An angry beast that might turn

The frontispiece of William H. Calvin's book features Edvard Munch's iconic painting The Scream, inspired by the vivid sunsets produced across Europe by the gigantic volcanic eruption in Krakatoa in 1883. Munch remarked that at sunset "the sky turned blood red ... and I sensed an infinite scream passing through nature". It is an appropriate image for the dangers that lurk ahead as the world warms, but the author also makes extensive use of the metaphor that appears in the title of his book. The Earth, he says, is suffering from a fever. The lab reports have come back and the diagnosis is all but certain - CO2 poisoning. Without radical treatment, the likelihood is of major complications ahead for the patient, our Earth. As Calvin puts it tersely: "The Amazon burns. Major cities drown. Deserts expand. Oceans acidify. Dwindling resources trigger genocidal wars with neighbours (think Darfur)."

The book provides an excellent - and disturbing - overview of the probable effects of climate change, very few of which are benign. Until recently the main debate about climate change was between the sceptics - those who either denied that global warming was happening or held that it is the result of natural rather than human causes - and the mainstream of scientific opinion. Today only a few reputable sceptics are left. Discussion has switched to the other side of the fence: is climate change more advanced, and more dangerous, than the mainstream perspective suggests? More and more scientists are taking the view that climate change is not incremental but involves thresholds that, when passed, can result in sudden and violent climate disruption. Shifting metaphors yet again, many who are worried about climate change see the Earth as fragile, as damaged by human intervention over the medium term. But perhaps the Earth is more like an angry beast, which will turn on us suddenly if we keep poking it with sticks. Calvin gives plenty of examples, including some taken from the past, where cases are known in which sudden and dramatic change in ecosystems has occurred.

Ice sheets, for example, such as those found in Greenland or Antarctica, can collapse very quickly. When the last major ice age finished, some 125,000 years ago, sea levels rose significantly in a period of only about a decade. Much of the ice on Greenland at that point melted and sea levels eventually rose to at least six metres higher than today. As Calvin points out, more than 30 per cent of the world's population today lives within a few miles of the seashore.

What are we, as collective humanity, going to be able to do to limit the level of climate change and contain its consequences - since most observers now agree that an increase in average temperatures by 2 per cent by mid-century is now more or less inevitable? Like many other writers on climate change, Calvin looks mainly to science and technology to provide solutions. He is optimistic, he says, about our chances of coming up with effective responses, even though we have only a relatively limited time-frame within which to discover them. We have parallels to build on. For instance, going to the Moon was a project occurring outside of wartime and was accomplished within a short time. Innovation can happen rapidly if sufficient motivation and resources are devoted to it.

Everyone has their favourite technology for combating climate change. Calvin's one is unusual - hot rock (geothermal) energy generation. Drill into hot granite, run water over it, and energy is produced as steam. Deep hot-rock energy can be developed in many different areas of the world and it is carbon-free. Maybe so, but, as with other areas, governments will have to provide a framework for such innovations. To me, there is not nearly enough discussion in the book of the political difficulties faced by climate change strategies. Calvin says somewhat ingenuously that "climate change is a challenge to the scientists but I suspect that the political leadership has the harder task". He is right; but one would have expected him to develop the thought in more detail than he does.