»Hurry up and close the door!«

Professor and glaciologist Dorthe Dahl-Jensen ushers me into the freezer in the basement of the Centre for Ice and Climate under the Niels Bohr Institute on Tagensvej street in Copenhagen.

The freezer keeps a cool minus 40 degrees Celsius, it is summer, and we are clad in short sleeves with bare legs. I shudder and watch anxiously as Dorthe Dahl-Jensen slams the door behind us and turns the large air lock so that no air comes in or out of the small room.

Inside, polystyrene boxes are lined up. Some of them contain the precious, and ancient, material which the centre does research on: Ice cores that have been taken up from deep, deep down in the Greenland ice sheet.

The ice may be up to 150,000 years old, and includes gas and air bubbles that researchers can use to estimate the age of the ice and the content of greenhouse gases. in this way they can map out what the climate looked like several hundred thousand years ago.

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»We rarely store the ice here, because the freezer is not stable enough. Most of the ice we have is in a huge freezer in [the Copenhagen suburb of, ed.] Glostrup,« says Dorthe Dahl-Jensen, explaining to me why the freezer is not packed to the brim.

I eagerly nod and take a glance at the locked door. Dorthe Dahl-Jensen does not herself seem to be particularly affected by the extreme cold in the small room. But then she caves in:

»Let’s get out of here, we are not dressed for being here.«

Gatekeeper for the funding

Dorthe Dahl-Jensen is the head of the Centre for Ice and Climate and has conducted research in Greenland and in the Antarctic for almost 50 years.

She became Denmark’s first female professor of physics in 2002, and she is world-famous for a number of scientific breakthroughs.

In spite of her warm nature, Dorthe Dahl-Jensen is often called the ‘ice queen’ in Danish media. She knows everything there is to know about ice and has excelled with research that has had a global impact for almost five decades.

In the summer of 2024 she was appointed the new chair of the board of the Danish National Research Foundation by the Danish Minister for Higher Education and Science Christina Egelund. The Danish National Research Foundation is an independent foundation that was set up by the Danish parliament in 1991.

It grants about DKK 470 million a year, and Dorthe Dahl-Jensen will now be in charge of distributing this money to research projects. She is looking forward to it.

»More and more research funding nowadays is put into boxes – they come from mission-driven foundations or are earmarked for specific research fields. And this means less and less is completely independent funding,« she says. The chairmanship in the Danish National Research Foundation was the only job she could ever have imagine accepting on top of her other work.

»The Danish National Research Foundation supports precisely independent research, and I think that is extremely important. This long-term research gives Denmark the cutting edge that allows us to be a leader in innovation and new products.«

History repeats itself

So what is the research that has sent Dorthe Dahl-Jensen and her team up to the top of the mountain of ice?

Advanced analyses of the ice cores – research that has helped to map out how the Earth’s climate has changed during the last two ice ages. And when we learn more about the past, the ancient ice can also help scientists predict the climate of the future.

During the last ice age (which began about 115,000 years ago, ed.) there were 25 sudden warming events, and the temperature over Greenland rose by up to 16 degrees in less than 100 years, says Dorthe Dahl-Jensen.

By mapping the causes and consequences of past temperature increases, researchers can identify how the current anthropogenic warming will affect us.

When I ask Dorthe Dahl-Jensen which of the scientific breakthroughs she is most proud of having contributed to, she highlights a study of the last interglacial period, the Eemian, where she and her team were the first to be able to reach conclusions about what happened to the ice sheet the last time global temperatures rose.

The study was titled ‘Eemian interglacial reconstructed from a Greenland folded ice core’ and was internationally recognized when it was published in the journal Nature in 2013.

»During the Eemian interglacial, we can see that the temperatures over Greenland were about five degrees Celsius warmer than nowadays, and we estimate that Greenland lost about 25 per cent of its mass. This corresponds to a sea level rise of about two metres,« says Dorthe Dahl-Jensen.

»We can use these results to assess to some extent how a new temperature increase could affect the ice sheet and the oceans.«

She explains that the melted ice during the Eemian Interglacial resulted in a large discharge of fresh water into the world’s oceans. The same trend can be seen to some extent today, as the ice melts and it rains more in the Arctic.

»The large oceanic water circulations are partly driven by temperatures and saline balances, and when changes are made to them, it has consequences for ocean currents. When temperatures increased during some of the sudden events of the last ice age, the great Atlantic circulation, or Gulf Stream, came to a complete standstill. We use these results to assess whether it can happen again,« says Dorthe Dahl-Jensen, and mentions that several climate projections predict exactly that the Gulf Stream may end before the year 2050.

»But of course you have no idea if this will actually happen. That’s the way it is with these kinds of models – there are risks, but no guarantees,« says Dorthe Dahl-Jensen. She mentions that it, ironically, will get colder in northern Europe if the Gulf Stream stops as a result of global warming.

Warnings ignored

In her almost 50 years of working with ice, Dorthe Dahl-Jensen has witnessed how the climate is gradually changing.

»We can see that it is getting warmer over Greenland. I remember one day back in 2012 when we were standing up there and it suddenly started raining. In the middle of the Greenland ice cap. This is very, very unusual, and we saw a rainbow,« she says. It has gradually become warmer over Greenland in the new millennium, and this means more precipitation.

Greenland currently loses about 280 gigatons of ice per year, which corresponds to an annual sea level rise of 0.7 millimetres, which is included in the 3.5 millimetres that the world’s oceans are currently rising. The other 2.8 millimetres come from melting ice elsewhere (for example Antarctica) and as a result of seawater expansion as it warms, says Dorte Dahl-Jensen. I ask if this is a lot.

»Is that a lot?« she repeats, pausing a bit.

»Well, yes. It is. 3.5 millimetres a year is 3.5 centimetres in ten years, which is 35 centimetres in 100 years. And when we talk about floods and the risk of flooding, those 10-20-30 centimetres actually mean a great deal,« she says. She adds that in her assessment it is pure luck that we have not yet been hit by a huge flood in the city of Copenhagen. This risk is steadily increasing year by year.

Dorthe Dahl-Jensen has, in her own assessment, »thought a lot about ice« since the mid-80s. Back then, ice cores and climate research were »exotic,« and very few people knew about the research or were interested in it.

For Dorthe Dahl-Jensen, however, it was much closer to home. She was born into a physics family – her father was a researcher at the Niels Bohr Institute in Copenhagen and worked for a period of time at the CERN research institution in Geneva, Switzerland.

She started studying physics at the University of Copenhagen in 1977 and specialized in glaciology in 1981, partly because she thought it sounded exciting with all the field trips that the subject entailed.

But even though the climate topic has moved from being something exotic to something that most people are both interested in and have strong opinions about, not enough is being done, according to Dorthe Dahl-Jensen.

»I think that we researchers use a lot of resources on talking about what is happening to our climate and what the consequences will be. But it’s as if people just don’t really listen,« she says and continues:

»And you have to try and not get frustrated over this. I remember [the former Minister for Environment and Climate and EU Commissioner, ed.] Connie Hedegaard once saying to me, you just have to go on and on and on, saying the same thing to people. And I think she’s right.«

Dorthe Dahl-Jensen has to admit that the world’s politicians have reacted very, very slowly to the warning signs that she herself has been talking about for many years.

»When there’s a general election, then everybody talks about climate. It is at the top of every politician’s agenda, it is the most important agenda for voters. But when the elections are over, the attention drops. And that’s super frustrating.«

What kind of climate future do you think we are facing? Can we reverse the trend?

»No, I don’t think we will act in time at all. No, not at all. I believe that we have to adapt to the major climate shifts that will inevitably come, and we must instead use our time and resources to adapt. And this a stupid way to act,« says Dorthe Dahl-Jensen, adding:

»I think we will only really do something when we start to feel the changes on our own body. Unfortunately, that’s how I think that humankind is… what would you call it … selfish.«

Emergency tent, rifle and outdoor stoves

Dorthe Dahl-Jensen cannot say exactly how many times she has been on field trips to Greenland, but she estimates that it must be somewhere between 30 and 40 times. The first time was in 1981, when she had just started as a student and was allowed to join the world-famous Professor Willy Dansgaard’s team.

On the Greenland ice sheet you have to be able to stay in extreme sub-zero temperatures and deal with snowstorms and hungry polar bears. But it is still the special sense of community during the expeditions that she highlights.

»It is characteristic of the camp that the projects are made in collaboration between many countries. There are usually people from at least ten different nations, and at least half are young researchers – that is, PhD students or postdocs,« says Dorthe Dahl-Jensen and adds:

»It’s a great summer school for our young people. They get to know people internationally, and gain a huge network.«

Most people quickly get used to daily life in the field where you only have to worry about drilling ice cores, making analyses, and otherwise just sleeping, eating and socializing with the 30 or so colleagues.

»But sometimes, in very rare cases, someone finds it awful to be so isolated. And once you get up there, there’s not much else to do but wait one month to get out of there again,« says Dorthe Dahl-Jensen. The research team is flown to the station in Greenland by special military planes that have skis attached to the undercarriage.

Sometimes people are sent out on missions that require them to drive up to 50 kilometres away from the established camp – for example, to drill ice cores or make radar measurements.

»People here have to be trained to be able to set up camp and to stay there if there is a storm. They go out on a snowmobile and always have an emergency tent, outdoor stove, and a rifle with them in case there is a blizzard and they have to stay. If a polar bear turns up, they have to shoot,« says Dorthe Dahl-Jensen.

Dorthe Dahl-Jensen and her team have twice had polar bears entering the camp itself. This is unusual, as polar bears live on the coast, and the camp is located hundreds of kilometres inland from the coast, says the researcher.

»When they’ve moved so far from the coast, we have to shoot them, because in this case they’re not going to leave again anytime soon,« she says, adding: »And we’re so sad when it happens.«

The research team must ask permission from the Greenland regional government before shooting a polar bear. And they should actually just leave it when it’s dead, because they’re in the middle of a national park.

»But we just can’t bear it, so we’ve buried the ones we’ve had to shoot. Now we have a small polar bear graveyard on the outskirts of the camp,« says Dorthe Dahl-Jensen.

Copenhagen, Greenland, Canada

In addition to her position as professor at the Niels Bohr Institute, Dorthe Dahl-Jensen was in 2019 appointed to the distinguished post as Canada Excellence Research Chair at the University of Manitoba in Canada.

Here she conducts research into how the melting Arctic ice affects marine life and how climate change affects the local population off the Canadian coasts.

She says she has received »one of the very best grants you can get« – DKK 100 million to lead a research programme. And that is one of the reasons why she has accepted a position so far from Denmark.

Another reason is that she would like to gradually begin to make more room for the next generation of researchers in her field.

»I have led the same ice core group for many years, and I would really like the next generation to start stepping up. And it will be easier for them if I’m not there,« she says.

Dorthe Dahl-Jensen can also look back on a period where she, and the rest of the management at the Centre for Ice and Climate, succeeded in creating a gender distribution consisting of an equal number of men and women – at least at the PhD and postdoc level, she says.

»We require that there needs to be female applicants every time we advertise a position. If there is not, then we will have to advertise again. We have to headhunt some women, or consider how we can make the position more attractive for women to apply for,« she says, and explains that this rule applies throughout the Niels Bohr Institute.

At the Centre for Ice and Climate, there have also been initiatives to make research attractive to parents. They don’t hold meetings after 4 pm for example, says the climate scientist.

»And I also think that women perhaps need more encouragement than men. Or being directly encouraged to apply for a grant or a position. I think women need to be seen. We’re very conscious of this.«

There is a narrative that women opt out of a career in academia because it is incompatible with a family life. Do you think that’s right?

»Yes, it’s right, but it’s also wrong. There is a lot of performance pressure in academia. But there is also the freedom to plan one’s own time. You can say: I’m off work today, and I will work at another time,« she says. Dorthe Dahl-Jensen has four children with her husband the scientist Jørgen Peder Steffensen, who is also a professor at the Niels Bohr Institute.

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Dorthe Dahl-Jensen is keenly aware of the narratives on both sexism and discrimination against women in the Science, Technology, Engineering and Mathematics, or STEM, fields.

The only time she has experienced this herself was in connection with her first field trip to Greenland in 1981. She was told there that she could not come because she was a woman. Fortunately there were many male colleagues who supported her, so she ended up going.

And although she hasn’t experienced anything like this since, she knows several female colleagues who have.

»I’ve been fortunate to have had male colleagues who have supported me throughout my career. But I know of cases where this has not been the case. This is changing, and I think it will help a lot when the older generation retires,« she says.

Climate anxiety and doomsday

It is important for Dorthe Dahl-Jensen that the next generation is ready to take over.

This applies to issues of gender discrimination, but also in terms of preparing them for what she herself learned from the former EU Commissioner Connie Hedegaard many years ago:

Say the same thing over and over and over again. And do it so people can understand it.

»We are shaping the climate diplomats of the future. So we have a very strong focus on teaching everyone how to communicate their knowledge. Everyone is trained in giving lectures, and everyone is asked to speak to the press if they contact us, which they often do,« says Dorthe Dahl-Jensen, and continues:

»I’m often the one who gets the phone call. But in the vast majority of cases I say: Try calling her, or her. Both in terms of just passing the ball, and in gradually making sure that everyone is trained to communicate our cause.«

When you tell ordinary people about climate change the most important thing is to use »everyday language« and to make sure you focus on the broad outlines, according to Dorthe Dahl-Jensen.

»As a researcher, you should not be too specific. You would be better off talking about climate change from a general perspective. And then you have to stick to one, or at the most two key messages.«
It is important to speak of solutions rather than just speaking of impending doom, according to Dorthe Dahl-Jensen.

»No one wants people to be anxious. We’d prefer people to start doing something.«

Many young people have real climate anxiety. Do you have any advice for them?

»First of all, I would say: The world is not going to end. It’s going to change and it’s going to be harder to live in, but it’s not going to end. And then you have to remember that there are many solutions that allow us to reduce the warming. The best thing you can do is to help. Choose an education programme that can help provide us with the solutions for the future. Because there will be solutions for everything«.