Journal Article

A Decomposition of Feedback Contributions to Polar Warming Amplification

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

2013

Overview

Polar surface temperatures are expected to warm 2–3 times faster than the global-mean surface temperature: a phenomenon referred to as polar warming amplification. Therefore, understanding the individual process contributions to the polar warming is critical to understanding global climate sensitivity. The Coupled Feedback Response Analysis Method (CFRAM) is applied to decompose the annual- and zonal-mean vertical temperature response within a transient 1% yr−1CO₂ increase simulation of the NCAR Community Climate System Model, version 4 (CCSM4), into individual radiative and nonradiative climate feedback process contributions. The total transient annual-mean polar warming amplification (amplification factor) at the time of CO₂ doubling is +2.12 (2.3) and +0.94 K (1.6) in the Northern and Southern Hemisphere, respectively. Surface albedo feedback is the largest contributor to the annual-mean polar warming amplification accounting for +1.82 and +1.04 K in the Northern and Southern Hemisphere, respectively. Net cloud feedback is found to be the second largest contributor to polar warming amplification (about +0.38 K in both hemispheres) and is driven by the enhanced downward longwave radiation to the surface resulting from increases in low polar water cloud. The external forcing and atmospheric dynamic transport also contribute positively to polar warming amplification: +0.29 and +0.32 K, respectively. Water vapor feedback contributes negatively to polar warming amplification because its induced surface warming is stronger in low latitudes. Ocean heat transport storage and surface turbulent flux feedbacks also contribute negatively to polar warming amplification. Ocean heat transport and storage terms play an important role in reducing the warming over the Southern Ocean and Northern Atlantic Ocean.

• Publisher: American Meteorological Society
• Subject: Albedo / Amplification / Atmosphere / Atmospherics / Carbon dioxide / Climate / Climate change / Climate feedback / Climate models / Climate sensitivity / Climate system / Climatology. Bioclimatology. Climate change / Clouds / Decomposition / Earth, ocean, space / Energy / Exact sciences and technology / External geophysics / Feedback / General circulation models / Global climate / Global climate models / Global warming / Heat / Heat transport / Long wave radiation / Marine / Meteorology / Ocean warming / Oceans / Polar regions / Polar waters / Radiation / Response analysis / Simulation / Southern Hemisphere / Storage / Surface temperature / Transport / Troposphere / Turbulent fluxes / Water vapor / Water vapour