In recent years, exceptionally large wildfires have been recorded in Australia, California, the Mediterranean region, and the Arctic. While there exists an established research effort on how Climate Change is leading these megafires and on how they are affecting land ecosystems, recent observations show that wildfires can also perturb marine ecosystems. Biomass burning injects massive amounts of aerosols into the atmosphere that are rich in organic matter, nutrients, and trace metals. When these aerosols fall over the ocean, they enrich surface waters with nutrients potentially triggering the accumulation of the microscopic marine algae that supports marine life, the so-called phytoplankton.
The fertilisation of phytoplankton by wildfires aerosols has been directly observed during the extreme 2019-20 fire season in Australia. These observations agree with previous modelling efforts on showing that fire activity might have immediate impacts on marine productivity, which are likely to increase with the current global trends in wildfires. The type, extension and consequences of these impacts are beyond our understanding as we have not yet defined which are the affected regions or which compounds are dissolved in seawater after the deposition of wildfire aerosols.
This project, called Impacts of PYROgenic aerosols on PLANKTON ecosystems (PYROPLANKTON), will analyse the problem from three different perspectives:
- First, the spatial and temporal variability of biomass burning aerosols deposition and its impact on surface phytoplankton will be evaluated from a synoptic perspective thanks to an original combination of ocean colour (OC-CCI), global fire products (FireCCI and GFAS) and a state-of-the-art atmospheric reanalysis (CAMS).
- Secondly, we will conduct ground-breaking experiments with ash from wildfires across the world to provide the mechanistic and detailed understanding on how biomass burning aerosols perturb seawater’s chemical composition and its impacts on marine microorganisms.
- Thirdly, we will produce the first global estimate of the current and future impact of biomass burning aerosols on marine primary production and carbon export.
The outputs of PYROPLANKTON will build a solid conceptual framework to inform the climate and ocean research communities and guide them to accurately simulate the full impact of wildfires in the Earth System. The project will face several ESA’s Living Planet challenges, following SOLAS recommendations on the necessity of closer interactions between remote-sensed data, field observations and modelling.