Human knowledge allows us to flourish, in numbers, and with living standards unimaginable to our ancestors. Our main advantage is mastery of energy. We  started on this path with agriculture. We co-opted animals to work for us. Then we discovered the steam engine and fossil fuels. Our productivity – and numbers - increased many fold. Some fear greenhouse gases from fossil fuels will affect climate and constrain development. This presentation focuses on managing  greenhouse gases. It seems the key to GHG management will be to use even more energy.

We’ve all heard time and time again that greenhouse gas from fossil fuel is warming the atmosphere and action is needed urgently. I’ve been hearing that for 15 years now, since I began my watch on the issue. Climate experts told us in the early nineties that warming evidence was still uncertain.  Another one or two decades would provide proof. The evidence is still weak and the scientific debate goes on. For the sake of evaluation we can postulate that  greenhouse gases must be controlled. Lets make that assumption  and move forward to consider how they might be managed.

Some diffidently propose that we start by improving energy efficiency and conserving it to avoid climate catastrophe. Experience tells us this approach will not  work. We’ve improved efficiency dramatically since our use of fossil fuel  began in earnest some 200 years ago. Conservation is countered as new applications for energy are found and emissions have escalated.

 We know plants take carbon dioxide from the atmosphere and combine it with water to produce food. Carbon is cycled continuously through  the environment by life on earth.  Our knowledge of the cycle provides us with  insight to tackle management of greenhouse gases head on.

This figure, from the Intergovernmental Panel on Climate Change (IPCC) provides an overview and indicates  it’s  magnitude. It is deemed the “natural” carbon cycle. Carbon is the common accounting currency of the materials involved. Carbon stores are shown on these figures in billions of tonnes of carbon. Annual flows are indicated with  arrows in billions of tonnes.  The atmosphere contains 730 billion tonnes of carbon in the form of carbon dioxide. Living plants contain about 500 billion tonnes of carbon.  Soils store about 1500 billion tonnes.  Fossil fuel stores are around 3000 billion tonnes. Humongous amounts of carbon are dissolved in the ocean and stored in rocks.. About 120 billion tonnes of carbon is cycled between the land and the atmosphere annually thanks to plants and photosynthesis. Similar processes take place in the ocean, and carbon dioxide is exchanged with the atmosphere.

This subset of the cycle quantifies carbon input from fossil fuels and land use changes. It is  called the human perturbation by the IPCC. It shows 5.3 billion tonnes being added to the atmosphere from fossil fuel burning. Humans are converting some land to different uses  adding another 1.7 billion tonnes to the atmosphere.

Here we see more detail on the fate of the 120 billion tonnes of carbon taken up annually by plants. Half  is almost immediately used for food by the plants themselves, returning carbon to the atmosphere. Nearly another half (55 billion tonnes carbon) is co-opted by animals and other organisms and ultimately returned to the atmosphere.

Ocean plants absorb   about 100 billion tonnes of carbon from the water. They and other organisms return most through respiration and decay. The net addition to the atmosphere from the   ocean is about 2 billion tonnes annually.

Consideration  of the carbon cycle raises some questions. Does division of the cycle into “human” and “natural” components tend to excessively  focus on   fossil fuel use as the “problem”? A recent paper addressed human  influence on climate through the development of agriculture. The author concludes humans began to influence climate nearly 8000 years ago. Humans cultivate 10 to 15% of land – and we control forests. We appropriate about 40% of plant production. It follows that we are responsible for 24 billion tonnes of the 60 billion tonnes of carbon incorporated by plants annually. Contrast that with the 6 billion tonnes from fossil fuels. Thinking about the carbon cycle suggests opportunities to better integrate our energy use with management of carbon.

Some organizations promote renewable energy as the ultimate greenhouse gas solution. They invariably avoid telling us  the rotation of the earth and the vagaries of weather make both solar and wind energy intermittent and unreliable. They don’t mention fossil and nuclear generators take up the slack when wind turbines are taking a break. They don't tell us extensive reliance on renewables requires expensive excess capacity, storage systems and alternate generation. Establishing those systems will compel us to use even more energy thanks to the inefficiencies introduced.

We are considering separating the carbon dioxide component of fossil fuel exhaust gases and sequestering it by pumping it back into the ground. These concepts  will require increased energy use for separation and pumping.

A proposal from the 80’s suggested a scheme to remove carbon from the atmosphere. The ocean is fertilized with iron to increase plankton growth which dies and sinks to move carbon dioxide away from the surface.  Carbon dioxide would be replenished from the atmosphere. Tests are underway. If this scheme works another new energy using industry could evolve.

Nuclear energy is often forgotten in the climate change debate. So is agriculture. Our review indicated it’s a four times bigger factor in the carbon cycle than fossil fuel. Could we modify agricultural  technology to help remove carbon  from the atmosphere?

Some carbon absorbed by plants  is deposited in the soil. Large quantities have been trapped over millennia. No-till farming practices are cited as one means of keeping carbon captured by plants sequestered in the soil to form a carbon sink. Animal wastes can also contribute. So far this carbon sink technology is fraught with uncertainty. How much plant  material left on the land is incorporated in soil? How long will it stay there? Will the carbon content of soil reach equilibrium and absorb no more?

Durable long lasting carbon is found in soils. Some of this is simply charcoal, presumably from forest and grass fires and has been there for centuries. Unusual charcoal  rich soils have been found in the Amazon basin.  This soil was most likely man made.  Some scientists suggest it was deliberately produced by a variation of slash and burn agriculture.  It remains highly productive centuries after it was formed.

Several organizations are proposing to produce charcoal from agricultural wastes as a soil amendment. One proposal generates energy and adds fertilizer as shown in the slide. Conversion of a fraction  of the wastes from our 24 billion tonnes of agricultural production into long lasting charcoal  could  help counter the 6 billion tonnes of emissions from fossil fuel. We burn fossil fuels to release carbon dioxide. Plants absorb it.  We heat plant material to establish a durable carbon sink which enhances the soil.

Nuclear energy provides beautiful images  too. This one shows two recently completed CANDU 6 reactors in China. We are reminded of human interaction with the  environment. The sky is hazy. The water is brown from  soil. We often promote  nuclear energy simply as a greenhouse gas free substitute for other fuels. It is more than that. The examples we’ve just discussed indicate energy is needed to manage carbon. The integration of nuclear energy into control of the carbon cycle can turn it into  a creator of  carbon sinks.

So – called known  reserves of nuclear fuel would supply world energy needs for only a few decades with current once through fuel cycles. Doug Lightfoot reminded us of this yesterday. Detractors conclude nuclear energy is insignificant to world energy needs. Fortunately, there are many alternatives to expand nuclear fuel supply . One is to simply find more and expand the quantity of “known reserves”. Advanced fuel cycles, thorium, the Monju breeder reactor prototype, nuclear energy futures, hydrogen and water desalination have all been discussed at this symposium. I take that as evidence the nuclear industry recognizes the challenge and is ready to take it on.

In summary, we may need to control atmospheric greenhouse gases if human development is to be sustained. Many have been convinced this is simply a matter of improving efficiency and conserving energy resources. Experience tells us that approach is inadequate and will fail. We will need to keep our focus directly on control of greenhouse gases to succeed. Nature has developed means to manage the composition of the atmosphere. The carbon cycle provides insight as to how it is done. Humans can help.   We will need to use even more energy.

James Lovelock came up with an interesting hypothesis when he worked with the National Aeronautics and Space Administration.  He suggested the existence of “a complex entity involving the Earth's biosphere, atmosphere, oceans, and soil; the totality constituting a feedback or cybernetic system which seeks an optimal physical and chemical environment for life on this planet." This later became known as the “Gaia” hypotheses after the goddess of earth from Greek mythology.  Perhaps we more often refer to Gaia as Mother Nature. Some say humans are using and abusing Gaia. I wonder if Gaia is using us to maximize her influence and productivity.