From cosmic explosions to terrestrial fires?

TL;DR

This paper explores how nearby supernovae could have increased atmospheric ionization, leading to more lightning and wildfires, potentially influencing climate change and human evolution during the Pleistocene epoch.

Contribution

It presents a novel hypothesis linking supernova events to increased lightning, wildfires, and climate effects, expanding understanding of extraterrestrial influences on Earth's history.

Findings

Evidence of increased wildfires around 2.6 million years ago.

Potential link between supernova-induced ionization and climate cooling.

Wildfires may have contributed to human evolutionary transitions.

Abstract

Multiple lines of evidence point to one or more moderately nearby supernovae, with the strongest signal ~2.6 Ma. We build on previous work to argue for the likelihood of cosmic ray ionization of the atmosphere and electron cascades leading to more frequent lightning, and therefore an increase in nitrate deposition and in wildfires. The potential exists for a large increase in the pre-human nitrate flux onto the surface, which has previously been argued to lead to CO2 drawdown and cooling of the climate. Evidence for increased wildfires exists in an increase in soot and carbon deposits over the relevant period. The wildfires would have contributed to the transition from forest to savanna in northeast Africa, long argued to have been a factor in the evolution of hominin bipedalism.