Atmosphere Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Dr Peter Manins, Environmental Consulting and Research Unit, CSIRO Atmospheric Research, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06746 9
Regional Air Quality (continued)
Occurrence of smoke and fire [A Indicator 4.13]
Smoke and fire are strongly associated with the occurrence of regional haze. They are also linked to several other environmental indicators, including aerosol loading (see Climate variability and change), and are discussed in the Biodiversity and Land Theme Reports.
There is marked variation from year to year in the prevalence of fires. Some data extracted from NGGIC (1998 and earlier) and AGO (2000) (Figure 159) show the mass of biomass burnt across Australia over 16 years. The estimated burning of biomass increased by about 40% between 1995 and 2000, but this apparent increase may simply be a result of a change in methodology.
Figure 159: Estimated fuel mass burnt across Australia in bushfires, forest fires and agricultural fires.
Source: Beer and Meyer (2000)
Table 36 presents areas burnt in southern Victoria. The variation depends on fuel availability, fuel dryness and weather conditions at the time and for the preceding weeks or months.
| Year | Bushfires (ha) | Year | Prescribed burning (ha) |
|---|---|---|---|
| 1992-93 | 186 | 1992 | 0 |
| 1993-94 | 206 | 1993 | 539 |
| 1994-95 | 265 | 1994 | 1 689 |
| 1995-96 | 7 | 1995 | 745 |
| 1996-97 | 1 489 | 1996 | 1 048 |
| 1997 | 556 |
Source: EPAV (1998).
In northern Australia, land management practices result in a regular firing of vast regions, with most of the region burnt every few years (see the Land Theme Report).
Implications
Although highly variable from year to year in any region, the prevalence of fires and biomass burning in Australia may be increasing. The consequent effects include increased haze and carbon cycling and hence climate impact, changes in biodiversity where the frequency of, and severity of, firing are also increasing, and accelerated soil erosion and runoff. However, it is not yet possible to be confident that the trend is real.