Who in Australia would have guessed the 2019-20 bushfires would trigger a huge, continent-sized phytoplankton bloom in the Southern Ocean? Deadly to animals, out of season, unprecedented in two decades of satellite records, this anachronistic event was tracked by biological oceanographers of the University of Tasmania, with results published in Nature.
Evidently, aerosols in the bushfire smoke, stoked by stratospheric winds, fomented the vast microalgae bloom. Iron in ‘low, but significant concentrations, but up to several times normal level’, was relished by microscopic ocean plants in photosynthesis for growth. Response to these off-season inflated-deposits and increased food source was rapid. While uneven, one critical day’s black carbon smoke level was a quarter of the usual January total.
In a complimentary study, other researchers estimate over 700 million tonnes of carbon dioxide were generated by the Summer New Year’s bushfires. Since phytoplankton blooms can act as carbon sinks, hopefully most of the catastrophe-generated, wind-blown CO2 was absorbed, although light and temperature are can be affecting factors.
Consequences, considerations, compensation – these studies by global ocean observing systems illustrate how Australian aerosols and carbon dioxide from major bushfires can viscerally impact on a distant environment.