Impacts
- The impacts of climate change are already clearly visible in Australia. …
- Southern and eastern Australia’s water supply reliability is expected to decline [and] to be accompanied by a growth in water demand due to population growth.
- Development and population growth in Australia’s coastal regions will exacerbate the risks from sealevel rise and … coastal flooding.
- Significant losses of unique Australian animal and plant species are expected to occur … disrupting ecosystem function and causing the loss of ecosystem services.
- The risks to infrastructure include the failure of urban drainage and sewerage systems, more blackouts, transport disruption, and greater building damage. …
- Heatwaves, storms and floods are likely to have a direct impact on the health of Australians, such as causing an increase in heat-related deaths.
Biological processes such as infectious diseases [such as dengue fever] and physical processes such as air pollution may affect health indirectly … - Moderate warming [and higher levels of carbon dioxide] in the absence of rainfall declines can be beneficial to some agricultural crops …
However, these positive effects can be [more than] offset by changes in- temperature,
- rainfall,
- pests, and
- the availability of nutrients
- Production from cropping and livestock is projected to decline over much of southern Australia, as is the quality of … crops.
Contents
Overview
Fire
Water
Coastlines
Ecosystems
Infrastructure
Food
Health
Commonwealth Science and Industrial Research Organisation
- Climate Change: Science and Solutions for Australia, CSIRO, 2011.
Helen Cleugh, Mark Stafford Smith, Michael Battaglia & Paul Graham: Editors.
Climate Change Impacts
Kevin Hennessy: CSIRO Climate Adaptation Flagship.
Introduction
Australia is the driest inhabited continent in the world. …
It is now likely that the world will see 2ºC global warming on top of changes already experienced within the lifetime of the current generation.
Without rapid action to reduce CO2 emissions, there is a serious risk that global warming could be as much as 4ºC by later this century.
For Australia, heatwaves, fires, floods, and southern Australian droughts are all expected to become more frequent and more intense in the coming decades. …
[The] greatest impacts will be felt through changes in- water availability …
- sea level [rise], and
- extreme weather events.
Australia is highly vulnerable to these projected changes in climate …
Global and national assessments show that a changing climate- affects food production,
- disturbs coastal margins,
- displaces species, and
- changes economies. …
Climate change impacts will increasingly be experienced first through extreme events rather than gradual changes in mean temperature or rainfall. …
[Current extreme] weather and climatic events … are most likely a combination of climate variability combined with [the effects of] anthropogenic greenhouse gas emissions …
[It] is very difficult to attribute specific causes to individual extreme weather events.
However, there are statistical methods for assessing whether an extreme event may have been made more likely because of increases in greenhouse gases.
Regardless of the cause, it is important to understand the impacts of existing extreme weather and climate events and use these as a window into future climate change in an enhanced greenhouse world.
[The 2009] Victorian bushfires … killed 173 people and more than 1 million animals, destroyed more than 2,000 homes, burnt about 430,000 hectares, and cost about $4.4 billion.
[High] temperatures, low humidity, high winds, and very dry fuel … combined to produce an extreme forest fire danger index (FFDI).
When the daily FFDI is greater than 50, the risk rating is ‘Extreme’ …
The bushfires of February 2009 had a FFDI that greatly exceeded 100 in many locations and, as a consequence, an additional fire rating ‘Catastrophic’ has since been added to the rating system.
An analysis of the annual total FFDI (i.e. the sum of daily FFDI indices) for the last 30 years shows that in southern Australia the index has been trending upwards [since the mid-1990s:]
Figure 4.1
(p 47, emphasis added)
Change in annual total Forest Fire Danger Index (FFDI) from 1974 to 2007 at Bendigo.
The dotted trend line shows an increase of 51 FFDI units per year.
[A] modelling study conducted by the Bushfire CRC, the Bureau of Meteorology, and CSIRO found that the simulated annual-average number of days with ‘Extreme’ fire danger increases by 5–25% by 2020 relative to 1990, for a 0.4ºC global warming.
For a 1ºC global warming, the number of ‘Extreme’ days increases by 15–65% by 2020.
By 2050, the number of ‘Extreme’ days increases … by 100–300% for 2.9ºC global warming.
Climate change impacts across Australia’s economy and environment
Water security
[Median] stream flow in the Melbourne catchments is estimated to decline by 10% [and] in south-western Australia … by 25% by 2030. …
[The] combination of growing demand and reduced supply that makes water potentially one of Australia’s most critical national issues.
[Run-off] in the southern [Murray-Darling Basin] between 1997 and 2006 was the lowest ever recorded.
(p 48)
The median decline expected for the MDB is 9% in the north of the basin and 13% in the south.
[Under present water-sharing arrangements, this could] reduce flow at the Murray River mouth by around a quarter …
In the driest years, water availability in the Condamine–Balonne basin could fall by over 20%, around 40–50% in the NSW water regions (except the Lachlan basin), over 70% in the Murray region, and 80–90% in the main Victorian regions.
These impacts point to a growing need for adaptive strategies:- the Murray–Darling Basin Water Agreement,
- the conversion of open irrigation channels to pipelines,
- desalination plants,
- the introduction of state water conservation plans, and
- the adoption of the ‘water-proofing’ of Adelaide as a model for other cities.
Coastal development
Continued development and population growth in Australia’s coastal regions — where around 85% of the population now resides — will exacerbate risks from [the likely increase in] severity and frequency of coastal flooding caused by climate change. …[Events] that now happen every 10 years would happen about every 10 days in 2100.
The current 1-in-100-year event could occur several times a year.
[Climate change risks to Australia’s coasts (2009)]
Figure 4.2
(p 50)
Estimated number of residential buildings at risk of inundation from a 1.1 m sea-level rise …
Some beaches could recede by hundreds of metres over the course of this century.
Remote Indigenous … communities living on the low-lying Torres Strait Islands are particularly vulnerable to sea-level rise.
Natural ecosystems
Significant losses of biodiversity are projected to occur in:- the Great Barrier Reef,
- the Queensland Wet Tropics, the Kakadu wetlands,
- south-west Australia,
- our sub-Antarctic islands, and
- eastern alpine areas. …
The four main threats are- the arrival of new (native and exotic) species in a region,
- altered fire regimes,
- land-use changes, and
- altered hydrology.
[One] of the key [responses] will be to protect native habitat [and] habitat connectivity so that native species can readily relocate as climatic conditions change. …
[A] 0.5ºC warming of the tropical oceans may cause bleaching of 30% of the Great Barrier Reef …
[A] 1ºC warming may bleach 65%.
Such changes could directly affect a tourism industry worth $5 billion a year and supporting around 70 000 employees.
[Other] projected marine climate impacts [include:]- the expansion of mangroves into newly flooded coastal lands
- declines in seagrass meadows and seaweed beds due to storms and warmer water
- the southward migration of tropical pelagic fish and other marine species
- a loss of diversity in coral fish and other coral-dependent organisms [and]
- a risk to marine food chains from ocean acidification, potentially affecting fisheries.
[Southward] migration of some species, particularly along the south-east coast of Australia [is already taking place.]
[A] modest climate change may induce … some ecosystems [to] ‘flip’ into a different state.
[Migration] inland or polewards, [raises] the issue of ‘coastal squeeze’ … where populated areas stand in the way of this natural adaptive response and … the Southern Ocean sets a boundary to southward migration of shallow water organisms.
The coastal systems most at risk are- estuaries and associated wetlands,
- coral reefs,
- tidal flat communities and salt marshes, and
- beaches where there is a lack of sand for replenishment.
Infrastructure
Infrastructure is particularly sensitive to changes in extreme weather in addition to more gradual changes in rainfall or sea-level rise.
Today’s design criteria for extreme events are likely to be exceeded more frequently in future.
[Acute impacts] include:- the failure of floodplain protection and urban drainage and sewerage systems,
- more heatwaves causing blackouts [and]
- buildings failing under excessive wind loads.
[Chronic impacts include] accelerated degradation of materials and infrastructure … associated with- higher temperatures,
- altered groundwater and soil conditions,
- sea-level rise, and
- changed rainfall regimes.
[Vulnerable infrastructure includes …]- water pipes,
- road surfaces,
- transmission lines [and]
- building [foundations and] materials
There are also indirect effects such as the increasing urban heat island effect … putting more demand on energy for air-conditioning.
The Victorian Government [has] conducted a risk assessment of its infrastructure [and found that buildings] have the greatest exposure and sensitivity to climate change by 2030, especially in relation to foundations, storm and flood damage, and bushfire risk.
(p 52)
Table 4.1
(p 53)
Climate change exposure and infrastructure sensitivity matrix for Victoria by the year 2030.
Agriculture and forestry
Experiments where CO2 concentrations have been increased by around 50% (to approximately 550 ppm) have produced growth increases of around 15% in crops …
In studies where CO2 has been increased up to 700 ppm, wheat yields have risen by 10–50%, cotton biomass by 35%, whole boll yields by 40%, and lint yields by 60%.
{[Additional] positive effects beyond that of CO2 fertilisation [include] a likely reduction in frost, and the prospect of longer growing seasons for some crops.}
However [a] 20% reduction in rainfall could reduce pasture productivity by 15%, and livestock weight gain by 12%, which would substantially reduce farm income.
There is likely to be a southward movement of pests and diseases as the southern regions warm.
The forestry and plantation industries are likely to face greater risk of fire.
(p 54)
Health
Direct and indirect impacts of climate change on human health
(Adapted from Figure 4.4)Direct impacts Indirect (system-mediated) impacts Changes to physical systems/processes Changes to ecosystem structure and function Biological changes: processes, timing - heatwaves [1]
- floods
- fires
- storms
- urban air pollution [2]
- fisheries
- constraints on microbes, nutrient cycles
- forest productivity
- mosquito density, range [3]
- photosynthesis crop yields
? ? ? ? Social, economic, demographic disruptions ? Health impacts - Heat-related deaths for people aged over 65 in six of Australia’s largest cities are likely to increase from around 1,100 per year at present to around 2300–2500 by 2020 and 4,300–6,300 by 2050 …
During a 2-week heatwave in early 2009, 374 heat-related deaths were recorded in Victoria. - [Increased] ozone pollution is projected to cause [an] increase in the … number of hospital admissions [of]
- [40%] by the period 2020–30 [and]
- [200%] by the period 2050–60.
- Australia can expect … 0.6 to 1.4 million more people exposed to dengue fever by 2050, as well as a rise in waterborne and food-borne diseases. …
Conclusion
Some impacts will be unavoidable in the short term because of climate changes already locked in due to past and current greenhouse emissions.
Adaptation on a scale far more extensive than is currently occurring will be essential [in order to limit these impacts.]
Adaptation alone cannot absorb all the projected impacts …
[It is, therefore,] clear that Australia’s approach to climate change needs to embody both adaptation and emission reduction strategies.
(p 57)
