Not the last generation on Earth [hopefully] but the last to enjoy relatively stable weather. Nature, Pearce warns us, does not ‘do’ reasonably smooth, proportionate changes in climate. – as misleadingly implied by the IPCC scenarios. The evidence indicates that past changes have often been drastic, taking place rapidly over centuries, decades or even years. Once change has started, it has been reinforced by positive feedbacks.

Humanity, causing environmental change, boosting greenhouse gases in particular, is this time providing the impetus. Some global mechanisms exert negative feedback, damping-down the changes. Mechanisms to provide positive feedback, however, there are aplenty, and they may already be operating. No one knows [yet] at what point the changes will become self-sustaining and beyond any human remedy. Those of a nervous disposition should not read further.

Pearce takes us on a tour of the climate changes and the mechanisms. Many effects are already noticeable: Shifts in El Nino, rising temperatures with unprecedented heatwaves, disappearing islands, extended drought, exceptional hurricanes, melting permafrost, loss of Artic sea ice, retreating mountain glaciers and faster glacial flow on Greenland and Antartica. Etc.

The most interesting part of the book is the focus on the human story. The watchmen of climate change, who will undoubtedly be heroes if humanity emerges reasonably intact from this crisis, are dedicated, doughty, dogged, determined and [I’m .struggling to maintain the alliteration] downright bloody-minded individuals. [Worthy successors of the Old Testament prophets, although they might not all thank me for the comparison.] Jim Hansen, George Bush’s top climate-modeller, has fearlessly spoken truth to power. Others, like Lonnie Thompson, of the Byrd Polar Research Institute, have borne great discomfort in pursuit of data from glaciers..

My favourite story is of Joe Farman’s discovery of the hole in the ozone layer. He is a string-and-sealing-wax physicist of the old school, who spent years patiently collecting ‘useless’ data from Antarctica. Sophisticated American satellites failed to detect the ozone hole because the software that analysed their results had been programmed to reject extreme readings (like: no ozone). In fact humankind has had a narrow squeak. It was little more than chance that chlorine rather than bromine was used in the manufacture of refrigerants etc; but bromine’s effect on the ozone layer would have been 100 times worse!

The book is unusual in other ways. It takes climate change sceptics seriously, although they may be hoist by their own petards. Yes, dramatic climate change (e.g. the relatively rapid switch between ice-age and inter-glacial) may be precipitated by small changes in the earth’s orbit or rotation. But how much more might climate be affected by an initially small change in the greenhouse effect? The book also advocates an immediate focus on cutting methane emissions (from landfill, farm animals etc) to reduce the rate of warming (since the extent of climate change depends on the rate as well as the amount). The useful concept of ‘wedges’ of actions to cut emissions is taken up. There is a timely reminder that the extent of melting ice etc may be as important an indicator of change as temperature rise. And Pearce does not conceal the uncertainty and disagreement within the scientific community (or the large areas of agreement).

A book by an individual cannot be strong in all aspects. The pressures from developing and least developed countries are viewed pragmatically rather than in the context of justice. Possibly the recommendations for action are a little low-key given the potential danger. One might have doubts about the ability of ‘the market’ to deliver, even with incentives. The consequences of ‘Peak Oil’ do not seem to have been fully factored in. No matter – the message is perfectly clear: by the time we understand for sure it may well be too late to take remedial action. ‘Unless the Lord keeps watch over a city, in vain the watchman stands on guard.’

Charles Jolly