From Prof Jeffrey D. Sachs.

Sir, Christopher Caldwell ("The evolution of creationism", September 6) is incorrect to say that the creationists are wrong on the science "but wrong in a way that is of absolutely no consequence to them unless they choose a career in horse-breeding or molecular biochemistry".

The US is choosing a president and vice-president who will have global influence over climate change, species preservation, energy systems and a host of other issues in which scientific knowledge is crucial.

To believe that Sarah Palin's ignorance about man-made climate change, her disdain for environmental conservation and her eagerness to drill for oil in nature refuges and other fragile ecologies, is a harmless fight between technocrats and democrats is to miss the whole point. Humanity is at a critical crossroads in which we either choose together to steer the planet to sustainability or suffer together the harrowing crises of hunger and conflict that will result from our collective unwillingness to face matters through both science and ethics. The US's anti-scientific leadership during the Bush years has already put the whole world at risk, and those risks have just multiplied dramatically.

Jeffrey D. Sachs,

Director,

Earth Institute,

Columbia University,

New York, NY, US