Hazards Questions Flashcards
Rift valley*
Natural causes of wildfires - Lightning
Lightning is the most common ignition source due to the intense heat it generates
Climate change is the biggest trigger of extreme lightning storms
Warmer and longer summers heat up the land surface. This coupled with an increase in carbon emissions causes stronger updrafts that are more likely to produce more powerful and frequent lightning.
A study estimates a 12% increase in the frequency of lightning strikes with every one degree celsius increase in temperature
Examples of wildfires caused by lightning - British Columbia, Canada
In Canada’s province of British Columbia lightning causes 60% of the reigons wildfires in an average year
2020 Bay area fire which destroyed 5 million acres of land, over 10,000 structures and killed 33 people was a consequence of lightning storms Warmer
Natural causes of willdfires - fuel
This often comes in the form of dry vegetation.
California in 2021 experienced a 65% rise in dry vegetation in just a few months
Several parts of Australia are characterised as a hot and dry climate and have recorded a steady decline in rainfall since 1970, making wildfires a regular occurance.
2019 was the warmest year on record and it was accompanied by 43 extremely warm days. In the same year the country experienced a bushfire crisis that resulted in the destruction of 11 million hectares of bush, forest and parks in the states of New South Wales and Victoria
Human induced wildfires: AO1
Can range from open burning such as campfires, equipment faulure and the malfunction of engines to debris burning, negligent discarding of cigarettes
Human induced wildfires: examples
According to government sources, 40% of wildfires that affect British Colombia in an average year are human induced
In the US the amount is more than double, with nearly 85% of the 100,000 wildfires affecting North America every year caused by human activities according to data from the National Park Service
Here, man made fired have tripled the length of North America’s fire seasons between 1992 and 2012, from 46 to 154 days.
Over the 21 year study period the major causes were debris burning and arson
Campfires and fireworks were responsible for 5% of the fires
Furthermore an analysis of recent california fires has found that human sparked wildfires are more extreme and destructive than nature induced ones as they move twice as fast, spreading about 1.83km a day
