A Fundamental Systems Analysis of Climate Change

Dear Colleagues:

I wrote this recently and thought it might be useful for some of you to read. Feel free to challenge my reasoning if you think I've gone off the reservation.

What I have been studying suggests that human impact on ecosystem function, while extremely complex can be understood by everyone. Indeed it must be understood by everyone if we as humanity, are going to change what can now be seen to be a predictable and probable catastrophic outcome.

I have learned that in science we must not assume things to be true, they must be proven.

The majority of observers have concluded (although I suspect in many cases they have assumed) that egregious emissions of CO2 and other greenhouse gases are either the sole or the main human impact on the climate.

I beg to differ.

I’m certainly not saying that human impact on climate change does not exist or that egregious emissions of CO2 and other greenhouse gases are a good thing.

What I am saying is that egregious emissions of CO2 and other greenhouse gases are not the sole human impact on the climate.

I’m also saying that actually human impact on naturally occurring climate processes began long before industrialization and egregious emissions of greenhouse gases.

Human impact can be seen to have begun to reduce biodiversity through the human induced extinctions of large mega-fauna perhaps as far back as 40,000 years ago. This would have caused undoubted ripple effects in predator / prey population densities and even landscape changes through changes in diet and physical impacts. However, evidence shows that it was human agriculture that really began to massively alter the Earth’s landscape and ultimately to massively reduce ecosystem function, altering several fundamental processes that effect the climate. These disruptions have been exacerbated by egregious human emissions of greenhouse gases.

What I have learned and what I now teach when asked is that human impact can be seen in a simplified form as the interruption of long-term evolutionary trends that have been continuous throughout evolutionary time. These are:

The reduction of biodiversity

Leading to the reduction of biomass

Leading to a reduction in the accumulation of organic matter

By disrupting these evolutionary trends human beings have altered 3 basic processes that have generated, regulated, filtered and continuously renewed the Air, Water, Food and Energy, that human beings and other life forms depend on to survive.

These include but are not necessarily limited to

reduced photosynthesis causing reduced carbon uptake (and reduced oxygen release)

reduced nutrient cycling through the loss of organic decay and reduction in microbiologic habitat in the soil

reduced infiltration and retention of rainfall in biomass, soil and geologic formations as well artificial increase in evaporation and temperature due to the reduction of vegetated canopy.

Evidence shows that these disruptions will cause precipitous loss of species, loss of hydrological function causing extreme weather events such as floods and drought, it will cause growing deserts, the erosion of fertility leading to reduced agricultural productivity and famine, and ultimately to ecosystem collapse in which the systems providing air, water, food and energy can no longer compensate and collapse.

Evidence also shows that this development trajectory leads to carbon disequilibrium where less carbon in the atmosphere is sequestered naturally in the vegetation and in the soil. This is exacerbated by egregious emissions of CO2 and other greenhouse gases and has lead to global climate impacts.

What is interesting about this is that there is also evidence that it is possible to restore large-scale damaged ecosystems including systems that have been degraded over vast areas and over historical time.

Through numerous case studies it is possible to show that it is possible to increase biodiversity, biomass and accumulated organic matter, effectively reversing the feared negative impacts described above.

It is not necessarily easy but it is possible.

If we took restoration on a planetary scale we would reach the scale necessary to deal with the problems we face.

I'd be interested to know what you think of these thoughts and whether you find this useful or not.

You can learn more of my work at and by watching "Hope in a Changing Climate" online at

John D. Liu
Director, Environmental Education Media Project (EEMP)
Rothamsted International Fellow for the Communication of Science
PhD Candidate, School of Human and Environmental Sciences, University of Reading
Assistant Research Professor, George Mason University
Senior Research Fellow, IUCN