Pioneer Run Creek, Titusville, Pennsylvania, USA, in 1865. One of the world’s first oil fields. From small beginnings, nearly every aspect of our lives is now dependent on fossil oil and gas.
When those lights first illuminated the shady, cool recesses of Peterhouse’s ancient hall, the world’s human population had reached about 1.2 billion. Although horses were still an indispensable source of power, the steam railway that reached Cambridge in 1845 had already led to a revolution in attitudes to travelling. A year after the great switch-on at Peterhouse, the first patent for a petrol-engine car was granted to Karl Benz in Germany. Eighteen years later the first plane would take to the air. In the expansive fenlands surrounding Cambridge, much of the drainage system that had been dug in Roman times had for centuries been powered by the wind. But even in these remote East Anglian flatlands times had changed. Some sixty years before the switch was first thrown to light Peterhouse, the last of some 800 wind pumps had been closed down, to be superseded by steam-powered alternatives. The obsolete technology was quickly swept away in favour of more flexible and powerful modern alternatives.
I make these points in order to underline the recent rapid pace of change, and to remind us of how quickly we have reached the point where we are now. All of these wonderful innovations were developed with the best of intentions. Pioneers like Benz wanted to create wealth and well-being and to improve people’s lives. But the huge benefits we have gained have not come without serious consequences. One of the biggest is on view up the road from Peterhouse, in a different part of Cambridge.
Ice core data has enabled scientists to build up a detailed long-term picture of carbon dioxide, methane and oxygen isotope levels in the atmosphere, and how average temperatures have changed.
Inside the headquarters of the British Antarctic Survey is what is without doubt one of the most remarkable archives ever accumulated. Kept in a building with a temperature permanently maintained at below –20° Celsius are tubeshaped sections of ice. They are about two feet long and some four inches in diameter. Some are white, others translucent. Meticulously labelled and filed on racks, these frosty samples were taken from the core of a drill that had penetrated one of the thickest layers of ice found on our modern Earth: an area called Dome C, high on the plateau of East Antarctica. As snow accumulated over thousands of years, it built up in deeper and deeper layers. The snow was compressed by subse-quent falls and the weight formed layers of ice, year after year for hundreds of millennia.
If the ice cores drilled out of Dome C were laid end to end they would stretch for about two miles, but it is not so much the depth the drill reached that is most remarkable: it is the age of the ice it found at the deepest levels. The further the drill went down, the older the ice it extracted, at the bottom pulling up samples more than 800,000 years old. The ice drill thus enables us to look back over the best part of a million years and so in a way is a time-travel machine.
Trapped in the falls of ancient snow are tiny bubbles of the Earth’s atmosphere as it was when the snow fell. When I last visited the centre, one of the scientists took an ice sample into the warmer corridor, where it began to melt, and I could hear it crackle as the bubbles of trapped air were released. By catching and analyzing these little bits of frozen air, scientists at the British Antarctic Survey have been able to take direct measurements of different gases. By analyzing different oxygen isotopes in the ice itself they can calculate accurate temperature measurements and these confirm that during the past three-quarters of a million years or so our world has undergone eight separate ice ages, each punctuated by warmer interglacial periods, like the one we are living in today.
One of the most dramatic findings to emerge from the study of these ice cores is how the levels of carbon dioxide have changed, and how closely they have matched the climate changes. Even in the warmest periods, the ice cores show that the concentration of carbon dioxide never went above about 290 parts per million – that is 0.029 per cent by volume of the air. In the 1780s, when the Industrial Revolution began in England, that figure stood at what was then a recent high point of about 280 parts per million. But the ice cores show how this figure has increased, and fast. A hundred years later levels had crept up to just below 300 parts per million. Another hundred years later, in the 1980s, carbon dioxide levels exceeded 340 parts per million.
Ice core data has enabled scientists to build up a detailed picture of carbon dioxide, methanol and oxygen isotope levels in the atmosphere and how average temperatures have changed.
Today there are more than 50,000 large power stations in the world, most of them burning fossil fuels to do what was done at Peterhouse in the 1880s – but now on a vast global scale. Between then and now the emissions we produce by generating energy in this way have grown from virtually nothing to billions of tonnes of carbon dioxide every year. And as the demand for power increases, so the number of coal- and gas-fired stations also goes up. In China and India today the process of industrialization is happening faster than ever before. China is opening one or two major coal-fired power stations per week. New cars are rolling onto China’s roads at a rate of about 1,000 a day. Of course, China and other countries are simply following a pattern of development seen in the West, but what I have been told by the climatologists makes it very clear that our collective way of life simply cannot continue like this if we are to avoid catastrophic impacts on our planet’s climatic stability.
Ice samples are a vital source of information, but for the past fifty years or so our knowledge of changing carbon dioxide levels has also come from direct measurements of the composition of the air. High on Mount Mauna Loa in Hawaii, as far away as possible from carbon dioxide sources such as forest clearance and industry, scientists have been able to monitor global change taking place before their very eyes. The measurements taken in Hawaii do not reveal the kind of slow change that occurs over tens of thousands of years, but a more rapid trend which is visible year on year. In 2010 the samples taken in Hawaii revealed that carbon dioxide levels had climbed above 388 parts per million.
What is perhaps even more alarming than the very high level of carbon dioxide is the rate at which it is increasing – for not only is it going up, it is going up at a faster pace. This is not solely because our consumption of fossil fuels continues to grow and that we continue to destroy vast areas of forest every year, but also because the natural systems that have so far absorbed most of the carbon dioxide we have released are now apparently doing so more slowly than they did in the recent past. It could also be because some natural systems, such as soils, are beginning to release carbon dioxide as a consequence of the warming that has already occurred.
Samples taken at the observatory on Mount Mauna Loa, Hawaii, since the late 1950s have revealed the fastchanging nature of Earth’s atmosphere. This famous diagram is known as the Keeling Curve after scientist Charles David Keeling who initiated this programme of measurement.
Diatoms at about 150 times magnification. There are about 10,000 species in this distinctive group of single-celled algae which are an important part of the plankton at the base of both marine and fresh water food chains. Diatom remains left in sediment samples can be used as effective proxies for climate change.
Unfortunately, the emissions