Block’s Indicator of Sustainable Growth

by Ray Block

A  scientific conference on climate changes at Oxford University’s Environmental Change Institute funded by the UK government  (September 28-30 2009) was sobering in its judgement that catastropic changes in global warming could happen within 50 years.

The 2007 IPCC climate change consensus forecasts were for average  increases of 2 degrees Celsius by 2100, with atmospheric levels of CO2 to be contained to no more than 450 parts per million. These forecasts are now considered to be too optimistic.

Most scientists now expect earth temperatures rising at an average 3 degrees Celsius  by 2100, with the possibility of 4.5 -5 degrees C  being realised. The implications are for deserts to spread, heatwaves to become more prevalent, ice caps to melt, and cyclones to be triggered.

Equally, the 2007 IPCC forecasts of 20cm-60cm increases in sea levels by 2100 are now seen also as too optimistic. 

Professor Stefan Rahmstorf, from the Potsdam Institute, warned that such an increase in global temperatures would result in sea level rises of between 1 metre and 1.3 metres by 2100 compared to 1990 levels. 

Temperature and sea rises of these levels, would be a dangerous tipping point. A continuing high carbon environment would set in motion potentially devastating 4 degrees C in the 2070s. But a “plausible worse case scenario is that we could get it by 2060,” said Dr Richard Betts, Head of Climate Impacts at the Hadley Centre.

The dramatic acceleration in climate forecasts were occasioned by paying close attention to projections of fossil fuel use continuing at about the same levels of the last 20 years.

“Previously, we haven’t looked at the impact of burning fossil fuels so intensely,” said Dr Betts. 

4 degrees C elsius rise would mask higher regional increases, such as an increase of 16 degrees Celsius (28.9F) in the Arctic, and 10 degrees Celsius (18 F) in western and southern Africa, and in the Americas affecting parts of the Amazon, and particularly around the north eastern corner.

Richard Betts  said he was shocked that so much warming could occur within the lifetime of people alive today.

The only optimistic note was that the future does not have to be a doomsday scenario. Said Betts: “if we get big cuts in greenhouse emissions soon, we can still avoid the worst consequences.”