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CSIRO report says Australia getting hotter with more to come

David Mark reported this story on Tuesday, March 4, 2014 18:30:00

MARK COLVIN: The two top authorities on Australia's climate say it's clear - the continent is getting warmer. The CSIRO and the Bureau of Meteorology published the latest State of the Climate report today.

Australia is experiencing more extreme heat and longer fire seasons because of increasing greenhouse gas emissions. The report confirms that temperatures in Australia have risen almost one degree over the past 100 years.

What's more, temperatures are expected to continue rising by up to one and a half degrees in the next 16 years alone and by more over the longer term.

David Mark reports.

DAVID MARK: The clear language in the CSIRO and Bureau of Meteorology State of the Climate 2014 report is at odds with the political debate about climate change in Australia; it's unequivocal.

PENNY WETTON: It's very clear that the global climate system is warming and that Australia also is experiencing that warming that we're seeing globally.

DAVID MARK: Dr Penny Wetton is a climate scientist at the CSIRO and one of the author's of the report.

PENNY WETTON: The fact that there's been an overall increase is starting to stand out quite strongly compared to those ups and downs you get from year to year.

DAVID MARK: The report says temperatures in Australia have risen by 0.9 of a degree since 1910. Seven of the 10 warmest years on record have occurred in the past 16 years. Extreme fire weather has increased as has the length of the fire season.

Average rainfall has increased, but rainfall has decreased by at least 15 per cent recently in the south of the country in autumn and winter.

And the report makes it clear why these changes are happening.

PENNY WETTON: The predominant cause of that increase in temperature, particularly since the middle of last century, has been increases in greenhouse gases.

Alternative causes for that do not have the capability to explain that increase in temperature. Australia is showing a very similar pattern of warming to what we see globally.

DAVID MARK: As Dr Wetton alluded to, the rise in temperatures has been accelerating, and that pattern will continue.

PENNY WETTON: We're looking at a further warming of perhaps about 0.5-1.5 degrees by 2030, compared to late last century. And if you look at later in the century, the warming could be 1-2.5 degrees by 2070 if we follow a fairly low pathway with our emissions globally of greenhouse gases.

But, if in fact we follow a higher pathway with our greenhouse gas emissions, the warming could be around 2-5 degrees.

It would be an extraordinary change. Take for example, a temperature change of about 3 degrees is about the difference between say a Melbourne and Sydney climate. So, you know, five degrees is quite a significant warming.

If you think about inland areas of Australia where we get very hot days now of perhaps 46, 47 degrees, you know it's going to push those hot days well over 50 degrees.

[my emphasis]

DAVID MARK: That will mean more extreme fire weather days - up to 300 per cent more by 2050 compared to the climate in the last decades of last century.

Sea levels are projected to rise by a third to one metre, depending on emissions. And droughts will become more frequent and severe - particularly in southern Australia.

PENNY WETTON: Well firstly, what we see in Australia when it comes to projecting future changes in rainfall is quite a clear pattern of decreasing rainfall across southern areas of the continent - mainly the areas that get most of their rainfall in the winter, because what we see is a projected decline in winter rainfall.

And so that includes south west Western Australia, across southern South Australia into parts of south-eastern Australia.

Away from that region, when we look at say northern Australia particularly, and summer rainfall more generally, we are not getting such a consistent message from our global climate models and various lines of evidence. There is a possibility of significant changes in rainfall, but we can't be so confident about the direction of change.

But in that southern area, we can be confident about the direction of change, and it's a decrease.

DAVID MARK: There was a time in Australia when the release of the State of the Climate Report and its predictions of increasing extreme weather, bushfires and droughts, might have sparked a political debate - particularly given the divide between the major parties over the price on carbon.

It seems those days are over. Labor did not raise the report in Question Time today.

The Greens Leader, Senator Christine Milne, did buy in on her way into the Parliament this morning.

CHRISTINE MILNE: The task in Australia is enormous. We have to not only turn things around, but start pulling those emissions right down, and you're not going to do it with a target of 5 per cent and you're certainly not going to do it with Direct Action.

The science is there, the reality for the farmers is there. South-eastern Australia is drying out; it is time we maintained the legislation we've got.

MARK COLVIN: The Greens Leader, Senator Christine Milne, ending David Mark's report.

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5 Mar 2014 Last updated 12:18 EST

CSIRO/BOM report provides a clearer picture of Australia's climate change

04 Mar 2014

A definitive report on observed changes in long-term trends in Australia’s climate has been released by CSIRO and the Bureau of Meteorology.

Bureau chief executive Dr Rob Vertessy said temperatures across Australia were, on average, almost 1°C warmer than they were a century ago, with most of the warming having occurred since 1950.

“Australia’s mean temperature has warmed by 0.9°C since 1910,” Dr Vertessy said.

“Seven of the ten warmest years on record in Australia have occurred since 1998. When we compare the past 15 years to the period 1951 to1980, we find that the frequency of very warm months has increased five-fold and the frequency of very cool months has decreased by around a third.

The duration, frequency and intensity of heatwaves had increased across large parts of Australia since 1950. Extreme fire weather risk had increased, and the fire season lengthened across large parts of Australia since the 1970s.

“We have also seen a general trend of declining autumn and winter rainfall, particularly in south-western and south-eastern Australia, while heavy rainfall events are projected to increase. Australian average annual rainfall has increased slightly, largely due to increases in spring and summer rainfall, most markedly in northwestern Australia,” Dr Vertessy said.

CSIRO chief executive Dr Megan Clark said Australia had warmed in every state and territory and in every season.

“Australia has one of the most variable climates in the world. Against this backdrop, across the decades, we’re continuing to see increasing temperatures, warmer oceans, changes to when and where rain falls and higher sea levels,” Dr Clark said.

“The sea-surface temperatures have warmed by 0.9°C since 1900 and greenhouse gas concentrations continue to rise.”

Key findings: Temperature

* Australia’s mean surface air temperature has warmed by 0.9°C since 1910.
* Seven of the ten warmest years on record have occurred since 1998.
* Over the past 15 years, the frequency of very warm months has increased five-fold and the frequency of very cool months has declined by around a third, compared to 1951-1980.
* Sea-surface temperatures in the Australian region have warmed by 0.9°C since 1900.

Key findings: Rainfall

* Rainfall averaged across Australia has slightly increased since 1900, with a large increase in northwest Australia since 1970.
* A declining trend in winter rainfall persists in southwest Australia.
* Autumn and early winter rainfall has mostly been below average in the southeast since 1990.

Key findings: Heatwaves and fire weather

* The duration, frequency and intensity of heatwaves have increased across large parts of Australia since 1950.
* There has been an increase in extreme fire weather, and a longer fire season, across large parts of Australia since the 1970s.

Key findings: Global atmosphere and cryosphere

* A wide range of observations show that the global 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.
* Ice-mass loss from the Antarctic and Greenland ice sheets has accelerated over the past two decades.
* Arctic summer minimum seaice extent has declined by between 9.4 and 13.6 percent per decade since 1979, a rate that is likely unprecedented in at least the past 1450 years.
* Antarctic sea-ice extent has slightly increased by between 1.2 per cent and 1.8 per cent per decade since 1979.

Key findings: Greenhouse gases

* Atmospheric greenhouse gas concentrations continue to increase due to emissions from human activities, with global mean CO2 levels reaching 395 ppm in 2013.
* Global CO2 emissions from the use of fossil fuel increased in 2013 by 2.1pc compared to 3.1pc per year since 2000.
* The increase in atmospheric CO2 concentrations from 2011 to 2013 is the largest two-year increase ever observed.

Future climate scenarios for Australia

* Australian temperatures are projected to continue to increase, with more hot days and fewer cool days.
* A further increase in the number of extreme fire-weather days is expected in southern and eastern Australia, with a longer fire season in these regions.
* Average rainfall in southern Australia is projected to decrease, with a likely increase in drought frequency and severity.
* The frequency and intensity of extreme daily rainfall is projected to increase.
* Tropical cyclones are projected to decrease in number but increase in intensity. Projected sea-level rise will increase the frequency of extreme sea-level events.

The State of the Climate 2014 report is the third report in a series and follows earlier reports in
2010 and 2012. To download the full report, click here. http://www.bom.gov.au/state-of-the-climate/

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