Thresholds and epochs in the Grand Climate System

The map – a thermally enhanced satellite photo – below shows September 2015 sea surface temperature anomalies – that is the difference from average temperatures over a period. During the most resent El Niño.  The oceans have a sun warmed surface layer overlaying the cold depths. Wind and planetary spin keep oceans and atmosphere constantly in motion. In places surface water sinks – driving deep ocean currents – and in others it upwells. Energy moves from the Sun to oceans and land from tropics to poles, to the atmosphere and out to space. It is technically a coupled, nonlinear system far from thermodynamic equilibrium.  A characteristic behavior of the Grand Climate System is relatively stable states punctuated by abrupt shifts that owe more to internal dynamics of the system as a whole than external factors such as greenhouse gases.  Traditionally called oscillations – they are more correctly in modern terms quasi standing waves in spatio-temporal chaos.   They are shifts in patterns of ocean circulation triggered by small changes in the Earth system.  Such as orbits, solar activity and greenhouse gases.

Grand climate
Source: NOAA NESDIS

‘We are living in a world driven out of equilibrium. Energy is constantly delivered from the sun to the earth. Some of the energy is converted chemically, while most of it is radiated back into space, or drives complex dissipative structures, with our weather being the best known example. We also find regular structures on much smaller scales, like the ripples in the windblown sand, the intricate structure of animal coats, the beautiful pattern of mollusks or even in the propagation of electrical signals in the heart muscle.”  Max Planck Institute

“You can see spatio-temporal chaos if you look at a fast mountain river. There will be vortexes of different sizes at different places at different times. But if you observe patiently, you will notice that there are places where there almost always are vortexes and they almost always have similar sizes – these are the quasi standing waves of the spatio-temporal chaos governing the river. If you perturb the flow, many quasi standing waves may disappear. Or very few. It depends.’  Tomas Milanivic

Polar annular modes are immense cyclones spun up over the poles by planetary rotation.  Imagine seesawing masses of frigid air spinning off high latitudes.  Where it meets warmer moist air it rains.  Coriolis force spins up wind driven currents into gyres in all the world’s oceans.  The physical mechanisms were described by great men of the Norwegian school of oceanography in the first half of the 20th century.   

This newish temperature index of Pacific Ocean states shows the warm ‘V’ and cool surrounds of a warm state.  Over the Pacific hot spot cloud is drying and dissipating adding gargantuan energies to the system.   These temperature patterns  shift between warmer and cooler irregularly.   The developers of the index call it epochs.  Based on multiple equilibrium states and sudden shifts – more likely evolving patterns in spatio-temporal chaos.  This pattern has profound effects on global weather and climate and it shifts at multidecadal to millennial scales.

Source: TPI (IPO( Tripole Index for the Interdecadal Pacific Oscillation

There are epochs triggered by changes to Earth system boundary conditions.  As far as I can tell the limits to climate change are some -10 and +12 degrees C.  In as little as a decade in some places.  Low summer Northern Hemisphere insolation and a cooler north Atlantic with glacial ice sheet growth.   Or cloud evaporating away.  The answer to this problem in fluid dynamics is literally incalculable.  

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