Sentences with phrase «global radiative feedbacks»

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

Niche Modelling concludes from the Leviticus data that net total global radiative feedback from water vapor, etc. is negative, rather than strongly positive, as estimated by the models cited in IPCC AR4.

That is global radiative feedback < global radiative forcing.

Not exact matches

(Top left) Global annual mean radiative influences (W m — 2) of LGM climate change agents, generally feedbacks in glacial - interglacial cycles, but also specified in most Atmosphere - Ocean General Circulation Model (AOGCM) simulations for the LGM.

The mechanism for reducing anthropogenic global warming, initiated through radiative forcing of greenhouse gases, is to stop emissions and reduce their concentration in the atmosphere to levels which do not stimulate carbon feedbacks.

Tsushima, Y., A. Abe - Ouchi, and S. Manabe, 2005: Radiative damping of annual variation in global mean surface temperature: Comparison between observed and simulated feedback.

He then uses what information is available to quantify (in Watts per square meter) what radiative terms drive that temperature change (for the LGM this is primarily increased surface albedo from more ice / snow cover, and also changes in greenhouse gases... the former is treated as a forcing, not a feedback; also, the orbital variations which technically drive the process are rather small in the global mean).

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.

Nevertheless, the results described here provide key evidence of the reliability of water vapor feedback predicted by current climate models in response to a global perturbation in the radiative energy balance.»

Abstract:» The sensitivity of global climate with respect to forcing is generally described in terms of the global climate feedback — the global radiative response per degree of global annual mean surface temperature change.

You are welcome to try something similar with global radiative forcing fluctuation, but if you do it will be rather tricky to isolate the cloud effect, since you have the snow and ice albedo effect to deal with then, which are largely temperature - related feedbacks.

On the possibility of a changing cloud cover «forcing» global warming in recent times (assuming we can just ignore the CO2 physics and current literature on feedbacks, since I don't see a contradiction between an internal radiative forcing and positive feedbacks), one would have to explain a few things, like why the diurnal temperature gradient would decrease with a planet being warmed by decreased albedo... why the stratosphere should cool... why winters should warm faster than summers... essentially the same questions that come with the cosmic ray hypothesis.

Gavin disputes that the main driver of the sea ice retreat is the albedo flip, but we are seeing not only polar amplification of global warming but positive feedback, which would not be explained simply by radiative forces and ocean currents.

Abstract:» The sensitivity of global climate with respect to forcing is generally described in terms of the global climate feedback — the global radiative response per degree of global annual mean surface temperature change.

(57k) When I state that the equilibrium climatic response must balance imposed RF (and feedbacks that occur), I am referring to a global time average RF and global time average response (in terms of radiative and convective fluxes), on a time scale sufficient to characterize the climatic state (including cycles driven by externally - forced cycles (diurnal, annual) and internal variability.

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.).)

The equilbrium global time average response (on a time scale sufficient to characterize externally - forced cycles (day, year) and internal varibility) to an imposed global time average radiative forcing is a change that balances the externally imposed forcing plus any non-Planck feedbacks (where the Planck response is part of the response to the other feedbacks.

Climate shifts in the Pacific Ocean with global implications for hydrology and radiative flux feedbacks.

Of course feedbacks can have offsetting effects — but if you accept the radiative physics of AGW, then you believe that adding CO2 to the atmosphere causes global warming.

However, the global dust burden and associated radiative forcing are substantially higher during glacial climates, so that the amplification of the dust load by this feedback is larger.

We use the estimation of radiative forcing for a doubling of CO2 to estimate that, without feedbacks, this change in radiative forcing would result in a rise of global temperatures of 1.2 C.

A simple method for estimating the global radiative forcing caused by the sea - ice - albedo feedback in the Arctic is presented.

How may low - cloud radiative properties simulated in the current climate influence low - cloud feedbacks under global warming?

This is typical of much global warming theorizing that over-relies on radiative physics (based on lab tests & QM) and views the climate as as a primarily linear chemical - thermodynamic system, rather than one modulated by biology and interacting feedbacks.

Ice albedo feedback change is mainly limited to high latitude NH * land * during deglaciation, and its effects — though strong — are limited compared to those of a radiative forcing over the global ocean.

The Greenland ice sheet plays a crucial role in the Arctic and global climate systems through its impact and feedbacks on radiative budget, ocean, atmosphere and ecosystems.

The method is somewhat circular, since forcing for each model is calculated each year as the product of its estimated climate feedback parameter and its simulated global warming, adjusted by the change in its radiative imbalance (heat uptake).

Each model's climate feedback parameter is derived by regressing the model's radiative imbalance response against its global temperature response over the 150 years following an abrupt quadrupling of CO2 concentration.

Radiative forcing can and is expected to create positive feedbacks that will amplify global warming in a non-linear accelerating progression.

The net radiative feedback due to all cloud types is likely (> 66 % chance) positive, although a negative feedback (damping global climate changes) is still possible.

Perlwitz et al. (2001) estimate that this feedback reduces the global dust load by roughly 15 %, as dust radiative forcing reduces the downward mixing of momentum within the planetary boundary layer, the surface wind speed, and thus dust emission (Miller et al., 2004a).

Motivated by findings that major components of so - called cloud «feedbacks» are best understood as rapid responses to CO2 forcing (Gregory and Webb in J Clim 21:58 — 71, 2008), the top of atmosphere (TOA) radiative effects from forcing, and the subsequent responses to global surface temperature changes from all «atmospheric feedbacks» (water vapour, lapse rate, surface albedo, «surface temperature» and cloud) are examined in detail in a General Circulation Model.

These climate changes are a result of human and natural climate forcings and feedbacks — the relative role of each in altering atmospheric and ocean circulation features, and even the global annual average radiative forcing, however, is still uncertain.

In the idealised situation that the climate response to a doubling of atmospheric CO2 consisted of a uniform temperature change only, with no feedbacks operating (but allowing for the enhanced radiative cooling resulting from the temperature increase), the global warming from GCMs would be around 1.2 °C (Hansen et al., 1984; Bony et al., 2006).

«Under these simplifying assumptions the amplification [f] of the global warming from a feedback parameter [b](in W m — 2 °C — 1) with no other feedbacks operating is 1 / (1 --[bκ — 1]-RRB-, where -LSB--- κ — 1] is the «uniform temperature» radiative cooling response (of value approximately — 3.2 W m — 2 °C — 1; Bony et al., 2006).

Estimating the Global Radiative Impact of the Sea - Ice - Albedo Feedback in the Arctic..