Climate change blamed as hotter Australia faces more intense rains, droughts

(Reuters) Australia faces a quickening pace of climate change, according to a snapshot of the nation’s weather.

A new government report says rainfall trends are changing and temperatures warming across the country.

The report, compiled by the Bureau of Meteorology and the Commonwealth Scientific and Industrial Research Organization, comes after 18 months of record rains in the country’s east, triggering floods that ended a devastating drought.

Each decade has been warmer than the previous one since the 1950s, the report said, with rising greenhouse gas emissions from burning fossil fuels, deforestation and agriculture blamed for the changes.

“We’re certainly seeing where the rain is falling is changing,” said Megan Clark, CSIRO’s chief executive. “We’re seeing more in spring and summer… a monsoonal signature across Australia’s north, and more rainfall in central Australia.

The report is only the second joint climate snapshot, with the first released in 2010 before the start of an intense La Niña event that triggered months of flooding, crimping economic growth and causing billions of dollars in insurance losses.

In hot water

A second, weaker La Niña in 2011 brought more rains. On Tuesday, the Bureau of Meteorology said the event was coming to an end, but rainfall in parts of Australia could still be above average.

La Niña is a periodic warming of the Western Pacific Ocean. It normally triggers above-average rains and cooler weather across northern and eastern Australia and Southeast Asia. The opposite phenomenon, El Niño, usually brings drought and warmer weather.

Clark said 2010-11 stood out for the peak rains and the equally record-breaking sea surface temperatures around northern Australia.

“This consistent rise in our sea surface temperatures has been a bit surprising,” she said.

“The other thing we’re seeing is when the conditions are right for rain, we’re getting a lot of rain.”

The report shows minimum Australian temperatures at night have warmed by more than 1.1 C since 1910, with most of this since 1960, and that the rate of very hot daytime temperatures, higher than 40 C, has been increasing since 1990.

Sea levels since 1993 around Australia’s north and northwest have been rising seven to 11 millimetres a year, two to three times the global average.

Temperature

  •  Each decade has grown warmer since the 1950s.
  •  Annual average daily maximum temperatures up 0.75 C since 1910.
  •  Annual mean daily average temperatures up 0.9 C since 1910.
  •  2010 and 2011 were Australia’s coolest years recorded since 2001, due to two consecutive La Niña events.

RAINFALL AND STORMS

  •  Past 15 years drier than average across the southeast, despite record rainfall in 2010 and 2011.
  •  The trend: Increased spring and summer monsoonal rainfall across Australia’s north; higher-than-normal rainfall across the centre, and a drop in late-autumn and winter rainfall across south.

OCEANS

  •  Global average mean sea level for 2011 was 210 mm above 1880 level.
  •  Global average mean sea level rose faster between 1993 and 2011 than during the 20th century as a whole.
  •  The heat content of the world’s oceans has increased during recent decades, causing oceans to expand and contributing to sea level rise.
  •  Sea surface temperatures have increased by about 0.8 C since 1910.

GREENHOUSE GASES

  •  Fossil fuel carbon dioxide emissions rose by more than three per cent per year from 2000 to 2010.
  •  The concentration of CO2 in the atmosphere in 2011 was 390 parts per million — higher than at any time for the past 800,000 years.

The Future

  •  Australian average temperatures are projected to rise by 1 C to 5 C by 2070.
  •  Number of both droughts and incidents of intense rainfall expected to increase.

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