A comprehensive new scientific report has warned that Australia faces a temperature rise of more than 5°C by the end of the century, outstripping the rate of warming projected for the rest of the world, unless drastic action is taken to slash global greenhouse gas emissions.
The research, led by Australian researchers from the CSIRO and Bureau of Meteorology, predicts that Australia’s national average temperature will increase by 2.8-5.1°C by 2090 in a high emissions scenario, compared to 0.6-1.7°C under a low global emissions scenario.
“There is very high confidence that hot days will become more frequent and hotter”, CSIRO principal research scientist, Kevin Hennessy said.
“We also have very high confidence that sea levels will rise, oceans will become more acidic, and snow depths will decline”
A decline in winter and spring rainfall in southern Australia is also projected by researchers, as well as a winter rainfall decrease in eastern Australia.
Extreme rain events, meanwhile, are projected to become more intense – as are periods of severe drought, with the report predicting drought periods would increase over southern Australia, and possibly elsewhere in the country, with a greater frequency of severe droughts.
The report is based on the most comprehensive projections ever released for Australia, with information drawn from simulations based on up to 40 global climate models.
Released on Tuesday, it coincides with the publication of an international study on Monday, from a team led by CSIRO’s Cai Wenju, which has predicted that extreme La Nina events forming in the Pacific will increase from about one in 23 years to one every 13 years because of rising greenhouse gas concentrations in the atmosphere.
The study concludes that an increase in “super La Ninas” will mean “more occurrences of devastating weather events, and more frequent swings of opposite extremes from one year to the next, with profound socio-economic consequences.”
The Australia-focused report – the first update of the agencies’ Natural Resource Management report since 2007 – builds on improved modelling to project how the climate for Australia and its major population centres is likely to differ by 2030 and 2090.
“This research has been strongly aligned with the needs of Australia’s natural resources sector”, Hennessy said.
“Other researchers are using this information to assess potential impacts and management options.”
Observed climate information indicates that Australian average surface air temperature has increased by 0.9° C since 1910, and many heat-related records have been broken in recent years. Sea level has risen about 20 cm over the past century.
Since 2001, the report says, extreme heat records have exceeded cold records across Australia by three to one for maximum temperatures and five to one for minimums.
Heatwaves have increased in duration, frequency and intensity across many parts of the country.
The Bureau of Meteorology has observed that since the 1970s, northern Australia has become wetter, southern Australia has become drier, the number of extreme fire weather days has increased in many places, and heavy rainfall has accounted for an increasing proportion of annual-total rainfall.
Snow depths have declined since the 1950s and cyclone frequency seems to have declined since the 1980s.