My students do little chemistry. By this, I don’t mean to impugn their reputation by suggesting their work habits aren’t all that they could be. Rather, I’m saying that they do chemistry on a small scale. They measure masses in milligrams or grams, and volumes in millilitres whenever they carry out chemical reactions. There is generally no need to work on larger scales, as no new information will be obtained. Financial considerations also often play a part in determining how much material is used in any reaction – chemicals can be surprisingly expensive!

On the other hand, some researchers do big chemistry, whose scale is limited only by their imaginations (and money again, of course). Big chemistry usually requires the collaboration of lots of research groups around the world and is often aimed at addressing big questions. One such example of big chemistry recently resulted in a group based in the Chemistry Department at the University of Otago, along with workers at NIWA in Wellington, winning the Prime Minister’s Science Prize for 2011. The big question these workers addressed was ‘what can we do to reduce carbon dioxide levels in the atmosphere?’

It is a fact that levels of carbon dioxide in the atmosphere are increasing. This could potentially lead to both an increase in the Earth’s temperature, and the oceans becoming more acidic, neither of which would be beneficial to life on this planet. It therefore makes sense to plan for such eventualities, and investigate ways in which carbon dioxide levels in the atmosphere could be controlled if necessary. And this is where the work of the groups at Otago and NIWA becomes relevant. It had been proposed that phytoplankton in the oceans could potentially absorb significant amounts of carbon dioxide from the atmosphere during photosynthesis, the process by which green plants convert carbon dioxide to organic materials and oxygen. While this hypothesis could potentially be tested in the laboratory, it would really take a large scale experiment to demonstrate its viability.

And a large scale experiment it was. Truly big chemistry. It involved seeding a small area of the Southern Ocean with iron (about 1.7 tonnes!), to encourage the growth of phytoplankton, and then monitoring the changes in carbon dioxide levels, using a variety of methods including satellite surveys. You can imagine the wealth of coordination and cooperation required to carry out such a study. The results were interesting; while it was found that enhanced absorption of carbon dioxide into the ocean did occur in the seeded areas, it was also found that the phytoplankton themselves released other potent greenhouse gases, such as nitrous oxide, into the atmosphere. This demonstrated that such an approach would not be effective at mitigating greenhouse gas levels in the atmosphere.

This might appear at first sight to be a negative result, but thanks to the big chemistry carried out, we now know that we must look for other ways to avert the deleterious effects of greenhouse gases in the atmosphere. The Prime Minister’s Science Prize is worth $500,000. Given that a Nobel Prize is worth $1.8 million, I think that’s pretty generous. Time to get my students working harder…