Interestingly close to home and heart.

Remember the recent bushfire season? Stupid question, of course you do. Well here’s a better one… did you know that a phytoplankton bloom as big as Australia sucked as much carbon dioxide out of the atmosphere as the fires put there?!

Satellite Image Credit: Van der Velde et al. 2021

The blooms sparked when ash from the fires blew far out into the iron-deficient Southern Pacific Ocean, where the influx of nutrients such as nitrogen, phosphorous, and (most importantly) iro,n allowed an unprecedented bloom during what is usually a low production point in the season!

But does that mean we should have more fires to mitigate climate change?

Well, because plankton is at the bottom of the marine food web, the carbon dioxide that they sequester ends up mostly being fuel for larger plankton, fish, invertebrates, and cetaceans. What’s left after digestion will be breathed or excreted back into the system as gas or within poo pellets. This means that a lot of the CO2 remains in circulation and can potentially get back into our atmosphere; however, it is the plankton and pellets that do not get eaten that are important for carbon sequestration (sucking out and storing it)! As they sink deeper and deeper, there is less of a chance of being eaten. Undisturbed ‘marine snow’ will end up on the bottom of the ocean floor, storing its carbon dioxide as rock for millions of years (so long as we don’t go and dig it back up)!

So, to answer the question at hand… no, the immense loss of biodiversity and release of carbon dioxide through such fires cannot be mediated or reversed by the explosion of phytoplankton productivity. It does, however, support a variety of marine life, and reiterates how complex and interconnected the physical, chemical and biological systems on earth truly are. To find out more on the study, and similar subsequent studies, email James Caffery or head over to: https://www.nature.com/articles/s41586-021-03805-8