Australasian Science: Australia's authority on science since 1938

Chronology from the Depths

By Stephen Luntz

Aimee Komugabe has abandoned a career in finance to examine deep water corals for evidence of climate change 4000 years ago.

Aimee Komugabe couldn’t decide whether she wanted to work in biotechnology or banking. She evaded that unusual choice by doing a PhD in which she dated climate shifts to help us understand the future for Australia and the South Pacific.

Komugabe was born in New Zealand but grew up in Uganda. Her father is a biochemist, so she says she “never thought twice about science” as a career. Although she had planned to return to her country of birth for university she ended up at the University of Technology, Sydney studying both biotechnology and banking and finance. “I liked studying finance particularly after the Global Financial Crisis because I wanted to understand it. I worked at the Commonwealth Bank, but then I realised I liked studying banking but not actually doing it,” she says.

With a year to go in her undergraduate degrees, Komugabe saw an advertisement for a placement in marine science at the Australian National University. “I’d always loved the ocean, but never thought of it as a career,” she says. “I knew I wasn’t going to get it because I had no background. I didn’t even really know what coral was, but I applied anyway.” The ANU was able to see Komugabe’s talent and took her despite her lack of relevant studies.

Komugabe came to the inland capital to study the ocean for 2 months, and stayed first for Honours and now her doctorate. “I liked how flexible ANU is. If you show initiative nothing is set in stone.”

She could already be earning more in banking than she is ever likely to make as a scientist, but has no regrets. “I am still in touch with some friends from banking and they are getting crazy allowances, but when I think about it I don’t work well in a highly stressed environment. In the end I want to enjoy where I work. I realise I’ll have to make a few sacrifices to have work I find meaningful, and as long as I can put food on the table I’m OK with that.”

The work currently occupying Komugabe is a study of black corals at the Research School of Earth Sciences. Black corals live in deeper waters than the more familiar tropical varieties, and grow far more slowly. “They have skeletons similar to insects, made of chitin, and look like shrubs. You can see rings like tree rings when they are cut,” Komugabe says. The rings are a puzzle, however. At depths of 300 metres there are no seasonal climatic differences, and oddly some shallower species lay down rings monthly.

Despite the depths at which her subjects live they feed on plankton falling from the surface, and thus provide evidence of what was happening in the world above at the time. “I’m looking at the last 4000 years of oceanic circulation, specifically at eastern southern Australia and the Tasman Sea,” Komugabe says. “This is one of the global hotspots, with ocean warming three to four times the average because the East Australian Current is strengthening” (AS, May 2012, p.10).

“The question is: has this happened in the past and, if so, when and why?” Black corals are very long- lived, giving her the chance to collect a continuous record.

“I use the ‘you are what you eat’ principle,” Komugabe says. “I look first for trace elements like phosphorus, vanadium and copper to see how they vary. Then I look at the age of the water based on isotope ratio. I use carbon dating and uranium series dating to measure the age of the coral itself.”

So far Komugabe says her efforts have been to establish the methodology’s validity. Results are promising, with corals showing warming in the Tasman Sea over the past century consistent with the instrumental record. She has also found signs, already hinted at by other papers, of a similar warming 3500 years ago where younger waters flooded the area around Tasmania. Komugabe hopes to be able to establish what happened during this event and open up discussion on the cause.

In the process Komugabe is challenging ideas about the stability of the Holocene climate and the speed at which black corals grow. The latter has significant implications for places where they are harvested intensely, such as Hawaii.

While it can be hard to maintain enthusiasm for a topic in the latter stages of a thesis, Komugabe doubts she will make a career in palaeoclimatic research. “I’d really like to work with local communities in making them aware of environmental issues,” she says. “I also want to help the lay person to know more about how science works. I’m concerned that the IPCC had to revise their reports because people didn’t understand scientific uncertainty.”