Interview with Alsak Grinsted, the Creator of Daily Glacier Bot

Daily Glacier Bot header (source: Twitter).
Aslak Grinsted (source: AGrinsted/Twitter).

Aslak Grinsted is a Danish geoscientist who teaches at the Center for Ice and Climate at the University of Copenhagen. He has carried out research on a variety of topics. His most widely cited paper develops a method for analyzing time-series data. He has also studied past and projected sea level rise, worked out a way to make use of data from ice cores that have undergone deformation, estimated the total volume of glaciers in the world, and thought through some of the consequences of possible geoengineering projects. In addition, he has analyzed recent changes in glacier lake outburst floods in Greenland .

We know Grinsted, not only as a researcher, but also as the creator of Daily Glacier Bot, which appears on Twitter. It makes the public aware of glacier retreat and climate change by showing two superimposed images of a single glacier, taken at different times. A slider allows the viewer to move back and forth in time to observe the rapid pace of ice loss. We invite you to follow this work @dailyglacier.

Grinsted kindly agreed to an interview, appended below.


GlacierHub: How did you first come up with the idea for Daily Glacier Bot?

Aslak Grinsted: I had been thinking about the idea for a long time before I finally decided to code it up. It was the Landsat bot that triggered the original idea. I have worked with Landsat images and the Randolph Glacier Inventory, so I had a clear picture in my mind about how I would go about making it.


GH: What do you hope that Daily Glacier Bot will accomplish?

AG: The bot just presents reality as it is, and allows anybody to judge for themselves. I hope that the bot can get the reality of climate change across to a few people who would otherwise not be receptive. It would also be great if experts would comment on the highlighted places. It could be anything such as fieldwork experiences, regional climate knowledge, links to projects or papers, and photos. That would be really interesting for non-experts.


GH: Your posts are remarkable in the way that they provide two images of a single glacier, taken at the same time of year, but separated by a number of years. How do you locate them? Do you have to do a lot of processing to get the spatial coverage to match so well?

AG: The bot is running from a cheap server that does not have many resources, so it is designed to only require minimal processing. First, the bot decides which glacier it wants to document, and then obtains a list of all available near cloud free scenes of the place. It then scores every possible image pair according to simple heuristics. It is designed to prefer images that are well separated in time, but almost from the same date, from autumn, and acquired from a similar orbital position. It does not actually “look” at the images before it starts making the comparison.


GH: Are there any specific posts that you are particularly proud of?

AG: There are many that I like. But here are three nice ones

GH: Daily Glacier Bot was covered in a post by Brian Kahn in a couple of months ago. Did his post help the website?  

AG: The piece in Earther did have an effect. Many checked it out, and the bot’s followers grew by 50%.


GH:  How does Daily Glacier Bot fit into your day job at the Niels Bohr Institute’s Center for Ice and Climate?

AG: The bot is primarily an outreach project made mostly in my spare time. I made it to show to the world just how widespread glacier retreat is. ​It is not directly useful for myself, but occasionally it finds some really interesting places. Who knows what it will find.

Some of the code will be useful for other projects such as for calculating ice velocities from optical feature tracking. I might also reuse it in my “exploration from space” course.


GH: You really channel Bender very well. I can hear him saying, “I show humanity what effects climate change has on the glaciers of Earth.” What do you think Bender would say about Daily Glacier Bot, now that it’s been running for a couple of months? [Bender is a robot character in the television cartoon series Futurama. He appears in the header of Daily Glacier Bot.]

AG: He would say, “This could mean the end of the banana daiquiri as we know it! Also, life.” Note this is an actual Bender quote.