Based on email and social media comments we receive, climate models are one of the least understood and most maligned tools used by Earth scientists.
What is a climate model? Putting aside the scientists from the Lamont-Doherty Earth Observatory who posed for a climate model calendar in 2014 (cover above), climate models are simply mathematical representations of Earth’s climate that are based on fundamental physical, biological, and chemical laws and theories. As NOAA explained in a story about the first general circulation model to include both the ocean and atmosphere, scientists divide the planet into a three-dimensional grid, use computers to solve the equations, and then evaluate the results when they “run” a climate model. As the story noted: “Models calculate winds, heat transfer, radiation, relative humidity, and surface hydrology within each grid and evaluate interactions with neighboring points.” The illustration below should help you visualize how the grids are laid out and some of the physical processes models include.
One of the first general circulation models was developed at Lawrence Livermore National Laboratory by Cecil “Chuck” Leith in the early 1960s. Unlike the NOAA model mentioned above, Leith’s model only simulated the atmosphere. What make Leith’s work so remarkable was that he was the first to produce a computer animation based on the model output. Watch the video below to see how these wobbling yet compelling animations looked.
From the very beginning, Leith’s animations attracted attention. “The one that I have is essentially a polar projection of the Northern Hemisphere, and you can see the patterns moving in mid-latitudes,” Leith explained during an oral history interview conducted by the American Institute of Physics. “I did it just because I knew we could do it, it would be interesting to look at, but it was almost too interesting. Whenever I’d go anywhere and give a talk about what I was doing, I would show the film and everybody was fascinated by the film, and they didn’t care what I said about the technical aspects of the model, as far as I could tell. And, in fact, Smagorinsky (another pioneer of climate modeling and the first director of NOAA) used to chide me about it a little bit. He says: ‘That’s just big plan showmanship. There’s no science there.’ But they started making movies too.” You can read more about Leith’s animation from Climate Central.
If the animation makes you curious about the history of climate modeling, try this chapter of Spencer Weart’s excellent book “The Discovery of Global Warming,” as well as this excerpt from Warren Washington’s autobiography “Odyssey in Climate Modeling, Global Warming, and Advising Five Presidents.” And if you’re looking for a more current take on climate models, how they work, and how they can be useful, see Motherboard’s new story and video profile (below) of NASA’s Goddard Institute for Space Studies (GISS). Finally, the TED talk by GISS Director Gavin Schmidt about models and the emergent patterns of climate change is well worth the twelve minutes.