The Terms of Reference for the study included evaluation of the impact on Australian “economy, environment and water resources” if no global response to climate change was initiated and also in the case, that policy changes did attempt to address the issue (The Garnaut Climate Change Review, 2007). Professor Garnaut was also tasked to suggest the role Australia must play in the international community to mitigate climate change and offer policy options for Australia. The final report was submitted on September 30, 2008.
The two chapters of the Review discussed in this paper deal with the three mitigation cases, current and projected climate change of the world in general and Australia in particular. The Review uses IPCC’s Fourth Assessment Report and subsequent research to reach its conclusions and recommendations.
With a small margin of error, the global average temperature has increased by about 0.76 degrees centigrade since the mid-1800s. The rate of increase is not uniform across this period and in all regions of the world. Notably, in the last century, the Arctic temperatures have risen at about twice the average rate in the last century and, since 1979, the rate of increase over land has also been twice that over the oceans. Also, since 1958, the troposphere has been warming faster and the lower stratosphere has cooled substantially indicating the likelihood of effects of greenhouse gases in the troposphere.
Oceans, having the capacity to “store thousand times more heat than the atmosphere”, are particularly vulnerable to temperature changes. Since 1955, 80% of the earth’s energy in its climate system can be accounted for by rising ocean temperatures. A direct consequence is a rise in the global mean sea level because of expanding water. The total sea-level rise in the 20th century is recorded as 170 mm while that during the years 1993 to 2003 rising at a faster rate of approximately 3.1 mm compared with 1.8 mm for the years 1961 to 2003. .  .