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‘We are at the start of a new climate regime’

Sonia Seneviratne is a professor at the Federal Institute of Technology ETH Zurich. Christian Schnur/Keystone

Swiss scientist Sonia Seneviratne is among the world’s most influential climate specialists. An expert on extreme weather events – like the exceptional heatwave that recently hit Canada and the United States – she says solutions exist if we’re prepared to change our habits.

This content was published on August 9, 2021 - 10:00

“I was heading out into space,” Sonia Seneviratne explains in an interview with SWI swissinfo.ch. “I was fascinated by planets, the universe, and I wanted to study astronomy. But then I told myself there was something more pressing here on Earth.”

So began Seneviratne’s career in environmental and climate sciences. Today, a professor at the Swiss Federal Institute of Technology ETH Zurich, she has been on the cutting edge of climate research, trying to understand what causes extreme weather events like heatwaves, floods and droughts.

Heat waves 150 times more likely

Her most important discovery is the existence of a direct link between extreme events and global temperatures, she explains, as well as the fundamental role of vegetation in keeping carbon levels down. It’s a link that was first reported in a groundbreaking report on the impacts of global warming of 1.5°C, published in 2018 by the United Nations Intergovernmental Panel on Climate Change (IPCC).

The Zurich-based researcher also looked into what caused the exceptional heatwave that hit North America in June. Due to climate change, she says the likelihood of such events has increased 150-fold. In other words, prolonged periods with temperatures approaching 50°C could occur every five to ten years, instead of once a millennium.

Through satellite measurements and field observations, Seneviratne also found that droughts have an impact on the amount of CO2 in the atmosphere, a phenomenon previously underestimated by climate models. During dry periods with high temperatures, plants absorb less CO2, which contributes to further warming of the air, she explains.

Thanks to this work and numerous scientific articles, Seneviratne was included in the list of the world’s 1,000 most influential climate specialists, compiled by the global news agency Reuters. Ranked in ninth position, she is the only woman in the top 30.

‘I wanted to learn the dictionary by heart’

As a child, Seneviratne was curious about the world around her and loved walking in the woods and observing the trees. In her free time, she would read a book or two a day. She also wrote short stories. “I wanted to learn everything, even the entire dictionary by heart.”

It was during the Rio Earth Summit in 1992 that she first became aware of environmental problems and climate change, the 47-year-old recalls.

Once she enrolled in a biology course at the University of Lausanne, she never missed a maths or physics lecture, her favourite subjects. “But I also have bad memories of lab work. I used to break everything,” she recalls with amusement. In the third year of her studies, she transferred to ETH Zurich, at the time among the few European universities offering an interdisciplinary programme in environmental science.

While there, Seneviratne gained knowledge about the effects of vegetation on the climate through her Masters work in the Amazonian rainforest and through a postdoctoral fellowship at NASA.

During an academic exchange at the Massachusetts Institute of Technology, she met several other women who wanted to become professors in a traditionally male-dominated field. “The biggest difficulty in Switzerland was the lack of female role models, which I had come across in the US. They opened up new horizons for me,” she says. Back in Switzerland, she was appointed to a professorship when she was just 32 years old.

‘One of the best researchers in Switzerland’

Modest by nature, Seneviratne “always manages to pinpoint the big questions in our field and helps solve them,” says Wim Thiery, a climatologist at Vrije Universiteit Brussel, who did his post-doctoral research in her laboratory, as quoted by the newspaper Le Temps.

In another Swiss French-language daily, 24 Heures, a climatologist from the University of Neuchâtel, Martine Rebetez, calls her “one of the best researchers in Switzerland. The first time I met her I said to myself: ‘Wow! Here is someone who is quite brilliant and doesn’t realise it. What’s more, she’s a really nice person’”.

Stop using fossil fuels 

“Climate change is now,” warns Seneviratne, who does not hide her frustration at the lack of decisive action on climate protection. “We are at the start of a new climate regime, but not everyone realises this.”

Switzerland is more or less prepared, she believes, but has not sufficiently grasped that the effects elsewhere in the world will also be felt here. “We import half our food from abroad. What will happen in the future if the world’s agricultural regions are hit by drought at the same time and decide, for instance, to suspend exports in order to meet domestic needs?”

The researcher calls for mobilisation at all levels. The solution, she says, is very simple: “We must stop consuming fossil fuels. The alternatives are there, although many people are afraid of change,” she says. “We don’t need to change our lifestyles fundamentally. We can keep leading equally comfortable lives while producing fewer emissions.”

Climate action in the courts

As a citizen, Seneviratne tries to reduce her own impact by decreasing her meat consumption, shunning a car and preferring the train over the plane for travel within Europe.

As a researcher, she is happy to present the current state of knowledge in her field in court, as she did in January during a trial against climate activists who had occupied a branch of the Credit Suisse bank in Lausanne. “Judges think more in the long term than politicians. I believe the courts can play an important role in fighting climate change, as shown by some rulings in Germany and France,” she says.

After the Lausanne trial, the judge stated that it was the "depth and precision" of Seneviratne's statements that convinced the court to acquit the defendants in the first instance. The climate activists were later convicted on appeal. While acknowledging the imminence of climate danger, the cantonal court found that the protest action "was not suitable to reduce or curb" greenhouse gas emissions.

Sleepless nights writing reports

Seneviratne also contributes to international climate reports. For the latest IPCC assessment report, the first part of which was published on August 9, she coordinated the chapter on extreme events. This activity, which is unpaid, comes on top of her daily work, and often spills over into the evenings and weekends.

“As a researcher, I find it an interesting task as it gives me a chance to read hundreds of studies and to see where the gaps are. But, above all, I do it because I feel I’m doing something useful to help tackle the climate emergency.”

“But, given the many sleepless nights,” she says with a smile, “I’m not sure I’ll take part next time.”

Sonia Seneviratne

Sonia Seneviratne was born on June 5, 1974, in Lausanne, in Vaud canton. Her mother was a piano teacher and her father, of Sri Lankan origin, worked for the Swiss multinational Nestlé. She studied biology at the University of Lausanne and environmental physics at ETH Zurich, where she defended her doctoral thesis on droughts and heatwaves in 2002. In 2007 she was appointed assistant professor – and in 2016 full professor – at ETH Zurich’s Institute for Atmospheric and Climate Science. In 2018, she co-authored the IPCC special report on the impacts of global warming of 1.5°C. Specialising in extreme weather events, she has written over 200 scientific publications. The mother of two children, she is married and lives in Zurich.

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