In an interview with the Financial Times, Lord Nicholas Stern has admitted that the 2006 Stern Review on the Economics of Climate Change (earlier post), which was widely regarded as one of the first comprehensive assessments of the potential effects of climate change on the world’s economy, underestimated the potential scale as well as level of risk that climate change presents to future economic development.
“Emissions are growing much faster than we’d thought, the absorptive capacity of the planet is less than we’d thought, the risks of greenhouse gases are potentially bigger than more cautious estimates, and the speed of climate change seems to be faster,” said Lord Stern.
The Review, which had asserted that global economic loss could be as much as 20% of GDP in the absence of sufficient climate policy, was greeted at the time with extensive criticism from economists, many of whom questioned the methods used by Stern and others, and asserted that the costs of inaction had been overstated.
However, Stern said yesterday that “the damage risks are bigger than I would have argued...We can’t be precise about what it would be like but you can say it would be a transformation.”
The Stern Review was developed over the course of a year at the request of the UK’s then-Chancellor of the Exchequer Gordon Brown (now Prime Minister), and released 30 October 2006. It focused on the costs of action necessary to achieve a 450-550 ppm CO2 equivalent level and a global temperature rise of no more than 2ºC.
Scientific support for such a target has since eroded. Recently, for example, NASA scientist James Hansen has called for a scaling back to 350 ppm CO2 from today’s approximate level of 385 ppm CO2.
The most optimistic emissions stabilization scenarios cited in the IPCC’s Fourth Assessment Report project a global temperature rise of 2ºC to 2.4ºC at 445-490 ppm CO2 equivalent if emissions peak between 2000 and 2015; however, they are outnumbered by almost 20 to 1 by scenarios that project a global temperature rise of 3.2ºC to 4ºC at 590-710 ppm CO2 equivalent. Feedbacks and tipping elements which have dominated recent climate change projection theory are not included in the scenarios.
Hansen, et. al. (2008) Target Atmospheric CO2: Where Should Humanity Aim?