State of the Environment Report for the City of Blue Mountains

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Climate Change This section highlights and discusses emerging issues with the potential to have a significant impact on the condition of our natural assets. Global warming, the phenomenon caused by an increase in atmospheric greenhouse gases will be the most significant issue facing humankind this century. Global warming has given rise to climate change which has a pronounced affect on natural ecosystems, agriculture/forestry, ocean productivity, the built environment, and human health. The impact of climate change, whilst variable, will almost certainly be felt everywhere on the planet by the middle of this century. Indications of global warming and other changes in climatic conditions have already begun to appear with the 1990s being the warmest decade since records were kept in 1861. The following figure indicates the trends in mean temperature increase or decrease ( 0 C/10 years) for 1910–2005 (Australia State of Environment Report 2006 At a Glance). 0.40 0.30 0.25 0.20 0.15 0.10 0.05 0.00 -0.05 -0.10 -0.15 -0.20 -0.25 -0.30 -0.40 Our Earth, the Greenhouse Planet The atmosphere is the most critical of environments as it regulates the very conditions that give life to our planet. Our atmosphere regulates the amount of radiation that reaches the earth’s surface, regulates temperature (through the greenhouse effect) and provides the specific gases that plants need to grow and animals need to breathe. The greenhouse effect occurs when gases in the upper atmosphere trap heat making the earth’s surface warmer. Some gases are far more effective at trapping heat than others and are commonly referred to as greenhouse gases, the most significant being water vapor, carbon dioxide, methane, and nitrous oxide. If there were no greenhouse gases, then the earth’s surface would be some 30 0 C cooler than at present. Atmospheric greenhouse gas concentrations fluctuate naturally, in cycles that last many hundreds of thousands of years. Depressions in these cycles are marked by ice ages interspersed with periods of high temperatures. Industrialisation marked the beginning of a rapid increase in human activities, such as burning of fossil fuels, deforestation, and intensive livestock farming, and an equally rapid increase in greenhouse gas emissions. In fact, the atmospheric carbon dioxide concentration is now at its highest level in 10,000 years. The figure below highlights the recent increases in global concentrations of three greenhouse gases (IPCC, 2001). Rising greenhouse gas levels will enhance the greenhouse effect resulting in a longterm increase in the average surface temperature of the earth, or global warming. The Intergovernmental Panel on Climate Change (IPCC) estimates that by the year 2100, global surface temperature will have increased by 1.4–5.8 0 C. Global warming is only one part of climate change, as other variables that are driven or influenced by surface temperature are also likely to change. These include rainfall and wind patterns, sea levels, and the operation of oceanic currents. The frequency and intensity of natural disasters such as floods, storms, cyclones, drought and wildfire are expected to increase. 32 2005–2006 Supplementary State of the Environment Report for the City of Blue Mountains
Section 4: Alert Climate Change Climate change and energy issues have grown significantly in importance ‘People nominating climate change as one of the two most important environmental issues increased to 13% in 2006 from 6% in 2003 and 2000, and those nominating energy conservation management increased to 7% in 2006 from 2 per cent in 2003. The number of people who say they often make an effort to reduce their fuel consumption and air pollution has increased by 10% since 2003 from 38 per cent to 48 per cent.’ From Who Cares about the Environment in 2006 A survey of NSW people’s environmental knowledge, attitudes and behaviours. Our Land and Water Climate change will affect both the land and the water in a variety of ways that will create significant challenges for land managers. As surface temperatures rise, rainfall will increase at higher latitudes and decrease at lower latitudes. Rainfall in the Sydney Region including the Blue Mountains may fall by 20–30 per cent by 2030 placing pressure on domestic water supplies (CSIRO, 2001). Shortfalls in supply will have to be made up through reuse of grey water, recycling of treated sewerage and increased residential rain water capture and storage. Declining rainfall will reduce groundwater recharge and stream flow affecting natural ecosystems. Storms will increase in frequency and intensity which will place further pressure on soil and streams, accelerating the process of erosion. Improvements to stormwater management will be essential in order to limit the impacts of these changes. In the soil, a warmer environment favours the growth of bacteria, which accelerates the decomposition process, hence, altering the nutrient cycle. Cycling of the nutrient, nitrogen, produces higher concentrations of nitrous oxide, which is a greenhouse gas with a warming potential that is 200–300 times more effective at trapping heat than carbon dioxide. An increase in atmospheric carbon dioxide concentration (necessary for photosynthesis) will allow more rapid plant growth. However, as temperature rises plant growth is likely to decline in response to reduced soil moisture and heat stress. Plant reproduction is typically dependant upon climatic variables. For example, apple and stone fruit bud burst is reliant upon chilling and some fruit growing areas may no longer be productive in the face of climate change. Development of new crop varieties with characteristics that will maintain productivity will be required to limit agricultural losses. The infrastructure that our society has grown reliant upon will be placed under considerable pressure as a result of climate change. Civil infrastructure built to withstand certain climatic variables will face higher and lower temperatures and more intense natural disasters, that may ultimately result in infrastructure failure or a reduced operational lifespan. Queensland investigated the impact of climate change on the states’ transport infrastructure and determined that impacts will be noticeable by 2030, and without significant adaptation of the transport infrastructure there is a real risk of severe failure by 2070. Council, as with other regulatory authorities and infrastructure managers, will need to adopt improved construction practices taking into account the potential for climate change and will need to address issues in the existing infrastructure. Our Natural Environment Many of Australia’s natural systems will be vulnerable to the effects of climate change due to the limited adaptive capability. Those ecosystems or species with specialised ecological requirements, limited distribution or mobility, will be most at risk. Climate induced changes affecting biota include: a change in rainfall distribution, intensity and seasonality, altered growth patterns associated with increased carbon dioxide, increased temperature affecting growth and heat stress and change in sea level affecting marine, aquatic and riparian ecosystems. Extreme events such as drought, flood, cyclones, and wildfire will increase causing further impacts. Already there has been observed changes in Australian biota as a result of global warming. These include early breeding in birds and reptiles, earlier flowering of eucalypts and early arrival of migratory birds. 2005–2006 Supplementary State of the Environment Report for the City of Blue Mountains 33
Page 1 and 2: Section 1: Biodiversity as a Natura
Page 3 and 4: Increasing our understanding Using
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Page 17 and 18: 2 Land as a Natural Asset 2005-2006
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Page 25 and 26: Section 3: Atmosphere as a Natural
Page 31: 4 Alert 2005-2006 Supplementary Sta
Page 35 and 36: Bibliography Australian Bureau of S

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