Hazards: Wildfires

Question 1

What are wildfires?

Answer 1

An uncontrolled fire, either natural or human- made, that occurs in open country or wilderness.
These are a natural, necessary and beneficial process for many ecosystems.
- Small scale to large scale and widespread.
- Spread rapidly and susceptible to changing direction.

Question 2

Where do wildfires happen most?

Answer 2

• Boreal forests in Alaska, Canada, Russia, China, Scandinavia •Savannah grasslands in Africa
• Tropical forests in Brazil, SE Asia and Africa
• Temperate forests in U.S., Europe
• Agricultural waste after harvests in U.S., Europe
  —> Increasingly (due to climate change) northern latitudes. Boreal forests (coniferous) get less PPT and have a fuel source (peat and deep layers of shed needles).
  —> Tropical rainforests often too humid – but recent burning for forest clearance – often gets out of control and spreads for long periods.
  —> Mediterranean climate regions: drought-resistant chapparal (shrubs rather than trees) with dry winds.

Question 3

Why do different ecosystems burn at different temps?

Answer 3

Different ecosystems burn at different temperatures due to the nature & structure of the biomass and its moisture content.
It varies from thin, dry grasses in savannahs to dense, massive trees of the boreal, temperate and tropical forests.

Question 4

What are the wildfires favourable conditions?

Answer 4

• Dry – often during a long period of drought • Wind
• Low humidity / low precipitation
• Ignitionsource
• Supply of fuel
• Accumulation of dead wood

Question 5

How does topography make a difference?

Answer 5

• Fires spread quickly on hills as the heat rises.
• Fire can also ‘jump’ across rivers and into areas due to lit debris which causes it to spread.

Question 6

What are crown fires?

Answer 6

burn the entire tree from bottom to top , which is classed as the most dangerous and destructive type of fire.
- a mild crown surface fire can spread up to 3m per minute
- a massive fire can reach over 100m per minute

Question 7

What is a surface (brush) fire?

Answer 7

only burn the leaf litter, meaning they are easy to extinguish.
- a small brush fire can spread at the rate of 1m per minute
- an intense fire can spread at over 3m per minute

Question 8

What is a ground (peat) fire?

Answer 8

e.g. dry peat or vegetation
beneath the surface,
- Slow moving
- Difficult to put out and can actually burn throughout the year if the weather conditions allow it.
- mild fire can start at depths of approx 25cm
- a big fire will burn at a depth of over 25cm

Question 9

What vegetation type and fuel is needed for a wildfire?

Answer 9

Vegetation should be dry to allow it to catch. Finer vegetation causes fires to spread quicker, but larger, thicker forms of vegetation burns for longer and more intensely.
—> Thick, continuous and densely packed vegetation with trees and thick bushes including vegetation with flammable oils - like eucalyptus.

Question 10

What climate and weather conditions are needed for a wildfire?

Answer 10

Wildfires occur in a climate that has enough rainfall to have sufficient plant growth , but considerable dry spells and droughts to dry out the fuel . Areas with dry seasons such as California allow for intense wildfires. Wind also causes fires to spread quicker.
—> Prolonged periods of drought and high rates of evapotranspiration, especially in the summer months in sub-tropical climates. A strong dry wind increases the risk.

Question 11

What fire behaviour is needed for a wildfire?

Answer 11

Fires spread quickly on hills as the heat rises.
- A fire at the base of a long slope with winds moving behind it, up the slope spreads quicker

Question 12

What’s a key idea for wildfires and climate?

Answer 12

Dry, warm and windy conditions increase fire ignition and their spread.
- Many climatic events can make wildfires grow more intense and extend wildfire seasons.
—> e.g. Katabatic winds like The Santa Ana Winds and Diablo Winds in California cause more wildfire damage.

Question 13

What is El Niño?

Answer 13

Involves warming of Pacific Ocean off West Coast of South America and affects global patterns of temperature and rainfall. Some places suffer devastating floods or long periods of drought.

Question 14

Why are wildfires becoming a problem?

Answer 14

• “Forest fires in the western US have been occurring nearly 5x more often since the 1970s and 80s. Such fires are burning more than 6x the land area as before, and lasting almost 5x longer.”
  —> Rising temps and drought (lack of rainfall) are two key risk factors.

Question 15

What are the natural causes of wildfires?

Answer 15

• lightening is particularly likely to start a fire if it occurs without much rain
• volcanic eruptions can produce very hot lava, ash or gas which can start fires

Question 16

What are some of the human causes of wildfires?

Answer 16

Most fires are started by people
- this can be accidental, e.g. dropping a cigarette, allowing campfires or bbqs to get out of control or fireworks
- it can also be started on purpose, e.g. arson

Question 17

How is loss of crops, timber and livestock an impact of wildfires?

Answer 17

Fires can particularly affect timber-growing areas as the loss of tree stock will take many years to replace.
—> Jan 2017, 40,000 hectares of pine and eucalyptus plantations were destroyed by forest fires in Chile.

Question 18

How is loss of life an impact of wildfires?

Answer 18

Although people can get out of the way of most fires, some move so fast that people can be trapped.
—> In Victoria state, Australia, bushfires killed 173 people in 2009.

Question 19

How is loss of property an impact of wildfires?

Answer 19

With urban expansion, the fringes of towns and cities are now susceptible. The cost of fighting fires from reaching homes can reach millions of dollars.
—> Urban sprawl in Sydney (AUS) and Los Angeles (USA)

Question 20

How is release of toxic gases and particulates an impact of wildfires?

Answer 20

Large-scale air pollution largely caused by illegal agricultural fires due to slash-and-burn practices.
—> Common in Indonesia. Their 1997/8 event described as the largest forest fire of recorded history. The haze was so big it affected Singapore, Malaysia and Thailand

Question 21

How is loss of wildlife an impact of wildfires?

Answer 21

Whilst some animals and plants can survive or escape fires, some move fast but some cannot and perish in the flames and smoke.
—> In Indonesia, the fires of 1997 destroyed the Wein River orangutan sanctuary on Kalimantan.

Question 22

How is damage to soil structure and nutrient content an impact of wildfires?

Answer 22

Extremely hot fires sterilize the upper layer of soils by killing microbial life. They burn off carbon stored in the soil and create water-repellant soils.
—> The 2013 Rim Fire in California burned at 1,450°F (most soils can withstand up to 950°F).

Question 23

How is evacuation an impact of wildfires?

Answer 23

Many people will flee from an area on fire and not be allowed back in. Emergency shelters and supplies need to be found, often for a long period.
—> In California (Oct-Dec 2017), over 50,000 people have had to be evacuated.

Question 24

How is increased flood risk an impact of wildfires?

Answer 24

If rain comes in heavy bursts, the loss of so much vegetation and the consequent decrease in interception, can lead to flooding.
—> June 2011, the Las Conchas Wildfire charred more than 150,000 acres in New Mexico. One month later, heavy rains flooded the burn area.

Question 25

What are some of the primary environmental effects of wildfires?

Answer 25

• Air pollution from ash
  -Water pollution -Habitats destroyed in fire
  -Toxic gases released in burning

Question 26

What are some of the primary economic effects of wildfires?

Answer 26

• businesses destroyed
• agricultural land damaged
• cost of fighting fires (firefighters, helicopters, water)

Question 27

What are some primary social effects of wildfires?

Answer 27

• People killed or injured in fires
• homes destroyed
• people go missing during evacuations

Question 28

What are some of the primary political effects of wildfires?

Answer 28

• gov buildings destroyed

Question 29

What are the secondary environmental effects of a wildfire?

Answer 29

• removing invasive species and stimulating seed germination
• migration patterns of animals affected
• increased CO2 from fires could heighten the greenhouse effect

Question 30

What are the secondary economic effects from wildfires?

Answer 30

• high cost of rebuilding and insurance payout
• sources of income lost
• discouraging visitors, losing tourism sector
• planes cancelled

Question 31

What are the secondary social effects of wildfires?

Answer 31

• homelessness
• food shortages from destroyed agricultural land
• health problems such as asthma from smoke inhalation

Question 32

What are some secondary political effects from wildfires?

Answer 32

• borrowing money for international aid
• pressure for government to do more about global warming due to increased frequency

Question 33

How can people prepare for wildfires?

Answer 33

• community preparedness in the form of early detection and suppression of wildfires is an important element in reducing the spread of impact of wildfires
• many countries have rural firefighting teams staffed by volunteers
• warnings released - increasingly through social media
• fire bans may be introduced
• red flag warning - issues when weather for extreme fire behaviour may be met
• a fire weather watch
• firebreaks of a ‘defensible space’ around their property

Question 34

How can you mitigate a wildfire?

Answer 34

• satellites and infrared sensors can detect thermal variation
• cameras are also used to detect the early ignitions of fires
• NASA drone technology for surveying vast areas
• deliberately back burning vegetation ahead of the fire front
• use natural barriers like rivers
• disaster aid and fire insurance

Question 35

How can we prevent wildfires?

Answer 35

• controlled burning reduces the amount of fuel (dead wood) —> yet this could get out of control and release CO2
• public awareness (rules in campsites and BBQs)
• fire bans during times of high risk
• ‘ smokey bear’ - 96% Americans recognise him and 70% can recall his message of fire safety

Question 36

How can we adapt from wildfires?

Answer 36

• play roles in the ecosystem development, by burning away old wood, enabling fresh growth
• planning regulations can be used to reduce the hazard associated with fires - restricting access to areas of risk during the fire season
• building design - buildings need to be relatively simple, cheap, made of natural products that dont cause pollution when burnt

Question 37

Why were the Australia wildfires significant?

Answer 37

Spanning from late 2019 to early 2020, these wildfires ravaged 24.3million hectares of land, causing significant ecological, social, and economic impacts.

Question 38

What were the causes of the Australian wildfire?

Answer 38

• Drought Conditions: Australia experienced prolonged drought conditions (it had its driest ever year in 2019, with rainfall being 40% lower than average) which created dry vegetation primed for ignition.
• Record-High Temps: Extreme heatwaves, exacerbated by climate change, dried out vegetation and provided ideal conditions for wildfires to spread rapidly.
• Human Activity: Some wildfires were sparked by human activity, including discarded cigarettes, campfires, and in some cases, deliberate arson.

Question 39

What were the main impacts of the Australian wildfire?

Answer 39

• at least 33 people died, including firefighters, a further 445 indirect deaths (e.g. smoke inhalation).
• 3,500 buildings were destroyed/damaged, leaving many communities devastated.
• Millions of hectares of land were scorched with 1 billion animals being killed - meant loss of biodiversity, destruction of habitats, and long-term ecological impacts.
• Smoke blanketed cities and towns, leading to poor air quality and respiratory issues for millions of people. Nearly 80% of Australia’s pop was affected in some way.
• economic losses of US$920million, including damage to infrastructure, loss of livestock, and impacts on tourism and agriculture.

Question 40

What were some of Australians main responses to the wildfire?

Answer 40

• Australian firefighters, supported by international assistance (e.g. NZ, Canada and USA), helped to contain and extinguish the wildfires. This involved aerial firefighting, ground crews, and strategic planning to combat the blazes.
• Authorities implemented evacuation orders to ensure the safety of residents in affected areas. Emergency services and military including the Australian Air Force provided support and assistance to those displaced by the fires.
• Communities affected by the wildfires rallied together, providing support and demonstrating resilience in the face of adversity.
• The Australian gov faced scrutiny over its climate policies and response to the wildfires, so calls for stronger action on climate change and increased funding for firefighting and disaster preparedness.
• Efforts to rebuild communities, restore ecosystems, and address the long- term impacts of the wildfires continue to be ongoing, with a focus on resilience and adaptation to future fire risks.

Question 41

What’s a conclusion for the Australian wildfires?

Answer 41

The Australia Black Summer wildfires of 2019/2020 were a reminder of the destructive power of wildfires and the urgent need for proactive measures to address climate change and mitigate future risks.
- The impacts of these wildfires will be felt for years to come, underscoring the importance of resilience, community support, and effective disaster response strategies in the face of natural disasters.