Natalya Gomez - Blog

Exploring uncertainties in future sea level changes

7/4/2023

This post was written for the 2023 Trottier Space Institute Annual Report.

Jeremy Roffman recently graduated with his M.Sc. from the Department of Earth and Planetary Sciences. He studied ice sheets and sea level change under the supervision of Prof. Natalya Gomez.
Significance: Coastal adaptation in the near future relies on accurate predictions of sea level change. This study demonstrates that it is necessary to include spatial and temporal dimensionality in 21st century sea level projections in order to fully capture the risk posed to global coastlines by mass loss from the Greenland and Antarctic ice sheets.
The melting of polar ice sheets is rapidly becoming the dominant contributor to future sea level changes. Sea level is commonly described as a uniform rise across all the world’s oceans. In reality, however, the geographic pattern of ice mass loss across the Greenland and Antarctic Ice Sheets produces a unique, spatially non-uniform pattern of sea level change. The pattern of sea level change will also evolve temporally, along with the acceleration of ice mass loss or gain in some areas of the ice sheets, and with changes in the location of ice mass changes.
A challenge currently facing researchers is the wide range of ice sheet models, whose predictions of the future of the Greenland and Antarctic Ice Sheets differ significantly. In turn, the sea level predictions associated with each ice sheet model projection will also vary widely. In a new study by master’s student Jeremy Roffman et al., authors calculate the spatially and temporally varying patterns of sea-level change that would arise from end-member Antarctic Ice Sheet evolution scenarios selected from the state-of-the-art ISMIP6 ice sheet model ensemble. The authors quantify the uncertainty in future sea level changes implied by the ensemble. By including temporal dimensionality in their projections, the authors show, for the first time, that sea-level rise along coastlines closest to the ice sheets may exceed the global average sea-level change early in the 21st century than in 2100, when sea level rise is most commonly reported in the literature. The study suggests that predictions of sea level change should take into consideration the full range of possible ice sheet evolution scenarios.
Citation: J. Roffman, N. Gomez, H.K Han, M. Yousefi, & S. Nowicki, Spatial and temporal variability of 21st century sea level changes, Geophysical Journal International, Volume 235, Issue 1, October 2023, Pages 342–352, https://doi.org/10.1093/gji/ggad170

June 21st is #showyourstripes day, a day to talk about climate change

6/21/2023

Today is #showyourstripes day, so let's take a moment to see how temperatures on Earth have been doing and talk about climate change. Here are figures of global average surface temperatures from 1850-2022, where each stripe/bar represents the average temperature over a year based on records all over the world. The red colors show the rise in average temperature in recent years. I decided to share this in stripes, bars and bars with numbers and axes so you can pick the one that feels most accessible for you.

You can go to showyourstripes.info to find stripes for different countries, regions and cities, and virtually everywhere you will see the stripes turn from mainly blue to mainly red.

Climate change is effecting every inhabited part of the planet. And climate action movements are happening across the world too. A difference can be made in so many ways and scales, and we are making progress, but much more, sustained, and faster action is needed than we are doing now.

If you’re not sure what you can do or how to start to this process, here are some suggestions. Your action for today or this week could be to set aside some time to start to work that out. You could have a conversation about climate change with friend or journal about it or read/watch/listen, learn and reflect about it. You could search for a local event or a community effort and show up to it. You could start knitting a climate stripes scarf (and then wear it or send it to me to wear). You could ask for help and support from your network or a professional if this feels overwhelming to you. You could take a moment to take in that we live all together on one planet for the rest of our lives and we are one part, in one moment in time, of an Earth system with a long history, not the center of it and not separate from it. And then, once you do a thing, make a plan to do it again soon. One day, one thing, one step at a time.

If you are a McGill student, you could apply to be a TA (graduate students) or take our new campus-wide course FSCI198 Climate Crisis and Climate Actions, an interdisciplinary, whole-person introduction to the climate crisis and individual and collective actions to address it. I will be joining an inspiring, interdisciplinary team to teach it this fall. See here for more information and the trailer for the course: https://www.mcgill.ca/ose/courses/fsci-198

Check out showyourstripes.info for more details on the figures I am sharing - they were first developed by Ed Hawkings.

Also check out biodiversitystripes.info for similar figures illustrating biodiversity loss over time.

Natalya

Experiments in Montreal

9/10/2022

Natalie is a McGill undergraduate student who working on a project headed by Dave Purnell to improve remote water level sensing using GNSS. She spent the summer doing field work around Montreal at La Fontaine Park and Ile St. Helene, to determine how instrument orientation impacted accuracy.

Figure 1 : apparatus at Ile st. Helene, including a visitor also admiring the view

Hello! After my winter semester research course I’ve been so excited to start a summer project here
with Natalya’s team. My research has consisted of working with Dave Purnell to improve instruments
measuring water level. This uses of GNSS-Reflectometry, which relies on ground receivers (the same
kind you might use for your car’s GPS) measuring direct signals from GNSS satellites against signals that have been reflected by some surface, like a body of water. To keep costs down but improve accuracy, multiple cheaper receivers can be placed together and used to take the same measurement, reducing unwanted error.

For me, this means a lot of field work around Montreal! Most sunny days from the past couple weeks have been spent on either Ile St. Helene or at La Fontaine Park. Here, I set up arrays of GNSS receivers and vary their orientation and separation from each other, then I measure the signal strength to decide if this has impacted accuracy.

Ile St. Helene has, in addition to the biodome and La Ronde, a series of trails across the island. On the southern tip there’s a lookout point with an unobstructed view of the St. Lawrence River, which makes it perfect for testing. Lots of groundhogs and red wing blackbirds stop by to keep me company, including one bird I was able to catch perched on a support pole.

In contrast to the tranquility of Ile St. Helene, the canal in La Fontaine Park is bustling with activity. Many people may walk and stand in front of the receivers, but this has not significantly impacted measurement signal strength. I have gotten the chance to answer questions from people walking by, which has been a great opportunity to practice explaining my project and discuss the applications. Don’t worry, there are still creatures to keep me company here too, in the form of duck families who live on the pond.
Natalie

Figure 2 : An up close view of one of my array set ups in a vertical orientation

Figure 3 : The lake in La Fontaine park

The Last leg

6/28/2022

Hi there! Welcome to Dave and I’s third and final post. Following the boat, we were able to explore some of Ilulissat and had lots of fun doing so. First, I will set the scene - the town is bordered on one side by Disko Bay and a multitude of icebergs, and on the other by snow-covered hills. Most of the houses are painted in bright colours providing a striking contrast to the rest of the landscape. The town’s center has a harbour through which fishing boats are constantly filtering in and out. One morning, Dave, Peng, Brian, and I visited the Ilulissat Icefjord which is the passageway through which ice calved from the Ilulissat Glacier (the most productive glacier outside of Antarctica) reaches Disko Bay and the ocean. We hiked along the shore of the icefjord and in the surrounding hills.

On June 11th, Dave and Peng flew back home :( while David, Brian, and I went to the second GNSS site located on a small island on the other side of the icefjord. It took about 15 minutes by helicopter to reach – and we witnessed some pretty incredible sights in those minutes (attached). Like at the first site, the wires to the camera and weather station had been chewed, so the data for those only lasted a few months. However, this time the GNSS station had maintained power and consequently had a large and up-to-date time series. Youpiee! David postulated that the wires were being chewed by animals attracted to the heat from the electricity (thinking it might be a tasty snack). Next time, we are aiming to add protective casing to the wires.

The next two days were spent downloading and organizing the data from the cameras and receivers of both sites. I learned that it is best practice to save your data on at least two devices, and also, if possible, to keep it on the original instrument until its next use. Having these days in Ilulissat also gave me a chance to tick some things off of my bucket list, such as going for runs around the icefjord and swimming in the Arctic Ocean (did not last long). David and Brian were also gearing up to visit their third and last site located near the glacier. They are planning to camp out for roughly 10 days to service existing equipment. As for me, the journey back home went much more smoothly than the first, which I am very (very) grateful for. And this brings me to the end of the story.

I am still in disbelief that I was able to participate in this fieldwork. I have learned so much about what it means to do field work (including the unwanted (but inevitable) plot twists, the need for persistence and organisation, and the excitement that comes when things do go right) and about the processes occurring in this region. I also feel incredibly lucky to have gained some insights on what it is like to live in Greenland, albeit very preliminary ones. And I am glad to have gone through this experience with a great group of people, which made it all the better.

Thanks for reading,
Izzy

First update from Greenland

6/13/2022

Hello again! We have just returned from the first SeaGPS station located on an island in Disko Bay. Dave and I spent five days aboard the Adolf Jensen with Professor David Holland from NYU, his post-doctoral student Peng, and a mountaineer named Brian. The Jensen’s crew consisted of Louie (the captain), Kaia, Johan, and Andres (the cook). They were all very nice and welcoming. Outside of the SeaGPS station, David had four moorings needing to be serviced in the area and dozens of CTD stations. The moorings had been anchored to the ocean floor for three years measuring temperature, salinity, and currents at a fixed location (and so had lots of useful info stored-up!). The CTD stations on the other hand measure ocean characteristics throughout the water’s vertical profile at a fixed point in time. Since the moorings had been there for so long, they had accumulated several deep-water organisms on their surface (who did not seem enthusiastic about being brought to the surface). This made the cleaning and servicing process more time consuming (and a

bit disturbing). We reached the SeaGPS station on the second day. I had spent a long-time hearing about and preparing to service the station, so it was exciting to finally see it. I have attached a picture so you can see it too! It turns out some hungry individual (perhaps a fox or seagull) had pecked and/or chewed the camera and weather station wires. This we believed caused the whole station to short-circuit, since the GNSS station had also turned off. As such, there was only a few months of data on these

devices:( Nonetheless, we were able to service the GNSS station and leave it in working-condition, which is a win.

We had great weather while on the boat – clear skies and smooth waters for almost the whole trip. I also had the opportunity to stare at icebergs for long periods of time. They were incredibly beautiful. It was also quite humbling to be near chunks of ice weighing as much as my house. Although, despite their enormity, they are surprisingly quiet as they float along - I wish I were that graceful.

I think that sums up our time on the Jensen. On June 8th we returned to land and said goodbye to the crew who were departing on their next journey the following day. Now Dave and I are looking forward to having bit of time in Ilulissat before he leaves and before I head to the next site. I will let you know what we get up to!

Izzy

New Summer Adventures

6/10/2022

As part of a project to understand how the ice, ocean, solid Earth and atmosphere interact at the periphery of ice sheets, Dave Purnell and Isabelle McIntyre from McGill are joining collaborators from NYU on a field expedition to Greenland to service and collect data from our instruments that are measuring sea level changes in Qequertarsuup tunua (Disko Bay) near Sermeq Kujalleq (Jakobshavn glacier). They had a rocky start, but are on their way now. Read on to hear more...

Well, Dave and I have had a pretty tumultuous start to our journey. Our flight from Montreal to Toronto was delayed causing us to miss our connecting flights to Reykjavik and Ilulissat. WestJet kindly organized for us to stay the night and fly to Vancouver the next morning, where we would then take off to Reykjavik. This part went smoothly but, upon arriving to Iceland, we discovered that our bags had not made the trip. The travel agency we are using also informed us that there was a flight to Ilulissat on June 4 (good news). However, there was only one seat left (less good). Dave booked that one and I got a ticket for the 7th. After sorting this out we went to explore some of Reykjavik. Attached is a photo of a tired Dave in a coffee shop. We also went down to the waterfront and checked out the Hallgrímskirkja church (both very nice). And after a much-needed nap, we hit the town for dins. Dave was brave enough to order some fermented shark and dried fish. After pawning some of it off to me, we agreed that we were glad to have tried the shark, but that neither of us would be repeating this in the near future.

The next day we were on a mission. Icelandair told us that they had found our bags in Vancouver and that they would be delivered to Ilulissat on the 5th. Dave would already be on the boat by this point, so we had to find some gear for him to bring aboard. Luckily, David and Denise Holland are very organized people and have some extra boots, coats, and gloves that we can borrow, so Dave and I got some more layers and essentials. Dave also submitted his PhD that day (!!!) so we went out for some fish and chips to celebrate.

This bring us to today. We got up early this morning for Dave's flight. I accompanied him to the airport in the hopes of squeezing on to the flight at the last second... and it worked!! Youpiee! As I am writing this we are flying over East Greenland. It's beautiful - below are some pictures. We will be headed directly to the research boat upon landing to start the second phase of our adventure. I'll let you know how it goes.

Izzy

The final leg of our Trip

1/4/2022

It’s been a while since the last post, but we’re currently writing to you safe at home in Montreal! We essentially lost track of time with all our activities in port and onboard the second leg.

We had an absolutely packed schedule in Jamaica, filled with outreach onboard Lehmkuhl and onshore, visits to the University of the West Indies Mona campus and marine research lab, and some exploration of the local cuisine thanks to our two new friends and colleagues, sea level scientist Deron Maitland and marine biologist Chauntelle Parkins, who joined the One Ocean course from UWI.

After giving talks about the science being done onboard at UWI, we had the privilege of listening to research presentations given by other graduate students at the university. In contrast to what we might be used to at McGill, much of the graduate research is focused on local impacts of climate change. Many students’ work revolves around the restoration of mangroves and their role in the local ecosystem and carbon budget, while others presented projects on regional sea level change and the health of seagrasses and corals. While climate change certainly poses a global threat, the perspective of our Jamaica-based counterparts is hallmarked by quite localized and tangible consequences of climate change and potential solutions to them. Our discussions at UWI, among other things, highlighted the importance of communication across areas of study and of the incorporation of perspectives that are representative of the diversity of the people who will be impacted by future climate changes, into the mainstream of science.

The second leg of the sailing expedition was marked with even more rope splicing as we finally reached our maximum rope length of over 1000m! The long-awaited day of this experiment coincided with another long-awaited event: swimming! As we “heaved to” (stopped the ship) for the ocean temperature measurements, the trainees and crew all enjoyed a couple of hours in the royal blue waters of the Caribbean Sea.

Just as we were wrapping up our experiments, the beautiful blue skies turned as we finally got some “interesting weather” as Prof. Spengler would say and we were doused in some refreshing rain. It was thus only fitting that we receive some meteorology lectures to understand the strange system we were sailing through. Other valuable discussions around climate action and EDI (equity-diversity-inclusion) were led by female professors and crew members who shared with us their experiences as women in male dominated fields. The grand finale to our last leg were the singing practices which led into our loud arrival in the Havana port: some of us were shouting from above the sails and some of us were on deck chanting as many sea shanties as we could.

In Havana, we again had the pleasure of doing outreach work with local high school students coming onboard. We had the added difficulty of having to present in Spanish this time but everyone, Spanish speaker or not, did an excellent job preparing for this challenge and the students surprised us with how much they already knew about the changing ocean conditions. The students were very vocal and interested, giving us hope for the future of the environment. The rest of the time was spent finalizing our research projects, reflecting on our contributions throughout the course, and enjoying salsa music and a couple of well deserved drinks. As per usual before travelling, we spent some time running around trying to get a PCR test for our return to Canada and while there may have been some tears, we all promptly received our negative test results.

It was hard to say goodbye to all our newfound friends and colleagues in the end but we feel certain we will meet again and hopefully continue collaborating. We have learned that science is enriched by a diversity of backgrounds and that even though some projects may seem daunting, they are worthwhile and most likely to help us grow professionally and personally.

-Jeremy and Julia

We made it to Jamaica!

11/13/2021

We just arrived in Port Royal and what a journey it was. We had a packed schedule every day and definitely had to adjust to being in the heat and humidity of the Caribbean, a wild but welcome change from Canadian autumnal weather. Jeremy immediately got sunburnt and Julia got seasick, but it feels like we started sailing forever ago and we’re certainly adjusted to life onboard at this point. It has been incredible to speak with so many brilliant scientists from around the world while we sail. Most fulfilling has been practicing giving our talks and lectures to other sailors on the ship, speaking with them about climate science, and discussing their fantastic questions. Most of the day is spent working on field measurements and analysis with our working groups, or performing tasks around the ship. Jeremy’s favourite ship-related jobs are those that involve climbing the rigging while Julia’s been her happiest telling people how to take proper field notes in those Rite in the Rains notebooks (thanks Christie Rowe)! We are currently docked in Port Royal, preparing our talks for the crew tonight and for local high school students tomorrow. We’re looking forward to a fantastic five days of climate outreach in Jamaica!

Jeremy and Julia

Hello from aboard the Statsraad Lehmkuhl!

11/8/2021

It was a magical moment to walk along the harbour to the ship last night and board after one last COVID test next to the ship. Most of us boarded last night and slept for the first time side by side in hammocks. This morning we met in the onboard classroom to get oriented and then students went to work in their research groups and instructors got in a line with other passengers and crew to help pass all the food on board. This afternoon we set sail and then the crew teaches us about our sailing duties.
Natalya

We made it to our flight to Curaçao!

11/7/2021

As with any adventures, the young heroes were submitted to a multitude of tests of strength and resourcefulness. It’s just not as fun when you are those heroes and running around the Toronto airport. From Jeremy getting caught between terminal train doors and Julia chugging 2L of water to get through security, to swapping out COVID test requirements and having to fill out yet ANOTHER form, we have been put through the wringer and come out victorious; we are finally boarded and en route.

After several weeks (or let’s be honest, months!) of applying for university approval and a whirlwind of packing and prepping this past week, it feels a bit surreal to actually be on our way. We’re so incredibly excited to board the Statsraad Lehmkuhl and meet the members of working research groups and the crew. As any mad scientists, we are ready to let our minds run with the crucial climate data we will collect at sea.

Stay tuned to see if we prove the existence of mermaids and the kraken!
Jeremy and Julia