disappear somewhere into space through strategically placed holes in the sky. They are trapped within the Earth’s atmosphere. This has always happened and there are various systems that can help correct any imbalance. When it comes to the climate one such system is the oceans. But such is the sheer scale of our emissions that this particular safety valve is becoming overwhelmed. Also, worryingly, the vast quantities of carbon dioxide absorbed by the oceans are changing the water’s composition, making it more acidic.
The effect so far is quite mild, but it will increase as the level of carbonic acid in seawater increases. It is a simple chemical relationship. More carbon dioxide in the atmosphere leads to more acidic seas. And if the sea is more acidic, then all sorts of creatures will find it harder to survive. Greater acidity, for instance, affects the ability of shell-forming animals to grow, which in turn could unbalance whole ecosystems, like coral reefs, and disrupt the food chains that support bigger animals, like fish and birds and, of course, us, because we catch the shellfish and fish and eat them. Also, if shell-forming creatures cannot function properly because of changes in the ocean’s chemistry, this could also have implications for the state of the atmosphere. Once they stop making shells, they remove less carbon.
This is just one of many thousands of examples that demonstrate how everything in Nature is connected – it works as a whole system, with changes in one part affecting the behaviour of others. As we change the atmosphere, so this causes changes in the oceans, bringing about ecological changes that in turn will potentially compound the speed and scale of changes in the atmosphere. The recent science seems to me to confirm what many people have felt for some time: namely that the relationship we have developed with the Earth during our technological and industrial age is a one-sided affair. It is not one of equals, but is based upon the master-and-slave model, and many see this as posing grave threats not only to the natural world, but to humanity as a whole.
The inconvenient fact is that the changes we have relatively recently set in train on Earth are occurring faster than any in human history, and on a larger scale. These changes have enormous implications for people everywhere. I believe it is necessary for us to think very seriously about how we curb our impact before it is too late. We might begin by looking in particular at how we use energy and land.
When it comes to energy, our world today depends on fossil fuels. From cars to fridges and from computers to airliners, every aspect of how we live now depends upon fossil fuels. Fossil energy has not only allowed the development of thousands of vast cities, but has also permitted the industrialization of farming and created the wealth to invest in tremendous advances in healthcare. Both these have enabled our population to climb towards seven billion and it continues to rise rapidly.
Fossil sun
Giant ferns that grew in carboniferous swamp forests 300 million years ago and microscopic plankton that once drifted in the oceans, were among the organisms that helped to create the coal, oil and gas deposits that now drive the modern world. Provided by the sun, energy that flowed through living organisms long ago in the Earth’s past was trapped, transformed and then held tight in the hydrocarbon compounds that now power our industrial societies. That energy source, which took hundreds of millions of years to accumulate gradually, is being used up all at once, and the carbon that was, in the process, taken out of the air and stored away over such vast periods is being released as carbon dioxide in a great single pulse. As a result, we are upsetting a balance established over millions of years, and on a massive scale. This is an indisputable fact and it seems to me that the ice cores and the graphs drawn from the Mauna Loa measurements act as a cold, silent and independent witness to the changes that have occurred after more than two centuries of industrialization.
RIGHT: This satellite image, covering an area approximately 2 miles wide, shows intact rainforest in green in the south of Brazil at the top of the image and agricultural land at the bottom of the picture across the border in northern Argentina.
However, it is not only fossil fuels that are causing an ever more pressing atmospheric crisis. Around a fifth of annual human-induced carbon dioxide emissions come from the continuing clearance of our planet’s forests, particularly the tropical rainforests. During 2007 I received the direst warnings from leading scientists as to the implications of this particular trend.
The tropical rainforests are to me without doubt the most incredible terrestrial ecosystems on Earth, and for a considerable number of years I have been working hard to convey this fact to as many people as possible. They are literally the Earth’s air-conditioning system, and are also a vital mechanism that moves water around the globe. Without them we would have less of the rain that, for now, allows crops to grow and farms to thrive, but they are also enormous carbon storage reservoirs. Billions of tonnes of carbon are locked up in them, but as the rainforests are degraded and cleared away by logging operations, or replaced by cattle pasture, or with plantations of commodity crops, such as soya and palm oil, the carbon that was once in the trees and the soil beneath them is transferred to the atmosphere as carbon dioxide, adding to the burden of greenhouse gases.
What makes matters considerably worse is how the tropical rainforests also absorb about 15 per cent of our emissions, such as those from cars and power stations. As they are cleared, so their ability to reduce the impact of our emissions from industry and transport is diminished. More than a third of the tropical rainforests have already been removed, the vast majority since the 1950s. The rest are fast disappearing, as demand for land to grow the crops that feed global commodity markets spirals upward. This is for me one of the greatest tragedies of our age, not least because it is unnecessary.
Necessary or not, the increased levels of carbon dioxide brought about principally because of fossil fuel combustion and deforestation have already led to an elevated global average temperature. Scientists are now confident that the net effect of human activities since the mid-eighteenth century, when coal use began to rise rapidly, has been one of warming. Global average temperatures have increased by about 0.8° Celsius since this time and there is strong evidence that most of the observed increase in temperature since the mid-twentieth century is directly attributable to increases in anthropogenic carbon dioxide and other greenhouse gases. This is now a mainstream view, backed by a vast body of scientific evidence.
Of course the changes we have caused to our planet’s atmosphere were not an intentional or conscious act. They are the inadvertent results of how we have grown economies, made life more comfortable and promoted people’s welfare. They are unintended consequences of what we have come to call development, and the process continues today as we seek to expand our comfort and solve problems in ways that generate yet more greenhouse gases. But it is different now, not least because I don’t believe we can go on any longer pretending that we do not know about the problems we are creating. Thanks to modern science we now know the consequences of the way we have chosen to live, and the way we have become used to meeting our needs – and we are also increasingly aware and informed about the grave legacy we are leaving for those who follow us in the near future.
OVERLEAF: Moon rise over an oil refinery. Refineries heat crude oil and pass it through catalytic cracking towers. Pollution released in the process causes the moon to appear red.
Melt
What I have been told by scientists for years has finally been accepted as common knowledge – at least among those prepared to face the facts. From humanitarian disasters on a grand scale to extreme conditions causing massive costs to the insurance industry, and from the inundation of low-lying coastal areas to the disappearance of rainforests owing to prolonged droughts, we could soon witness profound challenges that could become unmanageable if we do not act in time. The consequences for hundreds of millions of people living in developing countries will be disproportionately worse – although, for many, they