Understanding global change challenges: Vanishing ice
This blog post is part of an occasional series of interviews with AGCI workshop participants and lecturers engaging key global change challenges.
Around the world, ice in its many forms — from mountain glaciers and ice sheets to sea ice and permafrost — is disappearing at an alarming rate, reshaping landscapes and threatening water supplies for millions of people. This vanishing ice is a visible sign of a rapidly warming planet, with profound implications for ecosystems, sea level rise, and communities that depend on meltwater.
AGCI recently spoke with Dr. Heïdi Sevestre, a glaciologist, science communicator, and Deputy Secretary of the Arctic Monitoring and Assessment Programme (AMAP), about the speed and scale of vanishing ice as a global change issue, and the critical need to make the science of vanishing ice accessible and relevant to policymakers.
AGCI: Where is vanishing ice occurring, and how is it a global change issue?
Heïdi Sevestre: Vanishing ice definitely is a global change issue. We know that 10% of the land masses on Earth are covered by ice, and about 8% to 10% of our oceans are also covered by sea ice. So there is a lot of ice in the world, but what we’re seeing is that this ice responds very quickly to climate change. So whether it is ice that we find on top of the ocean, whether it’s ice we find in the mountains, whether it’s ice we find in the Arctic or the Antarctic, all of these different types of ice are reacting very, very rapidly to climate change.
AGCI: And how does vanishing ice and glacial retreat impact people’s lives and communities?
HS: If you look at mountain glaciers — for example, the glaciers in the Himalaya, in the Alps, in the Andes and Patagonia — what we’re seeing is that these are some of the most amazing water towers in the world. We use the meltwater from these glaciers for many different uses. It’s freshwater, that’s the great thing about it. So we use this water for drinking, for sanitation, for the production of hydroelectricity. We use the water to irrigate crops. In my country, we use the water from melting glaciers to cool down nuclear power plants during the summer months — and believe me, we understand how important these mountain glaciers are.
We’re also seeing that as these mountain glaciers recede, it not only affects the amount of water we get and when we get water from these glaciers, but it also creates a lot of hazards, a lot of risks. For example, in the Himalaya or in the Andes, we have a lot of lakes forming as the glaciers recede. And every now and then, these lakes might burst — the technical term is a glacial lake outburst flood. It’s like a tsunami in the mountains, and it can destroy everything over tens of kilometers into these narrow valleys. It really affects subsistence agriculture, it affects the communities downstream. This is certainly something we need to watch.
We also have two big ice sheets on Earth: in Greenland in the north and in Antarctica in the south. These two ice sheets are also responding very, very quickly to climate change, and they hold massive volumes of ice. For example, if Greenland were to disappear, it would increase sea levels globally by about 24 feet. If Antarctica were to melt out completely, it would increase sea levels by like 170, 180 feet. It’s really giant. And so if — and this is very much the case at the moment — if Greenland and Antarctica continue to lose so much ice, it’s billions and billions of tons of ice every year. New York, Miami, Shanghai — all these really populated areas that are very close to coastlines will be directly affected.
And there are two more categories I’d like to speak to very quickly, the first one is thawing permafrost. Permafrost is basically the frozen ground, and 23% of the Northern Hemisphere land mass is made of permafrost. It’s crazy how much permafrost there is. And as permafrost thaws, it not only affects infrastructure built on permafrost, but it also releases greenhouse gasses. And this is something we take very seriously. There might be microbes, bacteria, viruses coming out of permafrost, so it’s definitely something we need to watch.
“Whether you know it or not, your daily life is directly connected to the health of Arctic and Antarctic sea ice.”
–Dr. Heïdi Sevestre
And the last type of ice I’d like to talk about is sea ice, which covers parts of the Arctic Ocean and parts of the Southern Ocean around Antarctica. Sea ice is amazing at reflecting solar radiation. It’s like giant mirrors, a big white expanse, and it really helps to stabilize global climate. So whether you know it or not, your daily life is directly connected to the health of Arctic and Antarctic sea ice.
AGCI: And not just people who are in the nearby vicinity, right?
HS: Everyone on Earth. The whole climate system is connected to sea ice.
AGCI: Could you talk a bit about your work, how it relates to understanding and addressing vanishing ice as a global change issue?
HS: Absolutely. I’m very lucky to work for the secretariat of AMAP, the Arctic Monitoring and Assessment Programme, which is one of the Working Groups of the Arctic Council. The Arctic Council is a forum of the eight Arctic countries, including the U.S. AMAP is considered a “boundary organization,” and that’s very interesting for someone who has a scientific background like me. We are between academia and the governments of the Arctic. So the eight Arctic countries, and the observer countries, and the Indigenous communities also, of course — we call them the permanent participants — sit at the table of the Arctic Council. The way my job and my team’s job works is that the governments and the permanent participants come to us with a set of questions, and we have about 700, 800 experts whom we work with to answer these questions. We look at climate change, human health, contaminants in the Arctic, and we try to make sure that the science we produce with our amazing experts is directly relevant for policymakers.
Among all the things we’re looking at are changes in ice coverage, changes in ice volume, changes in the behavior of the ice, and the hazards connected to retreating glaciers and receding sea ice. I feel very lucky, actually, to be exactly where I am. We try to make sure that science has a direct impact on policies. It is a great challenge to ensure that the way science is done in the Arctic is harmonized, that we have a global overview of what’s happening in the Arctic. But we also want to guarantee that science is explained in a way that is understandable by policymakers, that we give them the right cards to make the right decisions. And I think being a scientist today is not just doing fieldwork, it’s not just publishing papers. A big part of our responsibility is to make sure our science is relevant to policymakers, and our science is understood by policymakers, by the general public, by the private sector. We have a huge science communication challenge ahead of us, and this is something I’m really passionate about.
I also have other projects that are not Arctic-related. Right now I’m preparing an expedition in Uganda. We have what we call tropical glaciers along the equator, the glaciers of Mount Kilimanjaro, for example. There are about 3,000 tropical glaciers left and they’re disappearing very quickly. There is almost no science being done on these glaciers anymore. Because they’re disappearing, so why should we care? But actually, these glaciers are culturally extremely important for the communities there. And they still matter tremendously for local biodiversity. There’s a lot of planning, a lot of physical training that goes into these expeditions. I feel extremely fortunate, really, really privileged to be able to travel to all these places. It might be very sad to see how quickly these environments are changing, but I think we have such an amazing mission to make the world care and to propel people into action.
AGCI: What do you see as the most important part of your work, and why?
HS: I want to preface my answer by saying that we still need data from the field. We need to continue taking the pulse of these glaciers, of the sea ice, of permafrost, and really understand how quickly things are changing. But to me, as an avid science communicator, one of our biggest challenges is to make people relate to the work that we do, to make people connect with these remote and mysterious regions, and to help them understand that everything that happens in the Arctic impacts the rest of the planet, and vice versa.
“Being a scientist today is not just doing fieldwork, it’s not just publishing papers. A big part of our responsibility is to make sure our science is relevant to policymakers, and our science is understood by policymakers, by the general public, by the private sector.”
–Dr. Heïdi Sevestre
There are bridges to build. And I think that using emotions and storytelling and stories from the field and traditions and the cultures of these amazing Arctic regions is definitely a way we can help people connect with this fantastic region.
At the moment, we’re really losing the Arctic as we know it. We’re losing the sea ice, we’re losing the permafrost, we’re losing the glaciers, we’re directly impacting our ice sheets. We’re about to cross tipping points that will irreversibly affect the rest of the world. And we need to explain that there are certain things on Earth that we cannot negotiate with. For example, we cannot negotiate with the melting point of ice. So to me, the biggest challenge we’re facing right now is to make sure that policymakers keep working with scientists, and respect the scientific methods, and are basing their decisions on the science we produce.
Another thing that really concerns me at the moment is geoengineering. When I was at COP28, I realized how attractive geoengineering is to some, and how dangerous it actually is. Geoengineering is by definition the … large-scale modification of our climate system. For example, people are talking about using floating silicate spheres to replace Arctic sea ice if and when Arctic sea ice disappears. Some think it would be a good idea to dump hundreds of millions of tons of little white spheres that would reflect solar radiation back into space, or that we should build sea curtains around Greenland and Antarctica that would prevent deep, warm water from melting the base of the ice sheets.
It’s crazy, but some people are taking this very seriously. There’s a lot of funding going towards this sort of geoengineering. The consequences will probably be totally insane both for the ecosystems, for ocean currents, for the chemistry of the ocean, and we need to be aware that we’re not going to fix climate change with that. Geoengineers say that this is going to buy us time. But it’s going to buy time for the fossil fuel industry so they can just continue burning oil and gas without being fought against.
So we need to be really, really careful. The climate system is not a machine where you just have to change one piece to make it work better. Everything is interconnected. If you play with the chemistry of the ocean, if you play with the albedo, with the color of the surface of the planet, it could create dramatic consequences. Let’s not go there. We know that the best, the cheapest, the most efficient and most beneficial way to fight climate change is to stop burning fossil fuels. We’re not going to do this from one day to the next, but we have to get there at some point. So let’s not believe in these sexy so-called techno solutions. They could be really, really dangerous. And who’s going to pay for the repairs? Who’s going to remove the sea curtains if they don’t work? We already cannot fund loss and damage. Who’s going to fund loss and damage that is connected to geoengineering?
AGCI: On the flip side, what do you see as the most exciting opportunities, or where do you see the opportunities to address these challenges in coming decades, or even sooner than that?
HS: There are many dimensions to your question. A lot of people think that retreating sea ice, melting glaciers, and thawing permafrost might create opportunities in the Arctic, but actually, we know that bringing a lot of industries into the region may negatively impact this region more than it will create any benefits. But in my opinion, I think it’s an amazing time to work in this field. Because we’re really seeing a big change in the way science is being done and the way science is being communicated. So first of all, how science is being done — I welcome this with open arms and I think it’s about time that we got there. Every research project in the Arctic now is being co-developed with Indigenous communities in the Arctic. And I think this is absolutely brilliant. We know who the true experts of the Arctic are, and they’re absolutely the Indigenous and local communities in the Arctic. And I’m so glad that we’re finding ways to write reports together, to co-develop research projects, research programs. The way science is being done in the Arctic is really shifting. We need to respect Indigenous knowledge and knowledge holders. For too long, scientists would tend to go to these places, meet the people, take the knowledge from them, and publish it without even mentioning where this knowledge was coming from. So it’s really great to see how the way science is being done in the Arctic is shifting.
But the way science is being communicated is also changing. We are facing a huge challenge in terms of science communication. We are in times when “fake news” is all the rage, when there are a lot of conspiracy theories. There is definitely a challenge to rebuild trust in science. And so it’s fantastic to see scientists who dare to be out there, to be more public, and to meet with policymakers, to meet with the general public, with the youth. We definitely need scientists to tell their stories and to make sure people can relate to them and can relate to their work. I feel really, really blessed to be 35 in a moment where there are lots of challenges to tackle. But I’m happy to see how my job is evolving. Because what obsesses me today is how can we have a positive impact? We really need to work with people like you, we need to work with artists, we need to work with Indigenous communities. We need to work with activists, with youth. And so there’s a lot that can be improved in terms of science communication at the moment.
AGCI: Why should all people care about vanishing ice whether or not they live in or near impacted regions?
HS: I think it’s such a brilliant question. First of all, because it’s beautiful! I mean, ice is just hypnotizing. It’s mesmerizing. Just a few hours ago, I went into a glacier, so inside an ice cave, which is carved naturally by the meltwater. And we went maybe 30, 40 meters inside the glacier. It’s the most beautiful thing I’ve ever seen. I mean, you feel your heart beating for every tiny ice crystal you see, and your headlamp is making this whole world shine, and it’s just unbelievable that this exists on Earth! And I’m a firm believer that beauty, that a sense of wonder, will really help people relate and connect with ice.
But on top of this, ice is also very important for many, many cultures. Not just because in the Arctic people travel on sea ice, people hunt and fish on sea ice, and it helps villages connect during the winter months. But because all over the world, people have traditions, beliefs, entire cultural systems that are built around the ice. And if we have perhaps forgotten most of it, we know that in the world today, there are about two billion people who use the meltwater from mountain glaciers. That’s a quarter of humanity. And when we look at sea level rise, 230 million people live between zero and one meter of elevation on coastlines. If we don’t act now, not only will we lose our water towers, not only will we have more hazards in these regions, not only will belief systems and traditions disappear with this vanishing ice, but we will also have really quickly rising sea levels around the world. To give you a bit of a timeline about this, if we continue burning as much fossil fuel as we are today, we could definitely get a meter of sea level rise in the next 45 to 50 years. It’s happening very, very quickly, and we need to prepare for this right now.
Whether you live close to coastlines or not, you will be impacted by massive migrations of people. And also migrations of industrial activities, migration of tourism, migration of agricultural crops. The world will look completely different without the ice, and it will also possibly create a lot of conflicts between countries. So we should deeply, deeply care about vanishing ice. And the problem with vanishing ice is that if we cross certain tipping points, we cannot stop, we cannot slow down the melting anymore. We know that most of these tipping points are around 1.5 or two degrees Celsius of temperature increase. It’s right here, these tipping points are very close to us. So it’s truly now or never if we want to prevent this ice from totally vanishing.
Dr. Heïdi Sevestre is an internationally renowned glaciologist, a leading voice in climate advocacy, and a member of The Explorers Club. Widely recognized for her extensive outreach efforts, Heïdi is often described as a scientist who engages in “all-terrain outreach,” sharing her knowledge across media platforms, the field, in books, and in documentaries. In 2022, she became the first recipient of the Shackleton Medal for her work in protecting polar regions and received the French “Rayonnement” Prize, environmental category, in 2023. In 2024, Heïdi was named a “European Young Leader” by Friends of Europe, representing France. Heïdi is a key figure at AMAP (Arctic Monitoring and Assessment Programme), part of the Arctic Council’s Working Group. Regularly leading scientific expeditions to polar and high mountain regions, Heïdi strives to make scientific knowledge more accessible and to inspire action against the climate crisis. She is the author of Climate Sentinel (HarperCollins France) and Tomorrow is Us (Editions du Faubourg), and currently features in the National Geographic series Arctic Ascent with Alex Honnold on Nat Geo / Disney+. In 2024, Heïdi’s research focuses on the Greenland ice sheet and tropical glaciers in Uganda, in collaboration with UNESCO, Project Pressure, and the Uganda Wildlife Authority.
See Dr. Sevestre’s AGCI workshop participation and presentations.