School of Earth and Atmospheric Sciences Professor Emeritus Peter Webster, author of a new university-level textbook on the complex relationship between the Earth’s atmosphere and its oceans, says it can be very tempting to think of the planet’s climate “in pieces.”

Webster calls that a reductionist approach, “where climate is assumed to be made up of many parts,” he says. “Of course all of the parts interact, but they do so in a non-linear and, sometimes, in a manner that is non-predictable.”

Dynamics of The Tropical Atmosphere and Oceans, published in April as the latest in the Royal Meteorological Society’s Advancing Weather and Climate Science Book Series with Wiley, takes a holistic approach, Webster says. “Holism claims that complex systems are inherently irreducible, and are more than the sum of their parts, owing to chaos and non-linearities. Emergent behavior may arise from complex systems that cannot be deduced from consideration of the components of the system alone.”

Viewing the atmosphere and ocean relationship holistically can positively impact public policy regarding climate change, Webster adds. “Taking a holistic viewpoint allows you to say that the sea-surface temperature will increase from between 0.5 to 1.5 °C in the next century, for example. This allows a range of options of policy makers to consider. If we use a purely reductionist method, we may come up with just one number, 1.2°C, and this is not much use.”

School of Earth and Atmospheric Sciences chair and professor Greg Huey says Webster’s textbook is a “capstone achievement to his career, which has to a large extent concentrated on the tropical atmosphere and its interaction with the ocean.”

In 2005, Webster was named an American Association for the Advancement of Science (AAAS) Fellow. He won the Sigma Xi Sustained Research Award from Georgia Tech in 2016, and he is the recipient of honors from the American Geophysical Union, the American and the Royal Meteorological Societies. Webster was chosen as the 116th Sir Edmund Halley Lecturer at Oxford University in 2015.

As explained by its publisher, Dynamics of The Tropical Atmosphere and Oceans is aimed at advanced undergraduates and graduate students. “It presents a unique and thorough view of the fundamental dynamical and thermodynamic principles underlying the large circulations of the coupled ocean-atmosphere system. Within, Webster describes a variety of large-scale tropical circulation systems ­— those measuring several thousand kilometres on a timescale of days to weeks — and how they interact with a multitude of higher frequency systems — those on a sub-daily timescale.”

Topics covered include the Hadley (north-south) and Walker (east-west) wind circulation patterns, interactions between the tropics and extratropics (the middle latitudes beyond the tropics), El Niño and the Southern Oscillation, equatorial waves, disturbances, precipitation distributions, and the changing structure of the tropics under climate change.

Webster says without understanding the basic dynamics and thermodynamics of the tropical atmosphere — the factors that impact weather and climate — “it is difficult to discern what is natural variability and what is human-caused.” The first 17 chapters deal with that basic knowledge. The last chapter deals with what he calls “the changing tropics,” and the way that sea-surface temperature has increased during the last 100 years. “This has involved changes in precipitation patterns and intensity, issues that are critical for tropical societies,” he says. “Thus we have attempted to construct a strong physical foundation to understand climate change as it advances. Why is this fundamental understanding important? It allows the development of climate change above and beyond that found in climate models.”