A humanist on thin ice Science and the humanities, people and climate change Tom Griffiths I feel lucky to have visited both of Earth’s polar ice caps. Seven years ago I voyaged to Antarctica on an Australian routine expedition ship to resupply one of the scientific stations down south. I experienced that awesome encounter by sea with the great ring of ice that surrounds the southernmost continent. You sail directly south from Australia across the stormiest sea in the world for nine days and then, finally, the ocean stills, for you are among giants. The icebergs. They loom into sight, at first a craggy eminence in the mist and then a faceted jewel revealing its edges and cliffs and threatening fragility. These great icebergs made me shiver with more than cold. In their stateliness and marbled grandeur they provoke a frisson of fear because of what they come from, because of what they are fragments of. You are heading towards a giant ice-making machine and these are the most trivial of its industrial residue. Two years ago I had a more intimate encounter with ice at the other end of the globe, when I visited Greenland. Instead of being on a container ship I was on a tiny fishing boat, and we sailed perilously close to fragmenting icebergs in an ice-choked fjord. I learned later that up to five people die every year in that bay from doing this, mostly Inuit fishermen from a small community of five thousand people and eight thousand sledge dogs. I was in Ilulissat, under the eaves of the bergs in Disko Bay, at the mouth of the fastest moving glacier in the world. It is now moving forty metres a day, and its pace has doubled in the past decade. The Sermeq Kujalleq glacier is allegedly the source of the iceberg that sank the Titanic. Now it is a physical and political frontier of climate change. This is where American senators fly in to get a visceral sense of what greenhouse gases are doing. 2 In the early twenty-first century, when you contemplate a retreating glacier, what do you feel? You are overwhelmed by a timeless wonder and a primal fear. You are witness to an ancient, remorseless natural force, one that makes humans seem trivial, expendable and irrelevant. Ice is abiotic and inhuman. Yet, with what we now know about global warming, you can no longer regard calving ice as simply natural. The pace and circumstances of the event implicate us. In our generation, ice has become moral and political. So now we have other feelings when we contemplate the melting ice – ethical anguish about humanity’s responsibility, political passion to reduce greenhouse emissions, apocalyptic doom about your prospects and even perhaps an opportunistic zeal about what your nation might have to gain in the short term. When Greenlanders recently voted for independence from Denmark, some noted that once the Greenland ice sheet melts, Denmark – one of the flattest countries in the world – will be under water anyway. Nationalism can look pretty parochial. At the beginning of the twenty-first century, we are standing on the brink of a precipice, but at least we know that we are. We surely don’t understand all the dangers and opportunities ahead of us, but we are now roughly aware of our predicament. That at least is an achievement. The same industrial capitalism that has unleashed carbon has given us a planetary consciousness that reveals a calving glacier not as a random, local act of nature, but instead as the frightening frontier of a possibly irreversible global, historical event. How did we come to this realisation? It emerged partly due to humans’ contemplation of glaciers. Understanding ice – its history and its future – is the key to understanding climate change. o0o A hundred years ago we didn’t know much about ice. At the beginning of the twentieth century explorers still thought they might find polar bears in Antarctica. Even fifty years ago we were still just finding out how much ice there is clamped to the base of the globe. One of the paradoxical responses I had to seeing both ice caps was to be reminded of just how much ice there is on Earth. After all, we do live in the lee of an ice age. The top thirds of the 3 latitudes of each hemisphere have ice. Admittedly, we live in a brief relatively warm phase, a precious interglacial. Calling our own geological age the Holocene and thereby separating it from the Pleistocene – the Ice Ages – is misleading. As humans, we are inhabitants and creations of an extended, continuing series of ice ages, the Quaternary. In the mid-nineteenth century a fine scientist shocked his colleagues and the public with a revolutionary view of the global past. I’m not referring to Charles Darwin, although that intellectual drama was happening in parallel. I mean the charismatic Swiss-born professor, Louis Agassiz, who in the late 1830s proposed not only that glaciers had moved rocks around and later retreated – hence explaining the puzzling presence of isolated boulders in Swiss valleys – but that whole countries had once been covered under miles of ice. There was something obsessive about Agassiz’s catastrophist crusade. He was prepared to be lowered into the bowels of glaciers to understand their dynamics. His friend and mentor, Alexander von Humboldt, warned him against the ambition of his theory: ‘Your ice frightens me.’1 The idea of a former ice age of such a massive scale took several decades to be fully accepted by the scientific community. It overturned the dominant scientific assumption that Earth was gradually cooling down through history. And it challenged the biblical account of a great deluge. Instead, Agassiz proposed that it was frozen water that had wiped Earth clean. Climate, it seemed, was capable of variability beyond remembered human experience, even beyond imagination. Although Louis Agassiz promoted the idea of an ice age, he did not spend much energy pondering its cause. It was this quest to understand the causes of ice ages that provoked the climate change science we rely on today. In the 1860s a Scottish scientist, James Croll, proposed an astronomical theory of ice ages, arguing that they were triggered by fluctuations in Earth’s orbit, tilt and wobble that affect the power of the sun. This idea was revived and improved in the 1920s and ’30s by the brilliant Serbian mathematician Milutin Milankovitch, but it long languished in the face of healthy scientific scepticism. The astronomical theory of ice ages finally gained confirmation in 4 the 1970s, following the acceptance of another theory – that of plate tectonics (continental drift) – and also due to new evidence of past climates, drawn from oxygen isotope analyses of deep-sea sediments. Today, we accept the Croll–Milankovitch theory of the astronomical cause of the ice ages, but we acknowledge that other factors are also involved – and that there are still mysteries. Fluctuations in Earth’s orbit and orientation are clearly triggers. But these astronomical patterns also interact with earthly factors. To generate an extended ice epoch like the Quaternary it helps to have some land close to the poles, and plate tectonics explains how the continents can get themselves there from time to time. But it is the much faster feedback mechanisms of the ebb and flow of ice sheets, and the fluctuations in greenhouse gases and their absorption in the oceans, that can amplify small changes in global temperature, thereby precipitating an ice age. How was human influence identified as a factor in modern climate change? Let us revisit four moments in that dawning understanding. Together they constitute a useful greenhouse history, a guide to the scientific insights – all of them in some way inspired by ice – that underpin our contemporary environmental consciousness. o0o It is 1859, the Origin of Species has just burst upon the world and we are in London in the laboratory of the Irish scientist John Tyndall. Like Louis Agassiz, Tyndall is a very keen mountain climber, and he too is spellbound by glaciers. He has just returned from a summer in the European Alps and in a few years will lead an assault on the Matterhorn. Tyndall is investigating a possible cause of ice ages; he is interested in how the atmosphere might control Earth’s temperature. He wants to test the accepted notion that all gases are transparent to radiant heat. In his laboratory he first tests the main gases in the atmosphere, oxygen and nitrogen, and he finds that, yes, they are indeed transparent. Perhaps he will abandon this experiment. But then he thinks to test coal gas. There it is, easily accessible to him, for it is piped into his laboratory for lighting, an industrial gas, mostly methane produced by 5 heating coal. When he tests it, he finds that it is opaque – it traps heat rather than letting it through. ‘Thus,’ as one writer put it, ‘the Industrial Revolution, intruding into Tyndall’s laboratory in the form of a gas jet, declared its significance for the planet’s heat balance.’2 Tyndall then tries other gases and finds that CO2 is also opaque. In 1859, already a celebrated year in the history of science, the role of greenhouse gases in controlling the temperature of the planet has been identified. Now it is 1896, and we’re in Sweden looking over the shoulder of Svante Arrhenius. He is doing lots of tedious calculations – he is also interested in what might cause ice ages and he is investigating whether levels of atmospheric carbon dioxide might be a factor.