ASSUMPTIONS
What about sunlight? What about the oceans? What if respiration is not constant but is temperature dependent?
Clearly there are limits to the rate of growth of plant matter. If plants are already using all the available light or all the available nitrates then the rate of growth cannot be increased further. This places a limit to the quantity of plant matter that can exist on the Earth. These equations assume that plants are not at the stage where their growth is limited by the supply of some mineral. It is assumed that a plant's growth is only limited by its size (big plants grow faster) and the availability of sunlight.
In addition:
Sunlight is already incorporated inside the affinity factor. Sunlight, mineral supply and the activities of every living species, determine the value of A for the Earth. If there were more sunlight and minerals then A would be a bigger number than it is. Similarly if we build a road where plants cannot grow then we have reduced the size of A.
You are probably, at this stage, having difficulty understanding how 'A' can simultaneously represent two different physical phenomena. How can it represent the affinity of an enzyme for a molecule and also the Gaia of the Earth? Fortunately physics has provided us with an analogy. The kinetic energy of a molecule of a gas (microscopic variable) describes how fast the individual molecule is moving. Yet the average of all the kinetic energies generates a property called temperature (macroscopic variable). So a number that applies to one molecule when averaged over a group creates a quantity that describes a property of the group.
A ballpark figure for A is around 50/kPa years. (New units especially inverse units are always a pain to mentally assimilate but here you just have to remember these figures: 50 /kPa years means the Earth can sequester 1 Gt of carbon each year and 25 /kPa years means the Earth can sequester 0.5 Gt of carbon each year. This is true while the atmosphere is out of equilibrium by .01 kPa. If the atmosphere were to be allowed to correct itself, the amount of sequestration will diminish as equilibrium is approached.) This is a measure of the fertility of the Earth. It determines how fast the plants can grow and sequester to achieve an equilibrium level of CO2. This value is dictated by: solar output, ozone levels, the temperature of the atmosphere, the availability of minerals in the soil, the currents in the ocean, the diversity of the plants and animals: anything that affects the plants' ability to grow and spread (even spreading in to new habitats - so the rate of mutation is a part of the fertility of the planet).
An analogous concept is horsepower. The horsepower of a vehicle, as measured by the rate at which it can climb a hill, is determined by many factors, these being: the cubic capacity of the piston displacement; the size and timing of the valves; the efficiency and timing of the spark plugs; the friction of the oil; the aerodynamic shape of the body; the inflation pressure of the tyres and many other criteria. Any one of a thousand different factors will affect the effective power of a motorcar. Similarly, any one of a several billion factors will affect the fertility of the Earth.
OCEANS
TEMPERATURE
The plot above shows two curves produced by a computer program. The lower, allows for respiration to be temperature dependent and the higher plot is produced when respiration is independent of temperature. If the purpose of the model is simply to demonstrate that rubisco is a regulator then we can assume that respiration is independent of temperature. If at some stage we wish to extend the model then we may desire to make some allowance for temperature dependent respiration.
THE MATHEMATICS OF HOW RUBISCO WORKS TO RETURN THE ATMOSPHERE TO THE EQUILIBRIUM LEVEL
If the species distributions are static then rubisco will work to maintain the equilibrium level. The equilibrium level is set by the rate of sequestration and the rate of release of CO2 by volcanoes and the actions of decomposers such as termites and fungi. If volcanoes increase in activity, CO2 levels will rise, and rubisco will become more efficient. More energy will be fixed into carbohydrate and more carbon will be sequestered. The CO2 level will begin to fall as long as the mineral cycles can keep up with the demands of the plants. Rubisco does not determine the equilibrium level, it just helps ecosystems return CO2, to the equilibrium level.
To reduce confusion the term "target level" will be used to refer to the CO2 level that rubisco is aiming for. If we are talking about an Earth with a particular set of plants and animals then the terms "target level" and "equilibrium" become interchangeable. The mathematics below only applies to the model.
This particular model is accurate if plant mass is increasing but not directly applicable if plant mass is not increasing. Essentially we are looking at the mathematics of those spinning balls (the governor) on a steam locomotive which ensures constant rate of motion no matter what the slope of the track.
If we let t approach infinity in equation 5 then
R= D/(A*P) is the stable carbon mass of all plants when the target level of CO2 has been reached. It is important to notice that this value depends on the initial conditions. If at time zero there is a lot of CO2 in the atmosphere then the stable level of R will be greater than if the atmosphere initially contained less CO2. This is not the situation that exists in the real world. In the real world, plants and animals have evolved a means of sequestering carbon in non-living material, e.g. xylem or calcareous shells. This improves conditions immeasurably and this fact is not taken into account in the two differential equations. Without this assumption the equations need a term for sequestration, become much less flexible and more difficult to solve.
The original purpose of the mathematical attack was to give some support to the computer simulation. However the mathematical exploration once begun, yielded an insight that was totally unexpected – the fertility of the Earth.
If we let t approach infinity in equation 6 then we have an expression for the stable partial pressure of CO2.
C= P*K2 - D/A This is only true at target level
Now D = A*P*K2 - AoO - Resp
C target level = (Resp + Ao * O)/A equation 7
We can see that the target level of CO2 in the atmosphere is determined by:
The magnitude of the respiration variable (the animal community has a moderate say in this)
The partial pressure of oxygen
The ratio of the affinities of the rubisco enzyme for oxygen and carbon dioxide
(These three factors which determine the target level had me bamboozled. In the computer models my brain was happy to accept that the amount of carbon in the atmosphere was controlled by net sequestering activities of plants and animals. Yet the mathematical model dictated that the equilibrium level was determined by the three factors above. My brain accepted both as truth even though both can not be true. The resolution to the problem arises when we realise that in the real world the amount of plant matter 'R' does not change, it always stays at around 2Gt.)
MODELS
All theories are models because all theories are simplifications of reality. These simplifications allow us to see the wood from the trees. Supercomputer models of climate are very complex and valuable tools. Improvements are made on a daily basis but any climatic prediction more than five years into the future can be taken with a grain of salt. The truth is that we do not yet, know enough about how ocean current circulation will change. With warmer oceans, how will the flux of CO2 change? Dimethyl sulphide is the principal sulphate aerosol, its release by coccolithophores seems to be at the mercy of viruses and grazing micro plankton. How can we program this into our supercomputers when we don’t really understand what is going on? This does not mean that supercomputer models of climate are a waste of time, it just means that a lot more sophistication is required. The success of any model depends on the truth of the data that we program into the model. While we can be confident about our understanding of physics and chemistry, the physics and chemistry is at the mercy of the biota. The surface area of the atmospheric-water interface in living systems is estimated to be 200 times that of the ocean-atmospheric interface. So if we are calculating the rate at which co2 dissolves into the ocean then we must also allow for the gas rapidly moving into and out of terrestrial organisms and the movement of groundwater into the ocean. In a prediction of future climate we would need to know which species are going to survive and their exact roles in all mineral cycles - information we are never likely to possess.
THE MEANING OF A
Although I have already explained the concept of A as representing the Gaia of the planet, you might not be convinced. There has to be some mathematical basis for this concept. The Gaia of the Earth is a number that describes how fast the plants and other life forms can get the carbon dioxide levels back to equilibrium whenever some disturbance upsets the carbon dioxide levels. Think of this analogy: R is the number of workers and A is their average level of skill. To work out how long a project might take to be completed we multiply R and A to determine the level of productivity. In this model R is the total carbon-mass of plants (excluding cellulose) and A, indirectly, represents a number describing how fast these plants can grow.
Let us apply the model to the whole biosphere. To do this we only have to make one assumption.
- Assume that the Earth is nearly full of plants. When extra growth occurs because of a rise in CO2 some new growth will go into sequestered carbon and some into protoplasm. Animals will quickly consume the protoplasm because animals have such prodigious powers of reproduction. These animals will themselves be consumed by something further up the food chain. The result will be that more carbon is sequestered. Eventually all the extra carbon will be sequestered. If this assumption is wrong, resulting in a permanent extra level of plant protoplasm, a greater increase the use of minerals arises, necessitating faster supply of iodine, copper, cobalt and other elements. Coordinating all the mineral cycles just to deal with a bit of extra CO2 is somewhat of a big ask when keeping plant protoplasm as a constant level is a much easier option.
dR/dt is the rate of growth of plants. Delta C( δC ) is .01 kPa. It is the imbalance in the CO2 level. The current CO2 level is 0.0380 kPa. The equilibrium should be 0.028 kPa as determined by the set of organisms that currently inhabit the Earth. This was the gas level in 1830 AD prior to the industrial revolution. (This argument assumes that Man is the same species today as he was in 1830. Genetically he is the same but from and ecological perspective he is a different species because his interaction with other species has changed so dramatically.)
If we assume that the Earth is long-term sequestering 1 Gt of carbon each year then we can set dR/dt= 1.0
We set the sequestered carbon to what R, should change by, even though R does not change. In the real world R does not change, probably because the Earth is full of plants. The equation does not consider sequestered carbon, so to work around the problem we set sequestered carbon to the change that would have occurred in R.
1.0= R*A (.01) The Earth is working 100 ppm (.01 kPa) outside of the equilibrium value and until the mass coral bleaching began, it seemed to be coping (ignoring other activities such as deforestation)
R*A = 100 Gt/ kPa yr
Now we must ask ourselves where does the value of 100 come from? The answer is obviously the fact that the Earth can, in its present condition, extract an extra 100 Gt of CO2 per year from the atmosphere when CO2 rises by 1 kPa, or in keeping with realistic movements of CO2, extract an extra 0.1 Gt of CO2 for a rise of .001 kPa (approximately 10 ppm). So we have R*A = the potential to increase the rate of extraction of carbon dioxide as carbon dioxide levels rise.
Let us consider the factors that might affect this "potential for increased extraction". We might consider the following: What if the Earth had no bees? Then the rate of pollination and the number of seeds that set would be reduced. After a large forest fire, CO2 levels would rise above equilibrium. The speed at which growth can proceed depends on the fertility of the soil and the rainfall. Growth in the burnt regions cannot proceed until the seeds are spread into these areas. Without bees, the trees will set less seed. The process of colonisation will be slower and the return of the atmosphere to equilibrium will take longer.
Now R can be calculated by measuring the total dry mass of plant matter (excluding cellulose). So we can place a new (global as opposed to microscopic) interpretation on the numerical value of A. We can take it as a measure of the quality of the Earth or the power of living things to balance the atmosphere. This is the same as a measure of how much plants can increase their growth rate in response to an increase in CO2. But not all of this increased growth will be due to the rubisco enzyme working more efficiently. The extra growth that takes place will depend on the supply of rain and minerals. If the plants run out of nitrogen then extra growth is not possible - so the efficiency of the nitrogen cycle is important. The Gaia of the Earth (A) and the total carbon-mass of plants (R) combine to determine how fast carbon dioxide can be adjusted.
The sequestering ability of a whole ecosystem is a product of the myriad of interactions of the species. If we knock down a forest then within a few years most of chlorophyll has returned. The chlorophyll may not be in the leaves of trees, it may be in weeds or grass. The problem is that the fertility of the ecosystem may only be a fraction of what it was. The new plants (pioneer species) will not be able to grow very fast if the topsoil has washed away. These new plants being small will not have the carbon sequestering ability of a fully functional forest.
Every time we build a city and exclude plants from places where they can catch sunlight, we reduce the value of A and R. If we only chopped the plants down and did not build the city we would only be affecting R and not A. When we pour the concrete, then we are reducing future potential for growth, so we are reducing A as well.
To push the car analogy a bit further: the horsepower of the engine depends on the number of cylinders and the efficiency of the combustion process. If someone disconnects a spark plug lead, then the horsepower is reduced. No permanent damage to the engine results and the damage can easily be repaired. This is analogous to cutting down some trees or mowing the lawn. If however the engine is seriously damaged by wear on the rings then the engine is less efficient until it is totally rebuilt. This is analogous to pouring concrete to build a city or causing the extinction of a species of bird or allowing top soil to be washed away. The damage lasts until the city is removed, or a new species evolves to perform the job that the bird previously did, or leaf litter regenerates the soil.
Every time we reduce the population of a species that helps a plant to grow we reduce the value of A. For example, supposing ants became less numerous, then the porosity of the soil would be reduced and less water would penetrate into the soil. The rate of growth of plants would be slowed. "A" is calculated from the rate at which plants extract carbon from the atmosphere. If any species becomes extinct and that species helps a plant to grow and sequester carbon, then the value of A will be reduced.
THE DEFINITION AND CONSTANCY OF R plus more
The definition of this variable is somewhat arbitrary. It is designed to be a measure of the carbon-mass of plant matter. In the mathematical model the definition is easy – if CO2 enters the plant and stays inside then R has increased in size. When the model is adapted to the real world some difficult decisions have to be made. We have to distinguish between sequestration and growth and unfortunately there is no clear method to make this distinction. The problem arises because there is no hard definition of sequestration. When a plant uses carbon to make a compound then the carbon may stay out of the atmosphere for twenty minutes or one hundred thousand years depending on happenstance. So we need to make an arbitrary decision whether formation of cellulose is a form of sequestration or growth. I argue that since cellulose is not recycled quickly and has no maintenance demands for energy it belongs in the sequestration category.
The value of R, rose to some maximum value, very early in the Earth’s history as the first cyanobacteria conquered all the available habitat. Subsequently, the amount of plant matter rose much more slowly as evolution of new species was needed to invade new types of habitat or convert non habitat into suitable space. One could speculate that most of the Earth was conquered by some sort of plant within 500 million years of the origin of the first cyanobacteria. The value of R today (guesstimated to be around 2 Gt) is more or less constant.
The Earth has been full of plants for around three billion years. For much of this time the plants were much more primitive than modern terrestrial species that inhabit the globe today. Over time the living things have become more diverse, more complicated, and more sophisticated. We can actually devise a means of measuring this sophistication. Whereas the Gaia is a number that measures how fast CO2 can be adjusted, Sophistication is measured by how fast the planet can adjust the Earth's radiance. The mean radiance of the Earth is currently around 230 watts per square metre. The living things can adjust this number by changing cloud cover, greenhouse gas content of the atmosphere or species make-up of forests and grasslands. So the Gaia is just one component of the Sophistication of the Earth.
(missing graphic -nasa image of the earth in the infra-red spectrum. Having difficulty uploading image)
Quiz Time:If the ability of the Earth to change the albedo and infra-red emissivity was measured via changes to the radiance, what would be the metric units of Sophistication?
THE MOST IMPORTANT EQUATION IN OUR PART OF THE UNIVERSE
It is time E = mc2 was demoted from first place in the mind of popular imagination. Here is an equation that may stop man's insane attitude to growth.
delta Seq = R*A*δC (equation 16)
Where
delta Seq is the rate at which the atmosphere is corrected. It is directly proportional to the rate of photosynthesis of plants
A is the Gaia of the Earth. (a number representing how fertile the Earth is per gigatonne of plant carbon)
R is the carbon mass of all living plant cells. (it does not include sequestered carbon such as cellulose in xylem)
δC is the imbalance in the Earth's atmospheric carbon dioxide determined by our assumption that the atmosphere was in balance in 1830 and that the same set of species is alive today. It does not matter that some species have become extinct, I’m just trying to explain what the mathematics means.
This equation is not startling at first glance. It simply says that the rate of correction of the atmosphere depends on three factors: the total living plant mass, the fertility of the Earth and the imbalance in carbon dioxide partial pressure. This equation is only true for small deviations from the equilibrium value of CO2. Rubisco can only increase growth when there are no other factors limiting growth such as the supply of minerals. Equation 16 is just as valid in a greenhouse growing tomatoes – to grow a lot of tomatoes it is necessary to have: a large number of plants, a high CO2 level, and all the conditions for high fertility such as fertiliser, temperature and light.
What is important is the meaning we give to this simple little equation. The fossil fuel industry will simply say "… you are telling us that carbon dioxide is food for plants; we knew that." What needs to be explained to the fossil fuel industry and everyone else, is that the Gaia of the planet can rapidly change. The death of large areas of Indian Ocean corals in 1998 is the portent of our future. The next big El Nino will probably wipe out most of the Pacific corals. This may knock the Gaia down by a large amount but my computer model predicts a scenario where dying coral actually give us a bit of breathing space in the short term but comes back to bite us in the long term. If the Atlantic conveyor shuts down and Europe freezes over, then the Gaia will drop some more. If this sort of scenario becomes reality, then humanity will be well primed to understand the concept of "Gaia of the Earth". The tomato greenhouse offers a graphic analogy – if the humans are taken out of the greenhouse then all the work is left undone. How many tomatoes are going to grow if the fertilising, weeding, spraying and planting are not carried out – all these tasks have to be done or the environment becomes infertile. As the animal life becomes extinct on this planet there are a lot of tasks that are not going to be completed.
To illustrate this point a little further. Japanese fisherman are having enormous trouble with the numbers of jelly fish that are filling their nets. Biologists see the obvious cause of the problem: too few predators of the jelly fish larvae. If you remove the sardines from the oceans don't complain when jellyfish populations explode.
According to Santo Bains of Oxford University (Nature volume 407 page 171) global temperatures soared around 55 million years ago when volcanoes pumped huge volumes of CO2 into the atmosphere. Bains concludes from barium sulphate in ocean sediments that very strong planktonic growth followed for 60 000 years and brought levels back down. However this data does not throw much light our current predicament because we need more information. How hot did the atmosphere become? How much CO2 was released and at what rate? To what extent were the ecosystems disturbed?
As with all laws, equation 16 is an approximation to reality. This does not reduce its importance. Maxwell's equations are not valid for atomic scales and have to be replaced by quantum mechanics to explain the behaviour of electrons in atoms. Newton's laws take no account of relativity. Equation 16 demonstrates to us that the Gaia of the Earth is measurable and it is a construct of all living processes. If minerals are recycled quickly, if plants can live in all habitats and if plants and animals can sequester carbon, then life can manipulate the atmosphere to maintain a habitable planet. When A for the whole Earth is large ~ 50/kPa yr then the atmosphere can be manipulated rapidly, when A is smaller ~ 20/kPa yr then the atmosphere is manipulated more slowly.
DEFINITION OF LIFE AND THE NEW FOURTH LAW OF THERMODYNAMICS
Many scientists consider that we do not yet have a satisfactory definition of what life is. Perhaps we have been overlooking something, something that should have been obvious. The Gaia Hypothesis states that life controls the planet. Taking the inverse of this statement we arrive at: Control of the environment is a feature of living things. This is the original assumption Lovelock made when working at the Jet Propulsion Laboratory - the idea, however, in his subconscious was probably less forthright and more along the lines "living things betray their presence by changes to the environment."
Consider this list of characteristics of living things taken from my school textbook, Science for High School Students copyright 1963, containing 1040 pages and weighing 2 Kg.
Movement
Responsiveness
Assimilation
Growth and development
Reproduction
The eminently qualified people who wrote this tome would have been well aware that: plants produce oxygen; plants shade the soil and produce leaf litter; animals defecate; worms move millions of tonnes of soil; bacteria assist in the weathering of rocks and bacteria drive the nitrogen cycle – to name but a few of the many ways living things affect the environment. But not one of the authors saw fit to consider, that changing the environment, is an important property of living things. Why? Over fifty of Australia’s leading scientists and science educators of the 1960’s could not see this obvious piece of induction.
The Second Law of Thermodynamics permits the possibility of life on Earth because the increasing order on the Earth is paid for by the increasing disorder of the sun. We need a fourth law to help us understand how life arises. Just how this law could be formulated mathematically requires some imaginative thought. (See fourth law link not available yet)
This new law needs to explain the logic of evolution and Gaian theory. Those who understand evolution find the development of adaptations and increasing diversity perfectly logical in terms of natural selection. Lovelock has been attempting to persuade the scientific community for thirty years that living things evolve cooperatively. As previously stated, the mental hurdle that we have to overcome, is: how can a new adaptation, that does not immediately benefit the individual, help it to survive? Early last century Erwin Schrodinger showed that electrons could tunnel through a potential barrier. His mathematics predicted something that had never been observed. Today we have the science in the reverse order (the normal order in which science is done): we observe (in this special case we 'infer') life doing something strange (life beginning from the inanimate) and we need the mathematics to explain how it can be done.
Translated into words the new Fourth Law of Thermodynamics says, "If life can evolve then it is most likely that it will evolve. This will happen because life is that system which is able to adjust its own chemical conditions and therefore able to propel its own development." With this law we can argue more convincingly against the hypothesis that life began in outer space. I have no deep-seated objection to life beginning in space but I’m suggesting that it is more probable for life to begin on Earth. Life must modify its environment as it progresses (to optimise its physical conditions e.g. temperature). It seems more likely to me that the first chemical interactions could modify the local physical conditions on Earth (be they underground or in a lake) more easily than modifying the conditions on some asteroid or gas cloud in space. If ninety percent of evolution, can occur on Earth as documented by the fossil record, then it seems likely to me that the first ten per cent of evolution also occurred on Earth.
GREENHOUSE DEBATE
How much evidence is needed to convince governments that it is time to take radical action to curb greenhouse gas emissions? Economists are keen to use forests (so called carbon sinks) so they can maintain coal dependent economies and standard of living. In fifty years when a forest has absorbed most of the carbon that it can, it ceases to be a carbon sink. Then what do we do? (In the words of Pieter Tans "it's difficult to conceive", his response to the suggestion that the biosphere could absorb greenhouse emissions). What if the forest burns down? Does the individual or company that sold the carbon credits pay back the money? More interestingly, to whom are the credits repaid? Carbon trading is a nonsense because there are no long term fail-safe carbon sinks that are available to mankind. Sequestration of carbon dioxide from coal burning power stations by pumping the gas into underground storages is never going to be competitive with wind and solar energy.
Polar ice cores indicate that the levels of greenhouse gases in the Earth's atmosphere have closely paralleled the changing climate over at least the last 250,000 yr. (Barnola et al.) The graph from Vostok ice cores is totally convincing. Keep in mind that knowing the cause of climate does not mean that we can predict all aspects of climate, such as ocean currents. (missing graphic shows temperature of the atmosphere and CO2 level for the past 300 000 years)
Diagram from http://www.noaa.gov/
Other ice cores have extended the data back to a period of 600 000 years.
Some of the other aspects of climate need to be elucidated. We still have to understand the mechanisms involved in cloud formation and ocean current/plankton dynamics. Understanding climate, as difficult as it has been, is only the beginning. The greater and more difficult task that lies ahead is understanding how all the species interact to manipulate the production or management of: dimethyl sulphide, growth on coral reefs and other feedback mechanisms of which we are totally unaware.
Much of the data is coherent but some mysteries remain. Why were the Ordovician and the Jurassic cool when the proxies for CO2 suggest this gas was high in concentration? Are the proxies to be believed or were other factors responsible? Our understanding of the Jurassic (205 – 135 mya) atmosphere is less evidenced based than the extensive work of Barnola that ties CO2 to climate.
The decision to avoid fossil fuel will not be made as a result cogent argument from the scientific community because the fossil fuel lobby is too powerful and our technological society is predicated on cheap energy. The scientific community has done all that it can. The decision will be a result of the weather and rising sea levels. Changing climate will disrupt food production and water supplies. Rising sea levels will drown all low lying coastal cities. We can only hope that when the real commitment to avoid carbon as a source of energy takes hold of public consciousness, that starvation has not pushed the world into armed conflict.
The northern summer of 2002 witnessed the worst forest fires in the history of North America. Hurricanes Katrina and Rita are harbingers of warmer oceans. When similar or even more severe storms return in the near future, the lesson will be learned. However the transition to alternative energy will take at least ten years and the recovery of the atmosphere will take between 300 to 5000 years depending on the actions of mankind.
If the Earth can sequester 1 Gt of carbon per year (nobody knows exactly what the figure is) and if all fossil fuels were banned, then most (80%) of the excess CO2 would be extracted in around 300 years. The process is asymptotic and it would take quite some time to make it all the way back to 280ppm. Realistically we do need to maintain an airline industry and carbon based fuels will be convenient is some small special niches. If we allow the airlines 0.3 Gt of carbon emissions then it could take several thousand years to restore the atmosphere. But this means the melting of all ice and a sea level rise of 80 metres.
The Greenland sheet is melting at an astonishing rate, it contains enough ice to raise sea level by eight metres. The western Antarctic ice sheet could, and probably will, break up within 100 or 200 years raising sea level by another eight metres. This estimate (100 - 200 years) is based on the only information that is available. Fourteen thousand years ago the western shelf was much larger. It broke down to its present size over a 500-year period, in response to a rise in CO2 levels of 50 ppm. The sea rose 130 metres. Since the industrial revolution CO2 has risen another 100 ppm. Will increases in snowfall at the poles compensate for increased rates of melting and ice calving at the edges? No. Over the past few years the GRACE satellites are measuring 132 (Western Sheet) 57 (Eastern Sheet) and 195 (Greenland), for a total of 384 cubic kilometres of ice melting each year (Nature Geoscience November 2009). But even these figures appear to be out of date. The graphs below show the melting rate from 2007 to 2009 has been close to 500 cubic kilometres per year. The IPCC is predicting half a metre of sea level by the end of the century. However this prediction is far too conservative according to the CSIRO and does not consider the possibility that large parts of the western ice sheet can break up rapidly. The Pine Island and Thwaites glaciers could rapidly collapse and melt.
Figure 1 shows the ice mass changes in Greenland for the period April 2002 to February 2009. The blue line/crosses show the unfiltered, monthly values. The red crosses have seasonal variability removed. The green line is the best fitting quadratic trend.
Figure 2.
Figure 2: Time series of ice mass changes for the Antarctic ice sheet estimated from GRACE monthly mass solutions for the period from April 2002 to February 2009. Unfiltered data are blue crosses. Data filtered for the seasonal dependence using a 13-month window are shown as red crosses. The best-fitting quadratic trend is shown (green line). From Velcognia 2009.
Long-term climate predictions are fraught with uncertainties. The Gulf Stream delivers enormous quantities of heat to Europe. Ice core and other studies in Greenland suggest that the Gulf Stream has in the past, shut down. This brings colder conditions to Europe and ultimately affects the Earth’s albedo. So it is possible that Europe could get colder while the tropics become unpleasantly hot. In this scenario with the ocean conveyor shut down, the ocean produces much less food because the up-welling of cold bottom water stops. In this condition it is possible that the oceans become anoxic cesspools. The oceans currently produce around 90 million tonnes of fish annually for our dinner tables. What will be the size of the catch if the ocean conveyor shuts down?
Using physics and chemistry and ignoring biology to model climate is total folly. It’s like trying to predict the future of a city by calculating the rate of weathering of concrete and rusting of iron while ignoring the activities of man. It is the activity of all living things that determines climate and how these living things manipulate physics and chemistry. As the climate changes the distribution and numbers of species changes and this feeds back into climate and affects the species again.
FUTURE CLIMATE
There are at least three possible advantages for the Earth developing a climate with large volumes of ice at the poles.
- The potential to accelerate the angular velocity of the Earth and possibly regenerate the magnetic field. This might not be theoretically possible.
- A rapid response to changes in the solar constant. While unstable systems are delicate to control they have quick response times. If the solar constant is not as constant as we think it is, then keeping the Earth in a critical state with a large volume of ice and more importantly, ice cover, provides a means of responding rapidly. If solar output increases, the Earth heats up and ice melts, heating the Earth even more. This opens up habitat for plants that sequester more carbon e.g. expansion of the taiga forest. An unlikely piece of logic but we have to be prepared to think outside the square.
- A means of achieving an average ocean temperature which is suitable for creating a global thermo-haline current. This current is important to the fertility of the ocean and land, allowing total photosynthesis to be maximised by establishing global or large regional climatic systems such as the monsoon. It assists in CO2 control by providing a rapid means of taking the gas down to deep bottom water. (missing graphic is an energy versus temperature diagram for the earth. It is a an arc convex side upwards, and shows the quantity of energy that living things have to manipulate to change the temperature of the atmosphere. The energy is used to either to melt ice or extract CO2 from the air. Both are achieved by plants taking CO2 from the air or respiration of organisms bringing CO2 out of storage eg bacteria acting on soil carbon.)
Life can remain stable at any position on the curve, as long as it is cool enough so that plants can grow. The graph implies that some force is attempting to move the Earth to the extreme right or left but this would only happen if ecosystems change. The change could be randomly generated such as the evolution of an upright walking ape or it could be the result of a genetically programmed cycle. Given the appropriate set of organisms the planet could be stable at any position on the upper part of the curve. The Earth managed to achieve a temperature of around 14 degrees C because it has developed genetic program to manipulate CO2. Glacial cycles may be part of this genetic program. A possible advantage of the Earth being located at the top of the curve would be a faster response time to a change in solar output. Location near the top gives a greater gene pool of both warm and cold ecosystems.
The new fourth law of thermodynamics provides a mechanism to explain how living things can use energy to improve their environment if given the luck, of a set of initial conditions that are favourable to the laws of chemistry. It does not guarantee the continuation of all species if conditions become unfavourable.
TWO HYPOTHESES
There is no shortage of energy in the universe or on Earth but the technology needed to harvest energy can be extremely sophisticated. There are two large sources of energy available to living things on our planet: sunlight and high temperature heat in the depth of the crust. Photosynthesis as performed by cyanobacteria is incredibly complicated requiring many sophisticated enzymes. Evolution of this feat needed around one billion years of development. At some stage, however, probably in parallel with photosynthesis, life also managed to develop a means of using underground heat. There are only two requirements needed to harvest this energy: marine organisms that form carbonate shells from bicarbonate in the ocean and a subduction process to take this carbonate down to the hot depths of the crust.
These two energy harvesting processes have totally different methodologies. Photosynthesis would have started out as a group process but today it has evolved into an individual process. Harvesting the Earth's heat remains a global process of patient cooperation.
Hypothesis One
Two hypothetical enzymes (they might have identical structure) softrockco and hardrockco with a structure almost identical to rubisco help balance the atmosphere. These enzymes control the metabolism of bacteria and possibly nanobacteria by dictating the rate at which CO2 is allowed to oxidise calcium oxide and calcium carbonate. The bacteria in rocks use this energy to perform vital processes in the mineral cycles. One of these processes is to even out pressure variations in CO2.
Reefs are eventually subducted into the Earth’s crust. Some million of years later, frictional heat performs the cement kiln process where the carbonate absorbs energy and decomposes into CO2 and calcium oxide. The CO2 enters the atmosphere as gas from volcanic vents. The calcium oxide reacts with other elements in the magma to form minerals such as plagioclase. These basic (basic meaning that the minerals react with water to form alkalis) minerals are a form of energy supply for bacteria in the rocks because the bacteria can extract the energy by using carbon dioxide to form calcium carbonate or magnesium carbonate. This allows the bacteria (probably a number of species working together) to act as a massive CO2 pressure regulator if they contain a molecule similar to rubisco that controls their rate of energy uptake by controlling the oxidation (using CO2) of the basic rock minerals.
So now we have two underground systems capable of removing CO2 from the atmosphere:
CaO + CO2 ---> CaCO3 mediated by the hardrockco enzyme ?
CaCO3 + CO2 + H2O ---> Ca++ + 2HCO3- mediated by the softrockco enzyme ?
Both of these systems give nature a method of smoothing out CO2 pressure swings and both are only possible courtesy of marine organisms that create carbonate. The presence of rubisco-like gene sequences in soil and archae bacteria has already been established but no one has been able to suggest what these enzymes do. To test the hypothesis we only have to show that both of these bacteria can crank-up their metabolic rates as CO2 levels rise. Without a specialist enzyme we would expect these organisms to adjust their metabolism in a somewhat linear fashion in response to CO2 pressure. If hardrockco and softrockco exist then we should see exponential increases in metabolism.
The two reactions above constitute part of what was considered to be chemical weathering. Schwartzman and Volk established that this process is accelerated 1800 times if life is present.
Although this hypothesis sounds preposterous because the net benefit to the environment occurs millions of years later, it uses exactly the same logic as all the rest of the Gaia hypothesis. If the enzymes ron (or equivalent enzymes), softrockco and hardrockco are shown in the laboratory to behave as I have predicted, the evidence for Gaia will be undeniable.
On learning that Philippa Uwins (University of Queensland) was studying nanobes in rock samples taken from kilometres below the seabed, I suggested to her that these organisms could derive energy from using CO2 to convert calcium oxide into calcium carbonate. Her reply was most encouraging. Electron micrographs revealed that the nanobes were much more likely to be associated with plagioclase rather than quartz and that kaolin booklets were located adjacent to the nanobes and plagioclase. So she agreed that it was likely that nanobes were using CO2.
Hypothesis Two: Coral keeps the Earth's magnetic field active.
The Earth’s magnetic field has been an enigma for many years, but Glatzmaier and Roberts have a computer model, the Geodynamo, which behaves much as the Earth's field does. This triumph of mathematics and computer power makes an amazing prediction that the outer core spins marginally faster than the mantle and crust.
The length of the day is controlled by currents in the mantle, tidal friction, coral reefs and ice. Reefs grow preferentially in warm waters near the equator and deposit their carbonate where it adds to the Earth’s moment of inertia, and increases the day length (by conservation of angular momentum). When ice at the poles melts some of the mass migrates to the equator and also increases the moment of inertia. As the crust and mantle slow down, this leaves the core spinning at a marginally faster rate. Does this effect have any influence on the magnetic field?
When Michael Faraday learned that electric currents could produce magnetic effects he asked himself if magnetism could produce electric currents. The law of electromagnetic induction was the result of his investigations. I don't know if relative motion between the core and the mantle can induce magnetism but if it does then gaian systems have probably developed the means of manipulating this effect. We can envision a scenario where a diminishing magnetic field upsets bird migration. The lack of birds reduces a marine herbivore leading to the proliferation of a highly sequestering algae, sending the climate on to a lower equilibrium of CO2. The actual situation will be far more complicated than this and most likely will involve the interaction of hundred of species over centuries, but at least we have some idea of where to start looking.
The figure below demonstrates that for most of its recent history, the Earth has been cool, reflecting a large amount of sunlight into space - not the behaviour that we would expect from a system that should be attempting to maximise photosynthesis. From this we can infer that other needs have taken precedence and there is a reason for this low average temperature.
We can note from the graph (NASA compilation) that when the climate emerges from a glacial cycle the curve is a steep continuous ascent. By contrast the descent is a series of descending steps. Whether this behaviour is essential to, or unrelated to generating currents in the outer core is unknown. From the average temperature change and the steepness of the rising curve we can infer that the transition from one part of the cycle to the other involves a large quantity of ice and a high rate of acceleration to the rotational velocity. Does isostatic rebound in the mantle have some beneficial effect to this wobbly pudding on which we live? (missing nasa graphic below of recent glacial-interglacial temperatures)
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