Australia's extreme heat is sign of things to come,
scientists warn
Hottest month ever shows temperatures rising faster than
predicted, say climate experts
Lisa Cox, Jonathan Watts and Australian Associated Press
Fri 1 Feb 2019 16.48 GMT Last modified on Fri 1 Feb 2019
18.30 GMT
Australia sweltered through the hottest month in its history
in January, spurring mass deaths of fish, fire warnings and concerns among
climate scientists that extreme heat is hitting faster and harder than
anticipated.
For the first time since records began, the country’s mean
temperature in January exceeded 30C (86F), according to the Bureau of
Meteorology (BoM), which said daily extremes – in some places just short of 50C
– were unprecedented.
“There’s been so many records it’s really hard to count,”
said Andrew Watkins, a senior climatologist at BoM, after January registered Australia’s
warmest month for mean, maximum and minimum temperatures.
This followed the country’s warmest December on record, with
heatwaves in every Australian state and territory. With colour-coded heat maps
of the country resembling blazing red furnaces for much of the month, the
authorities have recently issued a special report on the extraordinary heat.
A persistent high-pressure system in the Tasman Sea that
blocked cold fronts and cooler air from reaching the country’s south, and a
delayed monsoon in the north, contributed to the heatwave.
Climate change is the long-term driver. “The warming trend
which has seen Australian temperatures increase by more than 1C in the last 100
years also contributed to the unusually warm conditions,” Watkins said.
The bureau’s monthly report said the heatwaves were
unprecedented in their scale and duration. The highest temperatures of the
month were recorded in Augusta on the south-west coast, where thermometers
registered 49.5C , but the most relentless heat was in Birdsville, Queensland,
which endured 10 consecutive days above 45C.
Tasmania, where emergency services have been battling
bushfires throughout the past month, had its driest ever January. Watkins said
Borrona Downs in north-west New South Wales broke the record for hottest
minimum temperature, registering one night at 36.6C. This has a major impact on
ecosystems that have not been able to cool down during the night as is normally
the case.
This was compounded by drought. Large parts of Australia
received only 20% of their normal rainfall, particularly throughout the south-east
in Victoria and parts of NSW and South Australia.
Menindee in far-west NSW had four days in a row of
temperatures above 47C. This was the site of December and January’s mass fish kills
on the Darling River. Hundreds of thousands of native fish, including Murray
cod, golden perch and bony bream, died around the Menindee weir. The
authorities blamed “thermal stratification” as sudden shifts in temperature –
first hot, then cold – caused algae blooms and choked the water of oxygen.
After the most recent fish die-off on 27 January, the Labor
leader, Bill Shorten, said the Murray-Darling was “facing the makings of an
ecological disaster”. He said: “This is not standard, this is not normal. This
is a disaster.”
In parts of western Queensland and western NSW, there have
been long strings of more than 40 days of temperatures above 40C.
Cloncurry had 43 days in a row that exceeded 40C. Birdsville
had 16 days in January of temperatures higher than 45C including 10 days in a
row.
NSW, the Australian Capital Territory, Victoria and the
Northern Territory all had their warmest January on record.
The meteorological agency has warned that temperatures are
set to rise further in the years ahead as a result of climate change. In its
report last month, it said warming was contributing to a long-term increase in
the frequency of extreme heat, fire weather and drought.
“Australia is already experiencing climate change now and
there are impacts being experienced or felt across many communities and across
many sectors,” said Helen Cleugh, the director of the Commonwealth Scientific
and Industrial Research Organisation, which collaborated on the report.
The study, which is updated every two years, found that
Australia’s fire seasons have lengthened – in places by months – and become
more severe. From April to October, there has been a broad shift to more arid
conditions in south-eastern and south-western Australia. Sea levels have
already risen by 20cm and ocean temperatures are up by 1C, which is causing
acidification – 10 times faster than at any time in 300m years – which has
damaged the corals of the Great Barrier Reef.
Sem comentários:
Enviar um comentário