On a possibility of estimating the feedback sign of the Earth climate system

The growth rate of the second moment of the time series increment as a function of the increment range can be used for estimating the sign of feedback of the underlying physical system. The influence of the periodic nature of the time series to the growth rate of its structure function is considered. The approach is used to describe the variability of the time series of the global average outgoing long wave radiation (OLR). It is shown that the series annual cycle plays a crucial role in preventing the growth of the variance of the time series increments and leads to its nearly stationary long-range behaviour. The analysis of the OLR time series indicates that a negative feedback should dominate in the earth climate system. The example is believed to be useful for better understanding of the influence of the increasing concentration of CO2 in the Earth atmosphere.