On Monday March 11 at 6:30pm, Clean Energy For Eternity is hosting a public meeting at the St Johns Anglican Church in Bega.
The guest speaker will be Professor Lesley Hughes.
Professor Lesley Hughes is an ecologist in the Department of Biological Sciences at Macquarie University and an expert on the impacts of climate change on species and ecosystems. She is the co-convenor of the Terrestrial Biodiversity Adaptation Research Network, Chair of the Tasmanian Climate Action Council and a member of Climate Scientists Australia and the Wentworth Group of Concerned Scientists.
Professor Hughes was also a member of the Expert Advisory Group on Climate Change and Biodiversity for the Australian Greenhouse Office and the Department of Climate Change, and a lead author for the UN?s IPCC Fourth and Fifth Assessment Reports. Her research has been published extensively in peer-reviewed journals.
The meeting will be opened by Mayor Bill Taylor, I will give a brief up-date on what CEFE is up to, and Professor Hughes will give the guest lecture. I am hoping she will focus on how climate change will impact the Bega Valley, particularly in relation to sea-level rise, changing rainfall patterns and bushfire risk. Admission will be free, and CEFE is very grateful to St Johns for providing a venue.
Climate change impacts on fire weather
A new study produced by CSIRO and the Bureau of Meteorology provides important new information about increased bushfire risk across south-east Australia due to climate change. The study will help communities across south-east Australia prepare for a possible increased bushfire risk.
Researchers assessed changes associated with climate change and influences on fire-weather risk. The study, entitled “Climate change impacts on fire-weather in south-east Australia”, was completed by Kevin Hennessy from CSIRO and co-authors from the Bushfire Co-operative Research Centre (CRC) and the Australian Bureau of Meteorology.
Fire-weather risk relates to how a combination of weather variables influences the risk of a fire starting or its rate of spread, intensity, or difficulty to suppress. Fire risk is influenced by a number of factors including fuels, terrain, land management, suppression, and weather.
The study is based in south-east Australia, an area projected to become hotter and drier under climate change. According to the Bureau of Meteorology, in south-east Australia since 1950 rainfall has decreased, droughts have become more severe, and the number of extremely hot days has risen.
The study provides an indication of fire risk based on various combinations of weather variables including daily temperature, rainfall, humidity, and wind-speed. Two climate change models are then used to generate climate change scenarios for 2020 and 2050. The CSIRO climate models used for this report were developed with assistance from the Australian Greenhouse Office. Fire danger indices are then calculated for 2020 and 2050.
The key finding of this study is that the frequency of days with very high and extreme Forest Fire Danger Index ratings are likely to increase in south-east Australia by 4-25 per cent by 2020, and 15-70 per cent by 2050.
Several uncertainties in the study include changes in El Nino-Southern Oscillation events under climate change, the possibility of different results from use of other climate models, changes in rainfall thresholds required to control fires, and the quality of data for some weather variables.
For anyone interested in the threat of bushfires in Australia, ‘Burn-the epic story of bushfire in Australia’ by Paul Collins gives an excellent account of the history of catastrophic bushfire events, and our increased vulnerability due to climate change.
The warming impact on rainfall
Rainfall extremes are increasing around the world, and this lift is linked to the warming of the atmosphere which has taken place since pre-industrial times. This is the conclusion of a recent study which investigated extreme rainfall trends using data from 8326 weather-recording stations globally, some of which have records spanning more than a hundred years. The study, “Global increasing trends in annual daily precipitation” was published in Journal of Climate last month
Of all the stations analysed, two-thirds showed increasing trends over the course of the 20th and early 21st centuries.
“This kind of change is precisely what can be expected if one assumes that the intensity of the most extreme rainfall events will scale with the capacity of the atmosphere to hold moisture. This is well known to increase with temperature at a rate of about 7 per cent per degree.” said the lead author Seth Westra from the University of Adelaide.
“The greatest increases occurred in the tropical belt; the smallest in the drier mid-latitudes where you find most of the world?s deserts. In the higher latitudes, particularly in the northern hemisphere, the rate of change was close to the global average. Again, such changes seemed to be in quite close agreement with what global climate models say should happen as a result of global warming: a reassuring case of observations confirming theory.”
“The implications of this are likely to be significant for flood risk around the world. If the relationship between extreme rainfall and atmospheric temperature continues to hold, then this could mean as much as a 35 per cent increase in extreme rainfall intensity on average globally.”
Most flood-defence infrastructure, such as dams, levees, storm water systems and coastal flood defences, have been designed to handle historical flood risk. If the risk of flooding increases, then such infrastructure will have increasing difficulty managing floods in the future. This would either lead to increased damage costs due to the flooding, or necessitate expensive infrastructure upgrades or resettlement of low-lying communities. Even the increase in extreme rainfall intensity observed thus far is likely to lead to substantial challenges for some existing infrastructure.
This recent study shows that the intensification of rainfall extremes is not just a projection made by climate models but can already can be detected in the observational record.
In Australia we need to rapidly adapt to longer more intense droughts punctuated by increasingly extreme rainfall events.