Very little is known about the past climate of Perth, Western Australia, during the 19th century. Our team recently pieced together the oldest daily weather observations from south-western Australia spanning 1830–1875.
There’s a strong case for increasing 19th century climate data rescue efforts in the south-western region of Australia, due to the vulnerability of this area and its important geographic location for understanding weather patterns across Australia. With a more complete understanding of the past climate, we can better prepare for extreme events which are predicted to increase in frequency and severity.
The Australian Bureau of Meteorology’s State of the Climate 2020 report noted that cool season rainfall in southwest Western Australia (WA) has deceased since 1970 due to an increase in surface pressure across southern latitudes – a known response to climate change. Lower winter rainfall and higher temperatures mean the fire seasons are getting longer, with the February 2021 bushfires in Perth Hills proving as case in point, with around 11,000 hectares and over 85 homes destroyed.
Improving our understanding of long-term climate variability from the Southern Hemisphere is critical to quantifying future changes in Australia. To date, the majority of historical data recovery efforts across the country have centered on the colonial centres of south-eastern Australia.
Perth is located in the southern storm-track associated with prevailing westerly winds, which makes it important for understanding changes in the weather systems over time. Comparing observations from this site with the data we have for south-eastern Australia will help scientists understand how weather patterns have changed over southern Australia.
Sharing our research on the past climate of south-western Australia
In February 2021, we’ll present our most recent research on the Perth region as part of the 2021 Australian Meteorological and Oceanographic Society (AMOS) annual meeting and international conference. In a session titled The story of climate in Australia: learning from the past and planning for future impacts, our research assistant Zak Baillie will present a new historical climate dataset for southwestern Australia, covering the period 1830 to 1875.
This is the first time that historical weather observations from south-western Australia during the 19th century have been analysed in such detail. It includes near-continuous daily observations of air pressure, temperature and wind along with weather remarks, including rain days.
The observations we studied were recorded in 16 handwritten weather journals taken from the Swan River colonial settlement of Perth and begin shortly after the first European settlement of the region in 1829. These weather journals are currently the oldest meteorological observations for Perth.
The Perth Meteorological journals we recently analysed are a near-continuous sub-daily dataset of temperature, pressure, wind direction and weather remarks from 1830 to 1875.
Source: National Archives of Australia.
The team compared historical observations with modern instrumental observations from Perth. The analysis identified some interesting examples of significant storms and heatwaves that demonstrate the potential of using historical observations to analyse past extremes and their societal impacts.
For example, a significant heatwave identified in the historical observations was verified by looking at newspapers published at the time. The newly-transcribed historical journals showed an extreme heatwave from December 28 to 30, 1868. By searching the National Library of Australia’s digital collections on Trove, we found numerous newspaper accounts of this heatwave detailing the severity and impacts of the event.
Unfortunately there is still a gap in Perth’s historical climate record from 1876 until the Bureau of Meteorology’s records begin in 1900. We’ve been lucky enough to find some journals from Perth which will complete 20 years of these observations – but they need to be transcribed before we can analyse them.
Get involved in our upcoming citizen science project to help transcribe 20 years’ of historical climate records from Perth. Don’t forget to sign up to our e-newsletter, so you’ll be notified as soon as we launch.