Sentences with phrase «surface albedo feedback»

New techniques that evaluate surface albedo feedbacks have recently been developed.

These runs are examined for evidence of accelerated climate change associated with the removal of sea ice, particularly due to increasing surface albedo feedback.

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.

The three studies, using different methodologies to estimate the global surface albedo feedback associated with snow and sea ice changes, all suggest that this feedback is positive in all the models, and that its range is much smaller than that of cloud feedbacks.

Winton (2006a) suggests that about three - quarters of the global surface albedo feedback arises from the NH (see Section 8.6.3.3).

Then, one can presumably decompose this «total forcing» into its components which might include WV feedbacks, cloud feedbacks, surface albedo feedbacks etc..

Water vapour, lapse rate, cloud and surface albedo feedback parameters, as estimated by Colman (2003a), Soden and Held (2006) and Winton (2006a) are shown in Figure 8.14.

A new result found independently by Winton (2006a) and Qu and Hall (2005) is that surface processes are the main source of divergence in climate simulations of surface albedo feedback, rather than simulated differences in cloud fields in cryospheric regions.

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.»

At the global scale, the surface albedo feedback is positive in all the models, and varies between models much less than cloud feedbacks.

Plotting GHG forcing (7) from ice core data (27) against temperature shows that global climate sensitivity including the slow surface albedo feedback is 1.5 °C per W / m2 or 6 °C for doubled CO2 (Fig. 2), twice as large as the Charney fast - feedback sensitivity.»

In 2XCO2 simulations with the same aerosol deposition, ponds have a larger effect whereas aerosol effects are reduced, thereby modifying the surface albedo feedback.

A number of processes, other than surface albedo feedback, have been shown to also contribute to the polar amplification of warming in models (Alexeev, 2003, 2005; Holland and Bitz, 2003; Vavrus, 2004; Cai, 2005; Winton, 2006b).

However, the contributions of water vapour / lapse rate and surface albedo feedbacks to sensitivity spread are non-negligible, particularly since their impact is reinforced by the mean model cloud feedback being positive and quite strong.

The failures to reproduce the increase in precipitation (Wentz) and the surface albedo feedbacks (Roesch) were quite enough.

Since the TAR, some progress has been made in quantifying the surface albedo feedback associated with the cryosphere.

In AOGCMs, the water vapour feedback constitutes by far the strongest feedback, with a multi-model mean and standard deviation for the MMD at PCMDI of 1.80 ± 0.18 W m — 2 °C — 1, followed by the (negative) lapse rate feedback -LRB--- 0.84 ± 0.26 W m — 2 °C — 1) and the surface albedo feedback (0.26 ± 0.08 W m — 2 °C — 1).

Using feedback parameters from Figure 8.14, it can be estimated that in the presence of water vapour, lapse rate and surface albedo feedbacks, but in the absence of cloud feedbacks, current GCMs would predict a climate sensitivity (± 1 standard deviation) of roughly 1.9 °C ± 0.15 °C (ignoring spread from radiative forcing differences).

The surface albedo feedback amplifies the basic response by about 10 %, and the cloud feedback does so by 10 to 50 % depending on the GCM.