Ice and fire: How burning forests can help melt ice sheets
A song of ice and fire (and smoke and sunshine and algae)
Climate change is making forest fires worse. What’s less well known, is that those fires then drive climate change.
Burning plant matter releases CO2, but it also emits a heavy little particle called black carbon, which is very good at absorbing heat. When black carbon lands on ice or snow, it helps to darken it and increases the melt rate – this is called the albedo effect. This process is happening in icy regions all over the world – including in Greenland, in a place called the dark zone, where dramatic darkening caused by algae, dust and black carbon is rapidly melting the world’s biggest cryospheric contributor to global sea level rise.
And here’s the real problem: in its fire monitoring guidelines, the UN doesn’t require countries to report black carbon emissions. It’s very likely that existing climate models are underestimating the global warming effect of black carbon.
UPDATE: Professor Alun Hubbard did warn us that this was a very live field of study.
Algae don’t actually feed on black carbon (as leading ice scientist Jason Box pointed out on our YouTube video). They feed off nutrients tucked inside dust particles – that’s new dust landing on the surface and ancient dust melting through from below.
And as Alun Hubbard indicates, but could use extra emphasis, it’s the algae that are the biggest cause of the darkening in the Greenland dark zone. There could be a link between black carbon and ice algae, but we don’t know yet. And although we know that black carbon does affect ice and snow albedo in various places across the Arctic (and the rest of the world), no one has yet quantified the difference it makes in the dark zone.
New research on this area is expected to be published soon, so watch this space.
Written, produced & narrated by Georgie Johnson
Edited & animated by Sian Butcher
Script edited by Emma Howard
Sound & music by JPML.agency
Featuring Jessica McCarty (Miami University) and Alun Hubbard (Universities of Aberystwyth, Tromsø)
Footage: NASA, Greenpeace, Getty