Cutting airborne pollutants could have a large effect on climate

Science journalist Tatiana Moreno talks to Dr Apostolos Voulgarakis about the impact of airborne pollutants on our planet's changing climate.

Some airborne pollutants change the make-up of our planet's atmosphere where, according to a wealth of recent research, they can strongly influence regional and global climate.

"Pollutants such as aerosols [solid and liquid particles suspended in the air] and chemicals that produce ozone gas have always been in the atmosphere - natural smoke from wildfires is just one familiar example. But since the last century we have been adding more of these toxic constituents into the atmosphere and disturbing the planet's climate system," says Dr Apostolos Voulgarakis, a Lecturer in Earth Observation and Climate Physics at Imperial College London.

He says scientists need to do more to monitor what this means for regional climate patterns and understand what would happen to the planet's overall climate system if we stop producing these pollutants.

Dr Voulgarakis’s research in the Department of Physics includes work using climate modelling and satellite data to evaluate the impact of the pollutant ozone. In the troposphere layer, the bottom 12 - 20 kilometres of the atmosphere, this gas arises as a result of emissions such as nitrogen oxides and carbon monoxide that are generated by industrial or power plants, car exhausts and air travel.

In a recent study published in Nature Climate Change, Dr Voulgarakis and colleagues at NASA calculated that these gases could be having a greater effect on climate than scientists had previously thought.

They also suggest that with further study scientists could understand how these emissions are affecting different layers of the atmosphere simultaneously. They say this would more accurately predict what could happen to the climate system if these pollutants were to be completely eliminated.

Hazy future

Dr Voulgarakis talked about some of his recent research on 13 March in a seminar at the Grantham Institute for Climate Change at Imperial College London, titled "Bridging gaps in environmental change studies: ozone depletion, air pollution and climate change".

He explained that a group of airborne pollutants known as Short-Lived Climate Pollutants (SLCPs) are responsible for a substantial part of anthropogenic global warming, a conclusion that was also reached by a recent United Nations Environmental Programme (UNEP) assessment.

SLCPs such as black carbon, methane, tropospheric ozone and hydrofluorocarbons are the short lived pollutants that have the greatest effects on climate warming. The term 'short lived' describes the amount of time they are active in the atmosphere, which typically ranges from a few days up to 15 years. Other climate warming gases such as carbon dioxide, nitrous oxide and CFCs have life lengths of several decades or centuries.

Dr Voulgarakis said that limiting the emission of SLCPs is not a long-term solution for tackling climate change but cutting down on these pollutants will "gain us time" and improve air quality at the same time.

He emphasised that reducing them should be seen as a short-term solution for changes in climate, and that carbon dioxide emissions must be reduced at the same time to avoid long-term, permanent climate changes.

He is interested in researching this topic further to discover more about the various ways in which different SLCPs can act, especially in influencing weather and precipitation patterns; something he says "hasn't been understood very well yet".

"A further goal is to clarify the appropriate policies around SLCPs, and look at what the ideal emission reductions are and which technologies should be incorporated in order to control these toxic pollutants. This would reduce air quality problems and mitigate short-term climate issues at the same time."

Crossing disciplines

Dr Voulgarakis describes his research as sitting at the interface between several disciplines - climate and air quality, atmospheric physics and chemistry.

Since joining Imperial he is looking into how some air pollutants can affect rainfall. He explains that some research themes can benefit from drawing together convergent methods.

"In the past, researchers have looked at the impacts of pollutants, tending to focus on either their effect on air quality or on air temperature, and looking independently at the effect on different layers of the atmosphere. But with more communication among scientists from different disciplines, I’m certain that much common ground would be found.

"One of our current goals is to combine knowledge and use the most appropriate technologies and methods to understand SLCPs' combined effects on air quality, climate and weather patterns. We hope to be able to identify ways to solve the scientific problems of closely linked environmental disciplines simultaneously, and work towards giving policy advice that is unified," he continued.

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Dr Apostolos Voulgarakis joined Imperial College London in July 2012 as a member of the Space and Atmospheric Physics Group in the Department of Physics.

The author, Tatiana Moreno, is a science journalism student on placement at the Grantham Institute for Climate Change at Imperial College London.