Climatology

Abstract Climatology is the interdisciplinary study of the earth system that encompasses the atmosphere, hydrosphere, cryosphere, lithosphere, biosphere, and anthrosphere. Modern climatology includes not only these components but also importantly their interactions involving detailed global observing systems and complex computer‐based numerical models. The state of the climate system at any time is determined by the forcings acting upon it and the complex and interlocking internal feedbacks that these forcings prompt. Because of these feedback processes, the climate system does not respond to forcings, including human‐induced ones, in a smooth and gradual way and the response can be rapid and sometimes discontinuous. Climate models, with which we hope to predict future climates, must be able to capture such apparent discontinuities that have been observed in paleoclimatic records. To meet these requirements, modern climate models are composed of multiple interacting modules, which attempts to mimic components of the earth system, so that complicated feedbacks and synergisms in the climate system can be simulated faithfully. Human activities and associated needs, such as food and energy and water resources, are becoming increasingly dependent on, and even an integral part of, the climate system. With increasing evidence of the effects of human activities on the climate system, international bodies were established to coordinate scientific assessments of human influence on climate and to recommend appropriate mitigation and adaptation measures for policy makers.