At what rate will the Arctic sea ice melt if we double the concentration of greenhouse gases in the atmosphere? By observing the world, the only way to answer this question would be to keep on emitting such gases, and to see what happens. Doing such a one-time experiment with the real climate system is probably not the best way to proceed (although this is exactly what we are doing now – think about that).
Climate models offer an alternative to this real world experiment. A model is a simplified representation of a part of the climate system. They are usually so complex that we need super-computers to produce and analyze their results. In models, we control everything: we can restart experiments whenever we want, we can do experiments with the continents or the Sun removed, we can do experiments in the future … To put it in a nutshell, we can do EVERYTHING!
We have models for the ocean, atmosphere, land, sea ice, glaciers… Each of these systems is already complicated by itself to represent, but even greater difficulties arise when we have to make them exist together (as we say: to “couple” them). For instance, water must be transmitted from the atmosphere to the ocean or the land when it rains, and water must be sent back to the atmosphere through evaporation.
I work with an ocean and sea ice coupled model called NEMO-LIM3. Ocean and sea ice exchange momentum (e.g., ocean currents tend to drag rapidly moving ice), heat (e.g., warm waters melt ice from below) and salt (e.g., when seawater freezes to form sea ice, only a small fraction of the salt contained in the seawater is enclosed in the ice – the remaining salt is released into the ocean). My job is to refine the representation of the ocean and sea ice interactions in the model. I am especially interested in understanding how the exchanges between ice and water affect the upper layers of the ocean, and how this feeds back on sea ice.
– Antoine Barthelemy
Hi Antoine, my name is Jose and I attend Law Enforcement Officers Memorial High school. I was wondering if the increasing rate at which the polar icecaps have melted over the past 50 years had any significant increase in the salinity of the water in that area and world wide. I also was wondering if the amount of salt found in the ocean affected the rate at which it could cool down again., as in freeze back up.
Hi Jose, great question. I talked to Antoine, and surface salinity of the Arctic has decreased over the last 50 years, especially in the Arctic. And if surface waters are fresher, sea ice will more easily form in the ice growth season (as summer becomes winter). However, satellite data have shown that the extent of the annual Arctic sea ice has for the most part decreased over the last few decades.
Hello Lindsay, I wanted to know what other discoveries are you planning to discover with. The other scientists?
Hi Jennifer, that is a question that I wish I (or one of the scientists) could answer for you! Experiments and analysis will be happening with the data and water sample taken from this expedition for a long time afterward. I know that scientists will be sharing what they learn with each other as time goes on, because each of them can make their own discoveries and conclusions, but they can also learn even more about the “big picture” when each person shares the piece that they found out!
Hi Lindsay,
How exactly do you keep the ocean and sea ice interactions in the model to a minimum?
Hi Marlene, actually the idea is for the models to try to maximize the interaction between the components of the Arctic system, including the atmosphere, sea ice, and ocean. The presence or absence of any one component severely impacts the other components of the model, therefore impacting how well we can imitate the real world.