It's Only October, So What's With All These Bushfires? New Research Explains It

It's Only October, So What's With All These Bushfires? New Research Explains It Firefighters battle bushfires in Angourie, northern New South Wales, on September 10 this year, marking another early start to the season. Jason O'Brien/AAP

Summer might be more than six weeks away, but out-of-control bushfires have already torn across parts of eastern Australia in recent days, destroying homes and threatening lives.

As of Wednesday afternoon, up to 30 homes were feared lost or badly damaged by bushfires burning in northern New South Wales. About 40 fires burned across the state.

This did not come as a surprise to meteorologists and fire agencies. Record-breaking heat and windy conditions were forecast for parts of NSW and Queensland this week, prompting severe fire danger ratings.

We’re often told the Australian bushfire season is starting earlier. This year it began in September on the eastern seaboard. Last year and in 2013, significant spring fires hit NSW and in 2015 they affected much of the nation’s southeast.

But what lies behind this phenomenon? We examined seasonal fire weather history for 44 years at 39 weather stations to find the precise answer.

This analysis is the most comprehensive ever conducted in Australia. It confirms the strength of the relationship between climate drivers such as El Niño, climate change, and the Australian bushfire season. It also demonstrates that a few milder bushfire seasons do not mean climate change isn’t happening.

It's Only October, So What's With All These Bushfires? New Research Explains It A house burnt by bushfires in Laidley, southeast Queensland, photographed on October 9 2019. Scott Davis/AAP

Hot, dry, windy conditions spell fire trouble

The prerequisites for a severe bushfire season are high temperatures, low humidity, and strong winds that coincide with long periods of low rainfall.

These weather ingredients are used to calculate an area’s fire danger rating, using the Forest Fire Danger Index. The index produces a score reflecting the severity of fire weather on a given day, where zero represents minimal fire danger, 50 represents conditions where a fire ban may be issued, and 100 is considered potentially catastrophic.

Loss of human lives and property most often occurs on days when the index is high in a particular area. But strong seasonal fire weather doesn’t always translate to high-impact fires. Other factors in play include terrain, vegetation, ignition and the weather on the day.

In our research, we analysed the strength of the worst fire weather conditions to understand the relative severity of fire weather during different seasons and years, in relation to various climate drivers.

A Bureau of Meteorology video explaining bushfire weather.

Why is fire weather so different every year?

In Australia, the year-to-year changes in climatic conditions are largely driven by three factors: the El Niño Southern Oscillation, the Indian Ocean Dipole, and the Southern Annular Mode.

Each of these climate drivers involves either changes to sea surface temperatures, wind movements, or both. They can all can affect temperature and rainfall patterns across the Southern Hemisphere, including Australia.

Our research confirmed that across the continent over more than four decades, climate drivers have affected the variability of Australia’s fire weather.

Of these drivers, the El Niño Southern Oscillation is the most influential. Weather during an El Niño phase is typically hot and dry, leading to worse seasonal bushfire conditions.

The positive phase of the Indian Ocean Dipole often coincides with El Niño and exacerbates its effects. This phase generally results in lower than average rainfall across southern Australia.

But when these two climate modes are in a negative phase, our research confirms that Australia often experiences more rain and milder bushfire conditions.

The modes evolve over many months and their effects on fire weather persist for several seasons. Their state during winter and spring is a strong indicator for the rest of the fire season for much of Australia.

It's Only October, So What's With All These Bushfires? New Research Explains It The strength of the relationship between climate drivers and fire weather in spring. Purple squares show the strength of the relationship. Larger squares indicate a stronger relationship. User provided

The Southern Annular Mode refers to the north-south movement of strong westerly winds in parts of the Southern Hemisphere. When the mode is in a prolonged negative phase, fire weather conditions in Australia are worse - particularly in NSW. This effect is pronounced in winter and spring and means less rainfall and strong westerly winds.

The 2019 winter saw a persistent negative Southern Annular Mode, as did the 2013 and 2018 winter and spring seasons. There was a strong El Niño event and positive Indian Ocean Dipole in 2015. Australia’s bushfire season started earlier than usual in each of these years.

The converse is also true. In 2011 a strong La Niña (the opposite of an El Niño) resulted in milder bushfire seasons, as did the negative Indian Ocean Dipole of 2016.

Climate change is a culprit too

Long-term climate change in Australia is an undeniable reality. The State of the Climate 2018 report for Australia notes strong land surface temperature increases and a 10-20% decline in cool season rainfall across southern Australia since the 1970s. These changes are closely associated with increasing human greenhouse gas emissions, as well as natural variability.

The changed conditions has led to an average increase in the severity of seasonal bushfire weather across Australia - especially in southern parts of the continent. The increased severity affects all seasons but in particular spring, which means that, on average, the bushfire season is starting earlier.

It's Only October, So What's With All These Bushfires? New Research Explains It NSW Premier Gladys Berejiklian visits the control room at the NSW Rural Fire Service headquarters in Sydney on October 9, 2019. AAP/James Gourley

Pulling it all together

Our research has made clear that climate modes bring large and rapid swings to the fire weather, while human-induced climate change gradually increases background fire weather conditions. The trend generally means an earlier start to the bushfire seasons than in the past.

Climate change is definitely playing a role in producing the earlier start to bushfire seasons and overall more extreme seasons, particularly in southeastern Australia. However, the natural variations in climate modes continue to play a key role, meaning we should not expect every bushfire season to be worse than the last as a result of climate change.

Similarly, a few milder bushfire seasons among a string of record high seasons does not mean that climate change should be dismissed.The Conversation

About The Author

Chris Lucas, Senior Research Scientist, Australian Bureau of Meteorology and Sarah Harris, Manager Research and Development, Country Fire Authority

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Related Books

Life After Carbon: The Next Global Transformation of Cities

by Peter Plastrik , John Cleveland
1610918495The future of our cities is not what it used to be. The modern-city model that took hold globally in the twentieth century has outlived its usefulness. It cannot solve the problems it helped to create—especially global warming. Fortunately, a new model for urban development is emerging in cities to aggressively tackle the realities of climate change. It transforms the way cities design and use physical space, generate economic wealth, consume and dispose of resources, exploit and sustain the natural ecosystems, and prepare for the future. Available On Amazon

The Sixth Extinction: An Unnatural History

by Elizabeth Kolbert
1250062187Over the last half-billion years, there have been Five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists around the world are currently monitoring the sixth extinction, predicted to be the most devastating extinction event since the asteroid impact that wiped out the dinosaurs. This time around, the cataclysm is us. In prose that is at once frank, entertaining, and deeply informed, New Yorker writer Elizabeth Kolbert tells us why and how human beings have altered life on the planet in a way no species has before. Interweaving research in half a dozen disciplines, descriptions of the fascinating species that have already been lost, and the history of extinction as a concept, Kolbert provides a moving and comprehensive account of the disappearances occurring before our very eyes. She shows that the sixth extinction is likely to be mankind's most lasting legacy, compelling us to rethink the fundamental question of what it means to be human. Available On Amazon

Climate Wars: The Fight for Survival as the World Overheats

by Gwynne Dyer
1851687181Waves of climate refugees. Dozens of failed states. All-out war. From one of the world’s great geopolitical analysts comes a terrifying glimpse of the strategic realities of the near future, when climate change drives the world’s powers towards the cut-throat politics of survival. Prescient and unflinching, Climate Wars will be one of the most important books of the coming years. Read it and find out what we’re heading for. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.

 

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook-icontwitter-iconrss-icon

 Get The Latest By Email

{emailcloak=off}

LATEST VIDEOS

Did Scientists Get Climate Change Wrong?
by Sabine Hossenfelder
Interview with Prof Tim Palmer from the University of Oxford.
The New Normal: Climate Change Poses Challenges For Minnesota Farmers
by KMSP-TV Minneapolis-St. Paul
Spring brought a deluge of rain in southern Minnesota and it never seemed to stop.
Report: Today's Kids' Health Will Be Imperiled by Climate Change
by VOA News
An international report from researchers at 35 institutions says climate change will threaten the health and quality of…
How Supercharged Trash Gas Could Produce More Green Energy
by InnerSelf Staff
Synthetic compounds called “siloxanes” from everyday products like shampoo and motor oil are finding their way into…
300 Million Face Severe Risk of Climate-Fueled Coastal Flooding by 2050
by Democracy Now!
As a shocking new report finds that many coastal cities will be flooded by rising sea levels by 2050, Chile’s President…
Climate Warning: California Continues To Burn, Data Estimates Of Global Flooding
by MSNBC
Ben Strauss, CEO and Chief Scientist of Climate Central joins MTP Daily to discuss alarming new information about…
Stanford Climate Solutions
by Stanford
Climate change has brought us to a defining moment in human history.
Buying Renewable Energy From Your Neighbor
by NBC News
Brooklyn Microgrid, a project of parent company LO3 Energy, is looking to disrupt the more than 100-year-old energy…

LATEST ARTICLES

'4°C Of Global Warming Is Optimal' – Even Nobel Prize Winners Are Getting Things Catastrophically Wrong
'4°C Of Global Warming Is Optimal' – Even Nobel Prize Winners Are Getting Things Catastrophically Wrong
by Steve Keen
William Nordhaus was awarded the 2018 Nobel Prize in Economics for “integrating climate change into long-run…
A Battle For The Jet Stream Is Raging Above Our Heads
A Battle For The Jet Stream Is Raging Above Our Heads
by Tim Woollings
When prolonged periods of severe weather strike, two things often get the blame these days: climate change and the jet…
Rivers Are Changing All The Time, And It Affects Their Capacity To Contain Floods
Rivers Are Changing All The Time, And It Affects Their Capacity To Contain Floods
by Louise Slater, et al
The rainfall that has inundated the North of England is the latest in a long line of flood events that are becoming the…
Did Scientists Get Climate Change Wrong?
by Sabine Hossenfelder
Interview with Prof Tim Palmer from the University of Oxford.
The New Normal: Climate Change Poses Challenges For Minnesota Farmers
by KMSP-TV Minneapolis-St. Paul
Spring brought a deluge of rain in southern Minnesota and it never seemed to stop.
Dwindling Tropical Rainforests Mean Lost Medicines Yet To Be Discovered In Their Plants
Dwindling Tropical Rainforests Mean Lost Medicines Yet To Be Discovered In Their Plants
by Walter Suza
Growing up in Tanzania, I knew that fruit trees were useful. Climbing a mango tree to pick a fruit was a common thing…
Report: Today's Kids' Health Will Be Imperiled by Climate Change
by VOA News
An international report from researchers at 35 institutions says climate change will threaten the health and quality of…
Building With Bamboo Can Cool The Climate
Building With Bamboo Can Cool The Climate
by Kieran Cooke
If you want to cut global temperatures try building with bamboo, say UK-based researchers studying its thermal…