Climate change due to elevated concentrations of greenhouse gasses in the atmosphere is a major threat to native vegetation. Some existing and likely future impacts are documented in the paper Climate Change and Australia 281. Other changes to the atmosphere, such as increased levels of ultra-violet radiation due to the thinning of the ozone layer, are also potential threats to native vegetation. These changes are often more subtle than the total clearance of vegetation from the landscape, and may be more difficult to evaluate from a regional or continental perspective even with the aid of remote sensing techniques.

There is consensus among the world’s leading scientists that global climate change is with us, as documented in the extensive and critically accepted reports of the Intergovernmental Panel on Climate Change (IPCC). Evidence is accumulating from long-term studies that the climate trends of the past few decades are anomalous, and that these trends are already affecting the physiology, geographic distributions and lifecycles of species. The eight warmest years measured globally have occurred in the 1990s and 2000s, with 2002 the second warmest on record. The 1990s was the warmest decade ever recorded with measuring instruments, and the last 100 years were the warmest of the millennium, according to instruments and other means of estimating temperature.

These trends also apply in Australia 282. In 2002, Australia recorded its highest-ever average March–November daytime maximum temperature, with the temperature 1.6°C higher than the long-term average and 0.8°C higher than the previous record. Evaporation rates were also the highest recorded so far.

A recent major report on biodiversity and climate change addressed four questions about climate change that are believed to be important for governments 283.

1.  What are the current and future impacts of climate change on biodiversity?

2. What can we do to buffer these climatic impacts?

3. Who needs to make the relevant policy and management decisions?

4. What information is out there to help with these decisions?

The report represents a useful synthesis of our current understanding of climate change and its impacts on native vegetation and biodiversity. Drawing on this report will help regional managers address the complex issue of climate change impacts and adaptation.

	Action: 3.9
	Read the reports on climate change and its impacts on biodiversity in Australia and consider how potential changes in climate could affect planning and management at a regional scale.
	COST
	TIME
	COMPLEXITY

It is difficult to document the biological impacts of climate change on native plants and animals in Australia, largely because of the lack of long-term datasets and active monitoring programs. Nonetheless, evidence of change is reported such as thickening of vegetation in eucalypt woodlands as a result of increased CO2 supply (in addition to the impacts of grazing and altered fire regimes), increased establishment of snow gums in sub-alpine meadows and higher wheat yields associated with less frequent frosts. Table 11 presents some of the expected impacts of climate change and elevated CO2 levels for native plant species and vegetation types. The table demonstrates the current level of uncertainty associated with understanding and managing climate change impacts on living systems in Australia. Impacts will be further complicated by interactions and responses of invasive species, as well as responding to a changing climate where vegetation is fragmented. At the regional level, recent work has been undertaken on the impacts of climate change in Victoria 284. How the management of such impacts can be incorporated into regional planning is addressed in Questions 4 and 5.

Table 11: Expected impacts of climate change and changes in CO2 concentrations on native vegetation types and plant species in Australia



Source: Howden M, Hughes L, Dunlop M, Zethoven I, Hilbert D, Chilcott C (2003) Climate Change Impacts On Biodiversity In Australia. In ‘Outcomes of a workshop sponsored by the Biological Diversity Advisory Committee, 1–2 October 2002’. Canberra ACT. (Ed. CS Ecosystems). Commonwealth of Australia. pp66