Marine biogenic aerosols – the “Holy Grail” of climate science

Image supplied by Griffith University

Most people think of aerosols as something you’d get from a spray can but scientists are discovering more about how these atmospheric particles are protecting the planet.

Research led by Griffith University and the Bigelow Laboratory for Ocean Sciences in the USA, recently published by the American Meteorological Society, has revealed the role marine biogenic aerosols play in the Arctic and Southern oceans, helping the global challenge climate scientists face – understanding aerosol effects on warming.

Most aerosols have a cooling influence on the climate by reflecting sunlight back into space and altering cloud microphysics. Without their ‘masking’ effects, global temperatures would have increased more than they have since the 18th century.

Until recently aerosols have been acting like a ‘handbrake’ on global warming but Associate Professor Albert Gabric, of the Griffith School of Environment, warns the possible decline in emissions of natural and anthropogenic aerosols in the future could accelerate the warming process.

Phytoplankton, which include ice algae, live in sea ice and are major sources of marine aerosols which they release into the atmosphere. Acting like a global thermostat, these aerosols regulate warming during spring and summer, especially over the polar oceans.

Associate Professor Gabric said understanding aerosol effects was vital to accurately estimating ‘climate sensitivity’ or how much the earth will warm as we increased greenhouse gas concentrations, a figure that has fluctuated among scientists since the 60s.

“It’s incredibly important to narrow the estimated range of climate sensitivity (or how much the earth will warm),” he said.

“Aerosols and clouds are the biggest uncertainly in projections of future warming that we’re dealing with at the moment – they’re the Holy Grail of climate science. If we can narrow the range we’ll know how much we’ll warm and how we will need to adapt in the second half of this century.”

Associate Professor Gabric said as the sea ice melted during spring there was a huge release of aerosols.

“Unfortunately our global emissions of greenhouse gases are increasing and the Arctic sea ice is melting at such a fast rate we’ll likely have an ice free summer by the mid-2020s. It will be quite a dramatic change for the Arctic marine ecosystem and likely have climatic effects outside the polar regions.”

Associate Professor Gabric suggests aerosol emission patterns will need to be more closely monitored in the future. He is part of a team awarded a $1 million National Science Foundation grant to examine the production and cycling of marine biogenic aerosols in the polar oceans.

Source: Griffith University

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