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Vulnerable Earth

The Robert C. Barnard Environmental Lecture 2006. Delivered to the AAAS, Washington DC, 18 September 2006.

Growing awareness of the possible consequences of rapid climate change have made more people aware of the limited, ephemeral and precarious character of our present environment. Our whole being is within a wafer-thin atmosphere surrounding the surface of a planet as it turns in space at exactly the right distance from the Sun for life. We are tiny parts of a system of life whose complexity passes, and always will pass, human understanding.

That system is highly vulnerable. It is just that the shortness of our lives and the narrowness of our perspective on the past mean that we are mostly unaware of change, and until now have scarcely noticed the pressures on the environment. But the last couple of centuries have seen an extraordinary stretching of our understanding of space and time:

During these almost unimaginable stretches of time, there have been huge changes both from outside the Earth and from within it. From outside there have been big hits from space, and the changing relationship between the Earth and the Sun (wobble, tilt and orbit); and from within it there have been the slow movement of tectonic plates on the Earth's surface, vulcanism and earthquakes, drastic changes in climate, the rise and fall of sea levels, and not least the influence of life itself. All, whether fast or slow, illustrate the vulnerability of our planet.

First let us look first at what comes from outside. The objects from space that hit the Earth almost continuously range from the very small to the very big. The smallest are the daily hail of tiny objects. There was a fine shower of them at the end of last month. The biggest was the object which hit the young Earth more than four billion years ago, and led to the creation of the Moon.

Perhaps most famous was the Chicxulub event some 65 million years ago which caused, or at least contributed to, the extinction of the dinosaur family. Extinctions of this magnitude are a disaster for some, but an opportunity for others. Indeed the rise of the mammals, with humans a last-minute arrival among them, would not have happened without Chicxulub.

More recent was the Tunguska event of 1908 which destroyed some 2,000 square kilometres of forest in Siberia. Had it struck Washington, there would have been little left. Then there was the Peeskill object which stove in the back of an old Chevrolet in upstate New York in 1992, and the spectacle of the comet Shoemaker-Levy colliding with the planet Jupiter two years later.

The Lake Tagish event followed in 2000: it caused a loud bang, a shower of fragments, and an electromagnetic pulse leading to a temporary loss of power transmission on the ground below. Only a couple of months ago an asteroid sailed past the Earth at a distance slightly further away than the Moon. The next big one coming in our direction is timed for the late 2020s.

Within the Earth system tectonic plate movements can sometimes have dramatic effects. One example is the isolation of the three components of the Antarctic continent over 20 million years ago, and another is the joining of north and south America some four million years ago, each of which led to big changes in the direction of ocean currents and in climate world wide. More recent was the eruption of Mount Toba in Indonesia over 70,000 years ago, which put enormous quantities of volcanic dust into the atmosphere, helped trigger a renewal of glacial conditions, and may even have affected human evolution.

By comparison the eruptions of Mount Tambora in 1815, which led to the famous 'year without a summer', that of Krakatoa in 1883, that of Mount St Helens in 1980, that of El Chichon in 1982, and that of Mount Pinatubo in 1991, each with its specific global effects, were relatively minor.

Earthquakes are part of the same pattern. Mostly their effects, however destructive, are local. During the last century, each year there were an average of 20 earthquakes, measuring seven or more on the Richter scale. Most loss of life is associated with the tsunamis which, as in the last couple of years, can surge across the oceans doing enormous damage. Recently there has been concern about the possibility that part of the Cumbre Vieja volcano in the Canary Islands might collapse into the sea, causing a huge tsunami which could hit the east coast of the United States.

Now for the over turnings in the living world. Extinctions for whatever reason are an essential element in evolution. Few ecosystems or species last more than a few million years. Recently it has been demonstrated how, operating on Darwinian principles, organisms tend to create and maintain the living environment most favourable to them.

Thus they can offset and mitigate the consequences of catastrophes through complex systems of feedback. The Earth system behaves as a single, self-regulating system, comprised of physical, chemical, biological and even human components, operating within fairly wide limits. In a phrase this is Gaia theory, or earth system science. At present we are pressing Gaia hard without fully understanding the consequences.

Over the last 40,000 years, the human impact on the Earth has slowly, and then rapidly, increased. A periodical visitor from outer space would find more change in the last 200 years than in the preceding 2000, and more change in the last 20 years than in the preceding 200. The association between humans and their environment, including the micro-world in and around them, has changed at every stage of human evolution; from hunter gatherers to farmers, from country to city dwellers, and from tribal groups to complex hierarchical societies. Before the industrial revolution began some 250 years ago, the effects of human activity were local, or at most regional, rather than global. Now the impact is indeed global.

The idea may be hard to accept, but in its long history the Earth has not been in this situation before. In the words of the title of a recent book on environmental history, we confront Something New Under The Sun. This point was well brought out in a declaration published by some 1,500 scientists from the four great global research programmes at Amsterdam in July 2001. They stated squarely that:

"The nature of changes now occurring simultaneously in the Earth's system, their magnitudes and rates of change, are unprecedented. The Earth is currently operating in a no-analogue state ... The accelerating human transformation of the Earth's environment is not sustainable. Therefore the business-as-usual way of dealing with the Earth's system is not an option. It has to be replaced - as soon as possible - by deliberate strategies of management while meeting social and economic development objectives."

There are six main factors which have driven this transformation. Briefly they arise from

  1. human population increase;
  2. degradation of land, consumption of resources and accumulation of wastes;
  3. water pollution and supply;
  4. energy production and use;
  5. destruction of biodiversity;
  6. and climate change in its many aspects and impacts.

Of these factors,

  1. population issues are often ignored as somehow too embarrassing or mixed up with religion;
  2. most people are broadly aware of land, resource and waste problems, although far from accepting the remedies necessary;
  3. water issues, both fresh and salt, have had a lot of publicity, and already affect most people on this planet;
  4. how we generate energy while fossil fuel resources diminish and demand increases is another conundrum;
  5. damage to the diversity of life on which our species critically depends has somehow escaped most public attention;
  6. and climate change with all its implications for atmospheric chemistry is now broadly understood, apart from those who do not want to understand it.

All these factors are interlinked, and all represent pressure on the natural environment.

There is now a seventh factor recent in human experience. The effects remain mostly to be seen. They arise from the introduction of new technologies. Damage from chlorofluorocarbons to the atmospheric ozone layer, which protects ecosystems from harmful ultraviolet radiation from the Sun, was the first to receive major public attention. The eventual result was to establish international agreements to ban the manufacture and use of chlorofluorocarbons.

But this may only be the beginning. In a recent book by the President of the Royal Society (the British equivalent of the US National Academy of Sciences), Lord Rees explored the dangers arising from human inventiveness, folly, wickedness and sheer inadvertence. He had particularly in mind the ramifications of information technology, nano-technology and nuclear experimentation. His conclusion was to give our civilization only a 50 percent chance of survival beyond the end of this century. Last month the same thought was echoed by Stephen Hawking, who said that he did not know if the human race would survive the next hundred years.

What then are we to expect? Are we capable of establishing a lasting relationship of mutual benefit to the living Earth and those of its unruly inhabitants who are ourselves? How are we to recognise that the last 200 years or so have been a bonanza of inventiveness, exploitation and consumption which may not continue? All successful species, whether bivalves, beetles, swallows or humans, multiply until they come up against the environmental stops, reach some accommodation with the rest of the environment, and willy nilly restore some balance.

In fact most of the solutions to the problems we are causing are well known. Take population increase. The overall rate is still rising, but in several parts of the world, including our own, it is levelling off. The main factors are improvement in the status of women, better provision for old age, wider availability of contraceptive devices, lower child mortality, and better education, especially for girls and young women.

Take degradation of land and water. We know how to look after them both if we try. We do not have to exhaust top soils, watch them erode into the sea, rely upon artificial aids to nature, eliminate the forests with their rich variety of ecological functions, or pollute the water, fresh and salt. We already accept the need for conservation and for better understanding of the complexity of living systems, well brought out in the Millennium Ecosystem Assessment published last year. Some at least are aware of the risks of high technology, and are trying to cope with them.

We do not have to consume often irreplaceable resources at the present epic rate. A Chinese friend of mine has calculated that during the last century humans consumed 142 billion tons of petroleum and 265 billion tons of mineral coal. As someone recently remarked, it took around 200 million years to lay down the coal, oil and gas on which our society currently depends. We are consuming them over a period of around 200 years. Thus each single year we consume a million tons of fossil fuel deposit. This is profoundly affecting the chemistry of the atmosphere.

This brings me to what many believe to be the greatest problem of all: climate change, a threat to society bigger even than terrorism (as was recently said by the British Government's Chief Scientific Adviser). The science is becoming ever clearer and more precise. It relates primarily to the build up of greenhouse gases in the atmosphere, now at their highest levels for 650,000 years. We are heading back to the conditions of around 125,000 years ago when the relationship between land and sea was very different. All this will be brought out in next year's Fourth Assessment of the Intergovernmental Panel on Climate Change. It is also achieving much more prominence in public debate. Witness the special supplements in The Economist of 9 September and the Scientific American for this month.

What serious dispute there is about climate change relates mostly to the distinction between natural change and human-driven change. The one invariable element in climate is its variability. We are now better aware of the fluctuations of the past in and out of relative heat and cold, including the brief but relatively rapid cooling (some 12,000 years ago) and the marked warming (the so-called runaway greenhouse effect some 55 million years ago). Nonetheless the human impact is now becoming unmistakably evident, leading to the graph on the charts known as the hockey stick (which, although originally challenged, has been shown to be broadly correct).

The results for human society are becoming evident, and could become rapidly more so with a rich variety of positive feedbacks. In a few words, these results include

So far as humans with their increasing population are concerned, we can foresee changes

As with most other environmental problems, we know what to do about climate change if we have the will to do it. It is simple. We have to stop the growth of greenhouse gases in the atmosphere. This means radical changes in energy policy. These are not nearly as difficult as they are commonly presented. Some of you may have seen an article entitled "A Roadmap to US Decarbonization" in Science magazine of 1 September.

The arguments over nuclear power have been reanimated, not least in Britain, and there are a lot of fancy ideas in circulation, particularly carbon sequestration and development of bio-fuels, tidal power, and geothermal energy, but none could possibly cope with the problem by itself. The longer we take before doing something, the worse the problem will become. The uncertainties are alarming. When do we reach the tipping points from one climate regime to another? What will the results then be? Is it possible to redirect energy policies in time?

For all this we need global as well as national policies, and over the years, as the scientific evidence has mounted, there has been progress. Internationally we now have the Framework Convention on Climate Change of 1992, the Kyoto Protocol of 1997, and now negotiations on post-Kyoto after 2012. Most governments are contemplating action, although few have yet to show results.

I do not have to tell you that a particular problem is over the United States, where a concerted, often dishonest, campaign by vested interests has bemused public opinion. But even there individual states, notably California, and those in New England, are taking action on their own. Some corporations, for example General Electric, are doing likewise. I expect that many of you will have seen the film put together by Al Gore entitled An Inconvenient Truth, which well shows how inconvenient the truth is.

The US scientific community has been robust throughout the debate on climate change. The President of the US National Academy of Sciences was one of the signatories of the statement on Global Response to Climate Change by the eleven leading scientific academies in June last year. Then we have had an even more robust statement from your new President John Holdren about human disruption of the climate system, and the mounting dangers which lie ahead.

Nor should we forget the Gleneagles Declaration of July 2005, to which President Bush subscribed, and agreement on the G8 + 5 plan of action with forthcoming conferences. Even the Bush Administration is beginning to talk differently, although apparently still attached to the idea that technology can solve the problem, and continuing massive subsidies, over US$25 billion a year, to exploitation of fossil fuel reserves.

All are agreed that there is now an urgent need to bring in the world as a whole, in particular India and China. Last week I attended a joint meeting in Beijing of representatives from India and China about the implications for both countries, and the need for cooperation between them. As both are highly vulnerable to climate change, their biggest incentive is their own national interest. But without a lead from the industrial countries, who carry primary responsibility for what has happened, it is hard to persuade the rest of the world to make the fundamental changes in their development policies which are now essential. We are all inextricably involved.

The most difficult and perhaps painful requirement is to learn to think differently. We need change in a value system which gives primacy to market forces, exploitation of resources and ever-rising consumption. At present we seem to want to attach monetary value to almost everything. Of course some rule-of-thumb method of assessing and comparing values would indeed be useful, not least in giving comfort to economists and more plausibility to their models.

But somehow we have to bring in the factor of environmental costs. In addition to the traditional costs of research, process, production, and so on, prices should reflect the costs involved in replacing a resource or substituting for it, and the costs of the associated environmental and human problems. As have been well said, markets are superb at setting prices, but incapable of recognising costs. In both the short and even more the long term, any economy is a wholly-owned subsidiary of the environment.

In this field the Chinese seem to be ahead of the rest of the world in seeking to introduce new methodologies to assess the implications of what they call clean green growth, and the heavy penalties involved in failing to do so. A paper published by the State Environment Protection Administration and the National Bureau of Statistics in Beijing on 8 September brought out the artificiality of measuring wealth and wellbeing by simple GDP or GNP calculation. The conclusion in the China Daily that day was an editorial headed "The Greener the Better".

We have much to do, but there is at least one thing we can say for ourselves. We are the only animal species which could conceivably hope to do anything about the problems I have discussed. Looking ahead is a very chancy activity. Who could have foreseen the rise of information technology, and its enormous effects, even 15 years ago? Nonetheless I conclude this talk with some attempt to peer beyond the end of this century.

There will certainly be some sudden disruptions, whether as a result of volcanic explosions, earthquakes, tsunamis, impacts from space or even destructive wars using unimaginably horrible weapons. World wide the relationship between land and sea will change, and maps will need to be redrawn. The politics of the world will be different, with new hubs of power, wealth and culture. Who will be tomorrow's hegemony?

Ecosystems will be drastically changed, and agriculture to support our need for food with them. Human health will be drastically affected. There is a powerful synergy between pathogen transmission and environmental change. Old diseases will return, new ones will arise and spread, and the Grim Reaper will remain in attendance.

How our successors, if there be such, will react to these new circumstances is anyone's guess. They are likely to be living in a more globalized world of rapid communication, and we shall need better and more effective international institutions to regulate our affairs. They will almost certainly be fewer people, living in more dispersed communities, perhaps around 2.5 billion (roughly the number when I was born) rather than the 6.5 billion or even 8 to 9 billion which are now a possibility for later this century.

Developments in information technology may well lead to redesigning of at least some varieties of human, recalling the fantasies of H. G. Wells with his Eloi and Morlocks. Already chips have been inserted into some for a variety of purposes. What has been called automated evolution is a technical possibility in which the processes of natural selection would be enormously accelerated. All this is explored in a book by James Martin - The Meaning of the 21st Century - published in the United States last week.

On the one hand humans may thereby be liberated from many current drudgeries. Soon houses may be able to clean themselves, meals could appear on demand, cars could drive under remote instruction, and desirable genetic characteristics could be introduced on demand. All this seems unimaginable when so many still have to trudge miles to collect fuel, food and water.

On the other hand humans could well become dangerously vulnerable to technological breakdown, and thereby lose an essential measure of self-sufficiency. Already dependence on computers to run our complex systems, and reliance on electronic information transfer are having alarming effects. Here industrial countries are far more vulnerable than others. Just look at the effects of single and temporary power cuts or outages. More than ever individuals feel out of control of even the most elementary aspects of their lives.

Above all let us remember that we cannot rely on our own survival as a species. I sometimes wonder how long it would take for the Earth to recover from the human impact, and for another species more intelligent than our own and better capable of recognizing its own interests to take our place. Life itself, from the bottom of the seas to the top of the atmosphere, is so robust that the human experience could become no more than a short and certainly peculiar episode in the history of life on Earth.

For the moment let us also remember how small and vulnerable we are as creatures of a particular environment at a particular moment in time. We are like microbes on the surface of an apple, on an insignificant tree, in an insignificant orchard, among billions of other insignificant orchards stretching over horizons beyond our sight or even our imagining.


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