Climate Change, Third Edition: Chapter 4 - Numerical modeling of the global climate and carbon cycle system

This book primarily documents “observed impacts of climate change on planet Earth.” Within this chapter, I discuss numerical modeling of the earth system and show that it is a vital counterpart to recording observations, as it allows us to develop and test our understanding—at a mechanistic level—of the changes we see.

It is not true that climate predictions are based solely on the output from computer models. In fact, the basic science of our atmosphere and earth system has been known for centuries and is based on very well-known, established laws of physics which long predate the invention of computers. Today, we do indeed use computers to put numbers into these equations and process huge amounts of data to generate projections in high levels of quantitative detail. But these are meaningless unless they are based on sound, robust science knowledge and understanding of how our planet works.

Observations allow us to answer questions such as “is our climate changing?” and “how is our climate changing?” Process-based models allow us to answer, “why is it changing?” “how will it continue to change?” and “what can we do to address this?” For many decades, climate science has brought together observations and models as multiple and independent strands of evidence to tackle these societally crucial questions.