A Decomposition of Feedback Contributions to Polar Warming Amplification

Taylor, Patrick C.; Cai, Ming; Hu, Aixue; Meehl, Jerry; Washington, Warren M.; Zhang, Guang J.

doi:10.1175/jcli-d-12-00696.1

Cited by 241 publications

(196 citation statements)

References 48 publications

Supporting

Mentioning

178

Contrasting

Unclassified

Order By: Relevance

“…An annual mean cloud cooling effect at the top of the atmosphere may be a consequence of negative shortwave feedbacks in summer offsetting year-round positive longwave feedbacks, and clouds in the Arctic not increasing in height as much as clouds in other places, reducing top-of-atmosphere longwave cloud effects (30). Such annual mean top-of-atmosphere analysis, however, obscures the important role of clouds in altering the winter surface temperature and lapse rate of the lower troposphere (31), and in suppressing Arctic air formation. A year-round increase in cloud fraction damps the seasonal cycle of surface temperature, via increased shortwave reflection during summer and stronger longwave heating during winter, and is therefore in line with proxy evidence of equable climates.…”

Section: Discussionmentioning

confidence: 99%

Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming

Cronin

Tziperman

2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

High-latitude continents have warmed much more rapidly in recent decades than the rest of the globe, especially in winter, and the maintenance of warm, frost-free conditions in continental interiors in winter has been a long-standing problem of past equable climates. We use an idealized single-column atmospheric model across a range of conditions to study the polar night process of air mass transformation from high-latitude maritime air, with a prescribed initial temperature profile, to much colder high-latitude continental air. We find that a low-cloud feedback-consisting of a robust increase in the duration of optically thick liquid clouds with warming of the initial state-slows radiative cooling of the surface and amplifies continental warming. This low-cloud feedback increases the continental surface air temperature by roughly two degrees for each degree increase of the initial maritime surface air temperature, effectively suppressing Arctic air formation. The time it takes for the surface air temperature to drop below freezing increases nonlinearly to ∼10 d for initial maritime surface air temperatures of 20°C. These results, supplemented by an analysis of Coupled Model Intercomparison Project phase 5 climate model runs that shows large increases in cloud water path and surface cloud longwave forcing in warmer climates, suggest that the "lapse rate feedback" in simulations of anthropogenic climate change may be related to the influence of low clouds on the stratification of the lower troposphere. The results also indicate that optically thick stratus cloud decks could help to maintain frost-free winter continental interiors in equable climates.global warming | polar amplification | cloud feedbacks | paleoclimate O ne of the persistent mysteries of the "equable climates" of the Eocene and Cretaceous, ∼ 143-33 million years ago, is the warmth of midlatitude and high-latitude continental interiors during winter and, in particular, the frost-intolerant flora and fauna in parts of what is now Wyoming and southern Canada (1). Climate models can simulate warm conditions over the ocean, but they have difficulty simulating continental warmth away from the moderating effects of the ocean, especially if tropical warming is constrained to be K10°C. Although recent work suggests a relaxation of such tropical constraints (2), model−data agreement has been found only for model CO 2 concentrations that seem unrealistically high, and the mechanisms that maintain high-latitude warmth over land remain poorly understood (2, 3). Previous proposed mechanisms to explain the overall reduction of the equator−pole temperature contrast in equable climates include polar stratospheric clouds (4, 5), dramatic expansion of the Hadley circulation (6), increased poleward ocean heat transport due to ocean mixing by stronger tropical cyclones (7,8), and a convective cloud feedback (9). The convective cloud feedback has now appeared in multiple simulations of past and future climates at high CO 2 (10, 11) but is not effective at explaining wa...

show abstract

Section: Discussionmentioning

confidence: 99%

Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming

Cronin

Tziperman

2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Several recent studies have stressed the close connections between these processes. The surface albedo feedback (SAF) mechanism is reputed to have been an important contributor to the loss of Arctic sea ice over the last few decades (Screen and Simmonds, 2010b;Crook et al, 2011;Taylor et al, 2013). By synthesizing a variety of remote sensing and field measurements, both Flanner et al (2011) and Hudson (2011) concluded that the change in the radiative impact of the Arctic sea ice at the top of the atmosphere in the period 1979-2008 has been a reduced cooling of about 0.1 Wm −2 .…”

Section: Feedback Mechanismsmentioning

confidence: 99%

Advances in understanding and parameterization of small-scale physical processes in the marine Arctic climate system: a review

et al. 2014

View full text Add to dashboard Cite

Abstract. The Arctic climate system includes numerous highly interactive small-scale physical processes in the atmosphere, sea ice, and ocean. During and since the International Polar Year 2007-2009, significant advances have been made in understanding these processes. Here, these recent advances are reviewed, synthesized, and discussed. In atmospheric physics, the primary advances have been in cloud physics, radiative transfer, mesoscale cyclones, coastal, and fjordic processes as well as in boundary layer processes and surface fluxes. In sea ice and its snow cover, advances have been made in understanding of the surface albedo and its relationships with snow properties, the internal structure of sea ice, the heat and salt transfer in ice, the formation of superimposed ice and snow ice, and the small-scale dynamics of sea ice. For the ocean, significant advances have been related to exchange processes at the ice-ocean interface, diapycnal mixing, double-diffusive convection, tidal currents and diurnal resonance. Despite this recent progress, some of these small-scale physical processes are still not sufficiently understood: these include wave-turbulence interactions in the atmosphere and ocean, the exchange of heat and salt at the ice-ocean interface, and the mechanical weakening of sea ice. Many other processes are reasonably well understood as stand-alone processes but the challenge is to understand their interactions with and impacts and feedbacks on other processes. Uncertainty in the parameterization of small-scale processes continues to be among the greatest challenges facing climate modelling, particularly in high latitudes. Further improvements in parameterization require new year-round field campaigns on the Arctic sea ice, closely combined with satellite remote sensing studies and numerical model experiments.

show abstract

“…According to the example above, the cloud feedback plays the leading role if the sea ice-albedo feedback is disabled. If the sea ice-albedo feedback is active, it can dominate (Taylor et al, 2013). Winton (2006) found that the Arctic amplification arises from "a balance of significant differences in all forcings and feed-backs between the Arctic and the globe".…”

Section: Arctic Amplificationmentioning

confidence: 99%

Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review

2014

View full text Add to dashboard Cite

Abstract. Sea ice is the central component and most sensitive indicator of the Arctic climate system. Both the depletion and areal decline of the Arctic sea ice cover, observed since the 1970s, have accelerated since the millennium. While the relationship of global warming to sea ice reduction is evident and underpinned statistically, it is the connecting mechanisms that are explored in detail in this review.Sea ice erodes both from the top and the bottom. Atmospheric, oceanic and sea ice processes interact in nonlinear ways on various scales. Feedback mechanisms lead to an Arctic amplification of the global warming system: the amplification is both supported by the ice depletion and, at the same time, accelerates ice reduction. Knowledge of the mechanisms of sea ice decline grew during the 1990s and This article reviews recent progress in understanding the sea ice decline. Processes are revisited from atmospheric, oceanic and sea ice perspectives. There is strong evidence that decisive atmospheric changes are the major driver of sea ice change. Feedbacks due to reduced ice concentration, surface albedo, and ice thickness allow for additional local atmospheric and oceanic influences and self-supporting feedbacks. Large-scale ocean influences on Arctic Ocean hydrology and circulation are highly evident. Northward heat fluxes in the ocean are clearly impacting the ice margins, especially in the Atlantic sector of the Arctic. There is little indication of a direct and decisive influence of the warming ocean on the overall sea ice cover, due to an isolating layer of cold and fresh water underneath the sea ice.

show abstract

A Decomposition of Feedback Contributions to Polar Warming Amplification

Cited by 241 publications

References 48 publications

Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming

Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming

Advances in understanding and parameterization of small-scale physical processes in the marine Arctic climate system: a review

Recent advances in understanding the Arctic climate system state and change from a sea ice perspective: a review

Contact Info

Product

Resources

About