The Evidence: Positive Impacts of Human CO2 Emissions

Written by Dr Patrick Moore, Greenpeace co-founder

Patrick Moore, co-founder of Greenpeace provides a compelling study of the evidence in support of human emissions of carbon dioxide into the atmosphere.

Moore’s study, The Positive Impact of CO2 Emissions on the Survival of Life on Earth (June 2016) looks at the positive environmental effects of carbon dioxide (CO2) emissions, a topic which has been well established in the scientific literature but which is far too often ignored in the current discussions about climate change policy. Below are select extracts:

All life is carbon based and the primary source of this carbon is the CO2 in the global atmosphere. As recently as 18,000 years ago, at the height of the most recent major glaciation, CO2 dipped to its lowest level in recorded history at 180 ppm, low enough to stunt plant growth.

This is only 30 ppm above a level that would result in the death of plants due to CO2 starvation. It is calculated that if the decline in CO2 levels were to continue at the same rate as it has over the past 140 million years, life on Earth would begin to die as soon as two million years from now and would slowly perish almost entirely as carbon continued to be lost to the deep ocean sediments.

The combustion of ‘fossil fuels’ for energy to power human civilization has reversed the downward trend in CO2 and promises to bring it back to levels that are likely to foster a considerable increase in the growth rate and biomass of plants, including food crops and trees.

Human emissions of CO2 have restored a balance to the global carbon cycle, thereby ensuring the long-term continuation of life on Earth. This extremely positive aspect of human CO2 emissions must be weighed against the unproven hypothesis that human CO2 emissions will cause a catastrophic warming of the climate in coming years. The one-sided political treatment of CO2 as a pollutant that should be radically reduced must be corrected in light of the indisputable scientific evidence that it is essential to life on Earth.


It has been well demonstrated that the increase in CO2 in the atmosphere is responsible for increased plant growth on a global scale. Many studies suggest that nearly 25 per cent of human-caused CO2 emissions, or 2.5 Gt of carbon annually, are absorbed by plants, thus increasing global plant biomass.

A recent study postulates that up to 50 per cent of human CO2 emissions are absorbed by increased plant growth.30 This has been described as a “greening of the Earth” as CO2 reaches concentrations well above the near-starvation levels experienced during the major glaciations of the Pleistocene.31

The most prestigious Australian science body, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), has shown that CO2 particularly benefits plants that are adapted to dry climates. In higher CO2 environments, they become more efficient at photosynthesis, growing faster without using more water.32

It is not widely known that greenhouse operators worldwide inject additional CO2 into their greenhouses in order to increase the growth and yield of their crops. Among horticulturalists, it is well known that this practice can increase growth by 40 per cent or more. This is because the optimum level of CO2 for plant growth is between 1,000 ppm and 3,000 ppm in air, much higher than the 400 ppm in the global atmosphere today.37 Every species on Earth, including our own, is descended from ancestors that thrived in climates with much higher levels of CO2 than are present today.

The debate about climate change has one side insisting that the “science is settled.” Yet, there is no scientific proof that increased CO2 will result in disaster, as CO2 has been higher during most of the history of life on Earth than it is today. On the other hand, it can be stated without a doubt that if CO2 once again falls to the level it was only 18,000 years ago, or lower, there would be a catastrophe unlike any known in human history. We are advised by many scientists that we should be worried about CO2 levels climbing higher when, in fact, we should actually be worried about CO2 levels sinking lower.

The above are extracts – the full article is found at