A song of ice and climate: How Ireland’s glacial past can predict our future

5 days ago

Margaret Jackson conducting fieldwork in Peru. Image: Margaret Jackson

Lugnaquilla in the Wicklow mountains is the highest point in Leinster, but for one researcher it offers views not just of the beautiful landscape but into our deep past and potential futures.

Predicting the effects of climate change can be a tricky business. For Dr Margaret Jackson, a glacial geomorphologist and palaeoclimatologist, some of the answers lie deep within the geological record. From Antarctica to Iceland, Jackson studies the landforms and sediments left behind by glaciers to reconstruct how they grew and shrank over time.

“Because glaciers are highly sensitive to changes in climate, I can then use this information to infer past climate conditions,” she explains. “This gives us a way to work out the timing and magnitude of past climate change – key information for determining the sensitivity and likely future behaviour of our climate system in the decades to come.”

Glaciers whet Jackson’s research appetite early in her career. When studying for an MSc in Earth and climate sciences at the University of Maine, she spent six weeks in Antarctica studying the ice sheet, “camping, collecting data and just taking in the beauty of the place”, she says.

For her PhD at Dartmouth College, she studied “ice in the tropics” with a focus on glaciers in the Rwenzori mountains of Uganda. “We have very few records of past temperature from the tropics, and so we used glaciers as our window into the past to learn more about how climate has changed in the region since the end of the last ice age.”

Jackson then took up a postdoctoral position in the University of Galway to study glaciation in Peru before coming to Trinity College Dublin in 2020, where she is an assistant professor in geography. Much of her research now focuses on Ireland, but she is also involved in projects in Iceland, Peru and Antarctica.

Tell us about your current research.

I have two primary projects in their early stages. Both are focused on past glaciation in Ireland and what Ireland’s glacial past can tell us about our future.

When you look at future sea-level projections such as those summarised by the UN Intergovernmental Panel on Climate Change (IPCC), there is significant uncertainty about those estimates. Most of that uncertainty comes from the large ice sheets in Greenland and Antarctica, and their potential sensitivity to changes in climate.

We know that when you warm things up, ice melts. But what we don’t know is how quickly these large ice sheets will react to future warming. Will ice melt at a constant rate, or should we instead expect melt rates to increase, or perhaps only in certain regions? What is the relative sensitivity of these ice masses to oceanic or atmospheric warming? Are there climate tipping points where ice sheets may rapidly lose more mass?

Each of these questions has direct implications for future sea level, and so for our ability to plan and adapt to rising seas. Obviously, we can’t run experiments on the modern ice sheets to see how quickly they melt and then hit the reset button – but what we can do is look to the past and examine how (and how quickly) ice sheets responded to a warming climate.

During the peak of the last ice age, Ireland was covered by a thick ice sheet much like the ones that exist today in Greenland and Antarctica. When the ice age ended, the atmosphere and ocean started to warm and the Irish ice sheet began to melt away. There is quite a lot of data we can use to infer how quickly the ice melted. This data comes primarily from areas that are today offshore. But the modern terrestrial regions of the ice sheet are still largely undated, and so we have very limited information on how this ice sheet responded to warming.

Margaret Jackson waving at the camera from an observation tube in a cast expanse of ice and a pale blue sky behind her.

Margaret Jackson in an ob tube, which is a tunnel drilled into sea ice with an observation deck at the bottom. Image: Margaret Jackson

I’m working now to map and date the former position of the Irish ice sheet as it melted away at the end of the last ice age. This project has been funded by Science Foundation Ireland and is getting underway formally this coming summer. The results of this project will give us direct information about how a large ice sheet responded to warming in the past, and we can use this data to help train modern ice sheet models for future sea level projections.

You can imagine as the ice sheet melted away, ice still remained on highland mountain areas in places such as Wicklow. Mountain glaciers persisted in Ireland for a few thousand years at least after the Irish ice sheet retreated. This time period was marked by huge change globally as the world emerged from the ice age. More locally, it was also a period of abrupt climate shifts – ocean currents in the North Atlantic were disrupted by large amounts of fresh water from melting ice sheets being flushed into the sea. As a result, heat exchange from the North Atlantic ocean weakened significantly. This heat exchange helps keep Ireland’s climate mild, and so it’s very important for us.

‘Climate change is perhaps the greatest challenge we face’

Today, as Greenland’s ice sheet melts and fresh water is flushed into the ocean, there is some speculation that these same currents may slow down in the near future, which would have immense impact on Ireland. But in order to determine how significant these impacts would be for people and communities, we want to know how these past abrupt oceanic changes manifested in terrestrial Ireland. We don’t have much information on this at the moment, but this is where those mountain glaciers can come in.

If we can map and date past glacier fluctuations in terrestrial Ireland, we can model these ice masses and determine specific climate scenarios for each ice position – how cold or relatively wet or dry it would have been. This gives us insight into how these past changes sourced in the ocean were expressed on land. Ultimately, the project will provide data we can input into climate models to explore how our climate system behaves under different scenarios. This is the focus of the ACCTIR project, funded by the Environmental Protection Agency. It’s just recently launched and I’m excited to see what we learn.

In your opinion, why is your research important?

Climate change is perhaps the greatest challenge we face. Understanding our climate system and its capacity for change is a fundamental first step in projecting how our climate system will behave in the future.

Glaciers are very sensitive to changes in climate, and so make excellent thermometers. I explore the timing and magnitude of past glacier fluctuations and use this information to reconstruct past climate. These data give us insight into the natural variability of our climate system and its sensitivity to factors such as greenhouse gas concentrations in our atmosphere. We can then use this information to help understand the behaviour of our climate system today, and how it may respond in the future.

What inspired you to become a researcher?

My path to research was anything but direct. I always loved science and nature, but actually began my undergraduate career studying international relations. I was fascinated by climate change, and quickly realised the implications a changing climate would have for international policy and sustainable development. I switched to studying Earth sciences after my second year in order to gain deeper understanding of both climate and the wider Earth system. I found my classes interesting, but I loved conducting my own independent research project in my fourth year. Having the freedom and opportunity to explore a topic and to produce new data – brand new information – was really thrilling, and that stuck with me.

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After graduating, I spent two years as a Peace Corps volunteer in Morocco working with local communities to help survey and protect threatened flora and fauna, and after that spent a year teaching science in Eastern Europe. I really loved those experiences, but realised in both cases that I was most engaged when I was thinking about science, and that I missed the ‘research’ aspect of discovering new things.

It was after that that I applied to an MSc programme in Earth and climate sciences. I wanted to give myself an opportunity to really try getting into science and research. I absolutely loved it, and just went from there.

What are some of the biggest challenges or misconceptions you face as a researcher in your field?

Palaeoclimate can seem a bit esoteric to people, or as though it isn’t very useful in a world where we care so much about what is happening with our climate both now and in the near future. Making the connections between past, present and future when it comes to climate and climate change is very important.

Also, funding can be a challenge, which is certainly the case in just about every scientific field. I’m very fortunate to have financial support at the moment, but it can often be so difficult for researchers to plan their work and careers when project funding – including funding for research staff – is so hard to come by and difficult to predict.

Do you think public engagement with science and data has changed in recent years?

Yes and no. I think people were much more engaged with certain aspects of science and data dissemination during the early days and peak of the pandemic. We all wanted to know what was happening and what to expect, and were desperate for whatever information we could find (I include myself here!). This of course opened doors for bad actors and misinformation, something that is still an issue. But on the positive side, I’d say the public is now more aware that misinformation is out there and people think more about where information is coming from.

I think the pandemic also altered the way that many researchers went about framing their information for a public audience. Researchers had to rethink ‘virtual’ spaces as ways to communicate, which provides opportunity for so many more people to get involved with science and to exchange ideas. We are moving now into a more ‘hybrid’ world, which I see as an immense benefit for science and the wider public.

How do you encourage engagement with your work?

I try to participate in outreach events whenever I can. Programmes like Skype a Scientist are a fantastic avenue for researchers to share their work with a wide array of audiences. I’ve talked with classrooms of six-year-olds about camping in Antarctica and with community groups about climate change and sea level projections.

But some of the best outreach I do is in the field when I’m actually ‘doing science’. Last year, when we were working on Lugnaquilla, a family hiking through asked what we were doing, and after a quick chat they hung around to watch us collect samples. We quickly got them involved and many of our photos from that day show them holding scale bars and sample bags – they’ll absolutely end up as featured players in our ultimate publication! It was the sort of encounter you can never plan, but it’s in many ways the most fulfilling. You come away knowing that they will share what they did and what they learned with their own friends and family, and these ideas just start to spread.

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