Australia’s coral reefs and mountain-top ecosystems are set to suffer from climate change, according to the Intergovernmental Panel on Climate Change’s latest summary of the research.
The threats to these ecosystems are among a host of climate risks posed to Australia and New Zealand, which also includes increased danger from extreme weather events and bushfires, as well as the threat from rising seas and drying river systems.
Many of these risk have become even more evident since they were discussed in the previous 2007 IPCC report, and will almost certainly intensify even if remedial efforts are undertaken.
This report – the second volume of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report – deals with the impacts of climate change, our vulnerabilities to it, and how we might adapt. It contains a dedicated chapter on Australia and New Zealand, prepared by eight lead authors coordinated by me and Andy Reisinger, with assistance from 37 corresponding authors.
Its message should be cause for concern but, as we shall see, not necessarily despair.
Corals set to suffer
Significant impacts, including bleaching, coral death and a range of coral diseases, are leading to changes in the structure and species makeup of corals on both the Great Barrier Reef and Western Australia’s Ningaloo Reef.
These natural ecosystems have little ability to adapt and, other than reducing other detrimental effects such as nutrient run-off and over-exploitation, there seems little we can do about it in the short term.
The same is true of mountain-top ecosystems in Australia’s tropical and alpine zones. Mammals and birds, as well as whole sets of other species endemic to the tops of mountains, simply have nowhere to go.
Floods, heatwaves and fires on the rise
Extreme events such as floods, heatwaves and bushfires are all set to increase in both frequency and intensity. Recent events underscore our vulnerability to weather extremes.
Without serious mitigation, increases of up to 200% by 2090 for extreme rainfall events for some regions of Australia are projected in some models. For New Zealand the projections are for an 8% increase for each 1°C increase in temperature.
Hot days in Melbourne (over 35°C maximum) are projected to increase by 20-40% by 2030, 30-90% by 2070, and by 70-190% by 2070.
In New Zealand, spring and autumn frost-free land is projected to at least triple by 2080 and up to 60 more hot days (over 25°C maximum) are projected for northern areas by 2090.
Depending on the model used, days with a very high and extreme fire danger index will increase in Australia by 2-30% by 2020, and by 5-100% by 2050. For New Zealand, extreme fire days are projected to increase from around 0 to 400% by 2040), and by 0 to 700% by 2090, again depending on the climate model used.
But, unlike for coral reefs, we may be able to adapt to these problems, at least under the less extreme climate projections: that is, those that envisage gradually declining carbon emissions globally.
Both Australia and New Zealand are set to suffer more major flooding events – and as a result, simply bunkering down and hoping for the best may not be the most prudent course of action. So-called “transformational adaptation” may be the better long-term solution, with planned retreat from most vulnerable areas.
Similarly, sustained periods of extreme heat bring significant health risks, and the devastating impacts of bushfires on human life, property and ecosystems are all too well known. The Black Saturday bushfires in 2009 caused 173 deaths and destroyed A$4 billion worth of infrastructure. A further 374 deaths are estimated to have been caused by the extreme heatwave conditions in southeastern Australia in 2009.
Reduced rainfall in parts of southern Australia will impose greater stresses on water availability and consumption.
All of these risks, however, can be reduced to some extent by changes in management regimes. The IPCC report draws attention clearly to known impacts and current projections and are intended to provide the strongest possible scientific basis for governments to construct future policies.
Sea levels and droughts: an uncertain future
There are two more key threats, the severity of which will depend on how the various possible climate scenarios play out in the future.
If sea levels rise by a metre by the end of the century (within the range of model projections), the consequences for those who live in coastal towns and cities would be immense. That’s a particular problem for Australia and New Zealand, where the majority of the population is clustered in coastal areas.
Similarly, the drier scenarios projected by some models could affect Australia’s food productivity in its major food-producing regions: the Murray-Darling Basin, the far southwest and the far southeast. Our heavy dependence on these regions as the nation’s food bowls means that these risks, even though at the lower ends of the probability spectra, must be taken seriously. These less likely but more extreme scenarios project declines in annual rainfall of up to 30% for 2070 in South Australia with some larger declines seasonally.
Local steps but a lack of overall action
Some local governments are taking concrete steps to manage these various risks, but overall implementation is patchy. The preferred options have tended to be “incremental”: gradual adjustments that should allow us to maintain our current lifestyles. Examples include raising levee banks to cut flood risk; increasing fire-fighting resources and bushfire education; and the introduction of water-conservation programs.
These actions are all both necessary and desirable, but without strong action to limit future climate change – the subject of the IPCC’s next report in April – they will become increasingly inefficient, expensive and even futile in the long term.
The alternative is the sort of transformational adaptation mentioned earlier, which would involve taking more radical measures to address the threats. This might involve planned retreats from low-lying coastal zones or high-risk fire areas, or introducing new crop strains or shifting farming to new areas.
Some authorities and individuals have taken tentative steps down these paths, but it is clearly a huge challenge to coordinate such large-scale shifts. At least one local council on Australia’s east coast has attempted to promote planned retreat policies, only to have these overturned upon legal challenge.
Meeting the climate challenge
There is no doubt about the main threats that face Australasia, although there is obviously still some uncertainty about the finer details. In the seven years since the 2007 IPCC Assessment Report, we have learned more about potential climate impacts on biodiversity, human health, agriculture and forestry, rural communities and urban infrastructure.
During that time our knowledge about possible ways to adapt to these various threats has grown even faster. We might feel helpless in the face of the climate challenge, but really we’re not – although bringing action to bear will involve a big collective effort.
Without substantial adaptation the impacts will only intensify across all sectors of society and the environment. But as the report notes, there are many constraints on the implementation of such adaptation measures. These include the need for consistency and reduced uncertainty in projections, as well as more clarity on local impacts.
There is also a lack of guidance on principles and priorities for action, as well as the responsibilities of different levels of government, from the United Nations right down to local councils. There are also widely differing attitudes among the community to both climate change risk and the value of particular objects and places. These remain as challenges for the future.
IPCC reports give a wealth of information to politicians, but it is not their job to recommend policies. That remains the purview of politicians and the public - although everybody has a stake in meeting this challenge.
This article is based on the Executive Summary of the Australasia Chapter of the IPCC’s Working Group II report: Climate Change 2014: Impacts, Adaptation and Vulnerability. The chapter’s Executive Summary was prepared by Andy Reisinger, Roger Kitching, Francis Chiew, Lesley Hughes, Paul Newton, Andrew Tait, Sandra Schuster and Penny Whetton.