2018-04-28
Chris Johansen
The doyen of water in WA continues to be C.Y. OConnor, the engineer who designed and supervised construction of the Kalgoorlie pipeline at the end of the 19th century. Although, the reverence towards his memory may be slipping as his statue off Coogee beach was recently decapitated. Nevertheless, every year the National Trust hosts the C.Y. OConnor Lecture. This year the Lecture was presented by Neil Bennett from the Bureau of Meteorology (BoM), and who regularly appears on ABC News explaining weather events. The event, held at the Perth Public Library on 14th March, was also supported by the Water Corporation, whose CEO Sue Murphy gave an update on this organizations activities. This in itself was most impressive, explaining how Water Corporation is addressing the ever-increasing demand for water in WA despite ever-declining rainfall and groundwater reserves. This is being done through installation of desalination plants, recycling of sewerage/waste water, demand management and public education on efficient water use. The contrast with Cape Town, in a similar hydrological environment to Perth (southern hemisphere Mediterranean climate), is clear with this South African city on the brink of completely running out of water.
Neil Bennetts presentation was illustrated by slides derived from the State of the Climate Report 2016, this report being produced every two years by CSIRO and Bureau of Meteorology (BoM) – the next report is due at the end of this year. A more comprehensive analysis of climate change effects on WA may be found in 'Climate change: impacts and adaptation for agriculture in Western Australia. Bulletin 4870 of Dept. of Food and Agriculture, WA (2016).
Neil began by pointing out that the last three years were the warmest in history, for Australias mean average annual temperature. The warmest year since temperature records began, in 1880, was 2016, the second warmest was 2017 and the third 2015. The rising trend is illustrated in the BoM graph below. These rising temperatures have increased the bushland fire danger and length of the fire season, and temperature trends suggest that this will intensify into the future.
Rising ocean temperatures not only disrupt life forms that have evolved over millennia at relatively stable temperatures but also cause expansion resulting in sea level rise, in addition to that attributable to melting glaciers. Further, higher ocean temperature increases formation of carbonic acid and thus results in increasing acidity – particularly unpleasant for any creatures that have calcium carbonate exoskeletons, like shell fish and corals. It is not surprising that coral reefs are fast disappearing due to metabolic disruptions caused by a combination of high temperature and acidity.
The South West of Western Australia is a part of the world where the trend in decreasing rainfall is particularly high – a decrease of about 15-20 % over the last 50 years (depending on location). The graph of BoM total annual rainfall for South West Australia (an average of weather stations in the region) below shows that while rainfall maintained an average of around 700 mm from 1900 until the early 1960s, it declined subsequently. Climate models suggest that this trend will continue throughout this century, as carbon dioxide levels in the atmosphere increase (Smith and Power 2014, Journal of Hydrology: Regional Studies 2: 84–96.).
Generally, rainfall is decreasing in southern Australia and increasing in northern Australia, as indicated in the BoM graphic below. This is because of the southward displacement of rain bearing winter low pressure systems, now only just brushing the southern parts of the continent. More summer monsoon rain in the north can be attributed to higher temperatures causing more evaporation from the ocean and thus loading clouds with increased moisture. This monsoon rainfall is extending into the normally dry central parts of the continent. On a brighter note, we can expect some deserts to bloom, more frequently.
Carbon dioxide levels in the atmosphere have increased from 278 ppm around the year 1750 (determined from gases trapped in ice cores) to over 400 ppm now – and from 330 ppm in 1975 when direct atmospheric carbon dioxide measurements began at Cape Grim in Australia. Further, emission of other heat trapping gases, including methane and nitrous oxide, has markedly increased over the last century. But how can we assume that increased carbon dioxide levels are derived from fossil fuels or clearing of vegetation? By measuring the ratio of the carbon isotopes C12 and C13 in the atmosphere. C12 drives from burning of fossil fuels and vegetation clearing and the atmospheric C13/ C12 ratio has been rapidly declining, and at increasing pace, over the last two centuries.
In essence, all of the data presented by Neil Bennett, and elaborated in the State of the Climate Report and other BoM and CSIRO publications clearly shows that climate change is well underway and explains why it is happening. And the trends point to ever worsening consequences. Yet, conservative governments apparently remain oblivious to this information in maintaining their ongoing narrative that climate change is either not occurring or not worth worrying about and that we must endeavour to keep on burning fossil fuels and destroying vegetation. They remain fixated on maximizing 'economic growth within the current election cycle seemingly without a worry about long-term consequences, which will be dire for any future 'economy.
One thing I do not understand though is why conservative Australian governments keep funding the activities of these government organizations that produce all of these climate data, with their abundantly clear implications and which contradict government narratives. In this sense President Trump is much less hypocritical in that he has cut funding to any US research directly related to studying climate change and even banned the use of the words 'climate change and global warming from any government documents.
Header photo: Clouds off the WA coast at sunset. Wikimedia commons