Q&A with Geosciences professor Jorge Sarmiento

Department of Geosciences professor Jorge Sarmiento is one of the leading oceanographers in the world. From March 14-15, a conference named "Modeling the Living Planet" honoring Sarmiento's storied career and 70th birthday will be held in the Taylor Auditorium of Frick Chemistry Lab. Street Staff Writer Angela Wang sat down with Prof. Sarmiento to talk about his research, the symposium and his experience teaching GEO 202: Ocean, Atmosphere and Climate.

Daily Princetonian: What research do you consider most important?

Jorge L. Sarmiento: My biggest project is a combination of my career in many ways. It’s very difficult to measure the ocean because the water is opaque to most radiation, so you can’t measure properties in the water that goes down as deep as six kilometers and deeper without physically going there and collecting water samples of nutrients and measuring them.

But in recent years, oceanographers solved the problem of going out to the ocean by instrumenting Autonomous Robotic Floats called ARGO floats, which park at about a kilometer's depth, [...] where the water motions are served at the minimal, so they try and keep them roughly where they put them in. Every ten days, they will send down to two kilometers, turn down a whole bunch of instruments to measure temperature, salinity and pressure, float all the way to the surface, pop out an antenna and send all their data by iridium. It’s then available on the Internet almost instantaneously.

The whole ARGO network began 10-15 years ago, and there are now about 4,000 of those floats, all over the world. Meanwhile, we’ve done a lot of research in the Southern Ocean, the ocean that borderlines the Antarctic, in which we found that it’s massively important for global issues. It soaks up a quarter of the carbon that we are putting into the atmosphere. It also soaks up three quarters of the heat that we are putting into the ocean. The earth is warming up at a slowing rate because the water bodies are absorbing 98 percent of the heat, and about three quarters of that is taken up by the Southern Ocean. The water’s old and cold because the water comes from the deep water [mass] and comes up to the surface. This is where the deep water kind of empties out and fills in from the North Atlantic. If it is filling up, it must be emptying out. Where it’s emptying out is by moving upward and moving southward. About 80 percent of the emptying occurs, and the water is 1,000 years old or older. It’s very cold and very rich in nutrients. That’s why it’s so important in absorbing carbon dioxide and heat and feeding nutrients back into the ocean.

We know very little about how this actually occurs, since we have little observation down there, due to the harsh conditions. But now we are putting floats down there, and these floats survive under the ice and we are getting all the nutrient cycling and everything down there for the first time. It’s really extraordinary. The floats will stop five meters below the water surface if it is freezing, and repeat and store up to two years of data in themselves. More often, they pop up every year and send us the data. It’s just amazing. I think this is the most exciting observation data I’ve ever been involved in. It’s a revolution taking place in the field, and I am extremely lucky to be the director of it.

DP: Could you discuss the conference during spring break?

JS: Well, I am not going to a conference. My group, unbeknownst to me, went out and made a plan for the celebration of my birthday. They raised funding, invited people and told me about it—before it was too late for me to intervene! It’s something very nice. A lot of postdocs and students I’ve had over the years are coming. Technically, it will be a conference because everybody will be giving a research presentation. There are four basic topics that are all related to research that I’ve done, and they all work in parallel.

DP: Can you tell me about GEO 202 that you used to teach for undergraduates?

JS: "Introduction to Oceanography" is a course that I’ve been teaching for the past couple of years. The course was started by our current department chair, Bess Ward, who had taught it in the past. It’s had a funny history. It started off as a course for scientists and non-scientists -- people could take labs or not. I had it early in the morning, at 9 a.m., and for several years it typically had 20 students or so. One year, I thought to try a different time and see if it had an impact on it, so I switched it to 11-12:20. All of a sudden, almost 100 students signed up for it. I was flabbergasted. I dropped everything and had to rethink how to present the lecture to such a large group. I made some special effort to try and meet the students, because that’s what I enjoy being able to do with a small class. Everyday, I would have office hours for an hour and spend 10-15 minutes meeting with a student individually. Having 98 people is different from teaching a small class, so I switched it back to 9 a.m., and the number dropped back to 25-26. Then the department decided to reorganize the curriculum, and made it a true 200 level course for science majors. Ever since then, it’s been a group of 20 or so students. The last two years, the majority of the class ended up majoring in geosciences. We put more math in and had plenty of problem sets already. All students are required to take the lab, which, in the past, hadn’t been the case. Students could take the A or the B option, with the lab or without the lab. It’s just great to see these students in the department now.

Due to a reporting error, an earlier version of this article misspelled the name of GEO department chair and misstated the instructor of GEO 202. GEO 202 is taught by Alison Gray this semester, and not by Sarmiento, as it has been in the past. The 'Prince' regrets the error.