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Why Is the Southern Hemisphere Warming Slower? ✎

Original: "On the Warming of the Southern Hemisphere since 1955 and Recent Slowing-Down: Role of Sea Ice, Sun Spot and El Nino Variability"
· Alfred Laubereau, Hristo Iglev
arXiv:1807.05676 · 2018-07-16 · arXiv non-exclusive · independent analysis · 1 min
Geophysics Atmospheric and Oceanic Physics
Melting Antarctic ice has warmed the Southern Hemisphere more than greenhouse gases have.

From 1955 to 1979, Antarctic sea ice extent shrank by 23% in winter and 67% in summer, then partially recovered. It is like a spring that was slowly compressed and then released: the Southern Hemisphere climate responded with a delay of several decades.

Albedo is the fraction of sunlight reflected by a surface. Ice reflects a lot of light, while dark water reflects little. When ice melts, the surface absorbs more heat.

A one-dimensional, four-layer atmospheric model compared two warming sources from 1955 to 2015. The greenhouse gas contribution was 0.2 ± 0.05 K, while the albedo feedback from ice melt contributed 0.5 ± 0.1 K. The sum matches the observed temperature rise of 0.75 ± 0.1 K.

Extrapolation to 2015–2025 predicts a 33% slowdown in warming compared to 2005–2015. This is explained by the ocean's long memory: it continues to respond to past events.

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From 1955 to 1979, Antarctic sea ice extent shrank by 23% in winter and 67% in summer, then partially recovered. This is like a spring slowly uncoiling in the climate system.

\tau \frac{d(\Delta albedo)}{dt} = -\Delta albedo + G_{rel}(t)
The hemispheric albedo change lags behind the Antarctic albedo change with a characteristic time τ.
\sum_{i=0}^{4} \eta_{ij} T_i^4 = f_j \eta_{jj} T_j^4 - \frac{B_j - B_{j+1}}{\sigma}
For each layer j, the total radiative flux from all layers and the surface equals the flux emitted by the layer plus non-radiative heat transport.
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El Niño La Niña ENSO El Niño-Southern Oscillation relative ONI global warming Bjerknes feedback ERSST UAH satellite record Earth's energy imbalance Warm water volume greenhouse effect sea surface temperature anomaly seasonal cycle NOAA CPC sea surface temperature seasonal forcing Southern Oscillation Multivariate ENSO Index Ocean heat content