The 692-page Stern Review begins with a look at the science of climate change, for good reason, but this material will not be new to any frequent visitor to this site, so I will highlight only striking statements.
The first of these comes early in the "key messages" prologue to chapter one:
A warming of 5C on a global scale would be far outside the experience of human civilization and comparable to the different between temperatures in the last ice age and today. Several new studies suggest up to a 20% chance that warming could be greater than 5C. (pp3)
An interesting footnote about the well-known skeptic (and Exxonian) Richard Lindzen: It has been suggested that water vapor could act as a negative feedback on warming, on the basis that the upper atmosphere would dryout as it warms (Lindzen 2005). Re-analysis of satellite measurements published last year indicated that in fact the opposite is happening (Soden et al 2005). Over the past two decades, the air in the upper troposphere has become wetter, not drier, countering Lindzen’s theory and confirming that water vapor is having a positive feedback effect on global warming. This positive feedback is a major driver of the indirect warming effects of greenhouse gases. (pp9)
The risk of heat waves is expected to increase. For example, new modeling work by the Hadley Center shows that he summer of 2003 was Europe’s hottest for 500 years and that human-induced climate change has already more than doubled the chance of a summer as hot as 2003 in Europe occurring (Stott et al 2004). By 2050 under a relatively high emissions scenario, the temperatures experienced during the heatwave of 2003 could be an average summer. The rise in heatwave frequency will be felt most severely in cities, where temperatures are further amplified by the urban heat island effect. (pp17)
That last statement–that the heatwave of 2050 could be routine in my children’s lifetime–shocks. If that is routine, what then would be a heatwave? 120 degrees? 130?