Last week, it was Warsaw’s turn to host a disappointing meeting on climate change. Over the past two decades, many other cities have had this pleasure. This time, 195 countries painfully agreed to make a “contribution” to combating climate change, in place of a more robust “commitment”. The aim is still to reach a strong agreement in Paris in 2015. The chances of success must be negligible. Experience shows that.
What makes this depressing is that the world could probably eliminate the risks of catastrophic outcomes at limited cost, provided it acted quickly, effectively and in concert. In his new book, The Climate Casino, William Nordhaus of Yale, doyen of climate economists, argues that the cost of limiting the increase in global temperature to 2C would be 1.5 per cent of global output, provided the right action were taken. This is only half a year’s global economic growth. But abatement would be far costlier if countries responsible for half the emissions did not participate: keeping temperature increases to 2C would even be infeasible (see chart).
Professor Nordhaus, a moderate voice in this debate, explains why the world should accept the costs of action. The greenhouse effect is basic science. Emissions have risen rapidly. Atmospheric concentrations of carbon dioxide are now more than 400 parts per million – 50 per cent higher than before the industrial revolution and well above levels over the last 1m years. Global temperatures have risen over the past 150 years. The recent temperature plateau is not exceptional. Climate scientists have been unable to find an explanation for the increases in temperature, other than human activities.