Sentences with phrase «feedback equilibrium climate»

And it should be possible to measure zero feedback equilibrium climate sensitivity on a small scale if not on a planetary one.

Third, our calculations are for a single fast - feedback equilibrium climate sensitivity, 3 °C for doubled CO2, which we infer from paleoclimate data.

Not exact matches

Climate forcing in the LGM equilibrium state, relative to the Holocene, due to the slow feedback ice age surface properties, i.e., increased ice area, different vegetation distribution, and continental shelf exposure, was -3.5 ± 1 W / m2 (10).

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.

Now, clouds do not make heat exchange imponderable, especially in long term trends of climate analysis, the averages due to what we already know about dynamic equilibrium outcomes and what we observe in the feedbacks going back even greater then 30 years.

Equilibrium sensitivity, including slower surface albedo feedbacks, is 6 °C for doubled CO2 for the range of climate states between glacial conditions and ice - free Antarctica.»

Geoff any forcing is positive feedback and there are many of those loops at work now working against climate homeostasis and the more from equilibrium climate becomes more additional + ve loops just join the fray.

Polar amplication is of global concern due to the potential effects of future warming on ice sheet stability and, therefore, global sea level (see Sections 5.6.1, 5.8.1 and Chapter 13) and carbon cycle feedbacks such as those linked with permafrost melting (see Chapter 6)... The magnitude of polar amplification depends on the relative strength and duration of different climate feedbacks, which determine the transient and equilibrium response to external forcings.

It gets tricky now because the equilibrium climate sensitivity requires a timescale to be defined — barring large hysteresis, it isn't so large going out many millions of years (weathering feedback); there will be a time scale of maximum sensitivity.

Global temperature change is about half that in Antarctica, so this equilibrium global climate sensitivity is 1.5 C (Wm ^ -2) ^ -1, double the fast - feedback (Charney) sensitivity.

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.

The forcing and feedback (including the vertical temperature profile feedback) will be different in complimentary ways to result in the same magnitude of shift in equilibrium climate.

Starting from an old equilbrium, a change in radiative forcing results in a radiative imbalance, which results in energy accumulation or depletion, which causes a temperature response that approahes equilibrium when the remaining imbalance approaches zero — thus the equilibrium climatic response, in the global - time average (for a time period long enough to characterize the climatic state, including externally imposed cycles (day, year) and internal variability), causes an opposite change in radiative fluxes (via Planck function)(plus convective fluxes, etc, where they occur) equal in magnitude to the sum of the (externally) imposed forcing plus any «forcings» caused by non-Planck feedbacks (in particular, climate - dependent changes in optical properties, + etc.).)

(Within the range where water vapor feedback is runaway, zero change in external forcing»cause s» a large change in climate; the equilibrium surface temperature, graphed over some measure of external forcing, takes a step at some particular value.)

One can consider net PR+CR as a response to externally - imposed RF (external forcing) plus feedback «RF», or one can consider PR + CR — feedback «RF» as the response to the externally imposed RF; the later is perhaps more helpful in picturing the time evolution toward equilibrium (and illustrates why the time it takes for an imbalance, equal to: externally imposed RF — climate dependent terms (PR + CR — feedback «RF»), to decay is proportional to both heat capacity and climate sensitivity (defined per unit externally imposed RF).

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).

The feedback can become zero — or to avoid confusion regarding what is and is not a feedback — the equilibrium climate sensitivity can become infinite (or negative) in some conditions.

Once the ice reaches the equator, the equilibrium climate is significantly colder than what would initiate melting at the equator, but if CO2 from geologic emissions build up (they would, but very slowly — geochemical processes provide a negative feedback by changing atmospheric CO2 in response to climate changes, but this is generally very slow, and thus can not prevent faster changes from faster external forcings) enough, it can initiate melting — what happens then is a runaway in the opposite direction (until the ice is completely gone — the extreme warmth and CO2 amount at that point, combined with left - over glacial debris available for chemical weathering, will draw CO2 out of the atmosphere, possibly allowing some ice to return).

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.

But 3,2 °C is the best estimate for equilibrium climate sensitivity (that is when the runs of models consider all the feedbacks).

These additional feedbacks are not still accounted by GCM models, at least those used in IPCC 2007 for equilibrium climate sensitivity.

To translate this into 2xCO2 temperature impact (equilibrium climate sensitivity) means that this would be around 0.6 deg C including all feedbacks, compared to the Myhre et al. estimate before feedbacks of around 1.0 degC and the IPCC mid-range estimate including all feedbacks of 3.2 degC.

It is possible that effective climate sensitivity increases over time (ignoring, as for equilibrium sensitivity, ice sheet and other slow feedbacks), but there is currently no model - independent reason to think that it does so.

The climate system invariably tends to return toward equilibrium via feedbacks.

Second, for millennia, our climate has been relatively close to equilibrium, as discerned from the tendency of fluctuations to return to a steadier baseline, from energy balance studies, and from observational data on feedbacks.

[¶]... 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.

In contrast to climate models, which are biogeophysically - based systems models that incorporate time - delayed feedbacks and non-linear dynamics, the economic and demographic models that underpin the Intergovernmental Panel on Climate Change (IPCC) are price - based equilibrium climate models, which are biogeophysically - based systems models that incorporate time - delayed feedbacks and non-linear dynamics, the economic and demographic models that underpin the Intergovernmental Panel on Climate Change (IPCC) are price - based equilibrium Climate Change (IPCC) are price - based equilibrium models.

One empirical analysis of the type of F+G 06 does not tell that the climate feedback parameter Y is 2.3 ± 1.4 W m ^ -2 K ^ -1 with 95 % certaintyor that the equilibrium climate sensitivity is in the corresponding range 1.0 — 4.1 K. Those limits are obtained only, when the additional assumption of uniform prior in Y is made.

But seriously, I look at your use of terms like «forcing», and «feedback», and «equilibrium climate sensitivity», and «CO2 control knob», and I feel sorta like a modern redox chemist watching a bunch of biologists trying to study the cell by measuring its «phlogiston» characteristics.

The Equilibrium Climate Sensitivity (ECS) The Economist refers to is how much Earth temperatures are expected to rise when one includes fast feedbacks such as atmospheric water vapor increase and the initial greenhouse gas forcing provided by CO2.

Radiative Transfer Physics does not depend entirely on the simple absorbtivity of CO2, which by the way is effectively permanent in air when added by burning fossil fuels, compared to water which saturates and precipitates out depending on climate conditions, such as warming due the GHE, as a marginal shift in the dynamic equilibrium through feedbacks.

«The Earth's climate system is highly nonlinear: inputs and outputs are not proportional, change is often episodic and abrupt, rather than slow and gradual, and multiple equilibria are the norm... there is a relatively poor understanding of the different types of nonlinearities, how they manifest under various conditions, and whether they reflect a climate system driven by astronomical forcings, by internal feedbacks, or by a combination of both... [We] suggest a robust alternative to prediction that is based on using integrated assessments within the framework of vulnerability studies... It is imperative that the Earth's climate system research community embraces this nonlinear paradigm if we are to move forward in the assessment of the human influence on climate.»

I agree that reduction in snow or ice cover resulting from warming constitutes a likely slow positive feedback, but its magnitude may be quite small, at least for the modest changes in surface temperature that can be expected to arise if sensitivity is in fact fairly low, so the Forster / Gregory 06 results may nevertheless be a close approximation to a measurement of equilibrium climate sensitivity.

Imposing a flat prior on an observable property, such as the climate feedback or transient climate response, is equivalent to imposing a highly skewed prior on the equilibrium climate sensitivity, and therefore results in narrower posterior likelihood ranges on the climate sensitivity that exclude very high sensitivities.

Therefore, estimating equilibrium climate sensitivity based on measurements of a climate that's out of equilibrium requires making some significant assumptions, for example that feedbacks will remain constant over time.

- we lack a timescale short enough to consider the forcing as fixed (volcano, CO2 emissions, TSI variations) but long enough to get meaningful climate average (even if such average makes sense, that climate is only weakly chaotic) and certainly too short to reach equilibrium T. Equilibrium climate sensitivity is thus a purely theoretical construct not much more related to reality than the no - feedback senequilibrium T. Equilibrium climate sensitivity is thus a purely theoretical construct not much more related to reality than the no - feedback senEquilibrium climate sensitivity is thus a purely theoretical construct not much more related to reality than the no - feedback sensitivity...

Figure 1: Schematic diagram of the equilibrium fast - feedback climate sensitivity and Earth system sensitivity that includes surface albedo slow feedbacks.

Recently there have been some studies and comments by a few climate scientists that based on the slowed global surface warming over the past decade, estimates of the Earth's overall equilibrium climate sensitivity (the total amount of global surface warming in response to the increased greenhouse effect from a doubling of atmospheric CO2, including amplifying and dampening feedbacks) may be a bit too high.

the «fast» and «slow» feedback climate sensitivity are distinguished by the characteristic timescales of the feedbacks, and not by the time required for the surface temperature to reach a new equilibrium following an imposed forcing.

The basic results of this climate model analysis are that: (1) it is increase in atmospheric CO2 (and the other minor non-condensing greenhouse gases) that control the greenhouse warming of the climate system; (2) water vapor and clouds are feedback effects that magnify the strength of the greenhouse effect due to the non-condensing greenhouse gases by about a factor of three; (3) the large heat capacity of the ocean and the rate of heat transport into the ocean sets the time scale for the climate system to approach energy balance equilibrium.

The diagnosis of global radiative feedbacks allows better understanding of the spread of equilibrium climate sensitivity estimates among current GCMs.

Step changes to climate like El Nino or volcanic eruptions will impact climate for short periods because negative feedback loops take some time to recover to their equilibrium.

For a slow feedback climate sensitivity of 6 C for doubled CO2, the equilibrium temperature response would be expected to take much longer (at least several millennia), since this response has been shown to be a strong function of climate sensitivity (Hansen et al., 1985).

Webb et al. (2006), investigating a selection of the slab versions of models in Table 8.1, found that differences in feedbacks contribute almost three times more to the range in equilibrium climate sensitivity estimates than differences in the models» radiative forcings (the spread of models» forcing is discussed in Section 10.2).

IPCC projections are consistent with our understanding of the time scale of the ice - albedo feedback and equilibrium change in sea level rise due to paleo climate data.

The Planck response is a negative feedback; including it, the total feedback is -(1 / equilibrium climate sensitivity) and must be negative in order for equilibrium climate sensitivity to be finite.

The IPCC defines climate sensitivity as equilibrium temperature change ΔTλin response to all anthropogenic - era radiativeforcings and consequent «temperature feedbacks» — further changes in TS that occur because TS has already changed in response to a forcing — arising in response to the doubling of pre-industrial CO2 concentration (expected later this century).

Worst of all, a 4 C world may not be a stable climate state — climate feedbacks at 4 C may make a higher equilibrium point inevitable.

We assume that Chylek (2008) is right to find transient and equilibrium climate sensitivity near - identical; that allof the warming from 1980 - 2005 was anthropogenic; that the IPCC's values for forcings and feedbacks are correct; and, in line 2, that McKitrick is right that the insufficiently - corrected heat - island effect of rapid urbanization since 1980 has artificially doubled the true rate of temperature increase in the major global datasets.

Spencer's assertion in his book of that there has been a «mix - up between cause and effect» is quite a different conclusion from his recent article published in the Journal of Geophysical Research — Atmospheres in 2010, which concluded innocuously that «since the climate system is never in equilibrium, feedbacks in the climate system can not be diagnosed from differences between equilibrium climate states»... despite the fact that this is the exact diagnosis supporting his conclusion in the book.