Something Unobserved in Our Rivers – Wildfire Carbon

Something unobserved in our rivers – we all see the endless carbon fires, burning in the Amazon, Congo and Indonesian rainforests, in the Boreal forests of the high Arctic, even in the thawing peat permafrost of Siberia.

But while everyone is looking at the carbon rising upward, they are not seeing it flowing outward – and our rivers are turning black with the carbon of wildfires.

Only a handful of studies (ie. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153372 / https://www.watercanada.net/feature/soot-filled-rivers-mark-the-need-for-a-national-wildfire-strategy/) have measure wildfire carbon in rivers (as by-product of looking for other fire-related contaminants), finding that post-fire carbon is of an order of magnitude higher compared to before.

At a certain level of carbon absorption our oceans enter a phase of mass extinction, from which they take thousands of years to recover and re-balance from: https://eapsweb.mit.edu/news/2019/breaching-carbon-threshold-could-lead-mass-extinction. This phenomenon is known as, the ‘Rothman threshold’.

With the current levels of wildfire-carbon entering river basins almost wholly unobserved, the ocean’s remaining carbon budget – which is thought to be just 60 years and based on the atmosphere-to-ocean carbon flux alone – is unknown.

From where we stand within the threshold’s outer sphere, the world’s great carbon rivers (and the destruction within their basins) are of critical importance – with the Amazon alone delivering 1.425 Pg C per year to the oceans delicate carbon balance: https://frontiersin.org/articles/10.3389/fmars.2017.00076/full

If the Amazon rainforest were to transition to savanna grassland (the forest being reduced by 19,500 m2 per minute, and now an estimated 3% from its 20% deforestation state-shift threshold. https://advances.sciencemag.org/content/4/2/eaat2340) – drying out and burning in the process – this singular influx of carbon into the oceans could ignite the Rothman threshold’s process of destructive cascading of feedbacks.

Just the present rate of wildfire river-carbon could cut the ocean’s budget to a few decades. There is no warning in sight and no one is looking at the question – as the world’s forests burn, and her arteries run black, filling our dying seas with ash.

May 15, 2021