Forecasting carbon dioxide emissions in BRICS countries by exponential cumulative grey model

Grey models should give different weights to old and new information when dealing with different cases, whereas existing grey models always give greater weight to new information. With this in mind, a novel grey model is proposed in this paper. The model introduces an exponential parameter that regulates the weight of information by adjusting the size of the parameter. This model is used to study the carbon dioxide emissions of BRICS (Brazil, Russia, India, China and South Africa) countries. Firstly, the intelligent algorithm is used for multiple iterations to find the exponential order that minimizes the simulation error. Secondly, the raw data on CO2 emissions from BRICS countries are processed and grey differential equations are developed. Finally, the least squares method is used to solve the coefficients of the differential equation and to predict the CO2 emissions of these countries based on the corresponding time series. The results show that carbon dioxide emissions in Brazil and Russia are on a downward trend. China and South Africa show a slight upward trend in carbon dioxide emissions. India has a large trend of increasing carbon dioxide emissions. The results can provide reference value for the relevant authorities. (C) 2021 The Authors. Published by Elsevier Ltd.