Climate Change on a Living Earth
Most of you will know by now the main conclusions of the greatly respected Intergovernmental Panel on Climate Change's, 2007 report and I am sure that we all are proud that they were awarded this year's Nobel Peace Prize together with Al Gore. The report itself speaks of the real possibility of severe climate change but it is written in properly cautious scientific language and gives the impression that global heating is serious but the worst consequences are avoidable if we take appropriate action now. Inevitably the conclusions of the report need constant revision in the light of real climate change. Sadly, even the most pessimistic of the climate prophets of the IPCC panel do not appear to have noticed how rapidly the climate is changing.
My first intimation that we might be on the brink of disaster came in May 2004 when my wife Sandy and I visited the UK's primary climate research centre, the Hadley Centre. It is a place of excellence and an important part of the IPCC. While there we talked with a range of scientists; some were concerned with the melting of ice floating on the Arctic Ocean, others with Greenland's vanishing glaciers, and still others concerned with global heating in the tropics. Later in the day we heard from Peter Cox and Richard Betts about the way that the great tropical and boreal forests were changing as the world grew hotter. And we talked of our own concern about the way the ocean life was disappearing as the surface waters warmed.
These climate scientists with whom we talked spoke of their observations and models of global heating in the regions that each of them were investigating. Taken separately, each of these regional investigations presented convincing evidence of positive feedback and accelerating change. They told of their research in detail but in a detached - properly scientific manner - almost as if they were describing some other planet, not the Earth.
This was in itself disturbing; much more so was the fact that those concerned, for example, with the melting of polar ice, although aware of a similar vanishing of the tropical forests, seemed to present their own research as something separate from the heating of the whole planet. There was also a tendency to present the whole Earth system as if it was no more than the simple addition of its parts. Something, I knew was rarely ever true of a dynamic system. Sandy and I left with a deep sense that what we had heard was truly serious and the visit profoundly changed my view of the future.
In defence of my friends at the Hadley Centre, I have to say that almost everyone concerned with climate change in 2004, and that included me before the visit, had this detached approach to climate research. We were worried, but there was no sense of pressing urgency. I must add that this was what we all perceived was the correct and objective way to speak.
When I looked at the IPCC report again - it was with a new sense of awareness - I now saw it as the scariest official document I have ever read. It was all too clear that the message from climate scientists was not reaching the public and especially not in the USA, this of course was before Al Gore presented his book and film. I now take an apocalyptic view of the future because I see 6 to 8 billions of humans faced with ever diminishing supplies of food and water in an increasingly intolerable climate.
You may well ask how we scientists have let this potentially disastrous future steal up on us unaware. There are several reasons: among them is our success at solving the important but more manageable problem of stratospheric ozone depletion; I suspect that it has given us false confidence in our ability to deal with the far greater and more complex danger of global heating. Another reason for the slow recognition of the threat of adverse climate change is the division of Science into almost unconnected specialties.
If you look back at the writings of Earth scientists 40 years ago you will find them confident that the composition and climate of our planet were completely explicable from chemistry and physics and that life was just a passenger. Life scientists of the same time were equally confident that organisms evolved according to Darwin's great vision and adapted to the Earth described by their Earth science colleagues in the building across the campus.
This harmful and irrational division of science is slowly fading but it still persists and has led to the deplorable separation of the assessment of global change between two different international bodies: one based on physical science, the IPCC, and the other on biology, the Millennium Ecology Assessment Commission. The Earth is not so divided and so long as we treat it as two separate entities, the geosphere for the material Earth and the biosphere for life, we will fail to understand our planet.
Forty two years ago I was working at the Jet Propulsion Laboratory in California and was given the wonderful opportunity to see at first hand evidence about the nature of Mars and Venus. They were quite obviously dead planets and quite different from our lush and lively world, almost as different as is one of us from a stone statue. The Earth has an atmosphere that is wholly unstable in a thermodynamic sense; gases such as oxygen and methane are massively produced yet coexist at a stable dynamic equilibrium. I introduced the hypothesis that life at the surface of the Earth regulates the composition and chemistry of the atmosphere so as to keep it habitable. My friend, the Nobel Prize winning novelist William Golding, suggested I call the hypothesis Gaia.
Later during the 1970s I developed the idea further in collaboration with the eminent biologist, Lynn Margulis, but we soon discovered that what we called the Gaia hypothesis was far from popular with scientists. Biologists were particularly outspoken and in the 1970s they rubbished the infant hypothesis in the mistaken belief that it was like creationism, contrary to evolution by natural selection. The demolition was so effective that even today few scientists are happy with the word Gaia and many still see it as mere New Age fantasy. I went on to refute their criticism with evidence of self regulation gathered from the Earth and by mathematical models that illustrated how planetary self regulation of climate takes place. Gaia theory is a top down, a physiologist's view of the Earth system, and sees the Earth as a dynamic responsive planet and it explains why it is so different from Mars or Venus.
In different times these arguments would have merely been part of the natural history of science. Now, they seriously interfere with the evolution of a proper understanding of the Earth system when we badly need it. We need it to understand the consequences of adding greenhouse gases to the air and equally the consequences of removing natural forests for farmland; each of these acts disable the Earth system's capacity to regulate itself.
Most of the large climate models used to predict future climates still rely mainly on atmospheric physics, and this includes the models on which the IPCC report is based. The influence of the clouds and the ocean are incompletely included and that of the Earth's natural ecosystems hardly at all. Present day climate models are good at explaining past climates but seem unable to agree on the course of global heating beyond about 2050, by the end of the century predictions vary over a wide range.
This stark view was reinforced in May this year by the publication by Rahmstorf and his colleagues ["Recent Climate Observations Compared to Projections", Science 4 May 2007: Vol. 316. no. 5825, p. 709] of high quality measurements of the rise in global mean temperature, sea level and CO2. These showed that even the gloomiest predictions of the IPCC were underestimating the severity of climate change now.
Slide 1. Rahmstorf et al ["Recent Climate Observations Compared to Projections", Science 4 May 2007: Vol. 316. no. 5825, p. 709].
In 2001 there was a serious attempt to bring the Earth and Life sciences together. At a major scientific meeting at Amsterdam in the Netherlands, over 1000 Earth and life scientists signed a declaration that had as its first point: the Earth System is a self regulating system comprising all life including humans, the atmosphere, oceans and surface rocks. My friends who were at this meeting wrote to tell me that Gaia was now endorsed in science. But in science as in all human affairs the perceived conventional wisdom does not change easily or quickly. At Amsterdam scientists acknowledged Earth System Science but continued to work separately as before. One day we will unite as a single science they said but not yet.
It is easy to see why scientists are reluctant to abandon their familiar and comfortable paths. Darwinian biology in the hands of the distinguished Fellows of this Society, William Hamilton, John Maynard Smith and our previous president Lord May, has been a wonderfully rich and productive branch of science. But just as Newtonian physics was found incomplete at the particle and cosmic scales, so Darwinism is incomplete when it tries to explain the world beyond the phenotype.
In particular it fails to see that organisms do more than adapt to a dead and fixed world. They are naturally selected in a world that was changed by their ancestors and in turn their interaction with the material environment sets the scene for the next round of evolution. The air the ocean and the surface rocks are all either direct products of life or else massively altered by its presence.
Our difficulty in understanding the Earth can be compared with that of understanding economics. The 18th century economist, Adam Smith, is respected for his intuition of an invisible guiding hand that makes rampant commercial self interest somehow work for the common good. Two hundred years later we face a similar paradox. We know that the Earth is a benign and comfortable place for life and has been so for most of its history; so how have selfish genes allowed the evolution of an altruistic planet? It is easy now to see how fit organisms are naturally selected but how can the common good for all life also come from natural selection?
What we have discovered through Gaia theory is that as the Earth system matures it keeps its climate and its chemistry always fit for life, and the invisible hand that regulates is feedback between its living and non-living parts. But this knowledge has only just entered the domain of science and is not yet conventional wisdom. It took a long time before we recognised that feedback between social and market forces can not be ignored, so I suspect that we face a similar slow learning process about our relationship with the Earth.
Meanwhile we are still trying to shape it to our ends and needs and we ignore, even disable, its own powerful guiding hand. In our hubris we believe that we can be stewards of the Earth long before we understand it; perhaps Earth science and economics have more in common than we used to think. A few weeks ago the distinguished ecomomist P. Dasgupta, compare the complexity and non linearity of economic systems with that of climate systems.
Slide 2 - Arctic ice melt
The long term history of the Earth suggests the existence of hot and cold stable states. What the geologists refer to as the greenhouses and the ice houses. The best known hot house happened 55 million years ago at the beginning of the Eocene period. In that event between one and two teratons (Tt) of carbon dioxide were released into the air by a geological accident. We are fairly sure about this from measurements made by Professor Elderfield of Cambridge University and his colleagues and from the researches of Henrik Svensen and colleagues of Oslo University.
Putting this much CO2 in the air caused the temperature of the temperate and Arctic regions to rise 8C and of the tropics 5C and it took about 200,000 years for conditions to return to their previous state. In the 20th century we injected about half that amount of CO2 and we and the Earth itself are soon likely to release more than a Tt of CO2.
Global heating 55 million years (My) ago took place much more slowly than now; the injection of gaseous carbon compounds into the atmosphere may have taken place over a period of about 10,000 years, instead of about 200 years as we are now doing. The great rapidity with which we add carbon gases to the air is as damaging as is the quantity. The rapidity of the pollution gives the Earth system little time to adjust and this is particularly important for the ocean ecosystems; the rapid accumulation of CO2 in the surface water is making them too acid for shell forming organisms. This did not happen during the Eocene event because there was time for the more alkaline deep waters to mix in and neutralise the surface ocean.
There are other differences between the Earth 55 My ago and now. The sun was 0.5 percent cooler and there was no agriculture anywhere so that natural vegetation was free to regulate the climate. Another difference was that the world was not then experiencing global dimming - the 2 to 3 degrees of global cooling caused by the atmospheric aerosol of man made pollution.
This haze that covers much of the Northern hemisphere offsets global heating by reflecting sunlight and more importantly by nucleating clouds that reflect even more sunlight. The aerosol particles of the haze persist in the air for only a few weeks, whereas carbon dioxide persists for between 50 and 100 years. Any economic downturn or planned cut back in fossil fuel use, which lessened the aerosol density, would intensify the heating. If there were a 100 percent cut in fossil fuel combustion it might get hotter not cooler. This is why I say we live in a fool's climate. We are damned if we continue to burn fuel and damned if we stop too suddenly.
It is not difficult to make a numerical model of a live Earth with an ocean and land biota taking an active part in climate regulation and then try the experiment of adding a terraton of carbon dioxide to the model world as we are doing. I did this in collaboration with the geochemist Lee Kump and we published it in the science journal Nature in 1994 [Failure of climate regulation in a geophysiological model by James E. Lovelock & Lee R. Kump, Nature 369, 732-734, 30 June 1994].
Slide 3 - shows that when the CO2 in the air exceeds 500 ppm the global temperature suddenly rises 6 degrees Celsius and becomes stable again despite further increases or decreases of atmospheric CO2. This contrasts with the IPCC models that predict that temperature rises and falls smoothly with increasing or decreasing CO2.
You may ask why we should take this model seriously when so many of the world's climate scientists are in agreement on the IPCC predictions. First, although simple, it is a model of the whole Earth system and not merely one based almost entirely on atmospheric physics. Perhaps the most important message from this simple model is its implication that the ocean ecosystems dominate the cooler periods of the Earth's history and the Land ecosystems the stable hot periods. Andrew Watson and Corinne LeQuere, both from the University of East Anglia, have led groups who report this week an adverse change in the carbon dioxide sink of the northern and southern oceans. It could be that the malign effects of stratification are extending in the surface waters of the ocean.
What I have so far said seems to imply that there is little that can we do to prevent the Earth System moving to the hot stable state but in no way do I mean that there is no hope for us. I see our predicament as like that faced by any nation that is about to be invaded by a powerful enemy; now we are at war with the Earth and as in a blitzkrieg events proceed faster than we can respond. We are in the strange position of living on a planet where climate and compositional change is now so rapid that it happens too fast for us to react to it. For this reason alone, it is probably too late for sustainable development. Enlightened living of this kind might have worked 200 years ago in Malthus's time but not now.
The positive feedback on heating from the melting of floating Arctic and Antarctic ice alone is causing an acceleration of system driven heating whose total will soon or already be greater than that from all of the pollution CO2 that we have so far added. This suggests that implementing Kyoto or some super Kyoto is most unlikely to succeed.
Geoengineering schemes, such as sunshades in Space as described by Woods, stratospheric aerosols to reflect sunlight (Budyko, Dickinson Crutzen and Caldeira), and the artificial generation of marine stratus clouds (Latham), all have the potential to temporarily halt global heating and could be part of a comprehensive treatment. These technological fixes should not be condemned without considering their value as an extender of the time we have to act. In a longer run they are probably no more a cure than is dialysis for kidney failure but who would refuse dialysis if death was the alternative
There is a third approach that is less invasive and it is to think of the Earth as a live self regulating system and devise ways to alter the sign of the feedback from one or more of the five main climate regulating processes from positive to negative. The charity, Cool Earth, has proposed using its funds to pay indigenous peoples to protect their natural forest ecosystems not cut them down. Another example would be the biosynthesis of food using CO2, nitrogen and water from the environment. This would sequester CO2 in a constructive and profitable way and return farm land to its natural state as an ecosystem.
Chris Rapley and I raised the possibility that feedback from the ocean ecosystems that are 70 percent of the Earth's surface might be made negative by mixing cool nutrient rich subsurface water with the stable but barren floating layer of the ocean ["Ocean pipes could help the Earth to cure itself" - letter to Nature from James Lovelock and Chris Rapley, 26 September 2007.]. This would feed algal growth and make the surface a more efficient sink for CO2 and algal growth would release DMS (dimethyl sulphide), a precursor of clouds. This could be achieved by a relatively simple system of pipes and would be driven automatically by wave energy. Small scale attempts to do this have been described and they appear to work.
We were well aware that there could be practical reasons why this simple idea might not work; such as that the waters of the deeper ocean are richer in CO2 than the surface and to bring them up would add to the release of CO2 to the atmosphere. We raised the idea to show the value of thinking of the Earth as a living system whose gigantic stores of energy might be available for use in its and our interest. We hoped that our idea might stimulate other proposals of this kind and that among them was one or more that could do the job. We also wanted to show that the Gaian approach of stimulating the Earth to cure itself was more than mere rhetoric.
Perhaps our first task is to stop thinking blindly that reducing our carbon footprint is enough. We have to understand that by abrading the skin of our planet to provide farm land we have destroyed more than 40 percent of the Earth's natural ecosystems and these were what previously served to sustain a stable climate. Most of all, we have to understand that the Earth System is now in positive feedback and is moving ineluctably towards the stable hot state of past climates. I cannot stress too strongly the dangers inherent in systems in positive feedback. Imagine a wooden house whose occupants have built too large a fire to warm them and the furniture near the fire was smouldering. If they did not act immediately, positive feedback would ensure that the whole house was consumed by fire in minutes.
Few seem to realise that the present IPCC models predict almost unanimously that by 2040 the average summer in Europe will be as hot as the summer of 2003 when over 30,000 died from heat. By then we may cool ourselves with air conditioning and learn to live in a climate no worse than that of Bagdad now. But without extensive irrigation the plants will die and both farming and natural ecosystems will be replaced by scrub and desert. What will there be to eat? The same dire changes will affect the rest of the world and I can envisage Americans migrating into Canada and the Chinese into Siberia but there may be little food for any of them.
When we were hunter gatherers and only a few million of us occupied the earth we were in balance with Nature and the CO2 we breathed out was absorbed by the plants in its entirety. Now the air we breathe out adds 2 Gigatons (Gt) of CO2 to the air every year, four times the total of all the airlines of the world and the agribusiness food plants are no longer in balance with our breathing. We now face the stark choice between a return to a natural life as a small band of hunter gatherers or a much reduced high tech civilization also in balance with nature. Paul and Ann Ehrlich were right to say in 1980 that it was preposterous to imagine as possible a population of six billions living a first world lifestyle.
Because it might help slow the pace of global heating, we have to do our best to reduce emissions and lessen our destruction of natural forests to feed and house ourselves; but this is unlikely to be enough and we will have to learn to adapt to the ineluctable changes we will soon experience.
During the early Eocene global heating there was no great extinction of species and this may have been because life had time to migrate to the cooler regions of the Arctic and Antarctic and remain there until the planet cooled again. This may happen again and humans, animals and plants are already migrating. Scandinavia and the oceanic parts of northern Europe such as the British Isles may be spared the worst of heat and drought that global heating brings. This puts a special responsibility upon us to stay civilised and give refuge to the unimaginably large influx of climate refugees.
Perhaps we must steer a path between the counsel to perfection of Gro Brundtland's concept of sustainable development and the alternative counsel to perfection of the deep ecologist's vision of a return to living a life balanced within the Earth system. This middle way, which was touched on by Lord Rees in his book The Final Century will require some difficult choices on what technologies to abandon and what to retain; we should look on our path as a sustainable retreat. My friend Sir Crispin Tickell says we need a climate catastrophe recognised as such by everyone and strong effective leadership.
Perhaps the saddest thing is that if we fail Gaia will lose as much or more than we do. Not only will wildlife and whole ecosystems go extinct but in human civilization the planet has a precious resource. We are not merely a disease; we are through our intelligence and communication the planetary equivalent of a nervous system. We should be the heart and mind of the Earth not its malady. Perhaps the greatest value of the Gaia concept lies in its metaphor of a living Earth, which reminds us that we are part of it and that our contract with Gaia is not about human rights alone, but includes human obligations.