Is The Climate System “Stable” And “In Equilibrium” In The Absence Of Human Disturbance

I posted on text from the book

Tattersall, Ian, 2008: The World from Beginnings to 4000 BCE (New Oxford World History). Oxford University Press. 143 pp

in my post

Succinct Summary Of The Scientific Process.

The Tattersall book has an excellent overview of evolutionary development biology, as well as evolution, in general.  The concept of “punctuated equilibria” was presented in which biological species in the fossil record, as Tattersall writes,

“….have not generally shown evidence of slow change from one into another over the ages. Rather, they have tended to appear in the record quite suddenly, to persist relatively unchanged for periods of time that could stretch into millions of years, and then to disappear with equal suddenness, to be replaced by other species, which might or might not have been their close relatives”.

This behavior in the biological system is quite similar to what we see in the climate system [on all time scales ranging from viruses (e.g. influenza) and bacteria (e.g. antibiotic resistant stains) on yearly time scales to large mammal evolutionary changes on much longer time scales . In our paper

Rial, J., R.A. Pielke Sr., M. Beniston, M. Claussen, J. Canadell, P. Cox, H. Held, N. de Noblet-Ducoudre, R. Prinn, J. Reynolds, and J.D. Salas, 2004: Nonlinearities, feedbacks and critical thresholds within the Earth’s climate system. Climatic Change, 65, 11-38

we wrote

“The Earth’s climate system is highly nonlinear: inputs and outputs are not proportional, change is often episodic and abrupt, rather than slow and gradual, and multiple equilibria are the norm.”

Tattersall writes

“….let’s look at environmental change.  Ever since Darwin’s day, everyone has agreed that shifting –  sometimes dramatically shifting – climates have marked features of Earth’s history and have also been major determinants of the evolutionary patterns we see in the fossil record.  Certainly the period during which the human family, Hominidae, has been around has witnessed huge oscillations in environmental circumstances all over the globe.”

The answer to the question

Is The Climate System “Stable” And “In Equilibrium” In The Absence Of Human Disturbance is clearly NO.

The human disturbance, which is significant, as we summarized in our article

Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell,  W. Rossow,  J. Schaake, J. Smith, S. Sorooshian,  and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union,

is superimposed on the substantial nonlinear behavior of the natural climate system. The IPCC multi-decadal climate model simulations have not been able to replicate the natural climate variations, such that subtracting model runs with and without human disturbance is an inadequate approach to assess the real world influence of humans on the climate.  The Tattersall book provide further documentation of the natural variability of the Earth’s  environmental system. Nonlinearity is a fundamental characteristic of  biology and of climate.