Chapter 10: Carbon Cycle, CO2, and Climate

Abstract

Throughout most of this book, our discussions have focused on the steady-state characteristics of the cycles of biogeochemically important elements in the ocean. However, as more about the past behavior of these cy- cles was learned, we have to come to realize that these cycles have seldom been in a ‘‘true’’ steady state. It appears that variability is as much a fundamental prop- erty of these biogeochemical cycles as it is a property of the climate system in general (see discussion in section 2.5). In this last chapter, we explore the variability of these cycles on a range of timescales, from a few years to several hundred thousand years. In trying to understand the mechanisms that give rise to these variations, we will apply many of the tools and concepts that we have learned in the previous nine chapters. We eill focus on the carbon cycle, because of its central role in biogeochemical cycling and its interaction with climate as a result of the greenhouse gas properties of CO2 in the atmosphere. This cycle is also of particular interest given the fact that humankind has began to perturb the global carbon cycle dramatically and likely will continue to do so.