Gabi Hegerl on detection and attribution of climate change

Gabi Hegerl is famous for her work seeking to understand the processes driving climate variability, but she was initially destined to study language arts, and started off with seven years* of schooling in Latin.

Gabi Hegerl pursuing one of her passions.
Gabi Hegerl pursuing one of her passions.

Schools in Germany, at least in Gabi’s time, tended to place students into career tracks quite early, and for Gabi that meant language. But she never loved it, and soon realized “I always really enjoyed maths, even though it seemed a bit pointless”.

It turns out that her father, a lawyer, had an unfulfilled ambition to be a mathematician. But for reasons that remain unclear, he didn’t tell Gabi of his interests, and actively encouraged her to go into law. Due to the horrendous boredom of the subject, though, Gabi demured, initially pursing her interests in archaeology at the Ludwig-Maximilians University in Munich.

Describing archaeology, Gabi says “I found it really interesting but I found it just frustratingly illogical”. There was far too much fuzziness in data and interpretation, and she could never make it work entirely.

Reviewing her interests and skills, Gabi finally concluded that maths (and art!) were¬† immensely satisfying and continually challenging. I think the interview contains a terrific description of why people might study applied maths — a combination of a vast intellectual construct, the sense of building on prior knowledge, a simple end result, and direct applicability to real-world problems.

These interests in maths led Gabi to switch her PhD from computer logic to numerical fluid dynamics, focused on a Siemens-funded and high-risk project seeking to model fluid flow in the throat. A long way from climate science!

Juggling career options, and applying to software companies, Gabi was intrigued by the mismatch between mapped and actual glacial extents in her climbing haunts in the Alps and decided to — almost out of the blue — apply to the Max Planck Institute for Meteorology in Hamburg, working with Klaus Hasselmann and Hans von Storch.

Gabi thought of the climate work as an experiment, something to try out. But von Storch said it only made sense if an academic career was the final goal. Ultimately, Gabi agreed, even thought the salary was lower than in industry and she had to wrestle with family and relationship entanglements. “I felt putting myself to very hard work is much nicer if you feel it brings about something useful”.

Now, after a scientific career spanning the MPI, the University of Washington, Texas A&M, Duke and now the University of Edinburgh, Gabi is known for her pioneering work on the detection and attribution of climate change, climate extremes, and climate sensitivity.

Figure 3 from Gabi's most-cited senior authored paper (Nature 440, 1029-1032, 2006)
Figure 3 from Gabi’s most-cited senior authored paper, on climate sensitivity (Nature 440, 1029-1032, 2006).

We discuss the surprisingly large and long-lasting impacts of volcanoes on climate, disentangling internal vs. external controls on climate, why spectral analysis isn’t too satisfying without a mechanism,¬† whether or not models simulate extremes for the right reasons, how to work with Bayesian statisticians.

For me, though, the most interesting section of the interview comes in our discussion of Gabi’s work with her late husband, Tom Crowley, and the aftermath of his death in 2014.

Even after years of working with the climate community, I can think of scientists as independent constructs, visible by their papers and community activities, but not as part of a human system. The reality, of course, is intensely human.

Gabi experienced one of the most wrenching life changes one can imagine, and she tells me of the wonderful support she received from her colleagues (Simon Tett in particular), but also of the struggle to provide emotional support for her young sons and take up the family responsibilities previously handled by Tom — all while trying to keep her own career and vast network of collaborations going.

The children, naturally, emerge as the top priority, and Gabi cut back to 80% time. All of which, as she says, led to a loss of confidence in her own professional skills and knowledge. In the end, the huge challenge of working in the IPCC led to a rebuilding of faith in her abilities, showing, I think, the deep sense of personal satisfaction and confidence that can arise from contributing to a challenging scientific topic.

* In the interview, and initially on the show notes, 10 years of Latin was mentioned. It was actually seven years of Latin coursework.

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