A priceless proposition

Bjørn Lomborg's is an inconvenient voice. With The Skeptical Environmentalist (2001), he challenged the empirical evidence for global environmental meltdown; then he opened up a new challenge in Global Crises, Global Solutions (2004), which called for a more rigorous economic framework for prioritising global investments to improve human welfare.

This book is an abridged version of Global Crises, Global Solutions . There is no new material, simply a plainer, cheaper and more accessible flow of argument. It makes for good reading on subjects that I encourage all my students to reflect on. The original format, which has been repeated several times by different organisations in different settings, remains enticingly simple - ask a group of people how they would spend $50 billion with no strings attached to improve human welfare, based on a pre-determined list of 20 issues.

But if, two years on, the format remains enticing, then my original three criticisms of the approach also remain valid. First, the truly demanding challenge is how to raise that extra $50 billion. Second, the focus of the prioritisation exercise is on the short term and gives little weight to the need for and role of long-term political vision. Third, the approach assumes that the economic cost-benefit criterion displaces all others.

I am now also critical of this type of exercise for a fourth reason. The issues Lomborg tackles - education, HIV, malnutrition, trade, corruption, climate change and so on - cannot be compartmentalised into discrete investment packages. As these experts noted, growth in incomes reduces the long-term incidence of civil war, for example, and investment in education reduces the incidence of HIV.

The issue of climate change illustrates this well. In the 2004 book, the experts were asked to rank three climate change proposals - the Kyoto Protocol, an optimal carbon tax and a value-at-risk carbon tax. Is this really all that climate change boils down to, a subset of energy-related issues? Far from it.

Climate change presents society with a long-term frame of reference against which all its actions and aspirations must be evaluated. Global climate change visibly reveals to humanity for the first time in our evolution that there are physical interdependencies between behaviour in one part of the world and effects elsewhere, and between behaviour in one generation and manifestations in subsequent ones. Crucially, these interdependencies are structural and unalterable by human social or political design - no political system can negotiate to change the radiative warming potential of long-lived greenhouse gases, and no cultural revolution will alter the thermal expansion coefficient of the ocean. Climate change therefore transcends the classical welfare and justice issues that Lomborg is tackling.

Our destabilising climate provides the ultimate boundary condition for society. All policies are now climate-change policies, and all investments are climate-change investments. Unfortunately, it takes more joined-up thinking than is displayed by Lomborg and his experts to get this one right.

Mike Hulme is director of the Tyndall Centre and professor of environmental sciences, University of East Anglia.