3 Atmosphere | 2 Climate | 2.4 Resilience of Australia's climate
State of the Environment 2011 Committee. Australia state of the environment 2011.
Independent report to the Australian Government Minister for Sustainability, Environment, Water, Population and Communities.
Canberra: DSEWPaC, 2011.
At a glance
There is abundant evidence to show that significant global climate change has typically occurred over thousands of years, rather than over decades or centuries. However, in the past few decades, the cumulative effects of human activities (principally the burning of fossil fuels) have reached a scale that is challenging Earth’s resilience and driving unprecedented rates of change in the global climate.
Regardless of the effectiveness of future abatement strategies at international and national levels, increased temperatures associated with carbon dioxide emissions will be ‘largely irreversible for 1000 years after emissions stop’. So while efforts to mitigate climate change remain fundamentally important, human communities must plan for and adapt to climate change.
When viewed in the context of its highly developed economy and robust system of governance, Australia is well placed to adapt to climate change. However, Australia is also the driest inhabited continent and characterised by a high degree of climate variability. Australia is therefore significantly vulnerable at relatively low levels of temperature rise in key areas, such as water security, natural ecosystems and coastal communities, even if our adaptive capacity is realised.
The Earth’s atmosphere and oceans form a complex, coupled system, characterised at a global scale by a high level of short-term resilience. In general, significant global climate change has typically occurred over thousands of years in the geological record, rather than over decades or centuries. This is because changes to climate forcing (such as changes to incoming solar energy or atmospheric chemistry) typically occur over very long timescales. Only in the past few decades have the cumulative effects of human activities reached a scale that threatens to challenge Earth’s short-term resilience and drive change in the global climate at rates unprecedented in recent geological history.8,76
To date, the apparent resilience of the atmospheric–oceanic system has been a major factor limiting the rate and extent of change in climate (largely due to the capacity of the oceans to absorb carbon dioxide and heat). However, there is rising concern among climate scientists that, unless the growth in GHG emissions is soon slowed and reversed, continued increase in water temperature will reduce the oceans’ capacity to remove carbon dioxide from the atmosphere.77-78
At present, the oceans remove about a quarter of human-produced carbon dioxide emissions. As a result, the oceans have gradually become more acidic (with a reduction in the pH of surface waters of about 0.1 during the past 250 years). This trend is generally expected to continue, with a further reduction of 0.2–0.3 pH units occurring by 2100. Should this happen, it could have a major impact on the wide variety of marine organisms with carbonate skeletons, notably corals and plankton, thus potentially affecting the entire marine food chain (see Chapter 6: Marine environment).10
However, this remains an area of considerable uncertainty, as evidenced by the work of Law and her colleagues,79 whose modelling did not find a saturating Southern Ocean carbon sink due to recent climate change. Rather, they concluded that, although carbon uptake was reduced by wind forcing, forcing due to heat and freshwater flow resulted in an increased uptake. Debate on this issue is continuing in the scientific literature (e.g. see Zickfeld et al.80 and Le Quéré et al.81).
Although the changing physical resilience of the atmospheric–oceanic system is a critically important focus of concern, so too is the resilience of different human and animal populations to the changes in climate that are already occurring and will continue for the foreseeable future. The degree to which any population is resilient will depend on its sensitivity to specific elements of climate change and its capacity to adapt. Sensitivity will be influenced by factors such as location and the level of security of food and water supplies. In human populations and in the ecosystems of which they are part, adaptive capacity is strongly influenced by the rate at which change occurs. In the case of humans, this markedly affects our ability to anticipate change, develop adaptive strategies and marshal resources to adjust to change in a way that minimises harm and takes advantage of opportunities.
Resilience of human populations to climate change will vary between and within nations. As a general rule, within any society, the most marginal groups in terms of income, health and education are likely to be the most sensitive to climate change and the least well equipped to adapt without assistance from those better off. At the international scale, this generalisation holds true, as evidenced by many small island states that are highly sensitive to climate change–induced sea level rise and have inherently limited scope for adaptation. A critical role for policy makers at both national and international levels is therefore to recognise and reflect these variations in ‘social resilience’ when framing measures to adapt to climate change.
In the Australian context, a significant number of coastal communities are sensitive to sea level rise, particularly the Indigenous communities of Torres Strait, a number of which face inundation from rising sea levels. Across the nation, 160 000–250 000 homes are estimated to be potentially at risk of inundation from a 1.1-metre rise in sea level.82 By comparison with most small island states, the great majority of Australia’s coastal communities have considerable scope and resources to plan for and adapt to such change. However, without effectively coordinated planning and action at national, state and local levels, the potential resilience of these communities may not be realised.
For many of Australia’s Indigenous communities, climate change represents a major threat. In addition to sea level rise, increasing temperatures and likely (but less certain) changes in seasonal rainfall will impact these communities in many ways, including through changes to plant and animal populations.83 This is not to suggest that these communities lack resilience or a willingness and capacity to identify and seize opportunities that are likely to accompany change. As Professor Marcia Langton noted in an address to the National Indigenous Land and Sea Management Conference held in Broken Hill in November 2010, ‘… opportunities emerging from climate change includ[e] a growing industry in which Indigenous land and sea managers can be involved, such as carbon abatement and sequestration, solar and wind farms, biodiesel, and tidal energy. Green collar jobs should be black collar jobs. Indigenous rangers can provide very good environmental management services that can be marketed’.84