RECORD BREAKING SEPTEMBER HEAT AND CLIMATE CHANGE
Australia has broken all the wrong
records this year—we broke over 120
extreme weather related records in the
2012/2013 summer. We experienced
the hottest January on record, the
hottest summer and the hottest day
ever recorded in Australia. We have just
experienced the warmest September
in Australia’s history, as well as the
warmest 12-month period, and we are
on track to break yet another record
for the warmest calendar year ever
recorded in Australia.
Climate change means that we
are experiencing hotter days, and
heatwaves are becoming more frequent
and more severe. Heatwaves have a
wide range of negative impacts on
human health, agriculture, industry and
many plants and animals.
KEY FACTS:
This September is the warmest in Australia’s history, with the national average
temperature for the month 2.75 degrees above the long-term (1961–1990)
average. September 2013 also set a record for the largest positive anomaly
(difference between the observed temperature and the long-term average) for
any monthly average temperature.
The average temperature for Australia for the 12 months from October 2012
to September 2013 was 1.25°C above the long-term average. This was 0.17°C
warmer than any 12-month period prior to 2013.
The frequency and severity of hot days and heatwaves is increasing as average
global temperature is rising.
Although Australia has always had heatwaves and hot days, climate change is
increasing the risk of more frequent and longer heatwaves and more extreme
hot days, as well as exacerbating bushfire conditions. There have been more
than 100 heat-related records broken over the past year, and this year is on
track to become Australia’s warmest year on record.
Hotter days, occurring more frequently, present wide-ranging risks for human
health and wellbeing. Good community understanding of climate change
risks is critical to ensure we take appropriate action to reduce greenhouse gas
emissions and to put measures in place to prepare for, and respond to, extreme
weather.
It is essential to reduce CO
emissions rapidly and deeply to stabilise the
climate and halt the current trajectory towards more extreme weather events
and hotter average temperatures.
WHAT HAVE WE SEEN THIS SEPTEMBER?
The Bureau of Meteorology’s report today (BoM, 2013) stated
that not only is this September the warmest September
on record; but it is the warmest September by the greatest
margin of any recorded monthly temperature increase we
have experienced in Australia.
Currently 2013 is tracking to be the hottest
year on record for Australia. The average
temperatures for the previous 12 months
surpasses that of any 12 month period
prior to 2013 by 0.17°C. Previously the
hottest year on record was 2005. Globally,
the hottest 10 years on record have all
occurred during the last 15 years (NASA, 2012).
This September is part of a series of
records broken over the last 18 months
as Australia experiences persistent heat
continent-wide. There have been fewer
cold days and consistent above-average
temperatures. Widespread record warmth
has also been recorded in the oceans
around Australia.
The latest report from the Bureau of
Meteorology highlights the large number
of mean temperature records that have
fallen across Australia in the last year,
including:
- Australia’s warmest month on record (January)
- Australia’s warmest September on record
- Australia’s largest positive monthly anomaly on record (September)
- Australia’s warmest summer on record (December 2012 to February 2013)
- Australia’s warmest January to September period on record
- Australia’s warmest 12-month period on record (broken twice, for the periods ending August and September)
- Indeed, Australia’s warmest period on record for all periods 1 to 18 months long ending September 2013.
(see link)
THE CLIMATE CHANGE LINK?
Hot weather has always been common in
Australia. However, in the past few decades it
has become more common and severe as global
temperatures have risen.
Greenhouse gases in the atmosphere trap
heat, so the more greenhouse gases there
are in the atmosphere, the more heat is
trapped. The increase in temperature
observed around the world in the
atmosphere and in the ocean is directly
connected to the increase in greenhouse
gases from human activities (IPCC, 2013).
There has been a significant increase
in the frequency of hot days (days over
35°C) and hot nights over the last 50 years
in Australia (CSIRO and BoM, 2012). The
frequency of record hot days has been
more than three times the frequency of
record cold days during the past ten years
(Trewin and Smalley, 2012).
Australia’s average temperature has
already risen by 0.9°C since 1910 (CSIRO
and BoM, 2007). This is consistent with
the global trend of increasing average
temperature.
Although a temperature increase of
0.9°C may seem modest, small changes
in average temperature can have a
significant impact on the frequency
and nature of extreme weather events.
When the average temperature shifts,
the temperatures at the bottom and top
of the temperature scale shift too. As
the average temperature increases, the
distribution of the range of temperatures
shifts to include a greater likelihood of
more extreme hot temperatures and less
extreme cold temperatures. For example,
the number of record hot days across
Australia has doubled since 1960 despite
an average temperature increase of only
0.9°C (CSIRO and BoM, 2007).
WHAT ARE THE CONSEQUENCES
OF AUSTRALIA HEATING UP?
More frequent and more severe hot days and heat waves
affect human health, and plant and animal well-being.
We have seen the impacts of several heatwaves over the
last decade. For example, during the 2009 heatwave in
Melbourne, there were 980 heat related deaths—that’s 374
deaths more than would have normally occurred.
Heatwaves are the most significant natural
hazard in Australia in terms of loss of life.
Humans can only survive if our core body
temperature remains within a certain,
limited range. When we experience
prolonged and unusually intense heat,
our ability to cool ourselves through direct
transfer of our body heat to the air and
through sweating becomes less effective.
This results in heat exhaustion, which
can then lead to heatstroke and death.
The elderly, very young, people who work
outdoors and people with existing health
conditions are the most vulnerable to
extreme heat.
The impacts of extreme heat do not only
affect humans. As we saw during the
Melbourne heatwaves, increased heat
damages critical infrastructure including
energy transmission and rail transport.
Heat also affects the agricultural sector,
with animals more likely to suffer heat
stress and large increases in temperature
reducing the yield and quality of many
crops. Natural ecosystems are also affected
by extreme heat, with the large number
of deaths of flying foxes and cockatoos
during severe heatwaves being prominent
examples.
http://www.climatecouncil.org.au/wp-content/uploads/2013/10/cc.offthecharts1.pdf

