"Over the past three decades, Australian forests have undergone an 800 per cent increase in the extent of the area burnt bushfires, with researchers warning ecosystems are at risk because they are not able to recover between devastating infernos."


1990 - 2020 - 6 fires greater than 1million Ha
1960 - 1990 - 6 fires greater than 1million Ha.

(according to wiki)

https://en.wikipedia.org/wiki/List_of_major_bushfires_in_Australia

The 1940's to 70's was the global cooling.

So no evidence of increased Megafires.

Edit:

From the underlying paper -



Good heavens they lost the 1974-75 fire year.

"Improved estimates of preindustrial biomass burning reduce the magnitude of aerosol climate forcing in the Southern Hemisphere

Fire plays a pivotal role in shaping terrestrial ecosystems and the chemical composition of the atmosphere and thus influences Earth’s climate. The trend and magnitude of fire activity over the past few centuries are controversial, which hinders understanding of preindustrial to present-day aerosol radiative forcing. Here, we present evidence from records of 14 Antarctic ice cores and 1 central Andean ice core, suggesting that historical fire activity in the Southern Hemisphere (SH) exceeded present-day levels. To understand this observation, we use a global fire model to show that overall SH fire emissions could have declined by 30% over the 20th century, possibly because of the rapid expansion of land use for agriculture and animal production in middle to high latitudes. Radiative forcing calculations suggest that the decreasing trend in SH fire emissions over the past century largely compensates for the cooling effect of increasing aerosols from fossil fuel and biofuel sources."

https://www.science.org/doi/10.1126/sciadv.abc137

Another modelled study but from Antarctic ice cores. According to Liu et al aerosols have been stable over the last 250 years. So much for new aerosols causing cooling.

So it seems these megafires are not new.