Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Antarctic Sea Ice Expansion, Driven by Internal Variability, in the Presence of Increasing Atmospheric CO2

TitleAntarctic Sea Ice Expansion, Driven by Internal Variability, in the Presence of Increasing Atmospheric CO2
Publication TypeJournal Article
Year of Publication2019
AuthorsSingh, H. A., Polvani L. M., and Rasch P.J.
JournalGeophysical Research Letters
Volume46
Abstract / Summary

A number of physically based hypotheses have been proposed to explain the surprising expansion of Antarctic sea ice area (SIA) over the satellite era (1979 to 2015). Here, we use a fully coupled state‐of‐the‐art global climate model to show that internal variability alone can produce such multidecadal periods of Antarctic SIA expansion even as atmospheric CO2 increases at observed rates and the planet warms. When our model is started from a relatively warm Southern Ocean state, Antarctic SIA sometimes (in one of three ensemble members) expands over multidecadal time scales at a rate comparable to that over the satellite era. SIA expansion occurs concurrently with rising atmospheric CO2 and warming global surface temperatures, and SIA trends by region and sector resemble those over the satellite era. Our results suggest that internal variability over long time scales in the Southern Ocean region may suffice to explain Antarctic SIA expansion over the satellite era.

URLhttp://dx.doi.org/10.1029/2019gl083758
DOI10.1029/2019gl083758
Journal: Geophysical Research Letters
Year of Publication: 2019
Volume: 46
Publication Date: 12/2019

A number of physically based hypotheses have been proposed to explain the surprising expansion of Antarctic sea ice area (SIA) over the satellite era (1979 to 2015). Here, we use a fully coupled state‐of‐the‐art global climate model to show that internal variability alone can produce such multidecadal periods of Antarctic SIA expansion even as atmospheric CO2 increases at observed rates and the planet warms. When our model is started from a relatively warm Southern Ocean state, Antarctic SIA sometimes (in one of three ensemble members) expands over multidecadal time scales at a rate comparable to that over the satellite era. SIA expansion occurs concurrently with rising atmospheric CO2 and warming global surface temperatures, and SIA trends by region and sector resemble those over the satellite era. Our results suggest that internal variability over long time scales in the Southern Ocean region may suffice to explain Antarctic SIA expansion over the satellite era.

DOI: 10.1029/2019gl083758
Citation:
Singh, H, L Polvani, and P Rasch.  2019.  "Antarctic Sea Ice Expansion, Driven by Internal Variability, in the Presence of Increasing Atmospheric CO2."  Geophysical Research Letters 46.  https://doi.org/10.1029/2019gl083758.