IAG has warned Australia to expect more severe and frequent extreme weather and catastrophes, with the latest research reinforcing the need for urgent action on climate change.

The Bureau of Meteorology and CSIRO released their joint sixth biennial State of the Climate report, drawing on the latest climate research to describe year-to-year variability and longer-term changes in Australia’s climate.

The State of the Climate reveals Australia has seen a decline of around 16% in April to October rainfall in the southwest since 1970, and in the southeast there has been a decline of around 12% since the late 1990s.

There has been an increase in extreme fire weather, and in the length of the fire season, across large parts of the country since the 1950s, especially in southern Australia.

Oceans around Australia have warmed by around one degree Celsius since 1910, contributing to longer and more frequent marine heatwaves, and sea levels are rising around Australia.

IAG EM Natural Perils Mark Leplastrier says the report “highlights the need for us to take action now”.

“The science is telling us that the impacts of climate change are already affecting Australian communities,” he said.

“The trends we’re seeing…show Australia should expect more severe and frequent climate extremes in the form of devastating bushfires, storms, floods and sea level rise.”

IAG says it is critical that the latest science and climate information is shared to inform how Australians plan for and mitigate the impacts of severe weather events, including strategies for building resilience, land planning and building codes and ways to retrofit existing homes.

Continued investment in research will provide better data sets to inform planning to improve Australia’s resilience to natural hazards and major weather events, IAG says.

The report says that global concentrations of greenhouse gases in the atmosphere continue to increase, with 2019 reaching the highest levels seen on Earth in at least 2 million years. Each decade since 1980 has been warmer than the last.

Global mean sea levels have risen by around 25cm since 1880 and continue to rise at an accelerating rate.

“Australia needs to plan for and adapt to the changing nature of climate risk now and in the decades ahead,” the report says. “Reducing global greenhouse gas emissions will lead to less warming and fewer impacts in the future.”

It also says a decline in global fossil fuel emissions of carbon dioxide this year, associated with the COVID-19 pandemic, will have “negligible impact in terms of climate change”.