On Frequently Used Terms Related to Climate Change

Using terms with the same meaning is a precondition of academic exchange and coordinated international actions to cope with the global climate issue. However, the understanding and usage of some terms in the climate change field are incompatible among researchers, policymakers, and publics. In particular, the Intergovernmental Panel on Climate Change (IPCC) and the United Nations Framework Convention on Climate Change have used significantly different definitions of climate change, which may result in unforeseen problems in coping with the global climate issue. Also, when referring to future changes, the terms climate change projection and climate prediction are frequently used inconsistently. Other terms not always used with the same meaning are global warming, global change, global climate change, abrupt climate change, climate change monitoring, climate change detection, and climate change attribution. With respect to the term climate change, it is suggested that it be defined in academic circles as a change in any key climate variables or climate extremes on timescales of multidecades or longer periods caused by any drivers (natural or human and external or internal), whereas the term climate variability should be used to refer to variations on all the spectrums of frequency provoked by natural internal drivers or on high-frequency spectrums caused by natural external drivers. Following the IPCC terminology, it is suggested that climate change projection be defined as estimating possible evolutions of the climate state in the future on scales of decades or longer, based on development scenarios and climate models, with the estimate considered possible, internally consistent, but not necessarily probable. It is also suggested that the term anthropogenic climate change be used to express large-scale climate change caused by various human activities, especially global warming caused by greenhouse gas emissions from human activities and the corresponding changes in other components of the climate system as noted in the IPCC reports and international climate negotiations.