Variation of lightning-ignited wildfire patterns under climate change

March 10, 2023

The research paper titled ‘Variation of lightning-ignited wildfire patterns under climate change’ states that increasing global temperatures could result in more occurrences of “hot lightning” strikes around the world, resulting in an elevated risk of wildfires. Hot lightning, also known as long continuing current, is a type of lightning that lasts longer, i.e. 40 milliseconds to nearly a third of a second. This study is the first to analyze the correlation between rising global temperatures and hot lightning strikes, which are known to be more likely to trigger wildfires than conventional lightning.

How was the research conducted?

The research team from the Institute of Astrophysics of Andalusia in Spain and the Institute of Atmospheric Physics in Germany examined satellite images of US wildfires between 1992 and 2018 for this study. They found that almost 90% of the 5,858 selected lightning-ignited fires could have been started by hot lightning strikes.

What did the research say about the long-continued current lightning and wildfires?

29% of the wildfires were ignited due to long continued current lightning.

What is long-continued current lightning? The lightning flashes make discharges. During such times, electric charges flow continuously. Let us understand this in simple terms. Say lightning stuck for 1 milli-second. Charges from this lightning flow for a period of say 2 seconds. Now at second milli-second, the second lightning stuck for 3 milliseconds. The charges of this second lightning are assumed to be flowing for 3 seconds. And the charge flow during the time period between the second and third second will be high because there are two flashes of lightning. And now the third lightning stuck at the fifth milli-second for about 2 milliseconds. This process is continuous. Therefore, there is a continuous flow of charges. This induces wildfire.

The study says that earlier the time period between two consecutive lightning was more. Now, this has reduced and thus, the occurrence of long-continued current lightning has increased. And they are causing wildfires as the electron discharge from such occurrences has increased.

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