This study uses the World Bank income classification as a basis to examine the relationship between fluctuations in carbon emissions and fluctuations in GDP. In this context, according to the World Bank classification, time series of high income, upper middle income, middle income, lower middle income, low income and GDP and CO2 emissions for the whole world, including the period 1990-2020, are separated into trend and cyclical components using the Hodrick-Prescott filter. . Then, correlation and causality relations between the cyclical components of the series are analyzed. Correlation findings show that the relationship between fluctuations in GDP and fluctuations in CO2 emissions is positive. According to the causality findings, one-way causality is observed from fluctuations in CO2 emissions to fluctuations in GDP in the high-income group. Similarly, there is unidirectional causality from fluctuations in CO2 emissions to fluctuations in GDP in the upper middle income group and middle income group. In the lower middle income group, bidirectional causality is observed between fluctuations in GDP and fluctuations in CO2 emissions. In the low-income group, one-way causality is observed from fluctuations in GDP to fluctuations in CO2 emissions. It has been concluded that there is bidirectional causality between fluctuations in GDP and fluctuations in CO2 emissions worldwide.