Ladies and gentlemen most of you by now will be aware of the main conclusions of the highly respected Intergovernmental Panel on Climate Change, as 2007 report, and I am sure that we are all of us proud that they were awarded this year’s Nobel Peace Prize along 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 that the worst consequences might be avoidable. Particularly if we take appropriate action now. Inevitably the conclusion of the report needs constant revision in the light of real climate change. Sadly even the most pessimistic of the climate prophets who form the IPCC panel do not appear to have noticed how rapidly the climate is in fact 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 United Kingdom’s primary Climate Research Center, the Hadley Centre of Exeter. It’s a place of excellence and an important part of the IPCC, and while we were there we talked with a range of scientists, some were concerned with the melting of the ice floating in the Arctic, others with Greenland’s glaciers vanishing elsewhere in the world, and later in the day we heard, from Peter Cox and Richard Betts, two of the lead scientists at the Hadley Centre, about the way that the great tropical and boreal forests are not only vanishing just like the ice, but also changing as the world grows hotter. And then we talked of our own concern about the way that the ocean life was disappearing as the surface waters warmed and stratified.
climate scientist 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
that detached and properly scientific manner we expect from all of
the scientists. But it sounded to both of us almost as if they were
describing some other planet, not the earth.
This was it in itself disturbing, but much more so was the fact that most concern for example were the melting of polar ice, although well aware of their colleagues working on the similar vanishing of the tropical forests seem 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 is rarely ever true of a dynamic system. Sandy and I left with a deep sense that what we’d heard was truly serious and the visit profoundly changed my views as the future.
In defense 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 the same detached approach to climate research. We were worried but there was no sense of pressing urgency and I must add that this was all we perceived was the correct and objective way to think about it.
I looked at the IPCC report again, it was with a new sense of
awareness I now saw it was the scariest official document I’d ever
read it was all too clear that the message from the climate
scientists was not reaching the public and especially not in the
United States –I’m talking of course about 2004. This of course was
before Al Gore presented his book and film. I now take an apocalyptic
view of the future because I see the six to eight billions of humans
faced with ever diminishing supplies of food and water in an
increasingly intolerable climate.
You may well ask how have we scientists 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 is stratospheric ozone depletion. This employed nearly all of the lead atmospheric scientists at the time and I suspect that it gave us all a false confidence in our ability to deal with a far greater and much more complex danger of global heating.
reason for the slow recognition of the threat of adverse climate
change is the division of science itself into almost unconnected
specialties. If you look back at the writings of earth scientist,
just 30 or 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 at the same time period were equally confident that organisms evolved according to Darwin’s great vision and adapted to the earth that was fully described by their earth science colleagues in the buildings across the campus. This was a harmful and irrational division of science and I’m glad to say it’s slowly fading, but it still persists and has led to the deplorable separation as 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, I fear we will fail to understand our planet.
42 years ago I was working at NASA’s Jet Propulsion Laboratory in California and was given the wonderful opportunity to see at first hand evidence about the nature of our sister planets, 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 in a stable dynamic equilibrium. So, as David, said I introduced the hypothesis that life at the surface of the earth regulates the composition and chemistry of our atmosphere so as always to keep it habitable. My friend the Nobel prize-winning novelist, William Golding, suggested that I call the hypothesis Gaia. In some ways I wish he hadn’t because it’s caused a hell of a lot of trouble since.
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 in science.
Biologists were particularly outspoken and in the 1970s they
rubbished the infant hypothesis in the mistaken belief that it was
like creationism, contrary to the 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 a New Age fantasy.
I went on to refute their criticism with evidence of self-regulation gathered from the earth itself and by mathematical models that illustrated how planetary self-regulation could in fact take place. And nowadays Gaia theory worked on by a number of us including my colleague, Tim Linton, in the audience, is a top-down physiologist’s view of the Earth’s system and sees the earth as a dynamic responsive planet and explains why it’s so different from Mars and Venus.
Now in different times much earlier than this, these arguments would merely have been part of the natural history of science. Sadly, 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 farmlands, because each of these acts disables the Earth’s systems capacity to regulate itself. Most of the large climate models used to predict future climate still rely mainly on atmospheric physics and this includes the models on which the IPCC report is based. The influence of the clouds and of the ocean are only incompletely included, and that of the biota hardly at all.
Present-day climate models are good at explaining past climates that seem unable to agree on the course of global heating beyond about mid-century. By the end of the century predictions vary over a wide range but then who sensibly would try to predict that far ahead. This stark view was reinforced in May this year by the publication by Rahmstorf and his colleagues of high-quality measurements of the rise in global mean temperature sea level and C02. And these showed that even the gloomiest predictions of the IPCC were either at or underestimating the severity of climate change.
above slide is taken from the Rahmstorf’s paper, and it shows just
two of the panels. The lower one is the sea level change in
centimeters over time, and you can see the solid line here represents
the actual change. And here is the band of predictions from the IPCC
report. You can see the extent to which there is a gap here. It’s a
serious gap. Some approaching twice as fast a rate of melting as the
panel predicted. And then when you look at temperature again the
wobbling red blue lines indicate measurements of global temperature
whereas the band is the IPCC report. And you can see the actual
temperatures are wobbling very close to and occasionally above the
gloomiest of the IPCC predictions.
this is a much more recent one and it shows the melting of the
floating ice in the north polar region. And where this a business
report showing sales and profits the downfall here will cause the
anxiety amongst the shareholders and the board. But this is our
planet that we’re looking at, and the if you extrapolate the rate of
fall, which some have done, it would suggest that in as little a time
as five years there will be precious little ice left floating in the
North Polar Basin. If you just take the average it shows that all is
likely to be gone in 10 or 20 years.
Now this compares with the earlier IPCC predictions who said it might be gone by 2100. It’s a huge change and it’s happening, and what what is important about this is of course that when that white reflecting ice changes to dark sea, the added heat layer to the earth from the absorption of summer sunlight, not only up here, but also in the southern ocean will be a quantity comparable with the heating caused by all of the CO2 added to the air so far. If there’s any point I wish to make tonight if it is that the earth is joining our active global heating and with increasing enthusiasm.
In 2001 there was a serious attempt to bring Earth and Life sciences together. At a major scientific meeting in Amsterdam, in the Netherlands, over a thousand 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, ocean 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 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 they said we will unite as a single science, but not yet.
easy to see why scientists are so 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, and by a great good fortune
they had that most eloquent fellow, also an author, Richard Dawkins,
to put forward their thoughts before the public and as a
But just as Newtonian physics was found incomplete at the article and cosmic scales, so I think 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 fixed world. They are naturally selected in the world that was changed by their ancestors, and in turn their interaction with the material environment sets the theme for the next round of evolution. The air, the ocean, and the surface rocks are all either direct products of life, or else have been massively altered by its presence.
difficulty in understanding the Earth can, I think, usefully 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. 200 years later we face a similar paradox. We
know that the earth is a benign and comfortable place for life and
has been for most of its history, so how have selfish genes allowed
the evolution of so altruistic a planet.
It’s easy to see now how fit organisms are naturally selected, but how can the common good for all life also come through natural selection. William Hamilton said, I think we need a Newton to solve this problem, but I wonder if we have discovered that as the earth system matures it keeps its climate in chemistry always fit for life and the invisible hand that does the regulation is feedback between its living and nonliving 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 recognized that feedback between social and market forces cannot be ignored, so I suspect that we face a similar slow learning process about our relationships with the earth. Meanwhile we are still trying to shape it to our own 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.
science and economics have more in common than we used to think a few
weeks ago the distinguished economist, P. Dasgupta, compared the
complexity and non-linearity of economic systems with those of
The long term history of the earth suggests the existence of hot and cold stable states, what the geologists often referred to as the greenhouses and the ice houses. The best-known hot house occurred 55 million years ago at the beginning of the Eocene period. In that event between one and two teratons (Tt) of CO2 were released into the air by geological accident. We are fairly sure about this from measurements Professor Elderfield of Cambridge University and his colleagues and from the researches of Henrik Svensen and colleagues of Oslo University.
Putting this much carbon dioxide in the air caused the temperatures of the Arctic and temperate regions to rise about eight degrees Celsius and the tropics five degrees and it took about 200.000 years for conditions to return to their previous state. In the 20th century we injected about half that much CO2 and we and the earth it saw itself now looked soon likely to release more than a Tt of CO2.
Global heating 55 million years ago took place much more slowly than now. The injection of gaseous carbon compounds into the atmosphere may have taken place over a period as long as 10,000 years, instead of about 200,000 years, as we are now doing. The great rapidity with which we are adding carbon gases to the air is as damaging in some ways as a quantity. The rapidity of the pollution gives the earth system little time to adjust and this is particularly important for ocean ecosystems. The rapid accumulation of carbon dioxide in the surface water is making them too acid, for shell-forming organisms. This did not appear to happen during the Eocene event because there was time then for the mixing in as a more alkaline deeper waters to neutralize the surface ocean.
There are other differences of course between the earth’s 55 million years ago and now. The sun was half a percent cooler and there’s no agriculture anywhere, so that natural vegetation was free to regulate the climate. Another difference was that the world then was not experiencing that strange phenomena, global dimming: the two to three degrees of global cooling caused by the atmospheric aerosol from man-made pollution. The haze from it covers most of the northern hemisphere and offsets global heating by reflecting sunlight, and more importantly by new nucleating clouds that reflect even more sunlight.
The aerosol particles of the haze persist in the air for only a few weeks, whereas CO2 persists for 50 to 100 years, so that any economic downturn or planned cutback in fossil fuel use, which lessened the aerosol density, would intensify the heating, and if there were a hundred percent cut in fossil fuel combustion, it might get considerably hotter –not cooler–, and this is why I sometimes say I think we live in a fool’s climate we’re damned if we continue to burn fuel and damned if we stop too suddenly.
It is not difficult to make a simple numerical model of a live earth with an ocean of land biota taking an active part in climate regulation and then try the experiment of adding a Tt of CO2 to the model to mimic what we are doing. I did this in collaboration with the geochemist, Lee Kump, and we published it as long ago as 1994, in Nature.
The above slide is a simple model. The panel shows you temperature change as the CO2 goes into the atmosphere, starting off at something not far from what we have now. The panel also shows the temperature variations on a dead earth with no life on it, but a much hotter place, and the little bubbles are just seasonal and annual variations in the input of solar heat. They’re very useful in the model in that they diagnose the presence of positive feedback, where the amplitude of the fluctuations is greater than we have positive feedback, where it’s lower negative feedback.
the interesting thing about this model where it differs in two ways
from the IPCC models, is that it suggests everything goes along and
is regulated reasonably well, apart from the fluctuations, until
suddenly there’s a jump in temperature to a new stable state which is
well regulated. The IPCC if you look at it, seems to suggest
temperature just rises steadily with increasing CO2, and more
seriously suggests that if you cut back emissions it would go back
This model unfortunately suggests that once you get up to this region, or even a high on the slope, cutting back CO2 right down to pre-industrial levels makes very little difference to the temperature the system has committed itself to the change.
You may ask why should we take a simple model like this seriously when so many of the world’s climate scientists are in agreement with 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 ocean ecosystems dominate the cooler period of the Earth’s history (see previous slide: you will see the growth of algae here fluctuating) and land plants dominate the hot period, the greenhouse.
indication that this might be true comes from papers appearing just
this very week, from Andrew Watson and Corinne LeQuéré, both of
whom show measurements in the ocean indicating a decline in the
ability of the ocean system to take in CO2, and occurring in the last
What I have said so far seems to imply that there’s little we can do to prevent the Earth System moving to one of these hot stable states, but in no way do I mean that there is no hope for us and there’s nothing we can do. I am much more see our predicament as like that faced by a nation that is about to be invaded by a powerful enemy.
We’re now at war with the earth, and as in a blitzkrieg, events proceed faster than we can respond to them. We’re in the strange position of living on a planet where climate and compositional change, that’s to say geological change, is now so rapid that it is happening too fast for us to react to it. And I think if you think back to that changes in the floating ice, that shows you just how fast change can occur. For this reason alone I think it’s probably too late for sustainable development. Enlightened living of that kind that might have worked 200 years ago, in Malthus’s time, but not now.
The positive feedback on the heating of the melting of the floating ice in Arctic and Antarctic regions as I mentioned is equivalent, or nearly equivalent, to the heat from all of the pollution we have so far added. And this suggests that implementing Kyoto or some super Kyoto is unlikely to succeed.
schemes will certainly be tried especially in America, which is a
can-do nation, and that these include sunshades in space, such as
described by Lowell Woods. Stratospheric air ourselves to reflect
sunlight. A number of quite distinguished scientists have been
involved with that one. I think it was first suggested in the 1970s
by the Russian scientist Budyko, a considerable figure in atmospheric
science. It was followed up by Robert Dickinson in Arizona a few
years later, and most recently by Paul Crutzen in Germany, and by Ken
Caldeira in the United States.
And then there is of course the artificial generation of marine stratus clouds, just about the ocean, which Latham of NCAR has suggested. All of these have the potential, temporarily, to halt global heating and could be part of a comprehensive treatment. I know that the environmental movement does not like and has almost a gut reaction to technological fixes, but I don’t think we should to be condemned without considering their value as something that extends the time that we have to act. In the longer run I agree with the environmentalists, they’re probably no more a cure than is dialysis for kidney failure for one of us, but then who would refuse dialysis if deaths 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 first science of this kind of thinking came from the charity Cool Earth that proposed, quite simply, using its funds to pay indigenous people to protect their natural forest ecosystems as something much better than paying money to plant trees. You can’t plant an ecosystem it takes an incredible time for one to form.
Another example would be the direct synthesis of food from CO2, nitrogen and water taken from the environment. Now this would have two advantages one it would reduce the amount of land being used for farming, and secondly of course it would be a great way of sequestering CO2 from the atmosphere.
And there is a third approach that Chris Raply and I raised a few weeks ago in the journal Nature, and that was the possibility of using ocean ecosystems which are 70% of the Earth’s surface. Using them to turn them from positive to negative feedback on heating by mixing cool nutrient-rich subsurface waters with a stable but barren floating top layer of the ocean. This we thought would feed algal growth and make the surface and more efficient sink for CO2, and algal growth would of course also release dimethyl sulfide gas, which is 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 appear to work.
We are well aware that there could be practical reasons why this simple idea might not work such as the waters of the deeper ocean are richer in CO2 than the surface, and to bring them upward add to the burden of CO2 in the atmosphere. But we still think that the idea is worth trying experimentally rather than condemning on model calculations. We raise 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 hope that our idea might stimulate other proposals of this kind and among them would be one that might do the job. We also wanted to show that a Gaian approach to stimulating the earth to cure itself was more than mere rhetoric.
Perhaps our first task is to stop thinking blindly that by reducing our carbon footprint we are doing enough. We have to us understand that by braiding the skin of planet to provide farmland we have already destroyed 40% of the Earth’s natural ecosystems, and these were what previously served to sustain a stable climate. If we go on and take up the remainder for biofuels we really will be in trouble. Most of all we have to understand that the earth system is now in positive feedback and is moving ineluctably towards us the stable state of one of the past hot climates.
can’t stress too strongly the dangers inherent in systems in positive
feedback. Imagine that you’re living in a wooden house and the two
built so large a fire to warm yourself in the cold of winter that the
furniture near the fire begins smoldering, if you don’t get out soon
positive feedback will ensure that the whole house is consumed by
fire in minutes.
If you seem to realize that the present IPCC models predict almost unanimously that by 2040 the average summer of Europe will be as hot as the summer of 2003, when over 30,000 died from the heat. By then of course we may cool ourselves with air-conditioning and learn to live in a climate that is no worse than that of Baghdad now, without the wall.
But without extensive irrigation the plants will die and those farming and natural ecosystems will be replaced by scrub and desert. What will there be to eat? And the same dire changes will affect much of the rest of the world. I can envisage the Americans migrating into Canada. The Chinese, where will they go? Siberia perhaps, or possibly Africa.
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 breath the
sixth plus billions of us puts in two gigatons (Gt) of CO2 every year
and that’s four times the total of the airline’s the world. And the
agribusiness food plants do not keep it in balance in the way that
the natural ecosystems once did. We faced a stark choice now 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 as long ago as 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 of course our best to reduce emissions and to 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 changes that will soon take place.
During the early Eocene global heating there was no great extinction 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. So 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 the heat and drought that global heating brings. But this puts on us the special responsibility to stay civilized and give refuge to an unimaginably large influx of climate refugees.
Perhaps we must steer a path between the council to perfection and Gro Brundtland’s concept of sustainable development and the alternative council to perfection of the deep ecologists idea of a return to living a life balanced with the Earth System. This middle way was touched on by our president, Lord Rees, in his book The Final Century. But it will require difficult choices on what technologies to abandon and what to retain. Which I think we should look upon our path as a sustainable retreat. My friend Sir Crispin Tickell says we need a climate catastrophe soon, recognized as such by everyone and strong effective leadership.
Perhaps the saddest thing is it that if we fail, Gaia will lose as much or more than we do. Not only world wildlife and whole ecosystems go extinct but in human civilization our 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, and never forget we are part of the system, just another species. But we should be the heart and mind of the earth not a malady, and so perhaps the greatest value of the Gaia concept lies in its metaphor of a living on that reminds us that we are part of it and that our contract with Gaia is not about human rights alone, but it includes human obligations.