Interview: Drop in the ocean

Peter Liss talks to Carl Saxton about the acidity of the sea, climate change and architecture.

Peter Liss is a professor at the University of East Anglia, Norwich, UK. His research encompasses many aspects of environmental chemistry, with a particular interest in the biogeochemical interactions between the oceans and the atmosphere.

What projects are you currently working on?

One topic that I have been working on for several years is how the oceans affect the atmosphere in terms of releasing trace gases made by marine planktonic organisms. For example, dimethylsulfide, made by plankton in the oceans, is volatile, and is oxidised in the atmosphere to produce sulphur dioxide and sulphate. In the natural system this sulphur dioxide is the source of acidity in the atmosphere and lowers the pH of rain. We have added to that acidity, particularly in the northern hemisphere, by burning fossil fuels, which put man-made sulphur dioxide into the atmosphere.

How has climate change affected the oceans?

In several ways! The interaction is a two way process: climate change is affecting the oceans and the oceans are affecting climate change. An obvious example is that we are releasing more CO2 into the atmosphere. A good fraction of that (30%) is taken up by the oceans, which means that it is not in the atmosphere. Therefore the warming of the atmosphere we are experiencing would be more if the oceans weren’t taking up this CO2. An impact of this is that if the naturally alkaline sea water takes up more CO2, the sea water becomes less alkaline and the pH of sea water is reduced. The pH of the oceans will continue to decrease throughout this century if we continue to emit CO2 at the rate we are. This will affect organisms such as corals, microorganisms and plankton, particularly where their shells are made of calcium carbonate. We don’t know what effect the higher CO2 will have on other organisms such as diatoms, which are silicon based; it could be beneficial for them but this very uncertain territory.

What is hot right now in ocean research?

One of the hot research areas is ocean acidification. Increasing CO2 levels in the oceans makes them more acidic but only recently has this been studied seriously. It’s an interesting problem of which little is known. The issue is what will be the effect on the organisms that are present in the oceans, such as the plankton that are at the bottom of the food chain and also the effect it will have on other organisms higher in the chain. The best way of tackling climate change is to cut emissions; it is no good trying to engineer atmospheric temperature as it doesn’t solve the pH problem in the oceans.

Carl Saxton, RSC Publishing, 22 February 2010. Full article.

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