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For decades, it was believed there were fewer wildfires and emissions, and therefore lower levels of aerosols in the atmosphere, prior to the Industrial Revolution and its world-changing impacts wrought by modernity.

But a new study in the journal Nature Communications has turned that supposition on its head, indicating there has potentially been a reduction of fire emissions between 45 and 70 percent since the year 1750.

The aerosols that had been released in that era may have had a significantly underappreciated cooling effect on the planet, the paper adds.

“Our findings show there may be a significant gap between previous estimations and what was actually taking place in the pre-industrial atmosphere,” Douglas Hamilton, lead author, now of Cornell University, who conducted the work while at the University of Leeds, said. “This suggests the high possibility of a much-smaller difference in aerosol cooling between pre-industrial and present-day than we have previously thought.

“The implication is that the cooling effect of additional present-day man-made aerosol pollution may have bene overestimated,” the scientists added.

The pre-Industrial era fire emissions were compiled from four datasets known as AeroCom, CMIP6, SIMFIRE-BLAZE and LMfire.

The data was compared with other known datasets, including ice core cords, tree rings and geological evidence including charcoal in lakes and ocean sediment layers, according to the paper.

The aerosol physics and chemistry was modeled through computer simulations, comparing the pre-Industrial world, and that since 1750.

The biggest uncertainty among 26 unknown inputs in the models show that pre-industrial fire emissions were biggest variable driving aerosol concentrations.

The conclusion: as the human population has increased across the face of the globe, firefighting, fire prevention and also changes in land use have significantly curtailed wildfires.

“Scientists around the world use models to predict atmospheric conditions in the past. We believe these models need to be updated to take into account our new evidence,” Hamilton said. “To continue to study the history of the planet’s environment accurately, as well as more accurately predict how human activity impacts the Earth system, we now need to reassess our understanding of how much fires contributed tin the pre-Industrial era.”

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