Review: You can tell a subject's changing ideas by the gap between editions. Given that this is the fourth in 15 years we can see how far the science has come. It's worth remembering that only the same time prior i.e. 30 years ago, that global cooling was the main education topic and only a few mavericks considered global warming to be serious. Now it's the other way around we still need to make sure that we have the best information. Having recently worked through a controversial and heavily referenced text by a leading Australian writer it's useful to see how other arguments have been developed (especially as this book's subtitle is 'the complete briefing'). It's certainly comprehensive (rather than 'complete' given the nature of the material we've accumulated about this subject). The presentation is better with full-colour making ideas easier to follow. It can certainly claim to be a valid update with this edition almost twice the size of the second edition I reviewed some years back. Big question - how's it stood up to the passage of time?

Chapter one starts with a basic overview. We are told of a number of events around the world that are not "usual" give our past experience. This is put into the context of both vulnerability to change (i.e. we need to change because some communities are at a dangerous risk level) and a more theoretical framework for studying the issue of global warming (emissions, climate change, vulnerability and human systems). In keeping with current ideas adaptation and mitigation are key sub-themes. Chapter two gives a basic overview of the concept of the greenhouse effect showing the amounts and rates of energy transfer. One of the key ideas in global warming is the nature of products that give rise to the enhanced effect (i.e. the 'extra' part due to human activity). Chapter three outlines the key gases (not just carbon dioxide) and particles that are considered the principle components of global warming. Much debate has taken place about the role of past climates to our understanding. Chapter four explores these ideas looking at the past 100 years and then a further order of magnitude back to study hallucinates (although deeper geological ice ages and warming periods are excluded). The next chapter brings us squarely to one of the main areas of disagreement in the global warming debate - modelling. The atmosphere is extremely complex (if not chaotic in its responses) and computer models are still primitive by comparison. There is a chance to look at these models and to see how they work and some of the issues they raise. Interestingly, the IPCC has a range of models (as do other organisations) and all agree that modelling is a problem and that several scenarios are needed to get a balanced response. Despite all the issues and debate, most models still predict a rise in temperature. Chapter six takes these scenarios and recast them onto a global scale. This gives us some idea of what might happen, where (and to some extent, when). This is a turning point for the book's case because from here, the science gives way to change and solutions. We start with chapter seven which examines the types and magnitudes of change under a range of global warming scenarios. A very wide range of examples has been chosen with impacts upon ecosystems, fresh and saline waters, deserts, food supply, human health and, finally, cost. The basic argument is that the cost of doing nothing will be out-weighed by the damage caused. Chapter 8 takes on the brave topic of concern for the environment. The answer to the question of concern is played out against a backdrop of cases ranging from frog populations to equity and the future. Lest it should be seen as complete and finished, chapter 9 highlights the fact that most models and estimates are just that - there is always uncertainty in calculations and the trick here is to be as accurate as possible. Assuming this will happen, chapter 10 studies our responses and outlines solutions from political to engineering and the decisions needed to make some sort of way forward. Most of global warming centres around energy and energy useage with chapter 11 showing what can be done to reduce energy consumption and therefore greenhouse gases. Finally, there's the opportunity, in chapter 12, to put global warming in the context of other, equally pressing cases.

It's a big, sweeping canvas that seeks to highlight the key items needed to discuss global warming. It is inevitable that there are omissions but these do not detract, overall, from the message being conveyed. It is a remarkable book and one of the most comprehensive on the market. It deserves a wide readership.