Climate detectives reveal southeastern Australia’s climate back to 1788

Researchers have extracted climate information from Australian newspaper reports, farmers’ diaries, government documents and private journals, to extend our knowledge of the climate of southeastern Australia back to 1788. The information reveals the changing influence on our weather of El Niño and La Niña events on the region’s rainfall.

‘We found a real breakdown in the relationship between El Niño and La Niña events and rainfall in southeastern Australia in the early 19th century. Coincidently, between 1835-50, there were few La Niña events,’ said Dr Linden Ashcroft, a post-doctoral climate researcher at Universitat Rovira i Virgili in southern Catalonia, Spain.

The cycle of El Niño and La Niña events, spawned by changes across the Pacific Ocean, can create drought and flood in much of Australia.

‘Identifying wet and dry periods of the past is helping us figure out what is natural climate variability in Australia, and what is human-induced climate change. To understand the future, we need to improve our understanding of the past,’ said Dr Ashcroft.

‘We’ve recovered temperature, atmospheric pressure and rainfall data from 39 archival sources covering the years 1788–1859. We now have the most complete set of early instrumental data available for Australia.’

‘Southeastern Australia was dry from 1837-42, with drought returning to the east of the region from 1845-52. Tasmania was wet from 1836 to 1838, as was the east from 1843 to 1844.’

‘It was particularly cool during 1836 and 1847-49, including snow in Sydney and Melbourne.’

Australia’s official climate record, kept by the Bureau of Meteorology, begins in 1910. But historical climate records kept before the development of national meteorological organisations are valuable tools for improving our understanding of what has happened in the past.

The research, part of the South Eastern Recent Climate History project (SEARCH), offers new insights into the climate experienced by colonial Australians since European settlement in 1788. The project has brought together historians, climatologists, hydrologists, palaeoclimatologists and volunteers to reconstruct the climate of the highly-populated southeastern region, using more than 290,000 instrumental observations from national and state archives covering 1788–1860.

Dr Linden Ashcroft presented her results today at the 2017 conference of the Australian Meteorological and Oceanographic Society in Canberra. 

The Conference Program is available at: https://amos.eventsair.com/QuickEventWebsitePortal/amosmsnz2017/eventinfo

Twitter: #AMOS2017; @lindenashcroft

For further information:
Paul Holper, Scientell, 0407 394 661