Sunday is the day of rest for forest fires

Forest fires around the world are more prevalent on a Tuesday and less likely on a Sunday, according to a global study by researchers at the Australian universities of Melbourne and Monash.

The findings by Melbourne climate scientists Dr Nick Earl and Professor Ian Simmonds, and Professor Nigel Tapper from Monash, highlight the dramatic effect that humans, religion and culture have on Earth’s climate.

The three researchers found that forest fires around the world appear to be strongly influenced by the working week, and particularly on the days of rest associated with religion. Of the more than a billion global forest fires that burned between the years 2001 and 2013, Sunday was the least active day with only 104 million forest fires.

This is nine million fewer fires, or 8% less than the number of forest fires burning on a Tuesday – well into the working week.

“One approach to quantifying anthropogenic or man-made influences on the environment and the consequences of those is to examine weekly cycles. No long-term natural process occurs on a weekly cycle so any such signal can be considered anthropogenic,” the researchers write in a paper published in the journal Geophysical Research Letters.

“There is much ongoing scientific debate as to whether regional-scale weekly cycles exist above the statistical noise level, with most significant studies claiming that anthropogenic aerosols and their interaction with solar radiation and clouds is the controlling factor.

“A major source of anthropogenic aerosol, under-represented in the literature, is active fire from anthropogenic burning for land clearance and management. Weekly cycles in active fire have not been analysed before, and these can provide a mechanism for observed regional-scale weekly cycles in several meteorological variables.

“We show that these cycles in active fires are highly pronounced for many parts of the world, strongly influenced by the working week and particularly the days of rest associated with religious practices.”

Earl said that nature does not adhere to the weekly cycle, so the results highlight the influence that humans are having on the planet when it comes to fires. This study is the first time the seven-day weekly cycle has been analysed in relation to global fires.

The researchers found that while the weekly cycle of fires was distinctly evident for Australia and the United States, the weekend minimum rate of fires was not consistent around the globe: Regions with higher Muslim populations, such as Kazakhstan, had the least fires on Thursdays and Fridays.

“Friday is the ‘day of assembly’ and prayer for the Muslim faith, so it actually strengthens the argument for how religion impacts on our climate,” Earl said.

* Last month was the hottest October ever recorded, according to reports released on 18 November by NASA and the US National Oceanic and Atmospheric Administration, NOAA. The reports both noted that the global average temperature on land and ocean surfaces combined was almost 2 degrees Celsius above the 20th century average, marking a bigger departure from the average than even September's record-breaking temperatures.

So far, the world in 2015 has experienced the highest temperatures on average since 1880 when record-keeping began, according to the NOAA scientists. They point out that global temperatures have risen at an accelerated pace in recent years and that means an increasing prospect of more forest fires around the globe.