Letter Of The Month… Comment On “Local Councils Rise To Sea Level Challenge”

By Ray Johnson of Bondi Beach on December 5, 2013 in Other

Dear Editor, last month’s article titled Local Councils Rise To Sea Level Challenge (The Beast,
November 2013) appeared to suggest that the latest report from the Intergovernmental Panel on Climate Change (IPCC) forecast an absolute worst-case scenario of an 80 centimetre rise in sea level. If you read the primary documents the reality of the IPCC projections is much, much scarier.

The IPCC also said: “Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped.” On sea levels the summary stated: “It is virtually certain that global mean sea level rise will continue beyond 2100, with sea level rise due to thermal expansion to continue for many centuries.” And this is for the immediate and drastic intervention scenario where emissions peak around 2050 and then reduce.

There’s also mention of regional variation and, according to the CSIRO, Sydney’s rise will be plus 50 millimetres on the global average in 2030. In January this year the New South Wales government acknowledged regional variation and stopped recommending state-wide sea level rise benchmarks to local governments.

The IPCC is conservative in its methods. Predictive models that link to historical data of 5-metre plus sea level rises in previous warm periods have not contributed to the projections. There’s also mention, but not inclusion, of a possible collapse of marine-based sectors of the Antarctic Ice Sheet, with medium confidence that if this occurred it would not exceed several tenths of a metre of sea level rise during the 21st century.

Another ‘known unknown’ caused so much debate that a special report titled Policy Implications of Warming Permafrost was produced by the United Nations Environment Program following the IPCC decision not to include the emissions mechanism at all in modelling for the current projections. If the permafrost starts melting, massive amounts of CO2 and methane will be released, triggering a strong positive feedback loop. The report says: “Uncertainties are large, but emissions from thawing permafrost could start within the next few decades and continue for several centuries, influencing both short-term climate (before 2100) and long-term climate (after 2100).”

As I write, the draft report of the Climate Change Authority has just been released, nominating options of 15% and 25% reductions in greenhouse gas emissions by 2020 as Australia’s fair share of a global effort. All those nippers on our beaches should be hoping that there’s international agreement next year on the immediate and drastic intervention scenario. Otherwise their rates will have to pay for an awful lot of ‘beach nourishment’.