The researchers found that models with lower climate sensitivity are more consistent with observed temperature differences, particularly between the northern and southern hemispheres. The graph shows changes in the annual global-mean surface temperature (a) and the temperature difference between the northern and southern hemispheres (b) from 1850 to 2000. The red line represent high climate-sensitivity models, while the blue line represents models with low climate sensitivity. The black line shows observed temperature fluctuations collected by NASA's Goddard Institute for Space Studies Surface Temperature Analysis project, which more closely follow the blue line when it comes to interhemispheric temperature. The gray backgrounds indicate years when the difference between the high and low climate-sensitivity models are significant.