Wildfires

• Fort McMurray is located in Alberta, North Canada. It is located near Tar Sands, the largest industrial development on Earth, the 3rd largest oil reserve and responsible for 11% of total oil
• The Fort McMurray 2016 wildfire was caused by the 2016 El Nino which led to dry vegetation much earlier on in the year. Due to urbanisation, many houses were constructed within close proximity to the boreal forest and also set on fire
• Pyrocumulus clouds produce ash and cause lightning, leading to positive feedback as lightning starts more wildfires
• Impacts of the Fort McMurray wildfire

  • 90,000 evacuated
  • 0 died
  • CAN$1 billion loss
  • 600 work camps destroyed and 1/3 of 25,000 workers evacuated
  • CAN$9 billion damage
  • Mercury and led release
• Responses to the Fort McMurray wildfire

  • Government gave evacuees CAN$1,250
  • Fire aid relief concert
  • Canadian armed forces called
  • Insurance companies didn't pay out
• Wildfire is the generic name used for an uncontrolled rural fire.
• A crown fire spreads across tree canopies and affects forested areas
• A surface fire burns across surface vegetation
• A ground fire burns beneath the ground in layers of dry organic peat
• The ‘ladder effect’ describes the process of fires from the forest floor spreading to the tree canopy
• There are certain conditions that, when combined, are likely to result in a wildfire. These include a ready supply of fuel, usually in the form of dry vegetation, ignition sources (natural and human) and favourable climatic/ weather conditions.
• The behaviour of a wildfire (speed and direction of movement) is dependent on the type of vegetation (fuel), the climatic characteristics and the local topography (slopes, valleys, etc.).
• The type and amount of fuel influences intensity of the wildfire and the rate of spread. This is why grassland fires rarely produce the same intensity and degree of threat as forest fires.
• Heatwaves, droughts and cyclical climatic events such as El Niño can create favourable conditions for wildfires. Most wildfires occur during or after prolonged dry periods when the vegetation (fuel) has become dry and combustible
• Strong, dry winds blowing from continental interiors or deserts exacerbate the drying process – ideal conditions for lightning storms, which are a common form of wildfire ignition
• El Nino = a climactic condition happening on average once every six to eight years. Involves the warming of the Pacific Ocean and affects temperature and rainfall
• Research carried out in Indonesia in the 1990s showed that during the El Nino phase, there was a reduction in rainfall which coincided with an increase in forest fires.
• The vast majority of fires that threaten life and residential areas are the result of human actions, including discarded cigarettes and poorly controlled campfires. The most prone areas are in the so-called ‘wildland-urban interfaces’ – woodland that is close to large urban areas
• Heat transfer processes (essentially radiation, conduction and convection) preheat vegetation ahead of the flames, preparing them for ignition and rapid spread of the fire
• Heat transfer preheats material that is above the fire, therefore causing advance of the fire front vertically
• Experiments in Australia have shown that fires on a 20-degree slope advance at up to four times the rate of fires on level ground.
• Burning fragments of vegetation (called firebrands) can be carried ahead of the fire front by convection currents and strong winds igniting isolated spot fires, their very randomness presenting a significant hazard. Gravity is also responsible for spot fires – firebrands can roll downslope and start fires some distance from the fire front.
• Wildfires can affect local ecosystems, in some cases completely destroying them.
• Wildfires affect vegetation successions, causing secondary succession in forests and scrubland
• Loss of vegetation from wildfires affects the water cycle by reducing humidity and altering relative significance of transfer processes
• Preparing for Wildfires

  • Early detection systems including the Red Flag Warning issues when weather conditions for fire may be met
  • A Fire Weather Watch
  • People try establish firebreaks surrounding their property
  • People living at risk have house adaptations which include reducing vegetation around their house
• Wildfire Mitigation

  • Satellites and infrared systems can detect thermal variation, so people can evacuate and the impacts are mitigated
  • Back burning is where vegetation is deliberately burnt to remove fuel for wildfires
  • Disaster aid and insurance can mitigate the effects, but this is not accessible to everyone.
• Preventing Wildfires

  • Wildfires need fuel, controlled burning reduces the amount of fuel that is available to them.
  • Public awareness in areas where there are rules around the uses of campfires and barbeques
  • 1944 Smokey Bear in America is recognised by 96% and has let to a reduction in 40 million wildfires annually
• Adapting to Wildfires

  • Wildfires have a role to play in ecosystem development by burning away old and diseased wood enabling fresh growth, as well as directly stimulating germination of certain species. But this doesn't help protect lives.
  • Planning regulations can be used to reduce the hazard associated with wildfires by restricting access to areas of risk during the fire season.
  • Building design can be an effective form of adaptation
• Primary Effects of Wildfires

  • Loss of crops, timber and livestock
  • Loss of life
  • Loss of property
  • Release of toxic gases and particulate
  • Damage to soil nutrient content