This study compares the GCM-predicted warming in the tropical upper troposphere with satellite observations from 1979–2010. The IPCC AR4 GCMs predict a significant warming in the tropical upper troposphere, reaching a maximum at about 200 hPa, which is larger than the warming in the lower-middle troposphere. However, satellite data from the Microwave Sounding Unit (MSU) and Advanced MSU (AMSU) show that the warming in the tropical upper troposphere is significantly smaller than that predicted by the GCMs. The study uses temperature trends derived from MSU data, specifically T24 (upper-middle troposphere) and T2LT (lower-middle troposphere), to compare with GCM simulations. The results indicate that the observed warming in the tropical upper troposphere is much less than that simulated by the GCMs, suggesting that the models overestimate the warming in this region. The study also finds that the ratio of warming in the upper-middle troposphere to that in the lower-middle troposphere is significantly larger in the GCMs than in observations, indicating possible model biases. The study concludes that the AR4 GCMs overestimate the warming in the tropical troposphere, and that the discrepancy between models and observations is partly due to differences in the vertical temperature trends and the factor of amplification between the lower-middle and upper-middle troposphere. The study highlights the importance of understanding the causes of this discrepancy for improving climate models and understanding climate sensitivity.This study compares the GCM-predicted warming in the tropical upper troposphere with satellite observations from 1979–2010. The IPCC AR4 GCMs predict a significant warming in the tropical upper troposphere, reaching a maximum at about 200 hPa, which is larger than the warming in the lower-middle troposphere. However, satellite data from the Microwave Sounding Unit (MSU) and Advanced MSU (AMSU) show that the warming in the tropical upper troposphere is significantly smaller than that predicted by the GCMs. The study uses temperature trends derived from MSU data, specifically T24 (upper-middle troposphere) and T2LT (lower-middle troposphere), to compare with GCM simulations. The results indicate that the observed warming in the tropical upper troposphere is much less than that simulated by the GCMs, suggesting that the models overestimate the warming in this region. The study also finds that the ratio of warming in the upper-middle troposphere to that in the lower-middle troposphere is significantly larger in the GCMs than in observations, indicating possible model biases. The study concludes that the AR4 GCMs overestimate the warming in the tropical troposphere, and that the discrepancy between models and observations is partly due to differences in the vertical temperature trends and the factor of amplification between the lower-middle and upper-middle troposphere. The study highlights the importance of understanding the causes of this discrepancy for improving climate models and understanding climate sensitivity.