Addicted to Ice
Growing up in Newfoundland and Labrador, Canada, meant David Holland was well acquainted with ice in nearly every form from a young age. Years later, as a mathematics professor at New York University (NYU) and director of the university’s Center for Atmosphere Ocean Science he’s still surrounded by ice.
Now, his days are spent traveling the world studying ice-ocean interactions and developing computer models that explain how the world’s ice and oceans may fare in a changing climate.
“In the late 1990s, it was noticed that glaciers change a lot faster than people thought—they were much more dynamic. My background is in ocean science, so I was curious about this speed up and the ocean’s contributions,” Holland said. “So I became interested in studying and modeling this. I guess you can say I’m addicted to ice in a lot of ways,” he laughed.
Studying Ice Around The World
Holland’s fascination with ice has led to some interesting jobs throughout his career and has taken him on adventures spanning the globe.
While still in Newfoundland, he worked as a research engineer to determine ways to move icebergs in order to prevent collisions with ships.
“This technology really never panned out. In Newfoundland and Labrador and Greenland there are icebergs all over the place. We tried to blow them up, cut them in half and melt them, and what not. Really large icebergs are a challenge to move and really the easiest thing is to just get out of their way,” Holland explained.
South Of The Equator
After leaving Canada, Holland headed 10,000 miles south to Australia for a postdoctorate fellowship at the Australia Bureau of Meteorology. While there he worked on coupled modeling—pairing global ocean models with atmospheric models. It was an exciting time because he worked with a group of modelers who had just started to include sea ice in global climate models.
“As we were doing that in the 1990s, nobody had the vaguest thought sea ice in the Arctic would change the way it has today. We now know in the summer sea ice reaches half the extent it used to. That was something no one even remotely believed in the 1990s. Today those models still work pretty well, but they aren’t good enough to project the kind of sea ice behavior we’re actually observing,” he said.
After finishing his postdoctoral work in Australia and the United Kingdom, Holland was a research scientist at Columbia University’s Lamont-Doherty Earth Observatory. In 1998, he joined NYU as a professor where he lectures, develops computer models and plans research missions. His most recent mission supports an ongoing National Science Foundation-funded project in Greenland.
Field Work in Greenland
This July and August Holland was busy studying ocean and ice sheet interactions at the Ilulissat and Helheim glaciers in the fjords of Greenland. The work is part of a five-year (2009-2013) effort to improve the understanding of how warm, deep ocean waters are influencing ice sheet retreat.
Holland and a team of graduate students recorded meteorological observations and collected water temperature, salinity, oxygen, suspended sediment and current measurements using CTDs.
In sea-ice-covered areas, the team used a helicopter to first break up the sea ice before lowering an expendable CTD (XCTD) into the water column. An XCTD is an expendable probe that can be dropped from moving ships or aircraft. Data from the probe are transmitted by wire. For areas with less sea ice, the samples were collected by ship using a traditional CTD lowered off the side of the ship by winch.
Help From The Locals
Holland also looked to the local population of seals to help collect water column data in the fjords. He attached small CTDs with telephone transmitters on the backs of two seals. “I have two seals swimming around now and they email me every four or five hours with profile temperatures and salinity. Then I can look at a map and see where they are,” he said.
The CTDs will stay on for roughly 12 months and will fall off when the seals molt in the spring. Holland points out that every effort was made to meet animal welfare guidelines and ensure that no harm comes to the animals as a result of the CTD attachment.
Water column data collected by both humans and seals alike will be combined with the meteorological observations and used to develop a coupled ocean-ice sheet model. Ultimately, the data and the resulting model will help researchers quantify how the water from the melting ice sheet may change global sea level in the future.
Climate and Future Modeling
In the future, Holland plans to tackle a very tricky climate-related question: which changes in climate are occurring naturally and which are influenced by human activities? He will collaborate with others to make long-term observations in both Greenland and Antarctica to try to answer these questions.
He also hopes to develop models that will give us a better idea of how sea level may change in the future. “It’s going to take a long time to get that sorted out correctly, if at all, but the climate model may tell us about future sea level changes due to glaciers,” Holland said.
A Family Affair
Month-long trips in remote areas like Greenland require a tremendous amount of effort and teamwork. Data collection success is dependent on detailed planning done months in advance. And Holland’s wife Denise is always more than happy to lend a helping hand by taking on much of the logistics planning and coordination.
Denise is also an artist currently studying at NYU. She often joins him in the field to document the trips through photos and videos. “The trips take about a month or so and it’s nice to have family around to help,” Holland said.
Holland’s graduate students also play a critical role in the success of the missions. In addition to teaching two graduate-level courses, he always takes graduate students on missions to help with data collection and to gain valuable field research experience.
“It’s [field work] extremely valuable both to me and to them. The graduate students are very, very, capable, hard working and creative about coming up with solutions. It’s an all-around victory,” he said.
To learn more about David Holland and his ice-ocean interaction research, visit: http://efdl.cims.nyu.edu/ —Alicia Clarke