The potential impacts of global warming         (Part b)

Report of the Senate Environment, Communications, Information Technology and the Arts References Committee
The Heat Is On: Australia's Greenhouse Future
Table of Contents

Chapter 2

The potential impacts of global warming         (Part b)

Chapter 2 - Part a

More recent regional impact studies

2.67 New regional warming and rainfall change scenarios have recently been provided for the IPCC by an international group of authors for the Special Report on Emissions Scenarios (SRES). [1] Based on recent projections with seven different coupled ocean-atmosphere global climate models (AOGCMs), these scenarios suggest warmings over Australia by the 2050s, relative to mid-20th century conditions, of between 1ºC and 4oC depending on location and scenario, with most warming in inland areas. Warmings in the 2080s are estimated to be in a range of approximately 2ºC to 5.5oC. [2]

2.68 Corresponding rainfall change estimates are for rainfall decreases in the 2050s and 2080s in excess of one standard deviation (i.e. tens of per cent) compared with long term (30-year average) natural variability over much of southern, and especially south-western Australia, possibly as far north as southern Queensland. According to these results, only Tasmania will receive any substantial increase in rainfall. [3]

2.69 These conclusions have been supported by a recently released study by the Government of Western Australia, which endeavoured to examine the impacts of climate change on that State at a finer scale than had previously been undertaken. The Committee was told that the report:

2.70 In his submission to the inquiry, Dr Barrie Pittock stated that the new IPCC regional warming and rainfall change scenarios suggest a more negative rainfall outlook than was presented by the CSIRO in its 1996 scenarios. His submission then proceeds to outline the implications of what he describes as `the new global consensus on regional change over Australia'. [5]

2.71 Dr Pittock cites a number of examples from the AOGCMs which illustrate the likely consequences of the generally drier scenarios facing Australia, including:

2.72 The issue of climate change impacts on Australian fauna and flora was also brought to the attention of the Committee by the World Wide Fund for Nature. The Committee was told that:

2.73 The CSIRO admitted that there was `less consistency when attempting to describe future climate at a regional scale' and told the Committee that their research, `as well as examining changes on temperature and rainfall… is focusing on a limited number of issues that we regard as key to making more reliable our projections of climate in Australia'. These include:

2.74 CSIRO emphasised that `Australia's climate is subject to large year-to-year variations in rainfall':

2.75 Dr Robert Watson concurred with CSIRO's assessment that the interaction of global warming with ENSO patterns (El Nino and La Nina), was of great importance to understanding the potential impact of climate change on Australasia: