Australia suffers devastating bushfires

Catastrophic and unprecedented bushfires in Australia have killed more than 22 people, destroyed hundreds of homes and burned hundreds of thousands of hectares of land, causing massive devastation to wildlife, ecosystems and the environment.

The fires have led to hazardous air quality in major cities throughout Australia, impacted New Zealand and sent smoke drifting thousands of kilometres across the Pacific to South America. 

The long range transport of smoke reached both Argentina and Chile on 6 January, according to the national meteorological and hydrological services.

Wildfires release harmful pollutants including particulate matter and toxic gases such as carbon monoxide, nitrogen oxides, and non-methane organic compounds into the atmosphere. The fires have already released approximately 400 megatonnes of carbon dioxide into the atmosphere, according to the European Union's Copernicus Atmospheric Monitoring Service (CAMS). On 2 January CAMS saw that the highest concentrations of atmospheric carbon monoxide in the world were over the ‘clean’ South Pacific Ocean, having come from fires in New South Wales. Taking Australia as a whole, carbon dioxide emission hasn’t been particularly high this wildfire season, but emissions from New South Wales are many times higher than the 2003–2018 average.

In the first week of 2020, many parts of southern and eastern Australia, including the states of New South Wales and Victoria, saw catastrophic or extremely dangerous fire conditions, due to a combination of temperatures well above 40°C, prolonged lack of rain and gusty winds.   The Australian military was called in to help battle the blazes, with naval vessels evacuating residents trapped in a coastal town in the State of Victoria.

After a brief respite, temperatures are expected to rise again by the 10 January, according to Austtralia's Bureau of Meteorology.

Across Australia as a whole, spring 2019 (September to December) saw the highest fire weather danger as measured by the Forest Fire Danger Index (FFDI)1, with record high values observed in areas of all States and Territories, according to Australia’s Bureau of Meteorology. More than 95% of Australia by area had spring accumulated FFDI values that were very much above average, including almost 60% of the country that was highest on record for spring

The year 2019 was unusually warm and dry for large parts of Australia, with many records set, setting the scene for a “long and challenging fire season,” according to the Australian Seasonal Bushfire Outlook December 2019 for summer 2019/2020,

“The tendency for fire seasons to become more intense and fire danger to occur earlier in the season is a clear trend in Australia’s climate, reflecting reduced and/or less reliable cool season rainfall and rising temperatures. Fire season severity is increasing across much of Australia as measured by annual (July to June) indices of the FFDI, with the increases tending to be greatest in inland eastern Australia and coastal Western Australia,” it said.

The bushfire outlook is compiled by Federal government agencies, including the Bureau of Meteorology and the Bushfire and Natural Hazard Cooperative Research Centre.

Drought and high temperatures

Australia recorded its hottest day on record on 19 December, with an average maximum temperature of 41.9°C. In South Australia, a temperature of 49.9°C was recorded at Nullarbor, 49.8 at Eucla and 49.5 at Forrest.

According to the Bureau of Meteorology, the country as a whole observed its second-warmest mean temperature on record for January–November. The mean maximum temperature was highest on record for Australia over the same period, with mean minimum temperature also very warm at seventh-highest on record.

Nationally, November rainfall was very much below average, the driest on record out of 120 Novembers since 1900.

For the year to date (January–November), rainfall has been below to very much below average over much of Australia. For Australia as a whole, it was the second-driest January–November on record, coming in behind January–November 1902. It was the driest January–November on record for South Australia, and amongst the three driest on record for New South Wales, Western Australia, and the Northern Territory.

One of the drivers for this was one of the strongest Indian Ocean Dipole (IOD) events on record. When the IOD is positive, the waters off Australia’s north-west are cooler, dragging moisture away from the continent and leaving very dry conditions.

However, rainfall deficiencies have affected most of the New South Wales, Queensland and South Australian parts of the Murray–Darling Basin since the start of 2017. These longer-term deficiencies extend to parts of the New South Wales coast.

When compared to other 34-month periods commencing in January, the 34 months from January 2017 to October 2019 has been the driest on record averaged over the Murray–Darling Basin (36% below the 1961–1990 average), as well as over the northern Murray–Darling Basin (40% below average) and for the state of New South Wales (35% below average). All three regions have also been the driest on record for the 22 months from January 2018 to October 2019, whilst for the 27 months from August 2017 to October 2019 rank second in all three regions; only the 1900–02 peak of the Federation Drought has been drier.

The dry conditions of the last three years have been particularly acute during the cool season, which is important in many regions for generating runoff. Rainfall for the period from April to September was less than 50% of average in all three years in 12 of the 30 rainfall districts of New South Wales. The very much below average October rainfall over most of New South Wales and the Murray–Darling Basin as a whole has further exacerbated the effect of low inflows to date.

Relationship with climate change

The incidence of wildfires is greatly influenced by natural variability in our climate, including precipitation and wind, as well as other factors not related to the climate (eg land and forest management, building practices).

Australia’s state of the climate report 2018, issued in 2019, said that there has been a “long-term increase in extreme fire weather, and in the length of the fire season, across large parts of Australia.” Climate change, including increasing temperatures, is contributing to these changes,” said the report by CSIRO and the Australian Bureau of Meteorology.

Fire weather is largely monitored in Australia using the Forest Fire Danger Index (FFDI). This index estimates the fire danger on a given day based on observations of temperature, rainfall, humidity and wind speed. The most extreme 10 per cent of fire weather days) has increased in recent decades across many regions of Australia, especially in southern and eastern Australia. There has been an associated increase in the length of the fire weather season. Climate change, including increasing temperatures, is contributing to these changes, according to the state of the climate report.

Australia’s climate has warmed by just over 1 °C since 1910, leading to an increase in the frequency of extreme heat events.

There has been a decline of around 11 per cent in April–October rainfall in the southeast of Australia since the late 1990s.

Australia is projected to experience: • Further increases in sea and air temperatures, with more hot days and marine heatwaves, and fewer cool extremes. • Decreases in rainfall across southern Australia with more time in drought, but an increase in intense heavy rainfall throughout Australia

Source http://www.bom.gov.au/state-of-the-climate/State-of-the-Climate-2018.pdf