, clouds etc.) and so the true issue for climate sensitivity is what these feedbacks amount to.

Depending on meridional heat transport, when freezing temperatures reach deep enough towards low - latitudes, the ice - albedo feedback can become so effective that climate sensitivity becomes infinite and even negative (implying unstable equilibrium for any «ice - line» (latitude marking the edge of ice) between the equator and some other latitude).

part of the utility is that Charney sensitivity, using only relatively rapid feedbacks, describes the climate response to an externally imposed forcing change on a particular timescale related to the heat capacity of the system (if the feedbacks were sufficiniently rapid and the heat capacity independent of time scale (it's not largely because of oceanic circulation), an imbalance would exponentially decay on the time scale of heat capacity * Charney equilibrium climate sensitivity.

Our session on climate sensitivity and feedbacks has really great contributions, both talks and posters.

Dear RC, Is it not possible that scientists and mathematicians from the science of non linear dynamics (which maths I am presuming is being used in the maths of climate models) to shed light on the amplification and dampening of the climates feedback cycles and hence the so called «sensitivity» issue and hence the possible range of temperatures?

The figure for climate sensitivity to doubling of CO2 of 3.6 to 8.1 degrees Fahrenheit depends on water vapor being a large positive feedback.

And then there's the even higher Earth System Climate Sensitivity based on slower feedbacks, hovering around 6 °C / doubling, for a rise of 24 °C with four doublings.

In short, whatever the initial climate sensitivity is to a doubling of CO2, I just can't buy off on this positive feedback loop idea that says that temperatures are going to spin out of control once we pass over some «tipping point» that only seems to exists in some scientist's theoretical model.

The precise amount of warming will depend on climate sensitivity and the exotic feedbacks that are factored in, but I think you are dancing on the head of a pin with your comments -

This «climate sensitivity» not only depends on the direct effect of the GHGs themselves, but also on natural «climate feedback» mechanisms, particularly those due to clouds, water vapour, and snow cover.

Explore the sensitivity of the climate system to atmospheric chemical composition with emphasis on connections to biosphereic processes and feedbacks

Based on evidence from Earth's history, we suggest here that the relevant form of climate sensitivity in the Anthropocene (e.g. from which to base future greenhouse gas (GHG) stabilization targets) is the Earth system sensitivity including fast feedbacks from changes in water vapour, natural aerosols, clouds and sea ice, slower surface albedo feedbacks from changes in continental ice sheets and vegetation, and climate — GHG feedbacks from changes in natural (land and ocean) carbon sinks.

Based on the principles of radiative physics and reasonable estimates of feedbacks and climate sensitivity, I would say that any current oscillations beyond those we already know can't be strong so strong that they leave little or no room for what anthropogenic emissions are contributing to the temperature trend.

With a climate sensitivity of roughly 1 from «settled» CO2 science, some evidence for natural shifts in global climate of 0.5 - 1.0 degK, and a fair amount of uncertainty in feedbacks, my Italian flag (based on physics) will probably be mostly white if climate sensitivity is > 2.5.

[¶]... Basing our assessment on a combination of several independent lines of evidence, as summarised in Box 10.2 Figures 1 and 2, including observed climate change and the strength of known feedbacks simulated in GCMs, we conclude that the global mean equilibrium warming for doubling CO2, or «equilibrium climate sensitivity», is likely to lie in the range 2 °C to 4.5 °C, with a most likely value of about 3 °C.

The Figure 9.20 climate sensitivity PDF that is effectively based on a uniform prior in the climate feedback parameter Y is that for Gregory 02.

For a method for that, may I encourage you to look at Roy Spencer's recent model on thermal diffusion in the ocean: More Evidence that Global Warming is a False Alarm: A Model Simulation of the last 40 Years of Deep Ocean Warming June 25th, 2011 See especially his Figure Forcing Feedback Diffusion Model Explains Weak Warming in 0 - 700 m layer as Consistent with Low Climate Sensitivity His model appears to be more accurate than the IPCC's.

The closed - loop feedback gain implicit in the IPCC's climate - sensitivity interval 3.3 [2.0, 4.5] Cº per CO2 doubling falls on the interval 0.62 [0.42, 0.74].