Forecasting the global temperature increase for the xxi century by means of a simple statistical model

A simple statistical model is developed for the dynamics of the mean global annual temperature. The model combines the logarithmic effect of carbon dioxide concentration increase and the input by climatic cycles. Model parameters are determined from data of instrumental observations for 1850–2010. The model con-firms the presence of climatic cycles with the period of 10.5 and 68.8 years in the global temperature dynamics. The trajectories of the global temperature changes for the XXI century are obtained under the scenarios of car-bon dioxide concentration changes from the 5th IPCC Assessment Report. The comparison revealed that the global temperature trajectories from the Report are $0.9-1.8^{\circ}$C above those obtained in the model.