Homo Britannicus

by Chris Stringer

  So it seems that we are destined to live in a warming world – or are we? If the increase of melt water from thinning ice cover and thawing permafrost leads to a build-up of cold freshwater in the North Atlantic, we could instead suffer a Heinrich Event (named after the German scientist who first recognized them) lasting a few centuries, when the North Atlantic suddenly chills, and there is a massive southerly flow of icebergs (an event over-dramatically depicted in the film The Day after Tomorrow). As we saw in Chapter 5, the Atlantic Heat Conveyor that warms north-western Europe by carrying Gulf Stream waters on its surface has periodically shut down, with devastating effects on the climate of Britain and surrounding regions. Air temperatures over the Atlantic could sink by as much as 10 °C and in western Europe by 4°C. Careful research is being conducted to see if there has been any weakening of the Atlantic Heat Conveyor, and the worrying news is that such an effect has already been detected. A recent study of a transect across the subtropical Atlantic using data from the last fifty years suggests that the Conveyor there has weakened by more than 30 per cent.

  While more data from different depths and locations are now anxiously awaited to confirm the pattern or not, the situation does not bode well, and might give Britain a climate that it has never experienced before, one that is extremely continental (that is, one that matches the climates found deep within continents, without the moderating effect of the oceans). Continuing global warming of the atmosphere and land would mean our summer temperatures might continue to climb, first to Ipswichian or Hoxnian peak levels (about a degree higher than today) then to those of Pakefield (about 2°C higher) and beyond. However, in the winter, the effect of the icy Atlantic would dominate, giving us a highly seasonal climate more like that suffered by the Neanderthals at Lynford, or like Labrador today. However, based on past performance, Heinrich Events have generally been very short, so this strange situation might last only for a few centuries before the Gulf Stream switched back on, stoking up Atlantic temperatures again. As we saw in Chapter 5, some of these switches of Atlantic circulation have happened in the blinking of an eye, geologically speaking, so if the Atlantic observations presage the real thing, we may only have a few more years to prepare ourselves.

  So what should we do in the face of these enormous threats to our future? In his Four Quartets T. S. Eliot says, ‘human kind cannot bear very much reality’, but we must avoid the tendency to bury our heads in the sand, or deny the truth of what we have been doing to our planet. As far back as 1989, a prominent world leader addressed the UN with these words:

  While the conventional, political dangers – the threat of global annihilation, the fact of regional war – appear to be receding, we have all recently become aware of another insidious danger. It is as menacing in its way as those more accustomed perils with which international diplomacy has concerned itself for centuries. It is the prospect of irretrievable damage to the atmosphere, to the oceans, to Earth itself.

  What we are now doing to the world, by degrading the land surfaces, by polluting the waters and by adding greenhouse gases to the air at an unprecedented rate – all this is new in the experience of the Earth. It is Mankind and his activities that are changing the environment of our planet in damaging and dangerous ways.

  The result is that change in future is likely to be more fundamental and more widespread than anything we have known hitherto. Change to the sea around us, change to the atmosphere above, leading in turn to change in the world’s climate, which could alter the way we live in the most fundamental way of all. That prospect is a new factor in human affairs. It is comparable in its implications to the discovery of how to split the atom. Indeed, its results could be even more far-reaching.

  The evidence is there. The damage is being done. What do we, the international community, do about it? The environmental challenge that confronts the whole world demands an equivalent response from the whole world. Every country will be affected and no one can opt out. Those countries that are industrialized must contribute more to help those who are not.

  The work ahead will be long and exacting. We should embark on it hopeful of success, not fearful of failure. Darwin’s voyages were among the high-points of scientific discovery. They were undertaken at a time when men and women felt growing confidence that we could not only understand the natural world but we could master it, too. Today, we have learned rather more humility and respect for the balance of nature. But another of the beliefs of Darwin’s era should help to see us through – the belief in reason and the scientific method.

  Reason is humanity’s special gift. It allows us to understand the structure of the nucleus. It enables us to explore the heavens. It helps us to conquer disease. Now we must use our reason to find a way in which we can live with nature, and not dominate nature. We need our reason to teach us today that we are not – that we must not try to be – the lords of all we survey. We are not the lords, we are the Lord’s creatures, the trustees of this planet, charged today with preserving life itself – preserving life with all its mystery and all its wonder. May we all be equal to that task.

  Those were the prescient words of Margaret Thatcher, but not only were they unheeded by most of the world leaders who heard them, they were sadly also ignored by the Prime Minister herself, whose government proceeded to block or water down proposals to deal with the problems, as well as embark on the most massive programme of road-building the country had ever seen, implicitly encouraging pollution by motor vehicles. Although she would not bite the bullet, Mrs Thatcher at least acknowledged – seventeen years back – the stark reality that we have been conducting an uncontrolled experiment with the Earth’s climate system for at least three hundred years. In fact, from examining ice cores that record atmospheric changes some scientists believe the rot set in as far back as 8,000 years ago, when farming really took off and human numbers started to grow significantly for the first time. Before then, humans lived as hunter-gatherers, and were more or less obliged to follow the natural rules that limit the population densities of any animals at the top of their food chains. But it’s argued that once people in Europe and Asia began clearing forests for crops and pastures, they started to reverse a natural decline in CO2 content, and by 5,000 years ago had done the same with methane levels through increasing herds of livestock and by flooding fields for rice culture. In which case these early farmers may have inadvertently warded off the cooling that tends to happen as an interglacial passes its peak, as our present one might otherwise have done. If that is so, we have been fortunate, but our luck is quickly running out as we move into completely unknown territory, tinkering with the Earth’s climate machine.

  The effects of global warming will indeed be global, which is why no peoples or nations can afford to be complacent about it. Europe is currently devouring the world’s natural resources and producing pollution at twice the global average, although still well below US levels. Research suggests that its mountains and southern lands will be the hardest hit by climate change. Ten per cent of Alpine glaciers disappeared during the summer of 2003 alone, and at current rates 75 per cent of Switzerland’s glaciers will have melted by 2050. Snow lines are getting higher and less snow is being stored through the year, which will seriously impact hydroelectric power stations, and more obviously the skiing industry. Some Mediterranean cities are already intolerably hot and polluted in the summer, but this will get worse, and there will be an increase in forest fires and water shortages. Farmers in the north would benefit, at least for a time, from exploiting crops now grown in the south, but they are also likely to suffer much less predictable weather and a greater risk of flooding. With increased summer heat, rationed water supplies and arid lands, the Mediterranean region may be increasingly abandoned as millions of people move north, creating enormous new social and political pressures.

  The United States is far and away the biggest contributor to greenhouse gas emissions, and perhaps with the New Orleans floods it is starting to reap what it has sown,
since warmer seas fuel more powerful hurricanes. Cities will increasingly suffer from water shortages and baking summers, resorts which rely on skiing could see snows retreat by a thousand feet, and tropical diseases like dengue fever will spread in the south as higher temperatures and new wetlands create ideal breeding conditions for disease-carrying insects. Although increased rainfall in some areas will benefit agriculture, life for city-dwelling Americans will get increasingly uncomfortable as floods, heat and drought add to the pressures of crime, traffic congestion, compromised air and water quality, and decaying infrastructure. Stronger hurricanes will batter the southeast, downpours, ice and snow melts will feed flash floods, and an eventual sea level rise of seven metres would see Florida turned into an island. Commenting on President George W. Bush’s denial of the reality of global warming, Anthony Janetos of the World Resources Institute said, ‘Because the markets don’t have an efficient way to value what the seas, the rivers, the mountains and the forests actually contribute, they effectively ignore them. But you do that at your peril.’

  China is likely to become the world’s leading economic force, if damage caused by climate change doesn’t get in the way, but there is a great danger that it will repeat most of the mistakes that western industrialized nations have made in contributing to environmental degradation and greenhouse gas emissions. Chinese experts have warned that since 1950 there has been a gradual reduction in precipitation nationwide, since 1960 the volume of the six largest rivers has steadily declined, and since the 1980s its northern provinces have regularly suffered droughts and flash floods. Moreover they predict that two thirds of China’s high-altitude ice fields (about 15 per cent of the Earth’s total) would melt by 2050 if current trends continue. Already there are noticeable changes in vegetation patterns, and if climate change drastically affects rice production, one sixth of the world’s population would suffer.

  Our evolutionary homeland of Africa may be one of the most severely hit by the effects of global warming. The northern half of the continent is likely to suffer even worse droughts in the twenty-first century, with perhaps a further fall of 30 per cent in rainfall compared with last century, disastrous when about 70 per cent of the population depend directly on rain-fed agriculture. The south may not fare as badly, but as in other regions, weather throughout Africa is likely to get much more extreme. One of the icons of Africa, Tanzania’s ice-capped Mount Kilimanjaro, is rapidly losing its glaciers, and the country’s climate researchers have noted another growing trend: areas that usually get two rainfalls in the year are getting more, while those that get only one rainy season are getting far less, leading to growing aridity. Maize, the main staple crop, will be hit hard, and forests, rivers and hydroelectric power will be seriously depleted. The accelerating clearance of ancient forests in regions like the Congo basin is not only destroying rich biodiversity but is altering local climate, rainfall patterns, rivers and soils, fuelling the spread of deserts.

  The problems of Africa remind us that it is not only humans who are being affected by climate change. Scientists estimate that global warming may drive more than a million species to extinction by 2050, and this will be the coup de grâce for what has already been termed the Sixth Great Extinction in the history of life, and the only one that can be attributed to the action of a single species. The end of the last Ice Age saw the species of the world hit by a double blow: massive climate and environmental changes in a very short time as the world emerged from an unstable end to the last glaciation, plus the growing impact of humans, first as increasingly efficient predators and then as farmers, with associated environmental change and human population growth. The large and diverse mammal megafauna of the Americas and Australia, evolved over millions of years, went under in a few thousand, and Europe entered an interglacial without species like elephants, lions and rhinos for the first time since these creatures began their Pleistocene occupation of the continent. These disruptions to the natural world have continued right through to the present day, with the prospect of a third blow in the form of very rapid climate change, in a new direction and on an even greater scale. Many species that manage to survive will do so only by major changes to their ranges or life cycles. This is already showing itself in the oceans, where fishing stocks in the Atlantic have moved north: cod and haddock are now found north of Iceland instead of to the south, while warmer-water species such as monkfish are appearing there for the first time. In Britain, spring is starting about two weeks earlier than it did fifty years ago, with consequences for the first appearances of many species: Red Admiral butterflies and bumble bees have been sighted in January, and grass is now growing throughout the year. Some of our colder fauna and flora such as capercaillie and snow bunting, and arctic alpine flowers, are likely to disappear completely, with new immigrant species from the south taking their place. But globally some species have narrower tolerances, which is why many corals are dying as seas get too warm for them, or the chemistry of the oceans undergoes change. And if microscopic plankton is also adversely affected, as some experts fear, not only will this lead to extinctions through many food chains, but it will interfere with one of the main natural carbon storage systems, as I explain later.

  So what can we do in the face of this daunting catalogue of past, present and future woes? And are there any lessons from the past that might help us deal with what may be to come? It is possible that in the medium to long term we will be able to develop efficient and stable carbon sequestration – that is, underground or underwater storage of carbon direct from power station emissions, or extracted from the atmosphere to reduce the level of greenhouse gases. Possibilities include pumping CO2 deep underground, or converting it into mineral carbonates. Biological storage might also help – by adding iron sulphate to the oceans, the growth of plankton, including algae, would be encouraged (but with the danger of altering ocean chemistry). The former store carbon in their bodies, and these sink naturally to the seabed when they die, while the latter reduce CO2 levels and increase oxygen levels through photosynthesis. Other medium- to long-term solutions would be the successful development of virtually emission-free nuclear fusion power, by duplicating on Earth the process by which the sun creates energy, and finding ways to turn down the Earth’s thermostat by increasing the reflectance of the Earth’s clouds, so that less of the sun’s energy penetrates them to add to global warming.

  But these are all risky propositions to rely on, for one reason or another, and most scientists and environmentalists (plus a growing number of politicians) agree that we must act immediately to reduce the emission of greenhouse gases, and ideally return atmospheric levels at least to those of the last century. No less a figure than broadcaster and naturalist Sir David Attenborough recently confessed, ‘I’m no longer sceptical. I think climate change is the major challenge facing the world.’ A powerful reason behind his speaking out was the thought that his grandchildren would ask him why he had known about global warming and yet did nothing. Everyone has a responsibility to reduce their own ‘carbon footprint’: using less energy, more efficient and ideally renewable energy (such as solar, wind or tidal), and leading less polluting life-styles. This not only means driving the car less, or not at all, but also cutting back on air travel when it has never been so cheap (but never so costly for our planet). While this will come as a shock to an industrialized world that seems to expect permanent growth in energy consumption, wealth and mobility, we all need to make changes now, or generations to come will pay the price for our selfishness. And since every human is, unavoidably, a consumer and a polluter, human population growth itself must be curtailed and eventually reversed, before nature performs the task for us. The challenges may seem daunting, but if everyone contributes now by making small and consistent changes to their life-style, we can make real and measurable progress towards a better future for our species and the world. And we have a major responsibility in ensuring that our governments put the problem of global warming at the top of their list of p
riorities, not only when they are trying to get elected, but throughout their terms of office. We also need informed debate on the critical question of building a new generation of nuclear reactors that will certainly reduce the consumption of other sources of energy and carbon emissions, but at the cost of accumulating radioactive waste instead. Unless we address the threat of global warming properly through other measures, it may be forced on us.

  James Lovelock takes an especially grim view. He states:

  We are responsible and will suffer the consequences: as the century progresses, the temperature will rise 8 °C in temperate regions and 5° in the tropics. Much of the tropical land mass will become scrub and desert, and will no longer serve for regulation; this adds to the 40 per cent of the Earth’s surface we have depleted to feed ourselves. Before this century is over billions of us will die and the few breeding pairs of people that survive will be in the Arctic where the climate remains tolerable. So what should we do? First, we have to keep in mind the awesome pace of change and realize how little time is left to act; and then each community and nation must find the best use of the resources they have to sustain civilization for as long as they can. Civilization is energy-intensive and we cannot turn it off without crashing, so we need the security of a powered descent. We will do our best to survive, but sadly I cannot see the United States or the emerging economies of China and India cutting back in time, and they are the main source of emissions. The worst will happen and survivors will have to adapt to a hell of a climate.