Part 5 of our tour of the CliMA software stack. The series began with why we built a new Earth system model; last week covered radiative transfer, a Nobel-winning calculation, runnable in minutes. The total water vapor in Earth’s atmosphere, if it all rained out, would cover the globe with a liquid layer on average only about 22 mm (less than an inch) deep. We cannot see this water vapor in the air. It only becomes visible once it condenses into liquid droplets or ice crystals. Whenever we see a white cumulus cloud on a summer day, a thunderstorm anvil…
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By Zhaoyi Shen and Tapio Schneider. Part 4 of our tour of the CliMA software stack. The series began with why we built a new Earth system model; last week covered methane rain on Titan and the thermodynamics of moist air. Water vapor is the most important greenhouse gas on Earth. Removing all water vapor from an atmospheric column in a one-dimensional climate model cools the surface by 24 K, to well below freezing; removing the CO2 instead cools the surface by 17 K. Yet we do not track water vapor emissions, because water vapor provides a feedback, not a…
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Part 3 of our tour of the CliMA software stack. The series began with why we built a new Earth system model; last week covered sunlight and the pace of ice ages. On Saturn’s moon Titan, it rains. The drops are liquid methane, a centimeter across, and they drift down through the thick atmosphere more slowly than snowflakes fall on Earth. The rains return to each pole during the Titan summer—which comes around every 30 Earth years—and they fill lakes of liquid methane in the polar regions, creating the only standing bodies of surface liquid in the solar system besides…
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By Julian Schmitt and Tapio Schneider Everything in the climate system begins with sunlight. Weather, ocean currents, and the growth of forests are all powered by solar radiation entering at the top of the atmosphere. The amount arriving at any particular place and time is the insolation: the solar power passing through a unit area tangential to the top of the atmosphere. Insolation is a function of the solar radiative energy flux, which varies with the Earth–Sun distance, and the elevation of the Sun in the sky, which varies with location, time of day, and time of year. Aside from…
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By Tapio Schneider and Raffaele Ferrari. In 2018, with support from the Heising-Simons Foundation and Charlie Trimble, we convened a series of workshops on the “Future of Earth System Modeling.” We asked leaders in the field a question: given the data and computational resources available now, what would you do if you had to build a new Earth system model from scratch? Few if any wanted to do such a thing—understandably, since existing models embody decades of invested effort and whole communities of users depend on them. But the question was worth asking: no one had built a new Earth system model in…
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Over a 10-week summer period, the CliMA project welcomed three Summer Undergraduate Research Fellowship (SURF) interns. These undergraduate students were mentored by CliMA project scientists and software engineers on individual research projects that contributed to our model development. Thanhthanh Noel Nguyen, a second-year Caltech undergraduate, collaborated with Software Engineer Julia Sloan and the Land team. Her project focused on calibrating land models using FLUXNET observations, investigating how vegetation parameters vary with environmental conditions. Thanhthanh said “Julia was so patient and understanding to me, always ready to help … Everyone else at CliMA was also super friendly, and I always felt…
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By Renato Braghiere Vegetation plays a critical role in regulating Earth’s climate by absorbing sunlight, exchanging moisture with the atmosphere, and sequestering carbon. Yet, how vegetation is represented in climate models has remained surprisingly static for decades. Most climate models use a simplified classification called plant functional types (PFTs) — broad categories like “tropical trees” or “grasses” — and assign homogeneous optical properties to each. Real leaves, however, are much more diverse than suggested by PFTs. Their ability to reflect and transmit light varies with chlorophyll content, leaf thickness, and water content — traits that change with seasons, stress, and…
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By Dave Bonan The ocean contains a system of currents that connects different ocean basins. A significant feature of this system is found in the Atlantic Ocean basin and often referred to as the Atlantic meridional overturning circulation (AMOC). The AMOC is crucial because it transports warm water northward and helps circulate water between the deep ocean and the surface. As a result, the AMOC plays a vital role in regulating both regional and global climates and can influence weather patterns, such as the African and Indian monsoons, and the summer climate in North America and Western Europe. The AMOC…
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Numerical modeling is one of the pillars of ocean and climate science, and numerical simulations of ocean processes are critical for climate projections. Fortunately, recent rapid progress in computational tools — driven by AI — holds massive potential for accelerating numerical model development, and therefore progress in ocean and climate science. But this potential isn’t yet realized because traditional models can’t use AI hardware, don’t benefit from new programming tools and languages designed to accelerate AI model development, and can’t solve the full breadth of emerging ocean modeling problems. Enter Oceananigans — a popular, next-generation, GPU-accelerated ocean modeling framework developed…
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Land surface water routing describes how water flows on hillslopes and through river channels on the Earth’s surface. At a very high level, these processes close the water cycle on Earth and therefore are also required in climate models. Rivers provide freshwater to the ocean at river deltas, play a pivotal role in local wild environments, supply communities with water, and present flood risks during periods of high flow. Modeling river flow and other surface routing processes is an important task for any Earth system model. Many river models used in land surface models are rooted in the physical laws…
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