Tuesday, 4 March 2014

Australia - Heat Extremes Swamping the Record Books

Climate change is redefining the Australia of 'sunburnt country' poem
Australia's State of the Climate Report depicts a country where heat extremes are swamping the record books



3 March, 2014


As one of the country's most popular and iconic poems laments, Australia is a "sunburnt country" of "droughts and flooding rains".

Dorothea Mackellar's My Country endures with its "wide brown land" evoking "flood and fire and famine" and that "pitiless blue sky".
According to the New South Wales State Library, My Country is the "universal statement of our nation's connection to the land".
You can hear the echoes of Mackellar when Australian politicians are asked about the country's increasingly extreme weather events.
When Prime Minister Tony Abbott was asked about recent record breaking heat, he used Mackellar's poem to dismiss any link with climate change.
''They are just part and parcel of life in Australia," Abbott said. "Australia is, to use the famous phrase, a land of droughts and flooding rains."
But the climate that shaped Mackellar's Australia of the early 20th century is going through rapid changes thanks to the long march of human-caused climate change. 
The contradictions that Mackellar helped romanticize have become starker and more extreme.
The latest assessment of the country's climate, just released, finds that the fire seasons are already longer and riskier. The droughts will likely get harder as rainfall shifts.
Mackellar's "jewel-sea" is rising and becoming more acidic.
There's little poetry in the just published State of the Climate Report 2014, produced by the Bureau of Meteorology and the nation's science agency the CSIRO.
But there is a profound truth. The nation is 0.9C hotter than it was when Mackellar's verse was first published in the London Spectator magazine in 1908.
That same year, Australia's Bureau of Meteorology was established and two years after that, a network of meteorological stations had been built.
Streets are flooded as parts of southern Queensland experiences record flooding in the wake of Tropical Cyclone Oswald on January 29, 2013 in Bundaberg, Australia.Four deaths have been confirmed and thousands have been evacuated in Bundaberg as the city faces it's worst flood disaster in history. Photograph: Chris Hyde/Getty Images

State of the Climate
The State of the Climate Report is published every two years and summarises the conditions across the "wide brown land".
The 0.9C of average warming seen since 1910 is a seemingly innocuous statistic that hides major shifts in the country's climate. Says the report:
This warming has seen Australia experiencing more warm weather and extreme heat, and fewer cool extremes. There has been an increase in extreme fire weather, and a longer fire season, across large parts of Australia.
Karl Braganza, manager of climate monitoring at the bureau's National Climate Centre, told me:
When you look at large area averages, what looks like a small shift of 0.9C is actually quite large. Take, for example, how a small shift in your average body temperature can have some large impacts.
One example Braganza offers to illustrate the scale of the shift is in the number of times Australia experiences a day that falls in the top one per cent for heat.
Chart showing number of days annually where Australian area-averaged daily mean temperature is above the 99th percentile for the period 1910–2013. This metric reflects the spatial extent and frequency of extreme heat across the continent. Half of these events have occurred in the past twenty years. Image: Bureau of Meteorology/CSIRO

Starting from 1910 when Australia's records start, it took 31 years for the country to rack up 28 days hot enough to fall into that top one per cent. 
2013, however, managed to deliver this same number of extremely hot days in a single year.
The report says that seven of Australia's ten warmest recorded years have all happened since 1998.
In the last 15 years, "very warm" months are happening five times more often than they were between 1951 and 1980. There are now one third less cool months than before.
Even though cool records can still be set in a warming climate, the report says that since 2001 there are three daytime heat records being broken for every one cold record.
Nights are also warming faster than days. For every lowest minimum nighttime temperature record being set, there are now five highest minimum temperature records falling.
The risk of bushfires is increasing too.  Across 38 reference stations, the report finds that between 1973 and 2010 there was a statistically significant increase in the number of fire danger days at 16 locations.
The very worst fire-weather days have become more extreme at 24 of the 38 sites (only one location, Brisbane Airport, showed a decrease which was not statistically significant).
All this, the report says, comes as the world's climate system "continues to warm".
It is extremely likely that the dominant cause of recent warming is human-induced greenhouse gas emissions and not natural climate variability.
One study has found that the accumulation of greenhouse gases in the atmosphere had increased by as much as a factor of five the chances of Australia experiencing a record breaking heatwaves like that of summer 2013.
More sunburn in store
The report points to the likely range of warming the country will experience as global emissions continue to rise. Even under the most optimistic scenario for emissions, Australia will likely be between 1C and 2.5C warmer in 2070 than recent decades.
Higher emissions could see Australia on average almost 6C hotter than Dorothea Mackellar's already sunburnt country. The report concludes:
Atmospheric greenhouse gas concentrations continue to rise and continued emissions will cause further warming over this century. Limiting the magnitude of future climate change requires large and sustained net global reductions in greenhouse gases.
Australia is on the extreme end of most aspects of the human-caused climate change issue.
As a victim, the impacts are being seen in the flames of bushfires, in the ever hotter days and warmer nights and in the warming oceans.
As a contributor, the country continues to plough ahead with massive expansion plans for coal and gas exports while taking a leading role in per capita emissions.
Prime Minister Abbott surrounds himself with climate science deniers who think the science is a "delusion" or a cover story for creeping socialism.
Mackellar's verse was once a stand-alone definition of Australia, but not any more. Too much has changed.



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