Models, manifestation and attribution of climate change

Abstract

Results from a series of five surveys among five groups of international climate scientists about their evaluation of elements of climate models and of climate change are presented. The first survey was done in 1996, the latest in 2015/16. Thus, our snapshots of the opinions of climate scientists cover 20 years. The results describe a strong increase in agreement concerning issues of manifestation of climate change, i.e., that the warming is real and not influenced by changing measuring and reporting practices, and concerning attribution of this ongoing climate change to ongoing anthropogenic causes. On the other hand, the evaluation of the climate models has changed little in the past 20 years. There are still significant reservations with the models ability to incorporate clouds and to describe rainfall. Obviously the growing conviction of ongoing man-made climate change is based on a variety of explanations, with modelling not being the predominant line of evidence. We suggest that it may be the repeated assessments by the IPCC, based on paleoclimatic evidence and stringent statistical analysis of the instrumental record which have led to the growing consensus of the warming and its causation. We stress that the presented results concern the opinion of climate scientists with a rather broad background. Our results do not assess if the opinions of the surveyed scientists are “valid” or “right”, but they recognize the character of science being a social process.